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Fruit Notes

Prepared by: Department of Plant and Soil Sciences

Massachusetts Cooperative Extension, University of Massachusetts, United States

Department of Agriculture and Massachusetts counties cooperating.

Editors: W. R. Autio and W. J. Bramlage

Volume 52,No.l
WINTER ISSUE, 1987

Table of Contents

Apple Rootstock Evaluation in Massachusetts

Pomological Paragraph: Revision of Storage Handbook

Pomological Paragraph: Public Opinion About Alar

Mauget Microinjection of Oxytetracycline for Therapy
and Prevention of Eastern X-Disease of Peaches

Strawberry Arthropod Pests: An Introduction
to Strawberry Insect Pest Management

Pomological Paragraph: Market Basket Survey:
Good News for Retailers and Consumers

Monitoring and Control of Apple Blotch Leafminer: An Update

Pomological Paragraph: State of Maine Suspends Action on

Mandatory Tolerances for Alar*

Reducing Energy Costs in CA Storage

An Economic Analysis of Orchard Rejuvenation in Response to
the Reduction or the Elimination of the Use of Alar®

APPLE ROOTSTOCK EVALUATION IN MASSACHUSETTS: 1986

Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

With the increasing costs of land, labor, and all inputs of orchard
production, there is a need to intensify management. The use of dwarfing
rootstocks is one way to accomplish this while reducing some costs and
increasing returns. However, rootstocks must be evaluated thoroughly prior to
wide scale planting. In this paper 1 would like to present the results of two
rootstock plantings at the Horticulture Research Center in Belchertown,
Massachusetts.

The University of Massachusetts has been involved with the NC-140
Regional Research Committee for a number of years, and in 1980 and 1984
plantings were established at about 30 locations across the country and Canada.
The 1980 planting consists of Starkspur Supreme Delicious on Ottawa 3, M.7
(EMLA), M.9A (EMLA), M.26 (EMLA), M.27 (EMLA), M.9, MAC 9 (Mark), MAC
24, and OAR 1. The EMLA designation means that the source of the rootstock
was a clone which has had the viruses removed. A similar planting of these
rootstocks with Summerland Red Mcintosh as the scion cultivar was established
in 1985.

The 1984 planting includes Starkspur Supreme Delicious on Bud. 491, Bud. 9,
MAC 1, MAC 39, P.l, P. 22, seedling, CG 10, CG 24, M.4, M.7 (EMLA), M.26
(EMLA), Bud.490, P. 2, P. 16, P. 18, CG, and Ant. 313. Descriptions of the origins
of the rootstocks in both the 1980 and 1984 plantings can be found in Fruit
Notes 51(4):22-24.

1980 Planting

Tables 1, 2, and 3 show the sizes, yields, and amounts of suckering of the
trees in the 1980 planting after seven growing seasons. Based on trunk
diameter and height (Table 1), the largest trees were on MAC 24 roots, and
they were significantly larger than those on M.7 (EMLA). Trees on MAC 9
were similar in size to those on M.26 (EMLA). Trees on M.27 (EMLA) and M.9
were the smallest. Interestingly, those on M.9A (EMLA) were significantly
larger than those on M.9.

The hypothetical number of trees per acre (Table 1) was calculated from
tree spread. It was assumed that spacing between trees should be 40% greater
than the present spread, and the distance between rows should be approximately
8 feet larger than the spacing between trees. These data suggest that the
optimal density of MAC 9 is similar to that of M.26 (EMLA). MAC 24 requires
a very wide spacing, approximately 20 x 28 feet.

Yield for these trees is reported in Table 2 as yield per tree and per acre
(calculated from hypothetical tree density) for 1986 and on a cumulative basis.
Generally, the largest trees were the most productive per tree, but the

potential yield per acre was highest for trees on MAC 9 and M.9A (EMLA). In
1986, on a per acre basis, trees on OAR 1, MAC 24, and M.27 (EMLA) were the
poorest yielders.

Table 1. Tree size and hypothetical density in the 1980 planting as measured
on October 15, 1986

Hypothhtical

Trunk

Tree

number of

trees

diameter

height

spread

per acre (+

approx.

Rootstock

(ir

(ft)

(f1

spacing in

ft.)

Ottawa 3

2.2

8.4

7.4

214 (11 X

19)

M.7 (EMLA)

3.2

11.2

9.0

165 (13 X

21)

M.9A (EMLA)

1.8

7.4

5.4

342 (8 X

16)

M.26 (EMLA)

2.5

9.8

7.4

214 (11 X

19)

M.27 (EMLA)

1.0

5.2

2.8

952 (4 X

12)

M.9

1.3

6.2

3.4

760 (5 X

13)

MAC 9

2.5

7.8

7.6

218 (11 X

19)

MAC 24

5.0

14.4

13.0

83 (20 X

28)

OAR 1

2.6

10.4

5.2

377 (8 X

16)

*Means in a column not followed by the same letter are significantly different.

Table 2. Cumulative and 1986 yields per tree and per acre for the 1980
plant ing.

Rootstock

Yield yield

per tree per tree

(1986) (1983-86)

(bu) (bu)

Potent ia 1

Potential

yield

cumulat ive yield

per acre

(1986)

(1983-86)

(bu)

276 abed

817 ab

335 abc

835 ab

380 ab

1067 a

336 abed

944 ab

257 cd

762 ab

327 bed

1110 a

440 a

1131 a

226 cd

623 ab

181 d

539 b

Ottawa 3
M.7 (EMLA)
M.9A (EMLA)
M.26 (EMLA)
M.27 (EMLA)
M.9
MAC 9
MAC 24
OAR 1

1.29 c*
2.03 b
1.11 c
1.57 be
0.27 d
0.43 d
2.02 b
2.72 a
0.48 d

3.82 cd
5.06 be
3.12 d
4.41 be
0.80 e
1.46 e
5.19 b
7.51 a
1.43 e

*Means in a column not followed by the same letters are significantly different.

The number of suckers per tree and per acre are reported for each
rootstock in Table 3. On a per tree basis MAC 24 resulted in many more
suckers than any other rootstock. When the number of trees per acre were
considered MAC 24 and M.9 produced the most suckers per acre.

Table 3. The number of suckers per tree and potential number per acre for
trees in the 1980 planting.

Rootstock

Cumu la live

Potential

suckers

per tree

per acre

(1980-

86)

(1980-86)

0.8

171 b

4.2

693 b

1.6

547 b

5.0

1070 b

0.2

190 b

7.8

5928 a

1.4

305 b

118.4

9837 a

2.6

980 b

Ottawa 3
M.7 (EMLA)
M.9A (EMLA)
M.26 (EMLA)
M.27 (EMLA)
M.9
MAC 9
MAC 24
OAR 1

"Means in a column not followed by the same letter are significantly different.

In 1986 evaluation of fruit quality and ripening of fruit from these trees
began. Results will be reported in later issues.

1984 Plantin g

The trees in the 1984 planting are not old enough for a full evaluation of
tree characteristics, but tree size after 3 growing seasons and bloom are
reported in Table 4. Treus on Ant. 313, Bud. 491, and seedling roots were the
largest, and those on P. 2, P. 16, and P. 22 were the smallest. The number of
flower clusters were counted in 1986 and the bloom is presented as the number
of blossom clusters per unit of trunk cross-sectional area. Because of the
significantly higher amount of bloom, trees on B.9, MAC 39, P. 22, M.26 (EMLA),
P. 2, P. 16, and C.6 likely would fruit earlier than trees on the other rootstocks.
Further observation of these trees will give us insight into new rootstocks
which may perform well in Massachusetts.

Table 4. Tree size and bloom of trees in the 1984 planting.

Tru

Blossom c

lusters

diame er

Height

Spread

per cm^

' trunk

Rootstock

(in)

(ft)

cross-sectional area

Bud.491

1.59

ab*

7.1

4.4

0.03

Bud. 9

1.23

def

7.1

3.1

bcdef

8.87

MAC 1

1.29

cde

7.3

defg

3.3

abcde

0.45

MAC 39

1.04

6.9

3.1

bcdef

5.01

P.l

1.47

a be

8.1

bcde

3.2

bcdef

3.98

P. 22

0.78

4.7

1.8

8.24

Seedling

1.55

8.1

bcde

4.0

abed

1.24

CG 10

1.49

a be

7.9

cdef g

3.9

abed

0.99

CG 24

1.38

bode

8.2

abed

3.6

abcde

0.65

M.4

1.23

def

7.6

cdef g

3.3

abcde

0.80

EMLA 7

1.32

cde

7.9

cdef g

3.6

abcde

1.06

EMLA 26

1.19

7.1

ef g

2.9

cdef

4.51

Bud.490

1.43

abed

7.8

cdef g

3.4

abcde

0.91

P. 2

1.00

fgh

5.7

2.7

def

4.54

P. 16

0.85

5.9

2.3

8.33

P. 18

1.43

abed

8.2

abed

4.0

abed

0.65

C.6

1.18

6.9

3.3

abcde

6.18

Ant. 313

1.64

8.7

a be

4.8

0.50

'Means in a column not followed by the same letter are significantly different.

Conclusions

MAC 9 (sold as Mark) continues to perform extremely well under our
conditions. Trees are similar in size to M.26. They are more stable than M.26,
not requiring support at this point, and they are veiy productive. The other
rootstock which shows a lot of promise is M.9A (E\LA). The source of this
stock is derived from M.9A (a clone of M.9) after the viruses were removed. It
is considerably more vigorous and much more productive than standard M.9. It
could be particularly useful for plantings on posts. The additional vigor keeps
lateral branches more upright and productive longer.

In coming years we will be able to observe Mark with Mcintosh and
several other cultivars in differeni plantings around Massachusetts. It would be
advisable for growers to begin experimenting with Mark in small plantings but,
it is too early in testing to recommend it for large-scale plantings.

- 5 -

POMOLOGICAL PARAGRAPH

Revision of Storage Handbook

William J. Bramlage

Department of Plant and Soil Sciences

University of Massachusetts

The U.S. Department of Agriculture recently published a revision of its
Agriculture Handbook Number 66, "The Commercial Storage of Fruits,
Vegetables, and Florist and Nursery Stock."

The handbook discusses factors that can significantly affect quality
maintenance during storage, and is a wealth of specific information about the
postharvest needs and problems of many horticultural crops. Anyone working
with storage of horticultural crops should have this publication for quick
reference to needs for storing these crops.

Agriculture Handbook Number 66 can be purchased from the Superintendent
of Documents, Government Printing Office, Washington, D.C. 20402. The stock
number is 001-000-04478-8, and the price is $6.00.

POMOLOGICAL PARAGRAPH

Public Opinion About Alar
International Apple Institute

Are consumers concerned about apples? Not really, according to a
national study conducted by Opinion Research Corporation, a San Francisco
based market research firm. The study, conducted in July 1986, reports that
only an estimated nine percent of the population is even aware of any publicity
or news stories of health concerns about apples.

A surprising number of respondents to the study replied that the news
they heard about apples was good. In addition, many other respondents who
remember recently hearing something about apples in the news could not even
recall whether it was positive or negative.

Consequently, the overwhelming majority of consumers are not concerned
with apples and therefore, we hope retailers are not worried.

* * « * *

- G -

MAUGBT MICROINJECTION OF OXYTETRACYCLINB FOR THERAPY
AND PREVENTION OF EASTERN X-DISEASB OF PEACHES

Terry A. Tattar, Julianno Schi>5ffer,

and Daniel Cooley

Department of Plant Pathology

University of Massachusetts

Introduction

Peach X-disease has been considered one of tiie factors that limits
profitability of commercial peach product ion in the Nortlieast. This mycoplasnfia
disease has been brought into remission by trunk injection of oxytetracycline
antibiotics (2). However, the injection met'nods used were very labor intensive
and difficult for peach growers to use in commercial orchards (1). There also
is some evidence that these methods have led to significant trunk dam.ige over
time (Pierson, personal communication). Mauget (J.J. Mauget Co., 2810 So.
Figu<;roa St., Los Angeles, CA 90065) microinjection has been used widely for
trunk injection of shade trees by arborists to deliver f ert ili/.ers, fungicides,
antibiotics, insecticides, and micrunutrients. Recently, a Mauget capsule //ith
4% oxytetracycline (OTC) became available for experimental use in controlling
myc»)plasma diseases of trees. If a simple system of trunk injtsction like the
Mauget microinjection system could deliver oxytetracycline to peach trees
effectively, control of X-disease in peach orchards by trunk injection could be
performed by peach growers. The objcsct of this study was to determine if
Mauget capsules containing 4% oxytetraoycline could be used to control X-
disease in a commc^rcial peach orciiard.

Materials and Methods

Green Acres Orciiard in Wilbraham, Massachusetts was the test site for
this study. In late summer, 1985 it was noted that a number of trees in the
northeast corner of a 5- to 6-year-old peach block (a late variety mixture)
vvere exhibiting sy.nijto ns (reduced apical and radial growth, greatly reduc^^d
fruit yield, chlorotic and red-spotted foliage, prematire defoliation of inner
leav-is, and prematare bud break) of eastern X-disease. At this time several
trees in this corner of the block had already died and replacement trees had
been planted. A number of other trees had one-t'nird to one-half of their
crowns remov'id by pruning.

Antibiotic therapy was performed in an attemjjt to save the living trees
exhibiting X-disease sy^nptjas, and to protect a number of trees growing
adjacent to the affected ones. The metliod cliosen for therapy was trunk
injection with Mauget capsules, which contain 4 ml of i% oxytetra-cycline
(OTC) antibiotic and are disposable after use. On October 7, 1985 twenty-seven
trees were trunk injected using a dose rate of one capsul<i per two inches of
trunk diameter, measured at approximately one foot above ground. Since most
trees were approximately 5 to 7 inches in diameter, three capsules per tree was
the most common dose. To place the Mauget capsule in the tree, a drill hole
(3/16" in diameter and 1/2" dec^p) was made in the trunk approxim^i tely 2 to 4"
aboveground. The delivery tube and capsule were inserted immediately into the
hole. Most )f the capsules were einpty within two hours and all were empty by
the next day when the capsules were removed.

7 -

Results

In the spring of 1986 all treated trees appeared free of X-disease
symptoms. However, in late July and August, nine of the 27 injected trees
began to display X-disease syrrptoms. Most of these trees were the most
severely affected trees in the fall of 1985. One of these trees died by the end
of the growing season. The remaining 18 trees stayed in remission through
fruit harvest and fall coloration. Fruit yields on these trees were normal. The
wounds from the injection completely closed by the end of the 1986 growing
season.

Discussion

The effect of OTC therapy on this block was a partial success, with most
trees remaining free of X-disease synptoms in 1986. Since most of the trees
that went out of remission were in poor condition before injection, there may
be limited effectiveness of OTC therapy on trees in advanced stages of the X-
disease. The Mauget capsule delivery system for the OTC antibiotic appeared to
be an effective and sinple technique for injection therapy in this experiment.
Additional research is needed to evaluate further this preliminary study. We
are particularly interested in establishing levels of injury at which treatment is
effective, and levels where treatment is not effective.

Outlook

The effect of Mauget injection of OTC for X-disease control currently is
being evaluated in 5 commercial orchards in central and western Massachusetts.
Trees in these orchards were injected after harvest in September and October,
1986. An update of this research project will be made in the fall of 1987.

Literature Cited

1. Lacy, G.H. 1982. Peach X-disease: Treatment site damage and yield

response following antibiotic infusion. Plant Disease Reptr. 66:1129 -
1133.

2. Sands, D.C. and G.S. Walton. 1975. Tetracycline injections for control

of eastern X-disease and bacterial spot of peach. Plant Disease Rept.
59:573-576.

Acknowledgements

The authors wish to thank Dorence Green, Steven Smedberg, and George
Swain of Green Acres Orchards for their assistance and cooperation during this
study. We also thank the J.J. Mauget Connpany for supplying us with the
Mauget OTC capsules for these experiments.

*****

- 8 -

STRAWBERRY ARTHROPOD PESTS: AN INTRODUCTION
TO STRAWBERRY INSECT PEST MANAGEMENT

Karen I. Hausohild

Regional Fruit Agent

Hampden County Extension Office

West Springfield, MA

Conpared with other fruit crops grown in the Northeast strawberries have
relatively few insect or other arthropod pests. However, at least three of these
pests, if uncontrolled, can devastate the crop in any given year. Although
chemical controls are most often used, the populations of at least two of these
pests can be controlled, to a certain extent, by non-chemical measures.

The purpose of this article is to acquaint readers with the life histories of
and damage caused by the major strawberry arthropod pests found in our area.
Chemical control recommendations can be obtained from your county, regional,
or State extension personnel. Where appropriate, non-chemical control measures
will be outlined.

Tarnished Plant Bug

There are two insect species that are the most troublesome on strawberry
buds or fruit, the tarnished plant bug and the strawberry bud weevil ("clipper").
Their damage results in direct fruit loss or loss of marketable fruit. The
tarnished plant bug ( Lygus lineolaris P. & B.) is an oval-shaped, flattened bug
about 1/4 inch long, brown in color, and mottled with irregular blotches of
white, yellow, reddish-brown, and black. On the front third of the forewings
there is a clear-yellow, triangular area tipped with a black triangular spot. The
greenish or yellowish nymphs resemble adults except for their small size and
lack of wings. Larger nyrrphs are marked with 4 black spots on the thorax and
one on the base of the abdomen. The tarnished plant bug (TPB) has a 3 to 4
week life cycle; therefore, three to five generations of this insect can occur in
any one season.

Tarnished plant bugs overwinter as adults in protected areas such as leaf
litter, hedgerows, or even in strawberry mulch. They emerge from their
overwintering sites early in spring and feed on developing fruit tree buds,
weeds, alfalfa, or other crops. Apparently, strawberry is a preferred crop
because it initiates growth early in the spring.

Plant bugs have piercing-sucking mouthparts. As they feed they introduce
a toxic saliva into the developing strawberry fruit. This feeding results in
misshapen, catfaced berries, which, if abundant, seriously reduce the size and
number of marketable fruit. The most critical time for damage appears to be
immediately after petal fall, with less damage occurring during full bloom and
less to none occurring during the flower bud stage.

Although the basis for control of this pest is properly timed pesticide
applications, there are cultura 1 practices that may help. Good weed control will
help eliminate alternate food sources as well as egg-laying sites. Be sure to

- 9 -

control weeds in bordering crops and hedgerows. Since tarnished plant bugs are
early season pests, it may be helpful to avoid planting early maturing
strawberry cultivars if this insect is troublesome for you.

In New York state, as few as one TPB nyntph per fruit inflorescence is
thought to result in 30% fewer fruits with a corresponding 18% loss in berry
weight. Therefore, it is very inportant to be aware of this insect and the
potential for damage it can cause.

Strawberry Bud Weevil

The strawberry bud weevil, or "clipper" beetle, ( Anthonomus signatus Say)
is a dark reddish-brown beetle with black patches on its wings, and measures
about 1/10 of an inch in length. Weevils hibernate as adults in trash in or
near strawberry fields, coming out to feed and lay eggs in the developing fruit
buds in the spring. The female lays an egg in an unopened blossom bud then
girdles the stem below the bud so that the bud stem breaks, wilts, and falls to
the ground. The beetle grub inside feeds largely on the pollen of the unopened
bud. The legless, white grub feeds for about 4 weeks then changes to a pupa
and eventually to a weevil within the bud in which it developed. The newly-
emerged beetles feed for a short time then go into hibernation until the
following spring.

Yield losses due to egg-laying damage caused by the strawberry bud weevil
(SEW) can range from 50 to 100%. An average of one cut bud per 1.5 feet of
row, or one female beetle found per 40 row-feet, can result in economic
damage.

Since strawberry bud weevils overwinter in wooded areas, preferring areas
with early flowering species such as red bud and wild brambles, avoiding such
areas may reduce potential SBW damage. Also, there is some indication that
early flowering cultivars attract overwintering SBW, and therefore can be used
as a "trap" crop.

Because of the potential seriousness of this pest, it is inportant to watch
for the incidence of SBW in early cultivars. Look for cut buds, or the tiny
adults on the blossoms themelves. (Adults also feed on strawberry pollen.)

To help control SBW, remove excess foliage and mulch from renovated
strawberry beds immediately after harvest to discourage overwintering. If SBW
damage has been severe, plow under strawberry beds to reduce overwintering
populations.

Spitt lebug

Spittlebugs ( Philaneeus spp. ) are soft-bodied, tan to greenish, elongate
bugs about 1/8 to 1/4 inch long. The adults have blunt heads and prominent
eyes. Wings can be marked with spots, stripes or bands.

Spittlebugs usually overwinter as eggs in the stems of grasses or weeds.
Eggs hatch in the spring at about the time new strawberry leaves and flower

buds are showing. The small white nymphs settle on the new growth, and as
soon as they start to feed they start to excrete the spittle within which they
remain, and feed until they transform to adults. There are five nynphal stages
which last a month or more, depending on tenperatures. Only one generation
occurs each year.

Spittlebugs have-piercing sucking mouthparts which they use to feed on
plant juices. Feeding damage reduces plant vigor and can severely reduce
strawberry yields. When spittlebugs overwinter in plant crowns, early season
feeding can result in stunted, poorly-colored plants --da mage that looks very
similar to that caused by cyclamen mites.

Good weed control will help decrease damage by spittlebugs, as will
maintaining weed-free hedgerows.

Mites

Two-spotted spider mites ( Tetranychus urt icae Koch) are tiny, light-
colored mites that have two reddish to black spots on their bodies. These
mites overwinter as adults and become active as tenperatures warm in the
spring. If spring weather is warm and dry, mites build up rapidly due to their
rapid rate of development.

Spider mite feeding results in discolored or blotching of leaves, or under
heavy infestations, bronzing and drying of the leaves. Since spider mites spin
silken threads as they crawl around on leaf surfaces, in heavy infestations webs
may form over entire plants. Eggs are laid on leaf surfaces or are attached to
webbing.

Severe mite damage not only affects infested leaves, it also decreases
plant vigor and yields and can result in plant stunting and death. Early mite
control is essential to maintain plant health and yields. Good weed control and
attention to cultural practices may help with spider mite control.

Root Weevils

Over twenty species of root weevils are pests of strawberries. Of these
the black vine weevil ( Otiorhynchus sulcatus F.) and the strawberry root weevil
( O. ovatus L.) are the most irrportant. Although the adult weevils feed on
foliage, the most important damage results from larval feeding on roots. Larvae
are small, legless, white grub-like insects found in and around strawberry roots.

Once strawberry root weevils have invaded a strawberry planting they are
very difficult to control. Proper identification of the species is essential to
adequate chemical control, where chemical controls can be used. Prevention
and destruction of infected plantings are the best methods of dealing with
strawberry root weevils.

Root weevil populations increase as plantings are held over from year to
year. Therefore, cropping for fewer years will help prevent problems. Good
sanitation will also assist in preventing infestations.

- 11 -

White Grubs

Like root weevils, white grubs, the larvae of Japanes ? beetles and other
Phy llophaga species, can be severely damaging to strawb rry plants. White
grubs are generally more troublesome on newly turned S( d land, or in very
weedy fields. White grubs are C-shaped, about 1 1/2 inches long and have 6
legs. They spend one or more years in the soil while completing their
development. To prevent white grub infestations, do not plant strawberries in
newly turned sod and keep fields weed free. White grubs are extremely
difficult to control once they become established.

For additional information on these and other strawberry insect pests and
their control, refer to "Managing Diseases and Insects on Small Fruits" (MA
CES C-164R. 1985. D. R. Cooley, J. L. Drozdowski, W. J. Manning, C. F.
Brodel, and K. Haus<hild) or to the publications referenced below:

Schaeffer, G. A. "Pest Management for Strawberry Insects." In: Handbook
Series in Agriculture, Section D: Pest Management. CRC Press, Inc.

Williams, R. N. (Mar-Apr.) 1979. Two Insect Pests Increase in Ohio

Strawberry Fields. Ohio Report on Research and Development, pp. 24-26.

« * * * *

POLMOLOGICAL PARAGRAPH

Market Basket Survey:
Good News For Retailers And Consumers

International Apple Institute

A recent EPA-requested market basket study was conducted by Uniroyal,
manufacturer of the Alar chemical, and the news is good for retailers and
consumers. The study found that a random sanple of apples and apple products
taken directly from supermarket produce aisles, farm markets, and apple
orchards had levels of Alar far below the accepted legal level of 30 parts per
million (ppm). Moreover, it was even below the four ppm estimated by the
EPA.

Market basket research found that most apples, which contained any trace
of Alar, had an average of only 1.65 ppm. (That's roughly equivalent to one
and a half cents in ten thousand dollars.) In fact, close to 25 percent of the
apples tested had levels so low (0.1 ppm) they were not required for UDMH
analysis.

Consequently, because exposure to Alar is extraordinarily low, there is no
perceptible risk to public health while additional tests are being completed. In
addition, little or no spraying has been conducted due to apprehension about

the issue.

*****

MONITORING AND CONTROL OF APPLE BLOTCH LEAFMINER:

AN UPDATE

Thomas Green, Susan Butkewich, William Coli,
Kathleen Leahy, and Ronald Prokopy

Department of Entomology
University of Massachusetts

and

Glenn Morin and Roberta Spitko
New England Fruit Consultants

In previous issues of Fruit Notes, we reported on the behavior of apple
blotch leafminer (ABLM) moths [49(3):19-22] and on the use of red visual traps
to monitor this pest [48(2):ll-14]. During the 1986 season, we conducted
experiments to improve both monitoring and control of ABLM, in cooperation
with a number of apple growers.^

During the 1985 and 1986 seasons, many growers successfully used visual
traps hung horizontally in the tree canopy to determine the need for a pre-
bloom insecticide application for ABLM. In 13 of 14 orchards, where the traps
were used and no insecticide was applied for ARLM before bloom, the numbers
of moths captured on the traps accurately predicted the need for an insecticide
treatment.

We have experienced two problems \i using this trap. First, in most
cases, moth captures have been too few at tight cluster to make a treatment
decision. Wh(>n using Thiodiin ^^ for ABLM control tnis decision must be rnade
at tight cluster or earlier. Secondly, after a rail ABLM on the horizontal
surface of the trap lose their distinctive wingscal? pattern, making it difficult
to distinguish ABLM from other captured insects.

To correct both of these problems, we experimented with a new trap
position, tacking the trap vertically to the south side of tree trunks at knee
height. Results from our study of ABLlVI behavior indicated that the motJis
accumulate on the lower portion of the tree trunk during the day in early
spring, probably for warmth.

Our results this past season (Table 1) suggested that traps in this position
captured more ABLM earlier in the spring than did traps in the canopy,
although this difference was not statistically significant. ABLM were also more
easily recognized on the traps in the new position, even after a rain.

^The authors wish to express sincere appreciation to the following growers who
participated in this work: Richard Bargeron, Keith Bohne, Dana Clark, Ed
Roberts, and Mike and Tim Smith. Excellent technical assistance was provided
by Suong Nguyen and James Mussoni.

Table 1. Number of ABLM moths captured on red visual traps in two positions
at tight cluster and early pink, in seven commercial orchards.

Trap position

Mean ABLM captured per trap
Tight cluster Early pink

Horizontal in canopy
Vertical in trunk

l.l a*
3.8 a

9.3 a
18.1 a

*Means within a column not followed by the same letter are significantly
different at the 5% level.

Our results in 1986 suggest that if cumulative captures in this new
position exceed 3-6 ABLM per trap by tight cluster or 18-22 by early pink, an
insecticide treatment for ABLM may be desirable. This is a very rough
approximation, based on results in only 7 blocks. We will continue testing in
1987 to refine these estimates. In the meantime, wc liave continued confidence
in the treatment threshold of 13 ABLM per trap by early pink for traps placed
in the tree canopy.

We also tested a spray tank additive, Nu -Fi lm-17 ' '" (6 oz./lOO gal.), with
a single Thiodan^'^ (1 Ib./lOO gal.) treatment for ABLM at tight cluster.
Growers using Thiodan for ABLM usually have found 2-3 pre-bloom applications
to be necessary for good control. We hoped tliat Nu-Film-17, advertised as a
spreader-sticker which extends the residual activity of insecticides, would hel[o
to reduce the numbc of Thiodan applications needed.

Our results did not bear this out, however (Table 2), Nu-Film-17 appeared
to have no influence on the efficacy of Thiodan. It is noteworthy that both
the single application of Thiodan and the Thiodan + Nu-Film-17 reduced ABLM
mine densities, but not below our threshold of 0.13 first generation mines per
leaf, supporting previous evidence that a single application of Thiodan pre-
bloom usually is not sufficient to control ABLM.

Table 2. Effectiveness of Thiodan^'" + Nu-Film-17'''", Thiodan ilone, and no
treatment against ABLM. Applications were made at tight cluster in
four commercial orchards.

Treatment

1st Generation
mines per leaf

Thiodan

Thiodan + Nu-Film-17

Untreated

0.13 a*
0.14 a
0.26 b

*Means within a colunn not followed by the same letter are significantly
different at the 5% level.

- 14

VVc also tested a new material, Dimilin^'" for control of ABLM, Dimilin is
a chitin syntht sis inhibitor which acts against both ABLM adults and eggs.
Dimilin has lonj; residual activity and is reported to be non-toxic to beneficial
predators, reducing the risk of mite and aphid build-up associated with the use
of synthetic pyrethroids [see Fruit Notes 51(2):6-8]. A single application of
Dimilin (4 oz./lOO gal.) was very effective in controlling ABLM when applied at
tight cluster (Table 3), as was Vydate"*" (1.5 pt./lOO gal.) applied at early pink.
ABLM mine densities in the treated trees remained well below treatment
thresholds through the second generation.

Table 3. Influence of pre-bloom application of Dimilin'"^ and Vydate "^ on
ABLM densities in three commercial orchards.

1st Generation 2nd Generation

Treatment mines per leaf mines per leaf

Dimilin at TC 0.04 a* 0.08 a

Vydate at EPK 0.02 a 0. i? b

Untreated 0.26 b 0.60 c

*Means within a column not followed by the same better are significantly
different at the 5% level.

We also tested Dimilin for control of 2"*^ generation ABLM (Table 4),
applying a single treatment at 2"fl cover in one orchard, ard two treatments (at
2nd oover and 19 days later) in another orchard. Our results showed significant
reductions in ABLM larval densities in treated trees in both orchards.

Table 4. Influence of a single application of Dimilin (Block 1) at 2nd cover
(2C) and two applications of Dimilin (Block 2), one at 2nd cover and the
second 19 days later, on ABLM densities.

2nd Generation
Treatment mines per leaf

Block 1: Dimilin at 2C

Untreated 0.81 b

Block 2: Dimilin at 2C +

19 days later 0.05 a

Untreated 0.60 b

*Means within a column not followed by the same letter are significantly
different at the 5% level.

Our results with Dimilin agree vvith results from other states and Europe.
Hopefully, Dimilin will be available for use in the near future.

- 15 -

In conclusion, the visual monitoring- trap for ABLM has been used
successfully to determine the need for an insecticide application before bloom in
many orchards. A new position for this trap may improve its usefulness by
allowing an earlier treatment decision and reducing confusion in the
identification of the insects captured. Dimilin holds promise as a new selective
treatment option for ABLM without threatening biological control of mites and
aphids.

The ABLM has become an important pest in our region by having
developed resistance to organophosphate (OP) insecticides commonly used in
commercial orchards. Beneficial parasites which control ABLM very effectively
in unsprayed trees are killed by these OP's and other insecticides. Whatever
we can do to reduce insecticide use in our orchards, through the use of IPM
sampling techniques lor example, will help to spare these beneficials and allow
them to assist us in controlling ABLM.

* « * « *

POMOLOGICAL PARAGRAPH

State of Maine Suspends Action
on Mandatory Tolerances for Alar

International Apple Institute

Robert Deis, Director, Maine Bureau of Public Service, in an October 10,
1986, memorandum to food processors said that because "many food processors
have voluntarily decided to discontinue their use of Damino/-ide-treated raw
products and many farmers, part iculirly apple growers, have substantially
reduced their applications of Daminozide--we expect this will lead to a
significant reduction in public exposure--we are therefore suspending
implementation of mandatory state tolerances in hopes that the-y will be
unnecessary. "

The residue guidelines considered in Maine (and the basis for acceptable
voluntary action) are 1 ppm for infant and baby food and 5 ppm for general-
use, heated, processed food packaged before 10-1-86 and non-detectable and 1
ppm, respectively, thereafter.

Rather than setting mandatory tolerances, it was pointed out the state was
taking non-regulatory steps which include a survey of processors to clarify the
extent and nature of their Daminozide policies and to monitor residues of
Daminozide/UDMH in products sold in Maine. The memoriindum to processors
indicated that if product is found to have residues above what the state
considers acceptable levels, voluntary withdrawal of lots will be requested.

Reprinted from Apple News 17(5):l-2.

RBDUCIN*; ENERGY COSTS IN CA STORAGE

J. A. Bartsch

Cornell University

Agricultural Engineer

Dedication

This work is dedicated to Professor Robert M. Smock, who in 1938
published the results of his research on evaporator fan cycling to save energy.
We are grateful for his constant support and encouragement in this project and
in all fruit storage programs. Dr. Smock suffered a fatal heart attack on April
22, 1986 as he walked across the Cornell campus to his office in the Pomology
Department.

Introduct ion

The concept of reducing cold storage energy use through evaporator fan
cycling is not new. In 1938 R. M. Smock (2), a Pomologist at Cornell
University, wrote of his work, "Certainly no differences were indicated in this
study which would justify the extra power cost of continuous blower operation."
Smock's study indicated that fan operating time could be reduced by 45% with
no detrimental effect on fruit quality and condition. Thirty plus years have
elapsed, and now the merits of this original research are being discovered and
applied to modern CA storage in New York.

Storage Technology

Fruit storage technology has changed tremendously since the first cold
storages were built in New York State. The handling, cooling, and storage
milestones are highlighted in Table 1.

Table 1. Commercial loading and cooling rates for apples.

Year

Loading
Period

Cool ing
Time

Room
Atmosphere

Handling
Method

1924
1938
1945
1965
1986

2-3 weeks
2 weeks
1 week
1 week
5 days

1 week

1 week
3-4 days
2-3 days
"overnight"

Air
Air
CA
CA
"Rapid"

Barrels

Bu. Box

20 Bu. Bin

The industry began to use on-farm refrigeration for apples stored in
barrels around 1924. Professor Smock's study involved refrigerated air storage
of apples in bushel boxes in 1938. Around 1945, commercial CA storage was
begun, and by 1965, the importance of faster cooling was recognized and 20-
bushel pallet bins were in widespread use. Currently, commercial operations are
striving for overnight cooling and rapid CA.

17-

The technology change has required increased cooling capacity for pull
down, which Is reflected In larger evaporators and bigger air handling systems.
The very first refrigerated rooms relied upon gravity refrigeration and contained
no supplemental air circulating equipment. By 1938, forced air blower units
delivered 18 air changes per hour and added approximately 198 watts of heat
per 1,000 bushels of stored fruit. Current centrifugal blower units have a 28
air-change -per-hour capacity. Direct throw propeller fans on modern
evaporators deliver 90 air changes per hour. The present hardware associated
with both types of systems adds approximately 375 watts of heat per 1,000
bushels of fruit. The heat added by the fan motors is now 2 to 3 times greater
than the heat of respiration of the fruit (130-180 W/1,000 bushels).

The energy budget for a modern New York State CA storage is shown in
Figure 1. These data are for a 120,000 bushel plant equipped with flooded
ammonia refrigeration. The daily electrical requirements for cortpressors and
evaporator fans are shown along with the total for the refrigeration system.

2500

2000 -

1500

1000

500 -

• 40 Hp Conprcssor

'^''^^l^p^hiA,^^'^

7S Hp Compressor

'"' '^A'^^A^

OCT

NOV

occ

JAN

rcB

APR

MAT

Fig. 1. Daily energy consumptions in a 120,000 bushel CA storage, where fans
were operated continuously.

The "measured total" includes the relatively small amount of electricity used by
water pumps and condenser fans--a quantity which averages approximately 6% of
compressor use. The "metered total" is the daily average electrical use
calculated from monthly power company bills. Hot water heating, office space
heat, and the electricity used by CA burners and scrubbers are included in the
"metered total."

The data in Table 2 indicate that a total energy savings of 40% is possible
if evaporator fans could be turned off half of the time. Total savings approach
60% when fans ire off 16 hours out of 24 hours. Based on early research by
Smock and later reports by Yost (5) half-time reduction in fan operation is
feasible and causes no detrimental effects on stored fruit quality or condition.

Table 2. Daily energy use and potential energy savings through fan cycling
in 120,000 bushel CA storage

Item

Fans
cont inuously

Fans cycle
5 096 on, 5 0%

id
off

25%

ns cycled
on, 75% off

Fans

Coripressor

Condenser

750 kWh

500 kWh

30 kWh

375 WVh

375 kWh

23 kWh

188 kWh

313 kWh

19 kWh

Total use
% Savings

1280 kWh
0%

773 kWh
40%

5 20 kWh

59%

Air Handler

Eff

iciency

During storage trials (1), we investigated the efficiency of high velocity
direct throw air handlers presently used in CA storages. (Efficiency is defined
as the quantity of air returning through pallet runner openings conpared with
the total quantity of air delivered from the evaporator discharge). When
efficiency measurements were made in a 30,000 bushel CA room, 70% of the
discharge air never passed through the stacks; it simply short-circuited over the
top of the bins and back to the evaporator. When air flow was reduced 50% by
turning off half the fans, the return air flow decri;ased only 22%. Since the
measured return flow coming out of the stacks was still uniform over the entire
room, we concluded that half of the evaporator fans could be safely shut down
after field heat was removed and the CA room was sealed.

Control Strategies

The energy crisis of the 1970s prompted eastern growers to begin using
evaporator fan cycling to save energy. The first storage operators to employ
fan cycling simply turned their refrigeration systems off at night and back on
again in the morning during the winter. Research studies (2,4) indicated that
tennperature variations on the order of +^ 1**F from the set point would be
expected when systems were turned off for 12 to 14 hours. We found these
variations to ho, greater than those experienced when refrigeration systems
operated continuously. Since fruit quality and condition after CA storage in the
cycled rooms was equivalent to that in rooms operated continuously, the cycling
practice became widely accepted.

19 -

Our fruit storage industry currently enploys several control strategies for
fan cycling. Manual control is still used by some of the smaller growers. Time
clock control is used, and a few new systems employ programmable load
controllers to sequence fan and refrigeration operations. Presently, however,
the most popular technique is to cycle fans and refrigeration with a solid-state
thermostat. This thermostat, accurate to +^ 0.25OF, can be set to control only
temperature while fans run continuously during loading and pull down. Later
the thermostat is switched to control fans and refrigeration together. Remote
temperature sensors are installed in the CA rooms where the thermostat is used
to control fan cycling.

Initially we were skeptical of using a single thermostat sensor to control
all of the fans in the CA room. Our recommendation still calls for remote
tenperature sensors in all rooms whether fans are cycled or not. We encourage
growers to turn at least some of the fans on for 30 minutes each 12 hours
during very cold weather. We have recorded fan cycles of up to 36 hours off
and 1 hour on when the thermostat alone was used to cycle the fans with the
refrigeration.

After 3 years of experience we are not aware of any fruit condition
problems resulting from the fan cycling methods described above. Some
freezing damage has occurred in open, partially enpty CA rooms, because
insufficient respiration heat was available. Our biggest concern is that
compressor capacity in older plants now far exceeds the load developed in the
CA rooms when fans are cycled. During extended cold periods, machines may
sit idle for 24 hours or more, and provisions must be made to keep the
conpressor room warm. Heat reclaim from these compressors is no longer
possible during the storage season when the fans are cycled.

Temperature, Relative Humidity, and Atmosphere Variations Due to Fan Cycling

We find that the tenperature controller, not the fan cycling practice, is
the cause of major temperature variations in the CA rooms. We have
documented temperature variations in excess of + 20F in rooms with
continuously operated fans controlled by mechanical thermostats. Tenperature
variations in cycled rooms controlled by the solid state thermostats average +
1° or less.

Few data exist for relative humidity variations. Some very limited data
from new storage facilities indicate cycled rooms yield less defrost water than
identical continuously operated rooms. In theory, this should be the case, but
we do not have sufficient data to confirm it for commercial systems.

We are equally short of data on atmosphere concentration variations. In
one study of 1% oxygen storage in a 30,000 bushel CA room, no variation in O2
levels could be detected after the fans were off for 12 hours. This
determination was made by inserting sanpling lines into 6 stack locations during
loading and monitoring the oxygen level with an electronic analyz.er.

SI r

Fig. 2. Monthly energy use in a 300,000 bushel CA storage.

83-Ha
8S-fl6

Fig. 3. Monthly energy use In a 175,000 bushel CA storage.

21 -

Energy Savings

Eastern storage operators are sold on fan cycling to save energy and
dollars. We have documented the monthly savings by two of our commercial
cooperators and present these data in Figures 2 and 3. The "base year" is the
1982-83 storage season, when no fan cycling was used. Conversion to fan
cycling was conpleted in 1984-85; total energy use was reduced nearly 50% in
the process. The need for good storage management with fan cycling is
indicated in Figure 3, where higher than expected use occurred in 1985-86.
This was due to a tenporary change in refrigeration plant management from
October through February in this storage. The new manager was not
"comfortable" with fan cycling practices of the previous year and operated the
evaporator fans for a longer period of time each day during that season.

The fan cycling practice holds great promise for energy cost savings.
Energy rates in the Northeast currently average 11 cents per kWh and electric
costs are a significant part of the total storage budget. Our research has
shown that fan cycling results in a 60% savings in energy in commercial CA
storages. The simple payback on the fan cycling thermostat controller and
remote temperature sensing equipment is currently 4 to 5 months. The value of
energy saved is equivalent to 16 cents per bushel of storage capacity. We
estimate that the potential value of energy savings due to fan cycling is 1
million dollars annually for our CA industry in New York State.

Literature Cited

1. Bartsch, James A. 1982, Consunption and loss of energy in commercial

units. Proceedings of 3^"^ National CA Conference. Timber Press.
Beaverton, Oregon.

2. Blanpied, G. David. 1979. Effect of blower operation upon temperatures in

CA rooms. Unpublished data.

3. Smock, Robert M., and S. R. Shapley. 1938. Blower operation in farm cold

storage. Refrigeration Engineering Vol. 36.

4. Yost, G. E. 1980. Tennperature data from CA rooms operated with
intermittent fan cycles. Unpublished data.

5. Yost, G. E. 1984. Energy saving through the use of fan and refrigeration

cycling in apple cold storage. Transactions of the ASAE:497-501.

* * * « *

AN ECONOMIC ANALYSIS OF ORCHARD REJUVENATION

IN RESPONSE TO THE REDUCTION OR THE

ELIMINATION OP THE USE OF ALAR*^") ^

Martha Kimball and Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

Since about 1966, Alar''" has been used to extend the harvest season
for Mcintosh apples by controlling preharvest drop and delaying fruit ripening,
enabling growers to efficiently manage harvest labor and cooling capacity.
Without Alar*"', the number of harvest weeks for long-term storage is
decreased, thus increasing the quantity of fruit that must be harvested per day.
To accommodate this higher harvest rate, picking labor and cooling capacity
must be increased, raising production costs. Alternative methods of extending
the harvest season would help alleviate this critical problem.

This study examines the economics of replacing 50 acres of mature,
seedling-rooted trees (that are difficult to pick and lack good color
development) with dwarf and S(imi -dwarf trees that are more efficient to pick,
color well, and allow extension of the Mcintosh harvest. It is assumed that the
grower must replace this block over a 10-year period, rather than all at once,
so that income can continue to be generated each year. The objective of the
study >vas to determine the mix of different Mcintosh strains and rootstocks
that would best use farm resources under Massachusetts production and
marketing conditions during this orchard replacement.

The study was conducted using a multiperiod linear programming model
that was developed specifically for Massachusetts apple growers to aid in long-
range ()lanning of cultivar selection. That model looked at replacing standard
Mcintosh acreages with 7 different cultivars. However, given the commercial
importance of Mcintosh in Massachusetts, we have chose to replant only with
McIntosh--but to use a mix of Mcintosh strains on semi -dwarf ing and dwarfing
rootstocks that will spread the harvest season, best use available resources, and
maximi/.e prof itablility of the orcliarl.

We tried to achieve goals by selei^ting strains and rootstocks with specific
properties. Our goals and choices .vere: I) To produce trees smaller than
standard tliat will produce fruit witii hotter color and ripen earlier (Marshall
Mcintosh on M.7/V); 2) To produce trei^s sn^iller than standard but with fruit
ripening the same time as standard (Rogers Mcintosh on M.7A); 3) To produce
much smaller trees capable of producing fruit for rapid, early harvest (Marshall
Mcintosh on M.26); 4) To produr^e highly colored fruit ripening later than
standard (Marshall McI itosh on 0A.R1). Please note: OARl is an experimental
rootstock that !ias been found to delay ripening of Golden Delicious in Oregon
by about 10 days.

^This study was supported by a grant from the Massachusetts Fruit
Growers' Association

^Hanlon, W. L., C. E. Willis, and R. L. Christensen. 1976. \ framework
for long range apple variety decisions. Mass. Agrio. Exp. Sta. Bull. 621.

- 23

Four management limitations (constraints) were inserted into the model,
namely, cooling capacity, harvest labor, storage capacity, and replanting
acreage. These are described briefly.

\creage: The planting period for the 50-acre rejuvenated orchard was 10
years. Each year 5 acres were removed and replanted. The model also used a
20-year period--10 years beyond the end of replant ing--to evaluate consequences
of strain/rootstock selections up to the time the orchard readies full produc-
tion. For eaiih planting year, the model decided how many acres of each
strain/rootstock combination to plant for maximum prof itabli lity, given the
following set of conditions.

Storage. Most orchards divide the marketing of their crop between the
fresh market, during and immediately following harvest, and long term storage.
However, to simplify the model, we assumed that all fruit produced on the 50
acres was placed in long-term storage.

The storage capacity was set initially at 20,000 bushels. It was increased
to 48,500 bushels in year 20 .vh(>n most ,)lantings had reached lull tnat irity. All
trees less than 4 years old were considered nonbearing mid u-ed none <jf the
storage capacity. Trees older than 4 years were bearing .ind thMr yield used a
portion of the total storage capacity.

Harvest labor. The harvest season was divided into eifrht 3-day picking
periods. These extended from September 4 to October 1. A percentage of the
total yield for each strain-rootstock combination was harvested during at least
4 of these picking periods. Each combination had harvest labor needs specific
to its stage of growtJi because yield varies with strain, rootstock, and age of
tree. The available labor hours for eacii harvest period were deterrnined by
multiplying the number of pickers (set initially at 7) by ivorking hours per day
(set constant at 9) and by 3 days per Iiarvest period. For the 50 acres, 189
hours were available for each 3-day period.

Each strain-rootstock (^^mbiiat ion contributed to the use of harvest labor
depending on the yield, the tree's ag<!, the percentage of yield harvested during
a particular i)icking period, and the picking rate. In year 20, when most
plantings were matare, additiotial harvest labor vvas required. To enable the
model to operate, harvest labor was increased to 550 hours per picking period
(20 pickers) by year 20.

Cooling capacity. Field heat must be removed from th<i apples after
harvest. The (juantity of fruit that can be (tooled is limited by the size of the
refrigerating equip-nent. Cooling lapac^ity was evaluated to correspond with the
eight 3-day harvest periods. The total capacity was 9,000 bushels for 3 days or
3000 bushels per day.

Each strain-rootstock comoiiat ion contribut:!S to the orchard's returns to
management. This contribution dei)<;nds on the difference between revenues and
costs. In this study, returns to management covered overhead costs,
managernent labor, an<l profit.

Revenues were dependent on yic^Id, which varies accorcli ig to the trecs's
age, the strain-rootstock combiiation, and the (jrice. Price was held constant
for all years but varied with fruit gra<le. ^'or all trees, yield was assorted as
follows: 75% extra fancy, 15% utility, and 10)6 processing. The busiiel prices

- 24 -

were $10.00, $5.00, and $2.30, respectively. Obviously, dramatic differences
exist between the newly planted trees and the standard trees as to the
distribution of fruit into grades, but to simplify the model the proportions were
held constant and the differences were accounted for with yield differences.

Total cost for each strain-rootstock combination was the summation of the
following costs: site preparation, planting, nonbearing growing years 1 through
3, bearing growing years 4 through 20, harvesting, cooling, and storage. All
costs were figured on a per acre basis using current prices.

For the 20-year life span of the rejuvenated orchard, costs and revenues
were totaled and returns to management were calculated per acre for all strain-
rootstock combinations. An acre planted in year 1 incurred costs of site
preparation, planting, and nonbearing maintenance through the first 4 growing
years with no revenues received. In year 5, when these trees began to bear
fruit, revenues were positive and increased through matarity. Revenues were
received from these trees for 16 years. However, an acre planted in year 5
earned revenut^s for only 12 of the 20 years. Trees planted in year 10 earned
revenues for only 7 years within the framework of this study.

RESULTS

The discussion of results is divided between findings of the original set of
constraints, called the original modiil, and findings of the modified models
resulting when constraints .vere changed to reflect changes in availability of
orchard resources. Comments are included about each strain-rootstock
combination and about ?ach constraint.

Results of the Original Model

Table 1 presents the optimal lO-year plant ing plan for the 50 rejuvenated
acres, as determined by the original model.

Table 1. Planting plan for the original model.

Planting year Rogers/M.7A Marshall/M.7A Marshall/M.26 Marshall/OARl

10 5

2 2.2 2.8

3 5

4 3.9 1.1

5 5

6 0,1 4.9

7 5

8 5

9 5
10 5

TOTAL 0,1 36 13.9

Mar3hall/M.26. Marshall on M.26 was favored. The model suggested
planting 36 of the total 50 acres with Mar3hall/M.26. The early coloring strain
and the more open tree in this combination gives the earliest and longest
harvest season of the trees compared. Also, because of its precocity,
Marsha 11/M. 26 reaches full production earlier than other strain-rootstock
combinations. Therefore, this combination has less conpetition for labor ind
cooling capacity, and are the primary factors leading to its selection for the
most planting.

Marsha 1 l/OAR 1. The combliation of Marshall on 0AR1 composed
practically all the remainder of the 50 acres. This strain-rootstock combination
should yield later in the season, extending the harvest at least 3 days beyond
other combinations. A disadvantage is that full production is not reached until
approximately 3 years after Marshall/M.26. Also, it is less precocious and
begins bearing later than other combinations. Hence, its contribution to returns
to management was delayed. The model decided to plant 5 acres in year 10
because maximum yield would not be reached by year 20, so less burden was
placed on storage capacity. OARl is, at this time, purely experimentnl, and we
do not know how it will perform with a Mcintosh scion and under
Massachusetts conditions. However, it is obvious that a strain-rootstock
combiiation which ripens later than norrnal i:an be advantageous because of its
ability to expand the harvest season and reduce comijctition for labor ind
cooling.

Rogors/M.7A. The model suggested planting only 0.1 acre of Rogers/?4.7A.
Rogers and seedling Mcintosh are harvested over a similar time period.
Replacing seedling trees with Rogers on M.7A did not expand the harvest
season; thus, that action does not alleviate any pressures caused by the nonuse
of Alar''". However, some benefits may be gained with a smaller tree, such as
less picking time per bushel.

Marshall/M. 7A. No acreage was suggested for planting Marshall/M. 7A
given the conditions of the original model. This strain-rootstock combination
competes with MarshaU/M.26 for resources during the sane periods. Marshall/
M.7A's have a somewhat shorter harvest season than Marshall/M. 2fi, and a
higher percentage of tne crop is picked during the first week. Also,
Marshall/M. 7A reaches full production 1 year later than Marshall/M.26, so it
offered no financial advantage.

Some alterations were made in constraints to allow the model to operate.
First, to not violate the assumj^tion that all fruit must be stored, storage
capacity was increased frorn 20,000 busliels to 48,500 by year 20. Also, in year
20, cooling capacity was increased from 9,000 bushels to 0,800 to harvest
periods 4 through 8, which were the most prolific harvest periods. This change
resulted in cooling capacity becoming most constraining in period 3. Harvest
labor was set initially at 189 ho.irs jjcr 3-Jay harvest period. Thu .vas in<;rensed
to 550 hours by year 20 as trees reached full maturity. The 189 hours became
constraining in year 11 during the 4^^^ and 5t'i harvest periods. If labor was
reduced in the S^fi period, then Rogers/M.7A would not be planted. If the
amount of labor increased then the <]uantity of Marshall/OARl selected for
planting declined.

26 -

Results of Modified Models

After results of the original model were obtained, the magnitudes of the
constraints, or resources available, were (^hanged for labor, cooling capacity,
and storage. The following is a description of the overall changes made to the
constraints and of the responses to those changes. For a more detailed
discussion of the modified models, readers should refer to the Extension
publication we have written (to be published in January, 1987) that describes
this research at greater length.

Increasing the amount of harvest labor, cooling capacity, or both
simultaneously caused greater changes in the planting mix than changes in
storage capacity. Therefore, storage capacity was increased to handle all apples
and then held kept constant. Harvest labor md cooling capacity were increased
only in the most ;onstraining 3-day harvest periods in any year, as opposed to
being increased in all harvest periods for any year. This enabled the
identification of the harvest periods that demanded the greatest amount of labor
and cooling (Capacity. Also, this treatment made it easier to note how the
selection of different combinations was influenced by changes in harvest labor
and cooling capacity. Cooling capacity was most constraining in year 20, when
plantings ivere nature and produced Jtiaxi nurn yields. In this year for harvest
periods 4 through 8, cooling was increased in steps from the initial 9,000
bushels per 3 days to 10,000, and finally to 11,000 bushels per 3-day harvest
period.

Harvest labor was altered in year 11 for the 2T' through the 4^^ periods
(September 7 to 17). The number of pickers was increased in steps from 7 to 8
to 9 in year 11. With each picker working 27 hours in a 3-day harvest period,
the total hours available for each harvest period increased from 189, to 216,
and to 243. In year 20 harvest labor was most constraining during the 4*^" and
5^'^ harvest periods (September 14 to 17 and 1'^ to 21), so labor hours available
were raised to 5G7 per 3 days (21 pickers) for both periods.

Marsha I l/M. 26 . Marshall on M.26 was selected for planting most frequently
in all models. Overall, this strain-rootstock combination makes the best use of
resources as explained previously. However, the advantages do not inply that
Marshall/M.26 should be the sole strain planted on the rejuvenated acreage.
Such action would result in high labor ind <.ooling requirements concentrated
during the days of Marshall/M. 26's peak picking period. Again, the objective
vvas to determine the most profitable nix of strain-rootstock combinations that
would use the inputs available efficiently.

If ample harvest labor vas available at matirity of the orchard,
Marshall/M.26 replaced acreages selected originally for planting with
Marshall/OAR I. In the original model, no Marsiia ll/M.26 was chosen in planting
year 3. However, 2.5 acres were chosen when harvest labor and total cooling
capacity increased. For planting year 9, the original model decided to plant all
5 acres with Marshall/M.26. However, as harvest labor ind cooling became lass
constraining, less of this combiiation was chosen, with no Marshall/M.26 being
selected for year 10. Probably, this situation arose because labor and cooling
capacity were not increased to high enough levels.

- 27 -

Rogers/M. 7A. In the original model Rogers/M.7A was selected only in year
6 for 0.1 acres. When the number of pickers increased to 9 in year 11 for
harvest periods 3 and 4, 1.5 acres of Rogers/M. 7A was selected for planting in
year 1. However, if the number of pickers was greater than for the same
harvest period, planting Marshall/M.26 was more profitable. Acreage of
Rogers/M. 7A planted during year 3 increased when harvest labor increased
during year 20.

Also, selection of Rogers/M. 7A was sensitive to cooling capacity.
Increasing cooling to 11,000 bu per 3-day period during year 20 stimulated
approximately 3 acres of Rogers/M. 7A to be planted in year 8. This resulted in
a reducition of Marshall/M.26 acreage from !J acres to about 2 acres in year 8.
Rogers/M. 7A replaced 1.4 acres of Marsiiall/M.26 in year 9 for the same reason.

Hogers/M. 7A's picking schedule is more similar to Marshal l/OARl than to
Marshall/M.26. The bulk of the crops is harvested during the same 2 weeks,
but harvestinjf of Marshall/OARl extends about one half week past that of
Rogers/M. 7A. However, as more labor and cooling capacity become available
Rogers/M. 7A acreage increases while that of Marshall/OARl df'creases, because
Rogers/M. 7A begins bearing earlier and reaches full production sooner.

Marshall/M.7A. Because of earlier coloring Marshall/M.7A has a longer
potential harvest period than Rogers/M.7A. However, its harvest period
coincides with that of Marshall/M.26, but the latter has a more efficient use of
harvest labor. Therefore, in most cases, Marshall/M.26 was chosen rather than
Marshall/M. 7A. In fact, Marshall/M.7A never was selected until the 10th
planting year.

Marshall/OARl. OARl is attractive because; it may delay fruit ripening.
Extending the harvest season places demands on resources at times when other
strains place less or no demand on harvest labor md cooling capacity. It is
the one strain requiring harvesting in period 8, and it co(ni>etes only with
Rogers/M. 7A during period 7. In all rnodels, somi- .b^reage of Marshall/OARl
was selected for planting, because it comple nents other strains as an aid in
expanding harvest from 2 vveeks to 4 w;.'cks and provides more efficient use of
labor and cooling capacity.

CONCLUSIONS

It should be remenberid tliat the results of this study were specific to tiie
50-acre rejuvenated orchard described by a given set of conditions. Five acres
of the orchard was replanted yearly for 10 years. The research used the
methodology of multi-period linear programming to determine the number of
acres of 4 different Mcintosh strain-i-ootstock combiiations that should
comprise the replanted acres each year. The objective of planting a mix that
generates the greatest profit over the 20 year period was (^rjustraincd by the
amount of storage, labor, and cooling capacity available during harvest.

Given the limits, Marshall on M.26 composed 66 to 72% of the 50 acres
replanted in each of the alternative >nodels which used varying levels of harvest
labor ind cooling capacity. Marshall/M.26 requires more labor and mat trials at
planting time becau-;c; the trees may requin; staking and may require more

- 28

intensive in.'inageinent during the entire life of the tree. However, several
characteristics contribute to the selection of these trees as the best economic
choice: the trees reach full production earlier, the harvest period is longer,
and fruit can be harvested at a faster rate than those of other strains.

OARl is an experimental rootstock that is being field tested with Mcintosh
in Massachusetts. It was ised in this study to determine its economic potential.
Marshall on OARl was selected by the model when harvest labor and cooling
capacity ^fere most constraining. Due to the experimental nature of this
rootstock Marshall/OAR 1 is not suggested for planting, but these results show
that a combination of strain and rootstock which results in later ripening is
desirable and can have high economic potential. Recent results suggest that
Mark also may delay fruit ripening and may be able to provide benefits similar
to those projected here for OARl. Unfortunately, it also is experimental, but
lias undergone moie thorough testing tlian OARl at this time. Clearly, a
rootstock that delays Mcintosh harvest has great value in a strain-rootstock
mix.

Acres selected for replanting with Rogt^rs on "1.7A increased when harvest
labor and cooling capacity ivere more :ivailable. At the least constraining levels
of resources in the later planting years, Rogers/M.7A substituted for
Marshall/OARl. Thus, availability of labor and of cooling capacity affect
decision-making in this rejuvenation framework.

Lastly, Marsiiall on M.7A was selected minimally. This study did not
recommi'iiil planting MarshaU/M.7A when Marshall/M.26 is an alternative.
However, >vhen M.26 is not an alternativf; because of inadequate soil moisture,
too shallow a soil, or a desire to avoid the more intensive management
required, Marshall/M. 7A would bo the obvious replacement.

Every orchard functions under different conditions; yet, similarities among
orchards in growing and harvesting practices exist. This study examined a
hypothetical orchard. It did not use the costs of any specific orchard.
Alt'iough the results are specific to the rejuvenated 50 acres in the model,
suggestions for replant ing schemes can be rnade. To guarantee that all fruit be
harvested in all cases, harvest labor must be increased to 9 pickers for the 50
acres in year 11 and to 21 pickers by year 20. If this is not done, the entire
crop at full maturity cannot be picked. Also, cooling capacity must be
increased from the original ability to cool 9,000 busliels per 3-day picking
period, to 11,000 bushels per period by year 20.

Table 2 is a suggested 10-year planting mi >c for a rejuventated 50-acre
orchard. It is based upon the research results and should be used as an aid for
grower decisions. Again, because MarsIiaU/OAR I is experimental, it is not
included in the suggest ed plant ing mix. For rejuvenatid acreages of differing
sizes, the percentage values can be applied. For exatrple, in year 3, 60% of a
rejuvenated acreage would be planted with Rogers/M.7A, and 40% planted with
Marshall/M.26.

- 29

Table 2. Suggested planting mix in a 50-acre rejuvenated Mcintosh orchard.

Rogei

rs/M.TA

ir3hall/M.7A

% of

Mars!

mll/M.26

% of

Year

Acres

Planting

Acres

Planting

Acres

Planting

100

2.5

3.5

1.5

LOO

TOTAL

% of total acreage:

2H%

72%

The authors would like to thank the Massachusotts Fruit Growers'
Association for generously supporting this study.

COOPERATIVf EXTENSION SERVICE

U S DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS
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Fruit Notes

Prepared by: Department of Plant and Soil Sciences

Massachusetts Cooperative Extension, University of Massachusetts, United
States Department of Agriculture and Massachusetts counties cooperating.

Editors: W. R. Autio and W. J. Bramlage

Volume 52, No.2
SPRING ISSUE, 1987

Table of Contents

Soil Applications of Gypsum Can Improve
Apple Fruit Calcium Levels

Pomological Paragraph:
Reducing Fruit Load on Tree Leaders

Can Rootstock Affect Apple Ripening and Quality?

Pomological Paragraph: .
Pruning Well-feathered Trees at Planting

A Report on the 1986 Massachusetts
Apple IPM Program

Pomological Paragraph:
Early, Heavy Cropping of Apples

Results of 1986 Chemical Thinning Trials on Mcintosh

Timing the Tarnished Plant Bug: A Tale of Frustration

SOIL APPLICATIONS OF GYPSDM CAN IMPROVE
APPLE FROIT CALCIOM LEVELS

William J. Bramlage

Department of Plant and Soil Sciences

University of Massachusetts

Calcium (Ca) deficiency in the fruit is a chronic problem in modern apple
production. If this deficiency occurs, it causes poorer keeping quality of the
fruit .

There are 4 possible approaches available for dealing with potential Ca
deficiency in apples. These are cultural practices, soil treatments, foliar
sprays, and postharvest dips or drenches. These approaches were addressed
recently (Proc., Mass. Fruit Growers' Assn. 93: in press).

Of these approaches, soil treatments are generally the least effective due
to the poor ability of apple roots to absorb Ca from the soil solution. We
have tried numerous treatments and have obtained marginal benefits at best.
However, recent results from applications of gypsum (CaS04-2H20) have been
better than any from earlier studies of soil treatments and will be described
here .

We have conducted 2 major trials with gypsum. The first trial was
initiated by Dr. Mack Drake in 1976 in a block of mature, seedling-rooted
Cortland trees. Half of these trees received 80 lbs. of gypsum spread under
the canopy in April and half received no gypsum. Otherwise, the trees were
fertilized and cared for in an identical manner. These applications were
repeated annually through 1986.

During this period leaves and fruit were sampled and analyzed for mineral
concentrations, and fruit were usually stored in both air and controlled
atmosphere (CA) and their quality was assessed after long-term storage.
Results for analyses from 1977 through 1984 are summarized in Table 1. It can
be seen that gypsum treatments increased Ca concentrations in both leaves and
fruit. In addition, they suppressed magnesium (Mg) in both leaves and fruit,
and suppressed potassium (K) in the fruit but not the leaves. Treatment had no
effect on phosphorus (P) levels in either fruit or leaves.

The increased fruit Ca levels improved keeping quality of the apples
(Table 2). Both bitter pit and senescent breakdown were significantly reduced
after both air and CA storage. In the case of bitter pit, the reduced levels
of both Mg and K in the fruit should enhance the benefit from increased Ca,
since it has long been known that high Mg and K worsen the effects of low Ca in
causing bitter pit development. It should be noted that in 1985 there was a
severe bitter pit problem in the fruit on the trees. As we walked through this
block it was very clear which trees had and had not been treated with gypsum,
as the appearance of the fruit was markedly different. In contrast, little
bitter pit occurred in this block in 1986 and no difference was apparent at
harvest time .

The second gypsum experiment was established in 1980 in a block of
Delicious trees planted on MM. 106 rootstock in 1972. This experiment was set

up and conducted by Dr. William J. Lord until his retirement. The trees in
this block received either 0, 50, or 100 lbs. of gypsum spread beneath the

Table 1. Effects of annual gypsum applications of 80 lbs. per tree beneath the
canopy in the spring on fruit and leaf mineral concentrations. Cortland.
1977-1984.

Element

Treatment

Ca (ppm fruit,
% d.w. leaves)

Mg (ppm fruit,
% d.w. leaves)

K (%)

P (ppm fruit,
% d.w. leaves)

Fruit

No gypsum
Gypsum

142
162

303

273

0.63
0.60

420

417

Significance^

•kiiic

***

n.s .

No gypsum
Gypsum

Leaves

0.82

0.26

1.36

0.96

0.23

1.39

1.90
1.86

Significance^

iiik-Jc

***

n.s .

n.s ,

'Significance: *** = odds of 999:1; ** = odds of 99:1; n.s. = not significant

Table 2. Effects of annual gypsum applications, 1977-1984, on fruit quality,
Cort land .

Factor

No gypsum Gypsum Significance^

Firmness ,

lbs

. , harvest

13.4

After

air

stg

9.2

After

11.0

Bitterpit ,

, %,

after air stg

After

Breakdown.

1 "> J

after air stg

After

13.5

9.3

11.1

3
5

12
3

n.s.
n.s ■
n.s .

***

•kick

***
■k-k-k

'Significance: *** = odds of 999:1; n.s. = not significant,

canopy in April. These treatments were repeated each year until 1986, when the
100-lbs. application rate was discontinued. Each year leaves and fruit were
analyzed, and when available (the site is subject to frost), fruit were stored
in 320F air and assessed after long-term storage.

Results are summarized in Table 3. Gypsum increased Ca concentrations in
both leaves and fruit, and decreased Mg concentrations in both leaves and
fruit. It did not affect fruit K and slightly increased leaf K. Gypsum ut 100
lbs. per tree was no better than 50 lbs. per tree in any of these measurements.

Table 3. Effects of annual gypsum applications, 1980-84, on leaf and fruit
mineral concentrations. Delicious.

Gypsum (lbs. /tree) Significance^

Factor 50 100 vs 50 vs

50 + 100 100

Fruit Ca, ppm 145 153 152 *

Mg, ppm 263 258 255 **

K, Z 0.54 0.55 0.55 n.s.

Leaf Ca, % 1.22 1.32 1.36 **

Mg, % 0.36 0.32 0.32 **

K, % 1.36 1.42 1.43 **

zsignif icance: ** = odds of 99:1; * = odds of 19:1; n.s. = not significant.

In this experiment no consistent effect on fruit quality has been
measured. In part this probably is due to the large variability in cropping
among trees, and the consequent variability in fruit quality. For example, in
1986 a severe bitter pit problem existed but it was found only on the large
fruit that were produced on trees that had been damaged by frost. The large
effect of fruit size may have masked any possible benefit from the gypsum
treatments .

These results indicate that soil applications of gypsum beneath the tree
can increase apple Ca concentrations and improve fruit quality after storage.
The effects are modest in size but can produce measurable benefit under
appropriate conditions.

Use of gypsum can, however, create some problems. The obvious one is
suppression of leaf Mg levels. Mg deficiency is common in Massachusetts and
results in loss of vigor and productivity of trees. Our results have shown a
steady decline in leaf Mg in the Cortland block with continuing gypsum
application. Each year leaf Mg was lower than it was the previous year in the
gypsum-treated trees. Clearly, Mg levels would have to be monitored carefully
and corrective measures applied as needed if a gypsum program was adopted.

We do not know what effects long-term use of gypsum would have on soil
properties. These effects must be determined in future assessments.

Likewise, we do not know what application rate is optimum. Since spread
of the trees was different in the Cortland and Delicious blocks, it is more
useful to consider applications in terms of lbs. per square foot. The Cortland
trees were treated with 0.2 lbs. per sq. ft. annually, and the Delicious trees
with 0.3 and 0.6 lbs. per sq. ft. Since the higher rate on Delicious was no
different from the lower rate, it appears that something less than 0.3 lbs. per
sq. ft. may be optimum. However, a comprehensive experiment needs to be
conducted to determine effective rates.

Gypsum treatments are both laborious and expensive when applied as we did.
The material was evenly spread under the trees, a slow unpleasant task. Our
price for gypsum was approximately $0.08 per pound, and therefore the treatment
cost between $3 and $5 per tree per year using the rates reported here.
However, we do not know if gypsum needs to be applied annually. In 1986 the
100 lbs. per tree treatment under Delicious was discontinued, but fruit mineral
analyses showed that Ca level remained equal to that of fruit no longer
receiving gypsum.

At this time, 1 view soil gypsum treatment as an effective way to raise
fruit Ca levels when it is applied as we have. Perhaps the best way to use
gypsum is in an orchard or a block that is known to consistently produce low-
Ca apples. We have another block of Cortland trees that is in very fertile
soil and which produces excessive vigor and large fruit, and these fruit are
always badly affected with bitter pit and breakdown. In 1986 we established an
experiment in this block to see if we can improve fruit quality through gypsum
treatments. Our data show that treatments did not influence mineral
concentrations in this first year. Fruit were not analyzed the first year in
either of the earlier experiments, so this is the first time in which we can
determine the rate at which fruit mineral levels change over time. Based on
the earlier studies, we should see improvements next year.

1 have tried to emphasize that use of gypsum is still very experimental.
It will take a number of years before we can make recommendations with
confidence. However, it is obvious from the results shown here that soil
gypsum treatments can improve fruit Ca levels and quality under some
conditions. It is therefore a new weapon in the modern apple grower's arsenal
of techniques for coping with the ongoing threat of Ca deficiency in fruit.

POMOLOGICAL PARAGRAPH

Reducing Fruit Load on Tree Leaders

Growers should avoid allowing too many fruit to develop on the leader of
young trees. It may be advantageous to remove fruit from the entire tree until
the fourth year. Then for the succeeding years, depending upon tree size, the
removal of fruit from the leader should be continued.

CAN ROOTSTOCK AFFECT APPLE RIPENING AND QDALITY?^

Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

Interest in the effects of rootstocks on fruit ripening and quality began
a number of years ago. In 1930 Wallace (7) published data suggesting that
apples from trees on M.9 rootstocks had higher soluble solids (sugar) levels
and did not store as well as fruit from trees on other rootstocks. However, if
fruit from trees on M.9 were harvested earlier than others, then similar
storability was obtained, suggesting that M.9 encouraged earlier ripening. In
1944 Hewetson (4) published similar results using Mcintosh trees with various
interstocks. Fruit from trees with an M.9 interstock matured and colored
earlier. Perry and Dilley (6) confirmed these results using the ethylene
climacteric as an index of ripening. In their study Empire apples on MM. Ill
with an M.9 interstock entered the climacteric significantly sooner than those
on MM. Ill alone.

Lord et al. (5) used the ethylene climacteric and soluble solids as the
primary indices of Empire apple ripening and compared various interstock-
rootstock combinations with M.26, M.9, and M.27. They found few consistent
differences with respect to the percentage of fruit in the ethylene climacteric
5 days after harvest. However, consistent differences existed in soluble
solids content. Fruit from trees on M.27 had significantly higher soluble
solids than fruit from trees on M.26, with fruit from trees on M.9 intermediate
between the two. These results suggested that M.27 encouraged earlier ripening
than M.26, and possibly M.9.

Fallahi et al. (2, 3) compared the ripening and quality of fruit from
Golden Delicious trees on seedling roots, M.l, M.7, M.26, MM. 106, and OAR 1.
Using ethylene measurements they found that fruit from trees on M.26 appeared
to ripen earliest, and those from trees on OAR 1 ripened substantially later
than those from all other trees. However, OAR ] also had the highest percent
soluble solids, which is difficult to explain.

It is difficult, from the small number of studies, the small range of
rootstocks used in each study, and the somewhat inconsistent results to compose
a clear picture of the effects of rootstock on apple ripening and quality. The
objective of this study was to use a range of rootstocks, from the very
dwarfing M.27 to the very vigorous MAC 24, to assess rootstock effects on
ripening, size, and quality.

Materials and Methods

Starkspur Supreme Delicious trees on 9 rootstocks (Ott.3, M.7 EMLA, M.9A
EMLA, M.26 EMLA, M.27 EMLA, M.9, MAC 9 (Mark), MAC 24, and OAR 1) were planted
in a randomized complete block design with 10 replications at the University of

^This work was supported in part by a grant from the International Dwarf
Fruit Tree Association.

Massachusetts Horticultural Research Center in Belchertown, MA. To assess the
effects of rootstock on fruit ripening, quality, and size, 7 of the 10
replications were used, 5 planted in 1980 and 2 planted in 1981.

Starting on September 15, 1986, and continuing at 5 day intervals until
October 5, four fruit from each tree were harvested for the measurement of
internal ethylene levels. One-ml gas samples were taken from the core of each
apple to determine the ethylene concentration.

On September 29, 1986 ten fruit were harvested from each tree for the
assessment of fruit weight, length/diameter (L/D) ratio, flesh firmness,
percent soluble solids, and watercore incidence. Firmness was measured with an
Effegi Penetrometer with a 1 cm head. The percent soluble solids was assessed
with a hand ref ractometer , and watercore was characterized by visual assessment
using the method of Bramlage and Lord (1).

Results and Discussion

Table 1 reports the fruit weight, firmness, L/D ratio, percent soluble
solids, and watercore incidence. To accurately assess the effects of rootstock
on fruit size it is necessary to account for crop load. Table 1 also includes
an estimate of crop load in terms of weight of fruit per unit of trunk cross-
sectional area. Additional statistical analyses were performed on these data
to remove the effect of crop load from that of rootstock, and the differences
shown in Table 1 are true estimates of the effects of rootstock on size. Trees
on M.9 produced the largest fruit and those on M.27 EMLA and OAR 1 produced the

Table 1. Fruit parameters and crop load for Starkspur Supreme Delicious trees
on various rootstocks.

Fruit

Flesh

Soluble

weight

firmness

L/D

solids

Watercore

Crop ]

Load

Rootstock

(g)

(kg)

ratio

(%)

index^

(kg/cm2

TCAY)

Ott.3

184

8.39

0.97 ab

11.6 abc

2.0 ab

0.98

M,7 EMLA

196

8.57

0.99 a

11.1 be

1.8 ab

0.72

M.9 A EMLA

192

8.34

0.97 ab

11.4 abc

2.0 ab

1.33

M.26 EMLA

175

8.57

0.96 be

11.3 abc

1.8 ab

0.92

M.27 EMLA

157

8.89

0.94 c

12.0 a

2.4 a

0.91

M.9

200

8.39

0.95 be

11.8 ab

2.3 a

0.95

MAC 9

177

8.34

0.95 be

10.9 e

1.4 b

1.25

MAC 24

193

8.48

0.97 ab

11.1 be

2.4 a

0.42

OAR 1

153

8.98

0.97 ab

11.4 abc

2.2 a

0.27

^Watercore index: 1 = not present; 5 = most severe.

yTCA = trunk cross-sectional area.

^Means in a column not followed by the same letter are significantly different,

smallest. Note that trees on M.27 EMLA and M,9 had similar crop loads and
trees on OAK 1 had a very light crop, suggesting a substantial effect of
rootstock on fruit size. •

Few differences were seen in fruit firmness (Table 1) and those that were
present can be attributed to size, the smaller fruit being firmer. The L/D
ratio (Table 1) was highest for fruit from trees on M.7 EMLA and smallest for
fruit from trees on M.27 EMLA. The differences were statistically significant
and may be of commercial importance.

The percent soluble solids (Table 1) was highest for fruit from trees on
M.27 EMLA, whereas it was the lowest in fruit from trees on MAC 9.
Furthermore, watercore was most prominent in fruit from trees on M.27 EMLA and
MAC 24 and least prominent in fruit from trees on MAC 9. This relationship
suggests that there may be significant differences with respect to the timing
of fruit ripening, but soluble solids and watercore are not very accurate
indices of fruit ripening.

During the course of ripening, apples exhibit a very rapid rise in the
biosynthesis of ethylene, a gaseous plant hormone. Within the core area the
concentration of ethylene rises with the increase in biosynthesis, providing a
very accurate means of comparing the times of ripening. Figure 1 shows the
internal ethylene concentration of apples from trees on M.27 EMLA, M.7 EMLA,
and MAC 9. Other rootstocks were deleted from the graph to avoid confusion,
but were roughly grouped into 3 patterns. Generally, M.27 EMLA (along with
Ott.3, M.9, and M.9A EMLA) encouraged the earliest increase in internal
ethylene. M.7 EMLA (along with M.26 EMLA, MAC 24, and OAR 1) resulted in a
somewhat later rise, and MAC 9 delayed the increase in internal ethylene.

Ethylene (ppm)

10 h

2 -

M.27 EMLA

M.7 EMLA

— *—
9/15

MAC 9

9/20

9/30

10/5

Figure 1. The internal ethylene concentration of Starkspur Supreme Delicious
fruit immediately after harvest from trees on MAC 9, M.7 EMLA, or M.27 EMLA.

Figure 2 shows the moan internal ethylene concentration for all harvests,
and it is obvious that M.27 fclMLA and Ott.3 resulted in higher levels and MAC 9

0.8

Ethylene (ppm)

0.0

Ott.3 M.7E M.9AE M.26E M.27E M.9

ROOTSTOCK

MAC9 MAC24 OARl

Figure 2. The mean, internal ethylene concentration of fruit harvested
September 15, 20, 25, and 30 from Starkspur Supreme Delicious trees on the
rootstocks included in this study. E refers to those rootstocks derived from
EMLA clones. Bars with different letters represent means that are
significantly different at the 5 % level (Duncan's New Multiple Range Test).

resulted in lower levels. These data confirm the effect of these rootstocks on
ripening, showing a significant delay in the rise in internal ethylene caused
by MAC 9 and enhancement caused by M.27 EMLA and Ott.3. Additional
confirmation is provided by the data in Figure 3. This graph shows the
postharvest ripening rate of fruit from trees on the various rootstocks. Fruit
from trees on MAC 9 ripened the slowest and those from trees on M.27 EMLA
ripened fastest, suggesting that the fruit from MAC 9 were less mature when
harvested than those from M.27 EMLA.

The ethylene measurements support the suggestion of the soluble solids and
watercore data that M.27 EMLA encouraged earlier ripening, whereas MAC 9
delayed ripening.

Cone lusions

The results from the first year of this study suggest that rootstocks can
alter fruit size, fruit quality (in terms of soluble solids and the incidence
of watercore), and the time of fruit ripening. In 1986 M.9 resulted in the

largest fruit, while M.27 EMLA and OAR 1 resulted in the smallest fruit.
Ripening was enhanced by M.27 EMLA, resulting in higher soluble solids levels,
more watercore, an earlier increase in internal ethylene, and faster post-

Days to 1 ppm Ethylene

Ott.3 M.7E M.9AE M.26E M.27E M.9

ROOTSTOCK

MAC9 MAC24 OARl

Figure 3. The mean, postharvest ripening rate (days to reach 1 ppm internal
ethylene) of fruit harvested September 15 and 20 from Starkspur Supreme
Delicious trees on the rootstocks included in this study. E refers to those
rootstocks derived from EMLA clones. Bars with different letters represent
means that are significantly different at the 5 % level (Duncan's New Multiple
Range Test).

harvest ripening rate. MAC 9 delayed ripening, resulting in lower soluble
solids levels, less watercore, a later increase in internal ethylene, and a
slower postharvest ripening rate. Study of these effects will continue in 1987
to confirm the results presented here.

Are rootstock effects on fruit ripening of commercial significance? The
delay that may be provided by MAC 9 (Mark) may only be a few days, but it may
be of some help in expanding the harvest season for a single cultivar. Strains
of some cultivars are now available which ripen somewhat earlier than normal.
If these strains are combined with rootstocks which encourage earlier ripening
and the standard strains are combined with rootstocks, like Mark, which delay
ripening, significant expansions of the harvest season may be obtained. If
Alar* is not available for drop control in the future, it will be necessary to
use techniques like the one suggested here for cultivars such as Mcintosh to
allow harvest of the entire crop.

10
Literature Cited

1. Bramlage, W. J. and W. J. Lord. 1967. Watercore and internal breakdown
in Delicious apples. University of Massachusetts Cooperative Extension
Service Publication No. 11.

2. Fallahi, E., D. G. Richardson, and M. N. Westwood. 1985. Quality of
apple fruit from a high density orchard as influenced by rootstocks,
fertilizers, maturity, and storage. J. Amer. Soc . Hort . Sci. 110:71-74.

3. Fallahi, E., D. G. Richardson, and M. N. Westwood. 1985. Influence of
rootstocks and fertilizers on ethylene in apple fruit during maturation
and storage. J. Amer. Soc. Hort. Sci. 110:149-153.

4. Hewetson, F. N. 1944. Growth and yield of Mcintosh apple trees as
influenced by the use of various intermediate stem pieces. Proc . Amer.
Soc. Hort. Sci. 45:181-186.

5. Lord, W. J., D. W. Greene, R. A. Damon, Jr., and J. H. Baker. 1985.
Effects of stempiece and rootstock combinations on growth, leaf mineral
concentrations, yield, and fruit quality of 'Empire' apple trees. J.
Amer. Soc. Hort. Sci. 110:422-425.

6. Perry, R. L. and D. R. Dilley. 1984. The influence of interstem on
ripening indices of 'Empire' apples. Compact Fruit Tree 17:50-54.

7. Wallace, T. 1930. Factors influencing the storage qualities of fruit.
Proc. 1^*- Imperial Horticultural Conference, London.

*****

P(M10L0GICAL PARAGRAPH

Pruning Well-feathered Trees at Planting

William J. Lord

Department of Plant and Soil Sciences

University of Massachusetts

If you receive well-feathered trees from the nursery, it is important to
leave as many favorably positioned branches on the trees as possible, because
when all but 2 or 3 branches are removed, these tend to grow very vigorously
and develop narrow crotch angles when growing conditions are favorable. Head
the trees at 39 inches, or 10 to 12 inches above the highest, useful branch, if
the tree is well feathered. Do not head the branches, or remove any more low
branches than necessary. Heading adds to the problem of excessive vigor on
vigorous cultivars and delays production. Low branches contribute to the total
leaf surface of the tree. Low branches and extra scaffold limbs can be removed
in subsequent years.

A REPORT ON THE 1986 MASSACHUSETTS APPLE IPM PROGRAM

William M. Coli, Daniel R. Cooley, Kathleen Leahy, and Ronald Prokopy

University of Massachusetts

Acknowledgements: We would like to thank Keith Bohne , Bill and Henry
Broderick, Dana Clark, William Flint, Jesse and Wayne Rice, Ed Roberts, and
Tony Rossi for their cooperation. We also thank Glenn Morin and Robin Spitko
(New England Fruit Consultants) for their scouting reports which we included in
the weekly pest message on several occasions, and for the harvest injury data
in Table 1. Special thanks to Sue Butkewich and Tom Green.

Program funding was provided in part by U.S.D.A. (Smith-Lever 3(d) Pest
Management), the Massachusetts Department of Food and Agriculture, and grower
contributions. Individual grower support of the Apple IPM program and the Pest
Alert messages totalled $2870 in 1986, an increase from 1985. In addition, the
Massachusetts Fruit Growers Association, Inc. provided a grant of $1,600 which
was used to replace the aging IPM vehicle. Our "new" vehicle, which we use to
travel to monitored orchards and research sites, is a 1983 Ford LTD, and has
already begun to develop a sticky trunk. We sincerely wish to thank the
growers and the MFGA for their continued interest in and support of the
program.

Five commercial orchard blocks (plus a San Jose scale-infested commercial
block in Lancaster) and one block at the Horticultural Research Center (HRC)
were monitored weekly for arthropods and pathogens affecting fruit trees. Scab-
infested leaves which had been placed in wire cages at these 6 sites in March
were collected weekly and examined using squash mounts and counts of mature
ascospores, to determine apple scab spore maturity. In addition, temperature
and rainfall were recorded at the Horticultural Research Center (HRC), and
other pest information was gained by occasional orchard visits and reports
from Sue Butkewich, Tom Green, growers, Extension workers in other states, and
private-sector consultants.

This information was used to reply to grower calls and write twice-weekly
Entomology Pest Messages from April 8 to September 10. Plant Pathology messages
were written weekly during the primary scab season, and in response to observed
problems afterwards. Messages initially were transmitted to regional agents via
the University computer's mail program, but after August 1 were shifted to a
grant-funded, microcomputer-based, bulletin board system (BBS) called INFONET.

Entomology and Plant Pathology staff made a combined total of about 100
orchard site visits during the year, assessing pest problems faced by large and
small commercial orchardists. Staff also gave 27 Extension talks at grower and
other group meetings and 2 talks at professional association meetings, and
authored or co-authored 5 Fruit Notes articles and several journal or
proceedings articles. Entomology staff again cooperated with Dr. Rick Weires,
Hudson Valley Lab, on the Annual March Message. Bill Coli gave an invited talk
at the 29^*^ annual meeting of the International Dwarf Fruit Tree Association,
entitled "Techniques of Integrated Pest Management for Commercial Orchards."
Plant pathology initiated cooperative research on delayed, early-season
spraying with Dr. William MacHardy of the University of New Hampshire and Dr.
David Rosenberger, Hudson Valley Cooperative.

At 4 Twilight meetings in each of the 3 regions, growers were provided
with extensive IPM training including 2 hours at each session covering sprayer
calibration using the Tree-Row-Volume method. These calibration sessions
provided a total of about 450 grower-training-hours, all suitable for pesticide
applicator certification credits. A 5-page handout titled "Calibration of
Orchard Sprayers Using the Tree Row Volume Method" prepared by entomology staff
was distributed at these meetings. This information is also being incorporated
into a computerized expert system which should be publicly available in the
near future. We would like to acknowledge the support and assistance of Mr.
Bill Doe, Doe Ag. Sales, and Mr. Rick Clark, Orchard Equipment and Supply, who
provided substantial expertise in fine-tuning the calibration of several
diverse types of sprayers. We also would like to acknowledge the contribution
of the Regional Agents who assisted in presenting this material at the twilight
meetings .

Fungicide, insecticide, and insect growth regulator trials were again
performed at the HRC and at grower sites, testing chemicals which may be or
presently are a component of commercial spray programs. Evaluation of pesticide
effects on mite predators continued as did evaluation of disease-resistant
apple cultivars. A commercial test block of disease-resistant cultivars planted
in a randomized block design was established at the Rice farm in Wilbraham.
This planting is intended to assess the feasibility of using no fungicides and
a minimum of insecticides in a commercial setting, and to define further
horticultural characteristics and marketability of these cultivars.

Related Entomology research and adaptive studies continued to focus on
evaluation of selective, relatively non-toxic pesticides and development of
monitoring traps for Tentiform Leafminer, on timing of plant bug injury and
pesticide treatment for plant bug, and on the behavioral ecology of the Apple
Maggot Fly and the Plum Curculio. Other Entomology studies involved a test of
several visual traps for monitoring the Walnut Husk Maggot (an occasional peach
pest), a project to collect and identify unusual mite predators first found
last season in a low-spray orchard in Stow, MA, and, in cooperation with Dr.
Alan Eaton, University of New Hampshire, a survey to determine the distribution
in Massachusetts of Psylla mali , the European Apple sucker. P . ma 1 i is not
found as a pest in commercial orchards, but appears to be expanding its range
and may become a pest in commercial blocks in the future.

Insect/Mite Pest Status and Harvest Injury, 1986

Tarnished plant bug - TPB was once again the number one cause of insect
injury in the state's commercial apple orchards. In one block we visited
weekly, no pre-bloom insecticide was applied, and on-tree injury reached 4%.
However, most "dimples" were in or near the calyx, and would not likely have
resulted in fruit downgrading.

Plum curculio - Extremely favorable weather in late May caused PC to

emerge in most areas over a very short period of time, allowing some growers to

control PC with one insecticide application. In a few locations, however, PC
egglaying scars were seen in late June and early July.

Apple maggot fly - Trap captures continued this year into October in all
areas of the state, although overall numbers of AMF captured were not high, and
only one Extension-monitored block sustained any injury. Again this year peak

captures occurred in September in commercial blocks and in Dr. Prokopy's
orchard.

Table 1. Percent insect-injured fruit in on-tree surveys of 53 commercial
blocks, 1986, compared to orchard harvest injury averages from 1978-1985.

Insect pest

Percent injury^

1986

1978-1985

Tarnished plant bug
European apple sawfly
Plum curculio
San Jose scale
Leafrollers
Green fruitworms
Apple maggot fly
Other

0.83
0.01
0.75
0.11
0.02
0.03
0.05
0.02

1.74
0.40
0.51
0.74
0.03
0.08
0.06
0.01

^Data provided by New England Fruit Consultants. Sample consisted of 50 fruit
per tree on 6 to 16 trees per block, depending on block size.

Apple leafminers - Sticky, red, visual traps again were very useful in
predicting potential LM problems prior to bloom. Traps in 3 of 6 blocks
indicated the need to treat, later borne out by counts of sap-feeding mines. In
2 other blocks, overwintering generation moth captures remained just below the
provisional action threshold (12 moths per trap), and first and second
generation mines likewise never exceeded the economic injury level. In one of
these blocks (which also sustained high levels of white apple leafhopper injury
and received no Alar®) we noted a higher level of pre-harvest drop than was
seen in other monitored sites.

White apple leafhopper - White apple leafhopper was again a problem at
many sites in 1986, especially where l^'- generation activity was not noted and
controlled, or where only organophosphate insecticides were used against the
OP-resistant leafhoppers. A few blocks experienced serious, late-season WAL
buildup. Also, see later section on potato leafhopper.

Mites - In most orchards mite numbers were very low this year, possibly
due to frequent, heavy rains throughout the summer. A. fallacis predator
numbers were very high in all locations compared to recent years, and seemed to
be thriving despite the shortage of red mite adults.

Disease Situation

The 1986 season was characterized by extreme disease pressure largely
caused by prolonged wet weather and low temperatures. The major efforts of the
program were to monitor Venturia inaequalis ascospore maturity from April

through mid-June, to develop weekly messages and distribute them to Regional
Fruit Agents, to test new ergos terol-synthesis inhibiting fungicides for
potential use in the program, to continue with work on disease-resistant
apples, and to participate in grower training sessions for sprayer calibration
and disease-management information.

Leaves for the apple scab maturity assay were collected from an abandoned
orchard in November, 1985, placed in hardware-cloth cages, and left out in a
non-sprayed orchard over the winter. These cages were distributed to the 6
sites in March. Weekly collections were made by Kathleen Leahy, Jim Williams,
and Bill Coli. Leaves were then examined, squash mounts prepared, and counts of
mature ascospores made.

Squash mount data indicated that primary season lagged behind tree
development by up to 2 weeks. This meant that early season sprays were not
needed. In most areas, fungicide applications could have been delayed until
half-inch green or tight cluster at the earliest. In fact, no fungicides
probably were necessary until bloom this year. Wetting periods monitored at
Belchertown showed that there were no Mill's infection periods before May 7,
because during wet periods weather was too cool for scab development. At this
time most trees were in early bloom. There were several heavy infection periods
through the rest of May. A heavy wetting period (72 hours) occurred June 5-8,
and the effects of this are still being discussed. Scab development on late
terminals during the end of June suggested that there was a primary infection
period at the beginning of the month, and that the maturity evaluations had
estimated the end of the season before it had occurred. The alternative
suggestion is that during mid-May, primary infections occurred, and during the
heavy rains in early June, secondary scab was spread. Scouting in the tops of
trees showed lesions on early terminals and clusters, indicating that these
infections had occurred in mid-May. Because of frequent rains, extreme
pressure continued through the summer, causing greater than normal fruit scab
in some orchards.

Pest messages have stressed the need to scout orchards until infections
which might have occurred have had a chance to show up. During this period,
sprays should be applied as they were during primary season. However, some
growers immediately reverted to a reduced frequency and/or rate in their spray
schedule at the announced termination of primary season. In our tests, such a
reduction this year resulted in terminal scab infections of the type reported
around the state. This confirms our original recommendation: after the end of
primary season, orchards must continue to be sprayed on a primary schedule for
a period sufficient to allow any primary infection to be visible.

Other infections appeared to be caused by a failure to spray before or
immediately after critical infection periods in May, or by a failure to cover
the tops of large trees. Large trees were infected much more frequently than
properly pruned trees on dwarfing rootstocks. Scouting the tops of trees
revealed primary infections better than scouting other locations.

Tests at the HRC also looked at the efficacy of 3 ergosterol-inhibit ing
(EI) fungicides, Rubigan'" (Elanco) , Nustar'" (Dupont), and A-815'" (Uniroyal)
and compared them to a standard dithiocarbamate, Manzate™ 200. In some
treatments, the EI compounds were combined with the Manzate. In general,
sterol-inhibit ing fungicides were better than Manzate at controlling primary

scab. Nustar was superior to other materials. These materials can be applied
on an after-infection basis up to 96 hours following the initiation of an
infection. Next season, the upper limits of this time will be tested. In
addition, an application of one or more of these materials will be made this
fall to determine whether they have any effect on the ability of the fungus to
overwinter and produce ascospores in the spring. The tests at the HRC
represented a 150% increase over such tests in previous years.

There were no reports this year of the bud blast or cankering attributed
to fire blight on Marshall Mcintosh. The summer may have been too cool for
development of the disease, though fire blight did show up in at least one
commercial orchard. Alternatively, dormant copper or Bordeaux treatments or
in-season streptomycin may be alleviating the problem.

New or Unusual Outbreaks

Potato leafhopper - Widespread leaf yellowing of apple throughout
Massachusetts has been identified by New York state entomologists as injury
caused by the potato leafhopper. Leaf injury, a diffuse yellowing of
consecutive terminal leaves, results from PLH feeding, during which leafhoppers
inject a toxic saliva. Injury shows up later, often after leafhoppers have
left. With no insects present, PLH injury can easily be mistaken for nutrient
deficiency. PLH does not overwinter in the region, but is "imported" from
southern states as storms move up the coast. Because the summer of 1986 was
characterized by a greater than normal frequency of such storms, PLH numbers on
several crops were unusually high.

Catfacing insects on peaches - Catfacing continued well into the summer on
peaches in many locations this year, with injury occurring at one monitored
site in early August. The causative agent is not known, although a rather
damaged specimen which may have been oak hickory plant bug showed up on an AMF
sphere in late July. We will be monitoring the situation closely in 1987 to
determine if other pests such as stink bugs might be causing this injury.

European corn borer - A grower located close to a corn field experienced
late season damage from ECB - larvae tunneling into the calyx and through the
core of the fruit. Growers in similar situations would be well advised to
monitor ECB populations in August and September. Also, early in the season,
one grower reported damage to terminal growth of young trees apparently caused
by an insect larva which was collected and tentatively identified as ECB.

Plans for 1987

We will be increasing the number of monitored orchards from 6 to 10 in
1987; two of these sites will very likely be low-spray orchards. In addition,
we will be monitoring a number of peach and pear blocks for borers, catfacing
insects, psylla, and peach X-disease as well as other problems which may become
apparent .

The INFONET computerized bulletin board, operated in cooperation with Dr.
Wesley Autio, Department of Plant and Soil Sciences, will be maintained and
expanded in 1987. This BBS is the primary means of disseminating topical pest
management and horticultural information, pesticide registration news, meeting
dates, etc. to regional agents and other interested parties. INFONET will

continue to be directly accessible to growers with telecommunication ability.
The BBS number in Amherst is 413-545-4717. For information or a user manual,
please call Bill Coli or Kathleen Leahy at 413-545-2283 or Wes Autio at 413-
545-2244.

We propose to continue most 1986 activities, including: monitoring
weather, pathogens, arthropods, and tree development in 10 commercial blocks,
writing twice-weekly pest messages, presenting 4 grower training sessions in
each of the 3 regions, performing adaptive studies and pesticide trials,
authoring extension and other publications, and generating outside funding. In
addition, we plan to provide continued support of the National Park Service IPM
Program at Adams National Historic Site, which will generate $500 to partially
support the Apple IPM technician. If 2 grant applications we have submitted
are approved, we will also be initiating a large-scale study in commercial
orchards on the influence of ground cover on mite predator prey interactions
and buildup of scab inoculum and a study aimed at implementing very low spray
programs using traps for controlling directly apple maggot flies.

Calibration will be emphasized, although not as intensively as in 1986.
Every attempt will be made to coordinate Entomology and Plant Pathology
scouting, with increasing emphasis planned for looking for disease incidence in
commercial and abandoned orchards.

We plan to develop computerized expert systems to diagnose and advise on
problems. Initially, these will be for use by regional agents, though it is
hoped that growers will have access to them in the near future through INFONET.
At present, we have initiated work on root disorder diagnostics, fruit
disorders diagnostics, scab fungicide application recommendations, and sprayer
calibration. This work is also supported in part by the College of Food and
Natural Resources, and in part by a Public Service Endowment from the
University .

POMOLOGICAL PARAGRAPH

Early, Heavy Cropping of Apples

William J. Lord

Department of Plant and Soil Sciences

University of Massachusetts

Early, heavy cropping of apple trees is not always desirable when trees
are planted at wide spacings. Early, heavy cropping may stunt the trees. This
situation has been observed in a row of Cortland on M.26 with the severity of
stunting varying considerably within the row. Therefore, we may find that in
some instances heading back cuts on the extension growth of the central leader
and on shoots of the scaffold (framework) branches is desirable. This
procedure will stiffen the central leader and scaffold branches, promote
growth, and delay fruiting. An alternative to heading cuts is defruiting.

17
RESULTS OF 1986 CHEMICAL THINNING TRIALS ON MCINTOSH

Duane W. Greene and Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

Chemical thinning is one of the most critical activities undertaken by
apple growers each year. Effective thinning can mean the difference between
profit and loss not only the year of application but also the following year.

There have been no new chemical thinning agents registered in
Massachusetts in more than 20 years. However, during this period of time there
has been a steadily increasing demand for larger apples. We are continually
looking for new and better thinning agents, but until these are found and
registered it will be necessary to use more effectively those thinning agents
that are presently available.

Experiments were initiated at the Horticultural Research Center in
Belchertown in 1986 with two goals in mind: 1) evaluate the effectiveness of
several thinning treatments and combinations in an attempt to identify
promising treatments for future recommendations, and 2) determine the
importance of bloom intensity on final fruit set following a chemical thinning
treatment .

Experiment One

Mature Mcintosh trees (M.7 rootstock) with a heavy bloom were selected for
Experiment One. Thinning treatments were applied 16 days after full bloom on
May 26, 1986, when fruit diameter was approximately 10 mm. Treatments used
were: naphthaleneacetic acid (NAA) at 5 or 7.5 ppm and benzyladenine (BA) at
50 ppm. These were applied alone as a dilute spray or in combination with 1
lb. carbaryl (50 % WP) per 100 gal. One group of trees received no chemical
thinning spray and one received only carbaryl. After June drop all fruit on
previously tagged limbs were counted and fruit set was calculated. A 30-apple
sample was taken at harvest, weighed, and evaluated for percent color, flesh
firmness, and soluble solids (sugars) content.

Generally, a fruit density of about 5.5 to 6.0 fruit/cm limb circumference
on Mcintosh is considered to be ideal, and all treatments thinned when applied
alone, although only BA at 50 ppm and NAA at 7.5 ppm thinned adequately (Table
1). When carbaryl was combined with NAA or BA additional thinning occurred.
NAA at 7.5 ppm, BA, and carbaryl alone increased fruit size. Size was
increased further when carbaryl was added. No chemical thinning spray
influenced flesh firmness, soluble solids, red color, or seed number.

Because of its detrimental effects on mite predators the use of high rates
of carbaryl is discouraged. Attempts are being made to minimize the amounts
used. Although the effectiveness of carbaryl is somewhat concentration
independent, rates of 1/4 lb per 100 gal. or below may be insufficient to thin
adequately by itself. NAA is a very effective thinning agent but it is also
the compound most likely to over-thin. Lower rates of NAA are frequently
chosen to reduce the chance of overthinning. Therefore, the most satisfactory

chemical-thinning treatment would be one using a moderate level of carbaryl in
combinations with NAA. Acceptable thinning should be achieved without causing
overthinning or severely depressing the predator mite population.

Table 1. Effects of naphthaleneacetic acid (NAA), benzyladenine (BA), and
carbaryl (50 % WP) on fruit set and fruit weight of Mclntosh/M.7 apple trees.

Fruit/cm limb circumference Fruit weight (g)

Carbaryl (1 Ib./lOOgal.) Carbaryl (1 Ib./lOOgal.)

13.6

8.6

6.2

4.1

9.3

3.8

6.7

5.9

130

147

153

174

142

156

150

164

Treatment^ (-) (+) (-) (+)

Control
BA, 50 ppm
NAA, 5 ppm
NAA, 7.5 ppm

Average 8.9 **^ 5.6 144 ** 160

^Treatments were applied as a dilute spray on May 26, 17 days after full bloom.
NAA was applied as Fruitone N" and carbaryl as Sevin" (50 % WP) .

YTreatment effects on fruit set or weight were significantly different (5 %
level, Duncan's New Multiple Range Test) if not followed by a common letter.

^The effects of carbaryl on fruit set and fruit weight were significant at the
1 % level (Duncan's New Multiple Range Test).

BA is in the developmental stages as a chemical thinner. It is the only
chemical used alone that adequately thinned Mcintosh. It has performed equally
well as a thinner over the past 5 years on Mcintosh as well as on other
cultivars. BA presently is being sold as a branching agent on Christmas trees
and is also 50% of the active ingredients of Promalin'". We will continue to
evaluate this compound.

Experiment Two

A block of 16-year-old Mcintosh on MM. 106 was selected, and just prior to
bloom 70 limbs were tagged and the blossom clusters were counted. Limbs were
selected that had a wide range of blossom densities, some having as few as 15
and others having as many as 350. A dilute thinning spray containing 2.5 ppm
NAA and 1 lb. carbaryl per 100 gal. was applied with an airblast sprayer on May
27, 16 days after full bloom. Fruit set was determined at the end of June
drop .

It was found that the greater the number of blossom clusters at bloom the
more fruit that remained after June drop (Figure 1). However, the point that
we would like to e;iipluisize is that it requires a large increase in the amount
of bloom on a limb to cause a relatively small increase in fruit number. For
example, if the bloom on a limb was increased from 5 to 10 blossom clusters per
cm limb circumference, the fruit set after thinning would increase only from
about 5.5 to 6.5 fruit per cm limb circumference. NAA at 2.5 ppm plus J lb.
carbaryl per 100 gal. is a moderate thinning treatment, and adequate thinning
was obtained on limbs with blossom densities up to 10 to 12 blossom clusters
per cm limb circumference. NAA at 5 to 7.5 ppm plus carbaryl would have been a
better choice for the limbs having a heavier bloom.

Fruit per cm Limb Ore.

■

•
•

•

10
5

•

■
■

i^- •

• •
«• •

1 I

•
•

•

• •

•
•

•

•
•

• •

5 10 15 20 25

Blossom Clusters per cm Limb Giro.

Figure 1. Effect of blossom cluster density on final fruit set of Mcintosh
apples following a chemical thinning spray of NAA at 2.5 ppm plus 1 lb carbaryl
(50 % WP) per 100 gal.

Although blossom density does influence fruit set, treatments can be
selected that will operate effectively over a relatively wide range of
densities. NAA at 3 ppm plus carbaryl at 1 lb. per 100 gal. should be
effective on trees with low to moderate bloom, whereas NAA at 5 to 7.5 ppm plus
carbaryl at 1 lb. per 100 gal. would be more appropriate on Mcintosh trees with
a moderate to heavy bloom.

*****

20
TIMING THE TARNISHED PLANT BUG: A TALE OF FRUSTRATION

Ronald J. Prokopy, Susan L. Butkewich, and Thomas A. Green

Department of Entomology

University of Massachusetts

In 1976 we began what turned out to be 11 consecutive years of research on
(a) the stages of plant development during which tarnished plant bug (TPB)
injury to apple is initiated, (b) the most efficient method of monitoring the
appearance of plant bug adults, and (c) the efficacy of various pesticides for
controlling plant bugs. In 4 previous issues of Fruit Notes [43(2) : 10-14,
44(2) :l-5, 45(3):15-18, and 45(4)13-14], we reported our results of the first 4
years. In brief, we found that (a) apple flower buds, blossoms, and developing
fruit are susceptible to TPB feeding injury from silver tip to about one month
after petal fall, (b) susceptibility to bud abortion (abscission) is greatest
from silver tip until tight cluster, while susceptibility to fruit injury
(dimples and/or scabbing) is greatest from tight cluster to a month after petal
fall, (c) a 6 X 8 inch sticky white rectangle trap placed at knee height near
the periphery of the tree offers an effective method of monitoring the
abundance of TPB adults, (d) capture of 2.5 or more adults per trap from silver
tip through tight cluster or 4.2 per trap from silver tip through midpink
indicates an economically justifiable need for treating TPB adults with
pesticide, and (e) no given type of pesticide guarantees a high degree of TPB
control, though Cygon" may be the most effective material, followed by various
synthetic pyrethroids, Guthion", Imidan", and Lorsban" or Thiodan'", in that
order.

One major question that emerged from the first 4 years of work was: how
can one predict the best time to apply a pesticide against TPB? In other
words, could one piece together knowledge of the time of greatest
susceptibility of developing blossoms and fruit to TPB injury with knowledge of
the time of greatest abundance of TPB adults in the orchard and determine a
time at which pesticide application should be the most effective? For the past
6 years (1981-1986), we have attempted to answer this question through research
at the Horticultural Research Center in Belchertown, MA.

Methods

To gain information on the time at which fruit injury was initiated in an
unsprayed block, we placed cloth bags over branch terminals harboring
developing flower buds to exclude TPB adults for specified time periods. For
the first 3 years (1981-1983), we used 2 approaches to bagging buds. In the
first experiment, we employed 280 bags (half on Mcintosh, half on Delicious) at
silver tip. At each of 6 stages (tight cluster, early pink, late pink, petal
fall, 1 week after petal fall, 2 weeks after petal fall), we removed 40 bags
(20 per cultivar), thereby exposing the buds to TPB from time of bag removal
onward. Check bags remained in place the entire season. In the second
experiment, no terminals were bagged until tight cluster. At that time and at
each of the above stages thereafter, we bagged 40 terminals (half on Mcintosh,
half on Delicious), thereby preventing TPB from causing injury from time of
bagging onward. Check terminals remained unbagged the entire season. In both

experiments, all bags were removed from the beginning to the end of bloom to
permit pollination. For the last 3 years (1984-1986), we conducted a third
experiment in which we used a single approach to bagging buds. We emplaced 280
bags before silver tip (half on Mcintosh, half on Delicious). At the start of
each of 7 bud development stages (silver tip, green tip, half-inch green, tight
cluster, early pink, late pink, and petal fall) we removed 40 bags (20 per
cultivar) but replaced the bags at the end of that stage, thereby exposing the
buds to TPB only during that stage. In addition, 40 check terminals were not
bagged. As before, all bags were removed during bloom for pollination. In all
experiments, bagged and check terminals were examined in July or August for TPB
injury to fruit.

To acquire information on the abundance of TPB adults in these
experimental blocks during each tree development stage, each year at silver tip
we hung 20 sticky-coated, white visual monitoring traps (half on Mcintosh, half
on Delicious) in trees immediately adjacent to the trees with bags. TPB adults
were counted and removed from traps at each tree development stage.
To compare time of fruit injury initiation and time of TPB abundance with time
of pesticide treatment against TPB, each year in another block adjacent to the
above we applied pesticide to 8 randomly-positioned trees (all Mcintosh) at
each of 4 different tree development stages. On each tree, 60 fruit were
examined in August or September for TPB injury.

Results

Over the 6 years in which flower bud terminals were bagged with cloth to
assess the time at which TPB fruit injury was initiated, 6904 bagged and check
fruit were examined for injury. Normally, 6 years of research involving nearly
7000 experimental fruit is sufficient to gain a detailed impression of any
insect interaction with tree fruit. In this case it was not. The data (Table
1) reveal inconclusive, even conflicting trends. Thus, the results of
Experiment 1 (in which terminals were bagged at silver tip and bags were
removed permanently at successive stages beginning at tight cluster) suggest
that progressively less injury to fruit was initiated at successive stages
after tight cluster. Conversely, the results of Experiment 2 (in which
terminals were bagged permanently at successive stages beginning at tight
cluster) suggest that progressively greater injury to fruit was initiated at
successive stages after tight cluster. The results of Experiment 3 (in which
terminals were bagged permanently except during a given developmental stage)
suggest lack of a consistent trend in time at which injury to fruit was
initiated .

The visual trap capture data (Table 2) suggest TPB adults were on average
most abundant in the unsprayed experimental block from half-inch-green until
late pink. Comparatively few were captured before half-inch-green and after
pink. Time of peak captures varied considerably from year to year. We should
add that the consistent decline in trap captures from pink onward may have been
due only partly to decreasing TPB populations. It may have been due also to
declining ability of the traps to compete as visual stimuli with developing
foliage and blossoms.

The pesticide timing experiments (Table 3) reveal no clear picture of the
most effective time of treatment for preventing TPB injury to fruit. The only

Table 1. Percent TPB-injured fruit on terminals bagged with cloth during
specified tree development stages. Exp. 1 = terminals bagged at silver tip,
free of bags from designated stage onward. Exp. 2 = terminals covered with
bags from designated stage onward. Exp. 3 = terminals free of bags only during
designated stage.

% Injured fruit

Year Exp. ST GT HIG TC EP LP PF 1 WK 2 WK CK

Bags removed from this growth stage onward

1981 1

1982 1

1983 1

27.4

13.2

15.2

9.7

10.9

5.5

4.6

8.7

7.3

5.3

1.7

4.5

6.8

2.6

1.5

13.5

9.1

6.8

3.2

3.6

2.7

2.6

243

221

232

237

214

228

216

Average —

Total No. Fruit —

Injury as % of

TC Injury -- ~ ~ 100 67 50 23 27 20 19

Bags put on at this growth stage

1981 2

1982 2

1983 2

6.9

5.2

—

12.5

17.2

10.5

12.3

5.9

3.9

2.4

6.5

10.1

10.4

1.1

6.5

6.1

3.3

7.4

3.8

11.6

4.6

5.2

5.0

6.1

10.4

8.1

11.4

314

318

243

344

323

461

709

Average —

Total No. Fruit —

Injury as % of

CK Injury — ~ ~ 40 46 44 54 91 71 100

Growth stage during which terminals were exposed

1984 3

1.0

1.3

1.8

2.2

1.0

—

5.0

1985 3

1.5

2.4

7.4

1.8

9.8

6.6

—

10.0

1986 3

1.0

2.2

1.3

""""

4.3

Average

0.5

1.5

3.2

1.0

0.6

4.4

2.5

6.4

Tot. No. Fruit

335

332

247

305

325

384

369

—

304

Injury as %

CK Injury

100

Legend: ST=silver tip; GT=green tip; HIG=half-inch green; TC=tight cluster;
EP=early pink; LP=late pink; PF=petal fall; 1 WK=1 week after PF; 2 WK=2 weeks
after PF; CK=check.

Table 2. Capture of TPB adults on 20 visual monitoring traps at successive
stages of tree development. Traps were emplaced at silver tip and removed 2
weeks after petal fall.

Average no. adults captured per trap

Year

HIG

2 WK

1981

1.5

3.7

5.4

2.6

1.4

1982

2.4

2.8

5.6

1.0

0.4

1983

2.6

— "~

10.8

0.8

0.4

Average

2.2

5.8

3.9

1.3

0.7

(1981-83)

1984

0.9

0.4

5.0

0.7

1985

1.4

1.7

2.0

0.8

0.5

1986

0.4

0.1

— *"

Average

0.9

0.8

2.5

0.6

0.2

(1984-86)

Table 3. Injury to fruit by TPB adults on trees treated with pesticide at
different times.

% Injured fruit when pesticide
applied at

Year Pesticide HIG TC EP LP PF CK

2.3

0.3

1.6

3.6

5.6

2.6

4.3

2.8

4.4

5.9

3.0

3.8

5.3

7.0

5.2

1981 Ambush" 2EC (6.4 oz/100)

1982 Ambush'" 2EC (6.4 oz/100)

1983 Ambush" 2EC (6.4 oz/100)

Average (1981-1983) 2.6 2.8 3.2 5.0 5.6

1984 Pydrin" 2.4EC (3.5 oz/100) 0.6 0.8 0.4 0.6 — 1.3

1985 Pydrin" 2.4EC (3.5 oz/100) 0.6 1.3 0.8 1.3 — 0.4

1986 Cygon" 50EC (16 oz/100) 0.6 1.3 0.6 0.8 — 1.3

Average (1984-1986) 0.6 1.1 0.6 0.9 — 1.0

consistent trend was that holding off treatment until petal fall resulted in
very little reduction in injury. Even so, the best treatments (tight cluster
during 1981-1983 and half-inch-green or early pink during 1984-1986) reduced
fruit injury by only about 50% compared with unsprayed check trees. This
situation was true even though the pesticides used (Ambush", Pydrin", or
Cygon") were among the most effective known against TPB.

Conclusions

We conclude that conducting research on the time of initiation of TPB
injury to fruit in apple orchards and the time at which it is most efficacious
to apply pesticide for TPB control is no less frustrating than attempting to
manage TPB effectively in commercial orchards. Examination of 11 years of
pesticide trial data of numerous researchers in the eastern United States and
Canada reveals a truly incredible amount of variation from locale to locale and
from year to year within a locale in the effectiveness of any given material in
preventing TPB fruit injury. Our 11 years of sampling fruit at harvest in
commercial orchards throughout Massachusetts reveals an equally large variation
in TPB injury and in success at controlling TPB. The data presented here on
tests conducted in the same experimental orchard over 6 consecutive years
likewise are fraught with a high degree of variation, the causes of which are
uncertain. In fact, the picture we now have of how to control TPB effectively
is nearly as unclear as when we began these tests in 1981. It seems to us no
wonder, therefore, that growers have a difficult time dealing with the insect.

If we can conclude anything from the research reported here and from
observations we and others have made in commercial orchards, it is this.
First, initiation of TPB fruit injury may occur any time from tight cluster
through petal fall. Second, populations of TPB in commercial orchards may be
sufficiently great at any time from tight cluster to petal fall to cause
considerable fruit injury. Third, visual monitoring traps have proven over the
years to be sensitive in determining if TPB populations are sufficiently great
to merit possible pesticide application. Fourth, materials such as Cygon" and
pyrethroids are probably the most effective sorts of materials against TPB,
though their use in no way guarantees good control. Finally, if used,
pesticide should be applied against TPB sometime between half-inch-green and
late pink. But, based on the data reported here, we would not want to predict
what the outcome might be. Perhaps, as Rick Weires of the Hudson Valley Lab
and we have pointed out several times, we should be paying less attention to
TPB and more attention to factors such as bruising and mechanical injury to
fruit during harvest and grading. In virtually every Massachusetts orchard we
and others have sampled over the years, bruising, stem punctures and mechanical
injury have been responsible for far more culls (average of 29 bushels per acre
per year) than TPB and all other insects combined (average of 3 bushels per
acre per year) .

•k "k rk "k :k

COOPERATIVF EXTENSION SERVICE

U S DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS
AMHERST MASS 01003

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, S300

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POSTAGE & FEES PAID

USDA

PERMIT N.) G?G8

Fruit Notes

OCT 20 C7

Prepared by: Department of Plant and Soil Sciences

Massachusetts Cooperative Extension, University of Massachusetts, United
States Department of Agriculture and Massachusetts counties cooperating.

Editors: W. R. Autio and W. J. Bramlage

I ' ' ■ ' M C C

Volume 52, No. 3
SUMMER ISSUE, 1987

Table of Contents

Postharvest Calcium Treatments: Reducing the
Risk of Fruit Damage

Establishing a System for Automatic Monitoring
and Control of CA Storages

Pomological Paragraph: Use of Liquid-N,
for O, Pulldown in CA Storages

Does Summer Pruning of Mcintosh Pay?

Pomological Paragraph: Scion Cultivar Affects
Rootstock Shank Rooting

The Second Stage of Apple IPM in Massachusetts

Pomological Paragraph: New Mcintosh Strain Discovered

Integrated Pest Management and Biological Control Potential
for Strawberries in the Northeastern United States

SCIENCES LIBRARY

A New Program for Integrated Pest Management
of Strawberries in Massachusetts

Postharvest Handling of Blueberries

POSTHARVEST CALCIDM TBEATMEMTS: REDUCIHG THE RISK OF FRUIT DAMAGE

William J. Bramlage, Sarah A. Weis, and Patricia A. Shesgreen
Department of Plant and Soil Sciences
University of Massachusetts

Recently, we re-examined the potential benefits and risks from using
postharvest calcium (Ca) treatments ( Proc. Mass. Fruit Growers' Assn. 1986.
92:106-109). To summarize, if the harvested fruit are low in Ca, they have a
reduced storage potential. Postharvest dips or drenches with calcium chloride
(CaCl2) can significantly improve fruit Ca levels and storage potential.
However, CaCl2 dips or drenches can cause spotting of fruit, usually seen as
small, black, sunken areas on the cheeks of the fruit or bronzing at the calyx
end, which may be serious enough to downgrade the fruit. Our earlier
recommendation of 21 lbs of CaCl2 per 100 gallons of water [ Fruit Notes
48(4): 18-19] was excessive and led to an unacceptable amount of spotting. More
recently we have suggested 12 lbs of CaCl2 per 100 gallons of water. This
amount is sufficient to significantly improve fruit Ca levels and potential
storage life, yet greatly reduces the risk of fruit spotting.

During the past several years we have conducted a series of tests to try
to identify factors contributing to the amount of fruit spotting resulting from
postharvest CaCl2 treatments. Here we report the results of these tests.

Time in solution : Most Ca that enters fruit from a conventional
postharvest treatment is taken in slowly over time from a residue. Thus, time
in solution is not a factor for Ca uptake as long as fruit are covered by
solution and a residue is established. In our tests we routinely dip fruit for
20 seconds for uniformity, but a shorter time would be sufficient; there is no
benefit from a longer period. There is some direct entry of solution into the
fruit through openings in the skin surface. These include the calyx canal,
lenticels, and wounds, even ones not visibly apparent. All of these entry
sites are variable among cultivars, handling practices, and growing conditions.

Relative temperatures of fruit and water . Dips and drenches normally
employ cold water. However, fruit temperature can vary greatly. Our early
tests showed that the wanner the apple was at time of dipping, the more Ca it
absorbed. To determine the role of fruit temperature in spotting, we dipped
70°F Mcintosh and compared them with fruit first cooled to 320F. The solu-
tion was initially 50°F, but it either warmed or cooled during treatments,
depending on temperature of the apples. The warm fruit developed much more
spotting than did the cold fruit. The reason for this is probably that when a
warm fruit is plunged into cold water, the air inside the fruit quickly cools
and occupies less volume. This situation creates a partial vacuum that draws
solution into the apple through any openings in the fruit surface. Cells
around these openings are suddenly in contact with a high CaCl2 concentration
and they can be damaged, eventually dying and producing spots. Therefore, if
warm fruit are treated with a CaCl2 solution, a lower rate of CaCl2 may be
needed to avoid spotting. The better approach probably is to cool the fruit at
least partially before treatment or to ensure that the treating solution is at
a temperature fairly near that of the fruit.

Fruit maturity . The characteristics of a fruit surface may change during
maturation. Thus, fruit maturity might affect solution uptake and development
of spots after storage. We harvested Mcintosh early-, mid-, and late-season
(at 1-week intervals) from the same trees and dipped them in a series of CaCl2
solutions with and without diphenylamine (DPA) . Fruit maturity had no effect
on the amount of fruit spotting resulting from these treatments. Thus,
maturity does not appear to be a significant factor in development of spotting.

Addition of DPA . DPA increases Ca uptake from a solution when combined
with CaCl2, as is normally recommended. Why this occurs has not been
established. To find out if DPA increased spotting from Ca treatments we
compared two different CaCl2 concentrations, with and without DPA. We found
that DPA tripled the amount of spotting resulting from a given CaCl2
concentration. We also found that DPA alone caused significant spotting on
Mcintosh, especially around the calyx area. Why DPA increases spotting is
unclear. We tried two different formulations of DPA and got equivalent amounts
of spotting, with and without CaCl2. The recommended rate of CaCl2 use for
postharvest treatments may have to vary, depending on whether or not DPA is
included in the mixture. It should be noted that a number of fruit that were
treated with neither CaCl2 nor DPA developed some spotting after storage,
apparently as a result of latent damage to cells caused by orchard applications
of pesticides. (These trees had not been sprayed with foliar CaCl2.) Clearly,
not all spotting of fruit after storage is attributable to CaCl2 or DPA.

To follow up on these findings, in 1985-86 we conducted a large test in
which we dipped Mcintosh in solutions containing 4, 8, 12, or 16 lbs of CaCl2
per 100 gallons plus DPA, a surfactant, or neither of these materials. After
storage we measured both the increase of Ca in the fruit and the amount of
fruit spotting. As expected, both Ca uptake and fruit spotting increased in a
straight line as the concentration of CaCl2 in the dip solution increased. The
presence of DPA in the dipping solution did not increase the amount of Ca in
the fruit at the end of storage, but it increased the amount of spotting. Use
of the surfactant also had no effect on the final amount of Ca in the fruit,
but increased the amount of spotting, though to a lesser extent than did DPA.

Washing fruit after dipping . A report from Australia stated that treated
apples could be washed 3 days after dipping or drenching; the wash reduced
spotting but not total Ca uptake. To test this approach, we dipped Mcintosh in
12 lbs of CaCl2 per 100 gallons, washed them 1, 3, or 7 days after dipping, and
measured Ca uptake and spotting at the end of storage as compared with similar
samples that had not been washed. Washing 1 or 3 days after dipping greatly
reduced Ca uptake, while washing 7 days after dipping produced less of a
reduction. In this experiment CaCl2 did not increase spotting, whether or not
the fruit were washed. It appears that even if washing controlled spotting,
washing 3 days or less after dipping would nearly eliminate any benefit from
treating with CaCl2. Furthermore, the logistics of washing after dipping could
make this approach prohibitively time-consuming under our storage systems.

Interaction with iron . At a meeting last summer, a colleague from
Australia said that the cause of spotting was actually iron, which was
extracted from metal and put into solution by the CaCl2. At the same meeting,
a report from New Jersey indicated that presence of iron in water was the cause
of damage to peaches following hydrocooling. Thus, we conducted an experiment
to test the possible role of iron in apple spotting.

We set up solutions containing different concentrations of iron, with and
without CaCl2. Iron caused severe spotting, and when it was combined with
CaCl2 the spotting was increased. We also prepared CaCl2 solutions, 12 lbs per
100 gallons, in a plastic bucket and in a rusty metal bucket. The CaCl2
solution in a plastic bucket caused no fruit spotting, but the one in the metal
bucket caused substantial spotting. Our purpose in this test was simply to
find out if this avenue might lead anywhere, and it is obvious that it merits
further study. It is also noteworthy that in the washing experiment, described
above, we had no spotting from 12 lbs of CaCl2 per 100 gallons in 1986-87,
whereas in previous years spotting occurred. The dipping tank used in these
tests is made of galvanized iron and after years of use was starting to rust.
Last summer it was painted, and so the CaCl2 solution in 1986 was no longer in
direct contact with iron. Further tests must be made to establish the
importance of iron in this problem but the implications are consistent with the
comments of our Australian colleague, who said that eliminating metal tanks
solved their spotting problem.

In conclusion, it must be reaffirmed that a postharvest treatment with
CaCl2 can significantly increase storage potential of apples. It appears that
12 lbs of CaCl2 per 100 gallons of water is a reasonable compromise, increasing
fruit Ca levels significantly with a relatively small risk of spotting. (Note
that our assessment of spotting is very intense. Most of our "spotted" fruit
would still be in grade.) The CaCl^ must be Briner's Grade or purer , since it
is considered by authorities to be a food additive. The solution must contain
an appropriate fungicide, or mixture of fungicides, or severe rotting can
result. DPA or ethoxyquin can be applied with the CaCl2. We suggest adding 1
pint of vinegar per 100 gallons of solution to protect against possible adverse
effects of a high pH due to the CaCl2 ( Fruit Notes 50(2) : 18-20) .

We suspect that spotting results from the solution that enters the fruit
openings during the dip. Our studies show that spotting is increased when DPA
or a surfactant is included in the mixture, when the fruit are significantly
warmer than the solution, or when substantial levels of iron are present in the
solution. Under these conditions, perhaps the CaCl2 should be reduced to 8 or
10 lbs per 100 gallons.

We shall continue with these studies, to try to find conditions under
which the risk of fruit spotting from postharvest CaCl2 treatments can be
minimized or eliminated. These treatments have great value in increasing
storage life potential, and are extremely useful as a final technique when you
recognize at harvest time that a Ca problem exists. They are used routinely by
some Massachusetts growers, and are used extensively for apples in many parts
of the world. Their use should not be ruled out because of a fear of fruit
damage. However, they must be used with care, just as with any other chemical
application.

*****

ESTABLISHING A SYSTEM FOR AUTOMATIC MONITORING AND
CONTROL OF A CA STORAGE

Katrin Kaminsky and William J. Bramlage
Department of Plant and Soil Science

and

Ernest A. Johnson
Department of Food Engineering
University of Massachusetts

The Orsat gas analyzer is used almost exclusively in New England to
determine the concentrations of oxygen (O2) and carbon dioxide (CO2) within a
controlled atmosphere (CA) storage. Control of these levels is performed
manually by the storage operator. Although the Orsat method is inherently
accurate, the procedure itself for sampling and measuring the atmosphere in the
rooms contains much opportunity for human error. Also, since this operation is
time-consuming, atmospheres are generally measured and adjusted no more often
than once per day. Under this type of management considerable fluctuation of
the storage atmosphere can occur, and problems can go unnoticed or uncorrected
for some time. To compensate for these potential problems, significant margins
of error are incorporated into standard CA recommendations. Even so, serious
errors in atmosphere maintenance are still common.

There are alternatives to the Orsat method of measuring storage atmosphere
composition. Electronic devices for measuring O2 and CO2 are widely available.
A system using these devices to frequently and automatically measure O2 and CO2
levels was developed in England, and quickly was expanded to provide automatic
adjustment of O2 and temperature when they exceeded set tolerance levels. More
recently, automatic adjustment of CO2 has also been developed. These systems
are controlled by a programmed computer, and can be purchased as "package"
units. However, the costs of such units is discouraging for operators of the
relatively small storages that are typical of the New England apple industry.

Another alternative is the "user-built" system, in which a user assembles
his own system from available components, developing a system to meet his needs
and to stay within his financial resources. Such a system employs separate
components which are available for O2 and CO2 analysis, a personal computer for
data handling and initiation of sampling, measuring, and controlling devices,
and the necessary pump, valves, and relays to facilitate the whole process.
This approach has been applied successfully to both research and commercial
systems at a cost less than that of a package system.

It is our conviction that automatic monitoring and controlling of CA
storage atmospheres can significantly improve operation of New England apple
storages. To establish a demonstration, "user-built" system for use with the
storage rooms at the Horticultural Research Center, Belchertown, last year we
received a grant from the Massachusetts Society for Promoting Agriculture.
During the 1986-87 season, we assembled and operated this system. It is the
purpose of this article to describe the system and provide an initial
assessment of its operation.

The Horticultural Research Center contains five storage rooms, four of
which are normally operated as CA rooms; two rooms have a capacity of 2500
bushels each and the other two have a capacity of 600 bushels each.
Previously, temperature has been monitored by a single mercury thermometer
placed inside the door of each room, and any adjustment of temperatures has
been done manually. O2 and CO2 were measured daily with a single Orsat
analyzer, samples being drawn from each room with an electric pump. O2 was
added as needed by operating a controlled leak in the door, and CO2 was
scrubbed when necessary using a lime box. O2 pulldown was achieved with a
liquid-N2 system.

The system established in 1986 was as follows. Temperature monitoring was
upgraded by installing multiple thermocouples in each room, following Cornell
University recommendations (Cornell University Agricultural Engineering
Extension Bulletin 430). A coimnercially available paramagnetic O2 analyzer and
a commercially available infrared CO2 analyzer were obtained to replace the
Orsat analyzer. These electronic measuring devices were supplied with air
drawn from a room by a new electric pump through the copper sampling lines that
previously supplied the air for the Orsat. The existing solenoid valves on
these lines were wired via a relay board to a conventional personal computer.

A commercially available software package, designed for use in automatic
monitoring and controlling systems, was set up so that an air sample was drawn
hourly from each room and passed through the O2 and CO2 monitors. Analyses
were recorded on both a disc and on a print-out. Also, at each sampling time,
temperature at one thermocouple in each room was measured and recorded. Later
in the season a dewpoint indicator was purchased for humidity measurement, and
subsequently each sample was also measured for relative humidity and these data
were also recorded. Thus, an hourly record of O2, CO2, temperature, and
relative humidity within each room was automatically obtained. (The system
could have been programmed for either more frequent or less frequent sampling
or recording.)

The system can be programmed so that adjustments of temperature, O2, and
CO2 can be made automatically when the measured values exceed previously
established limits. For example, a temperature of 37°F might be desired and
the program might change the temperature control setting if it falls below
36.5°F or rises above 37.5°F. In our first season we continued to control
temperature manually and to operate the lime box manually. However, O2 control
was automated. Each room possessed 4-inch PVC inlet and outlet lines fitted
with large solenoid valves. A cylinder of N2 gas and a squirrel cage fan were
attached to the inlet manifold. The system was programmed so that when an O2
reading fell below 2.5% or rose above 3.5%, the control system was activated
via the relay board. This system vented either air or N2 into the room,
depending on whether O2 was too low or too high. Outlet valves were also
opened automatically to relieve the positive pressure caused by air or N2
addition to a room.

The system worked reasonably smoothly, given that this was its first year
of operation and we were developing it as time and availability of supplies
permitted. During the summer we shall complete some unfinished wiring and
plumbing, and we anticipate that we shall go into the 1987-88 season with a
completed system and with the operators now being familiar with the operation
and the equipment. The operators had little previous experience with computer

operation.

A detailed assessment of the operation of this system versus that of an
Orsat-monitored system will be published later. However, an obvious benefit
was the time-saving achieved by automatic monitoring of atmospheric conditions
in the CA rooms. This savings was especially appreciated during the initial
pull-down period. At this time, the hourly program was deactivated and a
continuous O2 reading was taken for the room being flushed with liquid-N2.
This allowed the operators to watch the changes in O2 level as the liquid-N2
was metered into the room.

Total cost of the equipment was approximately $8500. However, the
dewpoint indicator cost $1300 and was included in our system for research
purposes. Likewise, our system has greater control capability built into it
than a commercial operator might desire, since we may wish to completely
automate controls for research purposes.

The establishment of this system has created the opportunity for us to
demonstrate the feasibility and advantages of automatic CA operation. This is
neither a new idea nor new technology. Similar — and often more sophisticated —
systems are in commercial use in many parts of the world. Our objective in
this project is to lead the way in upgrading New England storage operations to
the level of many of the area's competitors, and through better storage
operation to provide a higher quality apple for the market.

*****

PCMOLOGICAL PARAGRAPH

Use of Liquid-N2 for O2 Pulldown in CA Storages

William J. Bramlage

Department of Plant and Soil Sciences

University of Massachusetts

During the past two years a number of New England CA storage operators
have used liquid-N2 for O2 pulldown. At the Horticultural Research Center,
Belchertown, we have used this system and have been very pleased with the
results (Proc. Mass. Fruit Growers' Assoc. 92:102-105). Dr. James A. Bartsch
of the Department of Agricultural Engineering, Cornell University, recently
published a factsheet entitled, "Creating a Low Oxygen Atmosphere with Liquid
Nitrogen." This information should be of interest and value to anyone using
this system or considering use of it. The factsheet "Agricultural Engineering
Facts, EF-9" can be obtained from William J. Bramlage, Department of Plant and
Soil Sciences, French Hall, University of Massachusetts, Amherst, MA 01003.

*****

DOES SUMMER PRUNING OF MCINTOSH PAY?

Duane W. Greene, Wesley R. Autio, and William J. Bramlage

Department of Plant and Soil Sciences

University of Massachusetts

The uncertainties about the future of Alar* and the possibilities of
adverse results on animal feeding studies led many growers in 1986 to use no
Alar* or a reduced amount of Alar* last year. A number of suggestions were
made last year to help growers cope with reduced Alar* use, and summer pruning
was listed as one of the procedures available to growers to help alleviate
problems associated with the nonuse of Alar*. Last year a summer pruning
experiment was conducted at the Horticultural Research Center using mature
Mcintosh trees. The results of this experiment are reported here.

There is a direct relationship between the amount of light a fruit
receives and red color development. Fruit that are exposed to direct or near
direct sunlight will develop red color early and the intensity of the color
will be great enough so that these fruit can be harvested as U.S. Extra Fancy.
Alar* has been indispensible to growers in controlling drop and retarding
ripening until fruit develop sufficient red color to be sold as U. S. Extra
Fancy. In the absence of Alar* fruit may fall to the ground before they
develop sufficient red color. If light penetration into the tree can be
increased by appropriate pruning techniques, fruit may develop red color early.
This early coloring would do two things. First, it would allow early harvest
of fruit that would have the potential for long-term storage. Secondly, it
would allow the harvest of a larger percentage of the crop as hand picked fruit
rather than as drops.

A block of mature Mcintosh on M. 7 rootstock that received no Alar* in
1986 was selected, the summer pruning treatments were randomized, then half of
the trees were summer pruned during the 3^*^ week in August. Only 1-year-old
wood and unproductive wood were removed. It required about 25 minutes for one
person to summer prune each tree. The first harvest on these trees was on
September 10.

Large cuts, particularly in the tops of trees, should not be made during
the summer. Falling branches, heavy with leaves and developing fruit, can
severely bruise fruit below. For summer pruning to be truly effective, large
thinning-out cuts must be made during the dormant period. These cuts will open
up a tree. The summer pruning further increases light penetration by removing
some of the current season's growth and unproductive wood.

There were many positive effects following summer pruning (Table 1).
Fruit on summer pruned trees had more red color, considerably more of them
graded U. S. Extra Fancy, and a much larger percentage of the crop was
harvested during the first picking (September 10). Because a larger percent of
the crop was harvested the first time, there were fewer drops and more hand-
picked fruit from the summer-pruned trees. Summer pruning did not influence
the total yield on these trees. However, approximately 2 more bushels of fruit
per tree were harvested as hand picks rather than as drops.

Table 1. Effects of summer pruning on Mcintosh fruit.

Parameter

Summer pruned

Not summer pruned

Change (%)

Red color (%) 57

U. S. Extra Fancy (%) 72

Crop harvested l^t pick (%) 79

Crop harvested by hand (%) 81

Drop (%) 19

Dormant pruning time (min/tree) 11

49
42
59
70
30
17

+ 16
+ 71
+34
+ 16
-37
-40

Did summer pruning pay? Let us assume a price of $1.60 per bushel for
drops and $8.00 per bushel of hand picks. There were 144 more bushels of hand-
picks per acre from summer-pruned trees with an additional return of $932.00.
It would take a pruner about 30 hours per acre to do a good summer pruning job
on these trees. Unless a grower pays his workers $31.00 or more per hour,
summer pruning more than paid for itself. This figure is conservative because
it required 40 percent less time to prune summer-pruned trees during the
dormant season, thereby producing additional savings. We feel that summer
pruning is a procedure that should be part of every grower's maintenance
program on mature trees, especially if Alar* is not used.

*****

POMOLOGICAL PARAGRAPH

Scion Cultivar Affects Rootstock Shank Rooting

Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

Many nurseries bud apple trees on certain rootstocks 12 to 18 inches above
the soil line. When these trees are planted in the orchard a large portion of
the originally above-ground rootstock material must be buried. The philosophy
behind this practice is that rooting along the long, buried shank may improve
the anchorage of the tree and reduce requirements for staking. However, in
some cases rooting does not occur and a less stable condition results than if
the trees were budded at a lower height and planted only slightly deeper than
they were in the nursery. A reason for this lack of rooting is given by Roy
Rom and George Moticheck in a study published this year (HortScience 22:57-58).
They found that the scion cultivar was the major factor affecting rooting along
the buried rootstock shank. In general, nonspur cultivars resulted in
significantly more rooting than did spur-types, possibly explaining the poor
shank rooting which has been observed with some trees.

*****

THE SECOND STAGE OF APPLE IPN IN MASSACHUSETTS

Ronald J. Prokopy

Department of Entomology

University of Massachusetts

Through 1977, most Massachusetts apple growers controlled apple insect
pests by making insecticide applications every 10 to 14 days, irrespective of
whether pest insects were present in sufficient abundance to merit such
treatment. From 1978 through 1982, our College received funds from a 5-year
federal Cooperative Extension Service grant to initiate a pilot program of
integrated pest management (IPM) in Massachusetts apple orchards. The
entomological part of the program had 3 major objectives: to promote the
buildup of natural populations of beneficial predators; to reduce pesticide
use; and to maintain or increase the high quality and quantity of fruit
produced. Our overall entomological approach to achieving these objectives lay
in intensive, careful monitoring of pest and beneficial, natural enemy
population abundances in participating IPM orchards, and in advising IPM
growers of need, optimal timing, and type of pesticide to be applied.

The results of this pilot program were highly encouraging. In fact, they
were so encouraging that 2 biologists in the program decided to form a private
IPM-consult antship business: "New England Fruit Consultants". From 1983
through 1986, NEFCO has been very active in providing IPM services to a
substantial number of Massachusetts apple growers. "Boston IPM", though active
largely in Vermont, has also provided IPM services to a few Massachusetts
growers. In 1986, about one-third of the apple acreage in Massachusetts was
serviced by these private consultants. In addition, results of a recent survey
we conducted [ Fruit Notes 51(2):11-16 and 51(3):19-25] indicate that more than
two-thirds of Massachusetts apple growers now employ IPM practices.

To what degree have IPM practices benefited Massachusetts apple growers?
Table 1 presents a summary of the amount of pesticide used each year in
Massachusetts IPM apple orchards from 1977 through 1986.

These results show that compared with pesticide use before the pilot
program, there was (on average) a 37% reduction in insecticide use and a 61%
reduction in miticide use during the pilot program (1978-82) and a 43%
reduction in insecticide use but essentially no change in miticide use in
orchards serviced by private consultants (1983-86). On average, fruit quality
in IPM orchards has equalled or exceeded that realized before the start of the
program. Finally, the growing of "healthier" (less-pesticide-treated) apples
and the reduced amount of spray drifting from the orchard into the neighboring
environment has created a favorable public image for IPM growers. It can be
concluded, therefore, that this first stage of IPM in Massachusetts apple
orchards has been a success.

The second stage of apple IPM is aimed at employing new pest control
methodologies to achieve a further reduction in pesticide use. The first stage
has relied on intensive monitoring of pest and beneficial predator abundances
and subsequent judicious application of needed, selective pesticides least
harmful to predators. In our opinion, this stage has taken us about as far as
it can in terms of pesticide reduction. The second stage will rely on

10
Table 1. Pesticide use in Massachusetts IPM apple orchards,

Dosage equivalents of

No.
orchards

Year or blocks Insecticide Miticide

1977 (Before IPM) 16 9.1 1.8

1978 (IPM pilot prog.) 8

1979 " " 16

1980 " " 18

1981 " " 19

1982 " " 36

1983

(Priv.

consults . )

1984

1985

1986

6.4

0.9

6.0

0.4

4.8

0.8

6.2

0.4

5.5

0.9

6.0

1.3

5.5

2.0

5.1

2.5

4.6

1.7

Dosage equivalent = actual amount of pesticide used divided by amount

recommended in Pest Control Guide.

Does not include oil spray against overwintering mite eggs.

knowledge gained of the behavior and ecology of pests and beneficial predators
and on employment of behavior-manipulation techniques as a substitute for use
of most pesticide treatments.

For the past 6 years (1981-86), one form of this second stage of apple IPM
has been used at my small (50-tree) orchard of disease-resistant apple trees in
Conway, MA. The approach has been as follows: (a) application of a pre-bloom
oil treatment against overwintering San Jose scale and eggs of the European red
mite; (b) 2 applications of Imidan (one at petal fall and another 10 to 14 days
later) for control of European apple sawfly, plum curculio, and first-
generation codling moth; and (c) use of red-sphere visual traps (1 or 2 per
tree) to capture and thereby control apple maggot fly adults. Table 2 is a
summary of the average percent (1984-86) of clean and insect-injured fruit on
the experimental orchard trees compared with several neighboring (200 meters
away), unsprayed trees.

This use of only 2 dosage equivalents of insecticide (compared with 5 to 6
in the average first-stage IPM orchard and 9 in non-IPM orchards) is not the
only benefit realized. The absence of any insecticide use from 10 to 14 days
after petal fall (early June) through the remainder of the growing season has
allowed key predators and parasites of mites, aphids, leafhoppers, leafminers,
and San Jose scale to flourish during summer months. The result has been no
need to make any application of miticide or other pesticide for control of
these secondary pests. In our opinion, this result strongly suggests that the

Table 2. Percent clean and insect-injured fruit from experimental and
unsprayed apple trees.

Experimental Neighboring

orchard trees unsprayed trees

Percent clean fruit 93.7

Percent injury by:

Plant bug 1.6 2.7

Sawfly 0.6 8.7

Curculio 3.5 96.0

Codling moth 0.5 58.0

Leafrollers 0.3 13.7

Apple maggot 0.2 82.3

Other 2.3

problems experienced even in IPM orchards with outbreaks of mites and other
secondary pests are due in substantial part to detrimental effects on
beneficial predators and parasites as a result of insecticide, fungicide or
herbicide applications (even judicious use of selective materials) from June
onward.

Can this approach used in the Conway experimental orchard be transferred
directly and successfully to larger commercial orchards? We doubt that it can
because of the amount and cost of labor that would be required to place and
maintain apple maggot traps in every apple tree. But variants of this approach
that are derived from knowledge we and others have gained of the behavior of
key apple pests over the past decade could prove successful. Thus, our recent
research on the host-finding behavior of sawfly, plum curculio, and apple
maggot adults has suggested that individuals entering an orchard from unsprayed
trees in nearby woods or hedgerows are most likely to visit first those apple
trees that are at the perimeter of the orchard and then gradually move into
interior trees. Because sawfly, plum curculio, and apple maggot populations,
as well as populations of every other key pest attacking apple fruit, originate
almost exclusively on unsprayed trees outside the orchard, intercepting these
insects at the perimeter of the orchard with traps (or spraying insecticide or
egg-laying deterring chemicals on the perimeter trees to prevent immigration
into the interior of the orchard) could constitute an effective variant of the
approach used in the Conway experimental orchard and allow us to enter the
second stage of IPM in Massachusetts apple orchards.

At present, the only truly effective traps for direct control of a key
apple pest are traps for capturing apple maggot flies. Visual traps developed
for plant bug, sawfly, and leafminer adults are effective for monitoring
occurrence of adults and are being used extensively in first-stage IPM apple
orchards, but they have not proven effective as yet for direct control.
Chemicals that deter egglaying (either pheromones emitted by the adults or
chemicals emanating from plant tissue wounded by egglaying females) are now
known, from our recent research, to exist in sawfly, plum curculio, and apple
maggot. None of these chemicals has yet been identified as to structure or has

been synthesized. Thus, it will be some time yet before they are available for
use. Sex pheromones for codling moth and most pest species of orchard
leafrollers have been identified by Wendell Roelofs and his colleagues at
Geneva, New York, and have been applied in massive amounts in and around
experimental apple orchards in an attempt to disrupt mating behavior and
thereby reduce numbers of larval progeny attacking fruit. But this approach
will require considerably more work before it is ready for implementation in
commercial orchards.

Thus, the picture appears rather bright for behavior-based management of
many key apple fruit pests in the future. In the meanwhile, it may be possible
at least to begin the second stage of apple IPM using knowledge and techniques
presently available.

Toward this end, we have received support from the Massachusetts Society
for Promoting Agriculture to carry out a 3-year experiment in several
commercial apple orchard blocks in which (a) all insecticide and miticide
spraying of the interior of each block would cease at the end of May (following
1 pre-bloom and 1 or 2 post-bloom treatments), and (b) the perimeter of each
block would be managed in such a way as to prevent immigration of key apple
pests into the interior from June until harvest. The perimeter management
techniques would be either (a) placement of sticky-coated, apple-odor-baited
red sphere traps for apple maggot flies in perimeter trees or adjacent woods,
or (b) application of insecticide to perimeter apple trees every 2 weeks from
June until harvest.

We realize this experiment of extreme reduction in insecticide use
involves high risk of some amount of insect injury to the fruit. At the same
time, we believe that if we do not venture forward into the unknown, we have
little chance of moving beyond present pest management practices.

*****

P(»10L0GICAL PARAGRAPH

New Mcintosh Strain Discovered

Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

A new Mcintosh strain (EG506 — Adams County Nursery) has been discovered in
the Hudson Valley of New York which is reported to ripen later than normal and
to hold on the tree for a longer period of time. We will be establishing a
planting of these trees in 1988 and will compare them with standard strains of
Mcintosh. If this strain acts as reported then it may be of great value in
expanding the Mcintosh harvest season.

*****

INTEGBATED PEST MANAGEMENT AND BIOLOGICAL CONTROL POTENTIAL
FOR STRAWBERRIES IN THE NORTHEASTERN UNITED STATES

David T. Handley
University of Maine

Strawberry producers in the northeastern United States are faced with a
number of arthropod pests with which they must compete in order to produce a
profitable crop. Applications of chemical pesticides has been the standard
method of control for many years, but is now being re-evaluated in view of
increasing costs, environmental contamination, the development of insect and
mite resistance, and the disruption of natural enemy complexes. Integrated
pest management (IPM) programs, developed for many major agricultural crops,
can improve pest control efficiency by exploiting all possible means of
management, including cultural, biological, and chemical, resorting to the
latter only when nonchemical methods cannot maintain pest populations below a
specific economic injury level. IPM may hold potential for strawberries grown
in the Northeast, but alternatives and supplements to chemical pesticides are
presently few.

Cultural control techniques for strawberry pests include sanitation, e.g.
removing dead plant material and weeds that may harbor pests, adjusting
planting times or patterns to avoid peak pest populations, crop rotation, trap
crops, and mechanical control, such as burning or flooding. Strawberry
production has incorporated some cultural control measures into the general
management scheme, such as rotation with other crops that do not share the same
pest complex, and renovation, during which disease-infected foliage and insect
overwintering sites are destroyed or tilled into the soil. The time of plowing
under old beds can affect the status of overwintering pests species. The use
of trap crops has received little attention for strawberry pests, but may offer
a means of reducing early outbreaks of some insects (9). Physical barriers are
effective against some insects, but generally have been considered too
expensive or labor intensive to be used (4). However, the recent introduction
of lightweight, synthetic row covers and application machinery may stimulate a
re-evaluation of this technique. Strawberry plant resistance to certain pest
species such as root weevils, aphids, and spider mites has been observed. To
date, however, this is not thought to provide economic control (1,7,10).

Biological control refers to the use of natural parasites and predators of
insect pests to maintain populations below economic thresholds. This technique
may involve searching out and importing exotic, natural enemies, and/or using
conservation and augmentation techniques to increase the effectiveness of
natural enemies, whether native or imported (3).

Several problems are inherent with the practical application of biological
control of northeastern strawberry pests. The strawberry plant is native to
the northeastern U.S. The wild strawberry, Fragaria virginiana , is thought to
be a parent of the now popular cultivated strawberry, Fragaria ananassa (2).
Therefore, a native pest complex exists that is both established and well
adapted. This situation greatly reduces the probability of finding effective
exotic natural enemies. In nearly every successful example of control using
exotic natural enemies, the pest itself was exotic. Furthermore, success with
exotic natural enemies usually occurs in salubrious, stable, and undisturbed

environments (3), none of which are characteristic of northeastern strawberry
plantings .

Utilizing conservation techniques for native natural enemies could prove
more rewarding. Chief among these would be the reduction of nonselective or
broad-spectrum pesticide use. Despite their effectiveness on a given pest
species, these materials can destroy natural enemy populations, initiating a
resurgence and possible population explosion for certain pests, including some
not previously considered economically damaging.

The effectiveness of native natural enemies is hampered by other problems
as well. Due to long coevolut ionary relationships, pest species likely
developed resistance mechanisms to most parasites, and the parasites themselves
may be plagued with hyperparasites . Native predators may provide some control
of strawberry pests. The root feeding larvae of weevils and scarabs are
attacked by birds and rodents, but these may themselves damage plants.
Predatory beetles also feed on pest larvae, tarnished plant bugs, and mites
(9). These predators are relatively nonspecific feeders, however, and are
thus less effective as control agents of a specific pest. Because they are
native, they will also have their own natural enemies, which will keep their
populations, and hence control potential, in check.

Augmentation of natural enemies, whether native or imported, involves
manipulation of the population such that control of the pest species is
improved. Typically, this is accomplished by rearing natural enemies
artificially and releasing them, either inundatively or as an inoculative
population (3). Such approaches are usually quite expensive and may not be
justifiable on a minor crop such as strawberries.

One of the most important barriers facing biological control potential in
strawberries is the relatively high value of the crop. Very small amounts of
damage may have significant economic effects due to the high cash return of
strawberry fruit. Therefore, when an economic injury threshold is determined,
it will be quite low, meaning only small pest populations need be present to
justify control measures (9). These thresholds may require pest numbers to be
below a level required for the natural predators to remain viable. This
condition would necessitate supplementary chemical applications, probably
causing greater harm to the natural enemies, or repeated inundative releases of
the natural enemy, much like a "biological insecticide".

Perhaps the most promising use of biological control in strawberries to
date is against phytophagous mites. In California, cyclamen mite has been
effectively controlled with Typhlodromus species. These native predatory mites
can provide adequate control without manipulation, but typically not until the
third year of a planting. To achieve control in first and second year beds,
the predator must be stocked. Research also suggests that stocking young
fields with cyclamen mite along with Typhlodromus could improve establishment
and effectiveness of the predator (6). Strawberry growers were not receptive
to this idea, and have since adopted an annual system of production which
eliminates the need for such controls. Strawberry plantings in the Northeast
are still maintained for several years, however, allowing cyclamen mite
populations to reach damaging levels. Although it is unlikely that the
predatory Typhlodromus could successfully overwinter, inundative releases of
the predator at specific pest population thresholds potentially could bring

about substantial control.

Successful control of the twospotted spider mite has also been achieved
with a predator. Releases of the mite Phytoseiulus persimilis before spider
mite populations attained an average of one mite per leaf provided effective
control in California (8). This predatory mite has also been used successfully
in greenhouses and under row covers (5). Control is temporary as the mite
completely eradicates its prey and therefore its food source under these
conditions. Similar to the Typhlodromus species, P. persimilis would not
likely survive the climate extremes of the Northeast. This would necessitate
annual releases of the predator, and the cost required may be prohibitive.

Despite inherent difficulties, biological control has some potential as a
component of an integrated pest management program for strawberries in the
northeastern United States. Research is needed to determine the effectiveness
of native natural enemies and the existence of exotic species. The strawberry
root weevil for example, is thought to have come originally from Europe, yet no
efforts have been reported to seek natural enemies there. Some strawberry
pests, including leaf rollers and aphids, are already known to be controlled
effectively by natural enemies (9). Only minor manipulation or alterations
may be required to bring about much greater biological control of other
species.

The increased exploitation of biological control agents, combined with
proper cultural practices and improved application strategies for chemicals,
could greatly increase pest control efficiency in strawberries and hence,
profitability. In addition, such an integrated proeram likely would reduce the
amount of pesticides used, and thereby reduce the potential hazards of frequent
and repetitive pesticide use.

References

1. Barritt, B.H. and C.H. Shanks. 1980. Breeding strawberries for
resistance to the aphids Chaetosiphon fragaefolii and C. thomasi .
HortScience 15:823-825.

2. Darrow, CM, 1962. The strawberry. Holt, Rhinehart and Winston. New
York. 447 pp.

3. DeBach, P. 1974. Biological control by natural enemies. Cambridge
University Press. London. 323 pp.

4. Downes, W. 1931. The strawberry root weevil. Can. Dept. Agric. Pamphlet
no. 5. 2nd ed.

5. Gould, H.J. and J. Vernon. 1978. Biological control of Tetranychus
urt icae (Koch) on protected strawberries using Phytoseiulus persimilis
Athais-Henroit. Plant Path. 27: 136-139.

6. Huffaker, C.B. and C.E. Kennett. 1956. Predation and cyclamen mite
populations on strawberries in California. Hilgardia 26(4): 191-222.

7. Kishaba, A.N., V. Voth, A.F. Howland, R.S. Bringhurst, and H.H. Toba.
1972. Twospotted spider mite resistance in California strawberries. J.

Econ. Entomol. 65: 117-119.

8. Oatman, E.R., J. A. McMurtry, and V. Voth. 1968. Suppression of
twospotted spider mite on strawberry with mass releases of Phytoseiulus
persimilis . J. Econ. Entomol. 61: 1517-1521.

9. Schaefers, G.A. 1981. Pest management systems for strawberries. pp.
377-393. In: Handbook of pest management in agriculture. D. Pimentel,
ed. CRC Press. Boca Raton, Fla. 501 pp.

10. Shanks, C.H., D.L. Chase, and J.D. Chamberlain. 1984. Resistance of
clones of wild strawberry, Fragaria chiloensis , to adult Otiorynchus
sulcatus and 0. ovatus . Environ. Entomol. 13:1042-1045.

•k i< -k -k -k

A NEW PROGRAM FOR INTEGRATED PEST MANAGEMENT OF STRAWBERRIES

IN MASSACHUSETTS

Daniel R. Cooley, Karen Hauschild, and Sonia Schloemann
University of Massachusetts

Last fall, -an integrated pest management program for strawberries was
funded by the University of Massachusetts Integrated Pest Management (IPM)
program. This article is intended to give a brief outline of the proposed
program, and invite comments from interested parties.

Strawberries offer a unique opportunity for integrated pest management,
for a number of reasons. Note that strawberries suffer important damage from
all pests: diseases, weeds, and insects. We intend to use the term pest in its
broadest sense, encompassing any agent which necessitates pesticide
applications .

In assessing the potential for strawberry IPM, we saw that while acreage
on a given farm is not generally large, the number of small farms producing
strawberries has steadily increased in recent years. As a result, there are a
number of new strawberry growers in the state. In addition, strawberries
require relatively frequent applications of pesticides in order to produce
well. This situation is complicated because only a few fungicides are
registered for use on strawberries, and the future utility of these compounds
is threatened because registration may be removed, fungus resistance has
developed, some of the pesticides used on strawberries are potential
groundwater contaminants, and some may affect non-target beneficial insects.
Also, strawberry growers frequently sell their crop to "pick-your-own"
customers, giving the public exposure to not just the product, but the fields
in which it is grown. And finally, many strawberry pests have also been studied
in recent years, either on strawberry or as pests of other crops. The general
biology and suggestions for innovative management strategies for these pests
have been developed, but have not been applied generally to commercial
strawberry production. Massachusetts is in a strong position to use this
knowledge since the three regional fruit agents all have an active interest and
good backgrounds in small fruit.

A few years ago, experience in developing and publishing the New England
Guide for Managing Diseases and Insects of Small Fruits (3) showed that there
was not a great deal of current knowledge on strawberry pest control. However,
a recent survey (5) has identified the most important pathogens. Several fungi
contributed to berry rots, and several other fungi contributed to root rots.
The most significant fruit pathogens (and the diseases they cause) were
Botrytis cinerea (grey mold), Phytophthora cactorum (leather rot), Haines ia
lytheri (tan brown rot), and Phomopsis obscurans (berry blight). The etiology
of each of these pathogens is distinct, but in general wet weather and
increasing fruit maturity cause more disease development. In unmanaged
situations, fruit rots can destroy the entire crop. Even using recommended
controls, adverse conditions can cause significant crop loss. For example,
gray mold causes between 20% and 60% loss in Quebec, depending on weather (4).
Leather rot losses in Ohio approached 40% in commercial beds in 1980 and 1981
(6). Gray mold is endemic in strawberry fruit, and Botrytis was frequently
isolated from all beds in the Massachusetts survey. Leather rot was also
frequently observed.

The most damaging strawberry insect and weed pests in Massachusetts have
not been determined. According to growers, the most important insect pests are
tarnished plant bug ( Lygus lineolaris ), strawberry bud weevil or clipper
( Anthonomus signatus ), white grubs ( Phyllophaga spp.), and strawberry root
weevil ( Otiorhyncus ovatus ). There is little doubt that tarnished plant bug is
the major contributor to misshapen strawberries (8).

Several weeds cause economic problems in strawberries, including several
grass species, Galinsoga, and thistle. Though growers cite these as the
problem weeds, it is not clear whether this is the case, and if so, how much
damage is caused. However, it is clear that weeds are a major factor causing
beds to be taken out of production.

Previous work supplies some tools to start an IPM program. Gray mold
epidemiology is partially understood. One study has shown that floral and
pedicel infections early in the season are more important to future berry
infections than direct infections occurring at or near harvest (7). A few
applications of a fungicide early in the season may be as effective as a series
of applications from bloom through harvest. Such applications could be made
more efficient by applying epidemiological data from Quebec which indicate that
temperatures from 15 to 20°C and relative humidities from 90 to 100% for at
least 28 hrs . are optimal for gray mold epidemics (4). An experimental model
for gray mold pressure is in the process of being published (1). A similar
model of temperature and moisture effects on leather rot infection has been
published recently (6).

Another element in a fruit rot control program would involve studying
fungicide retention and redistribution. Presently, growers often apply
fungicides every 3 to 5 days around harvest if weather is wet, on the
assumption that this will increase protection against berry rots. On apples,
captan remains effective for 1 week regardless of rain (9). Frequent
applications of fungicide around strawberry harvest may be useless.

Insect monitoring would be a key element in the program. Initial work
indicates that tarnished plant bug traps similar to those used in apple IPM (2)
could be successful in strawberry. One technique, using non-visual traps, has

suggested an economic threshold level of 1 nymph per 25 flower clusters, which
would provide a starting point for insect monitoring techniques (8).

Techniques for reducing herbicide use remain poorly developed in all
crops. To date, there has not been even a survey of the major weed species
affecting strawberry beds, though a survey is planned for this year. It may be
possible to reduce herbicide use in new plantings by using a dieback cover crop
during the previous season. Spot treatments rather than broadcast treatments
may be an effective way to reduce herbicide use post-planting.

Anecdotal evidence and experience in other IPM programs in the state
indicate that spray coverage may be one of the most important sources of error
in pest management. This can be caused by inaccurate calibration, or by
inappropriate equipment and calculations. Such problems could be examined
immediately.

At the outset, we have proposed a number of specific objectives for the
program.

1. Use crop development and weather data to time fungicide applications for
fruit rot control, and compare the results with typical calendar-based
timing.

2. Use insect monitoring techniques on three major strawberry pests,
tarnished plant bug, strawberry bud weevil, and two-spotted mite, in order
to time pesticide applications on the basis of the presence or absence of
the pest, and develop information for economic threshold levels.

3. Determine what weed species are important in strawberries in
Massachusetts, and determine the efficacy of present control
recommendat ions .

4. Test alternative fungicides against fruit rots, develop improved timing
for fungicide application via epidemiological data, and test alternative
cultural practices designed to reduce fruit rot.

5. Examine present sprayer calibration and equipment, and determine whether
inaccuracies or inappropriate techniques exist. If they do, suggestions
on how to improve sprayer efficiency and calibration will be made.

6. Develop appropriate expert system delivery systems for the IPM
information, using the INFONET electronic mail system to access Regional
Extension staff and interested growers.

7. Distribute pest messages on current status of pest problems and crop
development on a weekly basis prior to and during harvest, and at longer
intervals as needed thereafter.

The first year of the program we are concentrating on a survey of current
pest management practices, and beginning the testing of reduced pesticide
recommendations. With a limited number of growers in the Connecticut Valley,
we have established small sections of fields which will be treated as IPM
plots. These plots will be treated separately from the rest of the grower's
field. These plots will also be areas where pest pressure is most intensively

studied.

For example, this year there are a number of colored traps in place to
test the effectiveness of various colors in monitoring tarnished plant bug
populations. Fungicides will be applied according to flowering and berry
development, while Botrytis (the primary berry rot fungus) will be monitored on
last year's leaves and the developing flowers and fruit. Similar monitoring
will be done in non-IPM plots. It will also be possible to test the validity
of a new gray mold model (1). Weed species and numbers will be evaluated in
plots, and the herbicide practices of growers will be determined. The
comparison of pest pressure in IPM and non-IPM plots will allow us to evaluate
which practices are the most effective with the least pesticide impact. This
information will define directions for pest management practices which will be
refined in the following seasons.

We are at the beginning of the program. At this stage, we welcome the
comments and advice of any interested people.

References

1. Bulger, M. A., L. V. Madden, and M. A. Ellis. 1987. Influence of
temperature and wetness duration on infection of ripe strawberry fruit by
Botrytis cinerea . Can. J. Plant Pathol, (in press).

2. Coli, W. M., T. A. Green, T. A. Hosmer, and R. J. Prokopy. 1985. Use of
visual traps for monitoring insect pests in the Massachusetts IPM program.
Agric. Ecosystems Environ. 14:251-265

3. Cooley, D.R., J. L. Drozdowski, W. J. Manning, C. F. Brodel, and K.
Hauschild. 1985. Managing diseases and insects on small fruit in New
England. Massachusetts Cooperative Ext. Publication no. C-164R.

4. Devaux, A. 1978. Etude epidemiologique de la moissiure grise des fraises
et essais de lutte. Phytoprotection 59:19-27.

5. Drozdowski, J. L. and W. J. Manning. 1984. Strawberry disease survey
report. Unpublished manuscript.

6. Grove, G. G., L. V. Madden, M. A. Ellis and A. F. Schmitthenner. 1985.
Influence of temperature and wetness duration on infection of immature
strawberry fruit by Phytophthora cactorum . Phytopathology 75:165-169.

7. Powelson, R. L. 1960. Initiation of strawberry fruit rot caused by
Botrytis cinerea . Phytopathology 50:491-494.

8. Schaefers, G. A. 1980. Yield effects of tarnished plant bug feeding on
June-bearing strawberry varieties in New York state. J. Econ. Entomol.
73:721-725.

9. Smith, F. D. and W. E. MacHardy. 1984. The retention and redistribution of
captan on apple foliage. Phytopathology 74:894-899.

*****

POSTHARVEST HANDLING OF BLUEBERRIES

Wesley R. Autio

Department of Plant and Soil Sciences

University of Massachusetts

Blueberries ( Vaccinium corymbosum ) are very perishable once harvested and
must be handled carefully to maintain quality and reduce postharvest losses.
The primary quality factors, as outlined by the U.S. grade standards, are
maturity, color, size, and freedom from defect and decay (7). In a 3-year
study of blueberries at retail stores Cappellini et al. (3) determined the
reasons for postharvest berry losses (Table 1). Of the 15.2% of berries lost,

Table 1. Sources of blueberry losses in retail outlets. From Cappellini et
al. (3).

Percentage
Defect lost

Decay 10.7

Overripe or dehydrated 3.3

Mechanical or insect injury 0.2

Immaturity 1 .0

TOTAL 15.2

over two-thirds were lost to decay, so efforts to improve postharvest handling
of blueberries must reduce the incidence of decay to be successful. In this
discussion I will present general changes which occur during blueberry
ripening, factors which affect decay, and means for reducing decay and
increasing postharvest life and fruit quality.

Ripening

Blueberries are a climacteric fruit, meaning that they exhibit a rapid
rise and fall in respiration during the course of ripening. Throughout this
period many other changes occur, including a reduction in acidity, an increase
in sugar content, and a dramatic increase in anthocyanin content (the source of
the blue coloration). Table 2 depicts the timing of the major changes that
occur during ripening.

It is interesting to note that blueberries do not attain their full flavor
when they first become blue, but actually require an additional 1 to 2 days to
develop full flavor (8). This is reflected in Table 2 by a sharp decline in
acids (and rise in pH) and rise in sugars after the fruit become blue, both
changes improving flavor. The sugar/acid ratio reflects both of these changes,
and is what we perceive when we taste the fruit.

Table 2. Biochemical changes associated with Wolcott blueberry ripening,
Adapted from Ballinger and Kushman (1).

Total

Soluble

Sugar/

Antho-

acidity

solids

Sugars

acid

cyanins

Stage

as citric)

(%)

ratio

(mg/lOOg)

Immature -green

2.60

4.10

6.83

1.15

0.28

__ —

Mature-green

2.68

3.88

7.20

1.79

0.46

Green-pink

2.79

2.36

9.88

5.27

2.28

Blue-pink

2.81

1.95

10.49

6.20

3.26

173

Blue

2.96

1.50

10.79

6.87

4.69

332

Blue-ripe

3.70

0.50

12.42

9.87

19.95

1033

Decay

Decay is the primary source of berry loss after harvest (2). The 3 most
common decay organisms are anthracnose, gray mold, and alternaria (3).
Researchers have observed that decay is most prevalent in late-harvested
berries, where there is a higher percentage of overripe fruit. For instance,
at retail stores 10.9% of the berries are lost from early season harvests,
whereas 20.3% are lost from late season harvests (3). This apparent loss of
resistance to decay is related to the advancement of ripening and has been
correlated with an increase in the sugar-to-acid ratio (1) (see Table 2).
Thus, as fruit ripen their sensitivity to decay during the postharvest period
increases, and the sharpest increase is during the very latest stages of
ripening.

The primary entry point for decay organisms is the stem scar. Table 3
shows results of a study where some fruit had their stems removed and some did
not. Decay increased much more rapidly in those fruit where the stems were
removed, leaving stem scars.

Table 3. Percent decay associated with the stem scars of harvested blueberry
fruit. From Cappellini and Ceponis (2).

Days at 70'^F

Treatment

With stems

0.1

0.6

0.9

Without stems

0.7

3.8

6.7

Decay can be controlled adequately with postharvest fungicide dips but
resistance to applying pesticide after harvest and problems with application
preclude their use. Other means must be used to control postharvest decay.

Postharvest Handling

The simplest and most effective way of maintaining blueberry quality after
harvest is with the use of refrigeration . Cold temperatures slow ripening and
nearly stop decay. Some resistance to the extensive use of refrigeration of
blueberries exists because many growers are concerned that the sweating of
fruit after removal from the cold can increase decay, but research has shown
that decay is not significantly increased by sweating (4).

The optimum conditions for holding blueberries are 31 to 32*^F and 95%
relative humidity. Even at 40° there is substantially more loss to decay than
at 32" (Table 4). Under most circumstances, blueberries may be kept for 2

Table 4. Percentages lost associated with holding temperature,
and Kushman (6).

From Hruschka

Length of storage

Holding
temperature

2 wks

2 wks +
2 days at 70°

4 wks

4 wks +
2 days at 70°

32°
40°

10
13

18
28

18
30

36
55

weeks at 32° with very little loss (4). However, if some loss can be tolerated
they may be kept for up to 6 weeks. Late-harvested berries will not store as
well as early-harvested fruit, and any decay present at harvest will reduce
storage potential by providing an inoculum source (7).

Also, it is critical to cool the berries as quickly as possible. Ceponis
and Cappellini (5) studied the differences in losses associated with cooling
rate. Berries were cooled in 2, 48, or 72 hours and kept at 35°F for 2 weeks,
after which they were removed from storage and kept at 70° for up to 3 days.
Table 5 shows their results, and it is obvious that rapid cooling reduced
losses, particularly in the first 2 days after being transferred to 70°. Many
growers may not have cooling equipment available to reduce the temperature of
their berries to 35° in 2 hours, but it is important to cool them as quickly as
possible . Some success has been obtained by supplementing existing cooling
equipment with liquid nitrogen or CO2 to speed the cooling process (9).

Modified atmospheres around the fruit may improve longevity. Elevated CO2
(10 to 15%) seems to be the most advantageous modification because it inhibits
the growth of decay organisms. Table 6 shows data on fruit losses to decay

Table 5. The effects of cooling rate on the percent loss of blueberries. From
Ceponis and Cappellini (5).

Days at 70*'F after 2 wks at 35°

Cooling times (hrs)

2
48
72

0.8

2.0

6.8

17.2

2.7

6.9

14.1

20.7

3.7

10.8

20.6

24.8

after cold storage with high CO2. The CO2 enriched atmosphere significantly
reduced loss during and after storage. The use of CO2 enrichment of storage
rooms may not be feasible for blueberry growers, but enrichment of small lots
of fruit may be accomplished with the use of plastic films. Research studies
have used plastic envelopes to enclose several 1-pint baskets and have injected
CO2 directly into the envelopes to enrich the atmosphere. A high CO2
environment will develop naturally after enclosure in plastic but will take 5
to 7 days to reach 10-15%. Even with this delay in the development of a high
CO2 atmosphere the benefits of sealing in plastic may be significant. However,
plastic must be removed when the berries are removed from cold storage .

Table 6. The effects of CO2 enrichment on the percent loss of blueberries
after cold storage. From Ceponis and Cappellini (5).

Days at 70° after 2 wks at 35°

Percent CO2

12 to 15 0.9 2.1 5.7 12.6

2.4 6.6 13.8 20.6

CONCLUSIONS

1. Keep blueberries COLD (31 to 32°F). The most effective means of
maintaining blueberry quality is through refrigeration.

2. Cool blueberries QUICKLY. Significant benefits exist from rapid cooling.

3. Seal in plastic to increase CO2 if longer storage is desired. Research
has shown that high CO2 can significantly reduce blueberry losses to
decay. Plastic films may be used to develop and maintain a high CO2
environment around the fruit.

24
References

1. Ballinger, W. E. and L. J. Kushman. 1970. Relationship of stage of
ripeness to composition and keeping quality of highbush blueberries. J.
Amer. Soc. Hort . Sci. 95:239-242.

2. Cappellini, R. A. and M. J. Ceponis. 1977. Vulnerability of stem-end
scars of blueberry fruits to postharvest decays. Phytopath. 67:118-119.

3. Cappellini, R. A., M. J. Ceponis, and G. Koslow. 1982. Nature and extent
of losses in consumer-grade samples of blueberries in greater New York.
HortScience 17:35-36.

4. Cappellini, R. A., M. J. Ceponis, and C. P. Schulze, Jr. 1983. The
influence of "sweating" on postharvest decay of blueberries. Plant
Disease 67:381-382.

5. Ceponis, M. J. and R. A. Cappellini. 1983. Control of postharvest decays
of blueberries by carbon dioxide-enriched atmospheres. Plant Disease
67:169-171.

6. Hruschka, H. W. and L. J, Kushman. 1963. Storage and shelf life of
packaged blueberries. U.S.D.A. Agric. Market. Res. Rep. 612.

7. Kader, A. A., R. F. Kasmire, F. G. Mitchell, M. S. Reid, N. F. Sommer, and
J. F. Thompson. 1985. Postharvest technology of horticultural crops.
Cooperative Extension, University of California.

8. Ryall, A. L. and W. T. Pentzer. 1982. Handling, transportation, and
storage of fruits and vegetables. Vol. 2, AVI, Westport, CT.

9. Saltveit, M. E., Jr. and W. E. Ballinger. 1983. Effects of anaerobic
nitrogen and carbon dioxide atmospheres on ethanol production and
postharvest quality of blueberries. J. Amer. Soc. Hort. Sci. 108:459-
462.

•k -k ic if if

COOPERATIVF EXTENSION SERVICE
U S DEPARTMENT OF AGRICULTURE
UNIVERSITY OF MASSACHUSETTS
AMHERST MASS 01003

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. S300

BULK RATE

POSTAGE & FEES PAID

USDA

PERMIT No G2r,8

Fruit Notes,"";

Prepared by: Department of Plant and Soil Sciences ' ^' MA S ^

Massachusetts Cooperative Extension, University of Massachusetts, United
States Department of Agriculture and Massachusetts counties cooperating.

Editors: W. R. Autio and W. J. Bramlage

Volume 52, No. 4
FALL ISSUE, 1987

Table of Contents

Evaluation of Mcintosh Strains
in Massachusetts

Potato Leafhopper in Massachusetts
Apple Orchards

Redfree: A High Quality, Early-season, Disease-
resistant Apple

Effects of Fertilization on Apple Quality

Pomological Note: Rabbits in Orchards

Cranberry IPM in Massachusetts — What it Means

and How it Works

Growth Regulators in Orchard Management

Pomology Group Moves

Orchard Mice and Voles

EVALUATION OF NCINTOSH STRAINS IN MASSACHUSETTS

Wesley P.. Autio, William J. Lord, and William J. Bramlage

Department of Plant and Soil Sciences

University of Massachusetts

Many Mcintosh strains have been discovered throughout the years. Some
have been good and others not so good. To be accepted now, new strains must
have a high percent red color, yield well, and emerge from long-term storage
with high quality. To assess Mcintosh strains, a planting was established in
1979 at Green Acres Fruit Farm, Wilbraham, MA, including Morspur, Marshall,
Imperial, Macspur, Eastman, Gatzke, and Rogers Mcintosh on M.7A. This planting
is maintained by the grower.

Trees have fruited since 1983, and the yields are reported in Table 1.
Most strains, with the exception of Eastman, yielded similarly each year and on
a cumulative basis. Eastman trees yielded the fewest fruit each year from 1983
to 1986, with a cumulative yield less than half that of the other strains.
Eastman also was the smallest tree in terms of trunk circumference (Table 1).
However, this fact did not account for the low yields, since they also were the
least yield efficient trees from 198:) to 1986 (Table 1).

Table 1. Yield per tree (bu) in 198j through 1986 and on a cumulative basis,
cumulative yield efficiency, and 1986 trunk circumference of Mcintosh strains
planted in 1979.

Yield per tree (bu)

Yield Trunk

efficiency circum.

Strain 1983 198^ 1985 1986 Cumulative (kg/cm^) (cm)

Morspur

0.4 ab*

1.1 ab

1.1 abc

5.2 a

7.7 a

2.31

27.7 a

Marshall

0.3 be

1.4 a

1.1 be

4.1 a

6.8 a

2.11

27.8 a

Imperial

0.5 a

1.1 ab

1.6 ab

4.8 a

8.0 a

2.11

29.7 a

Macspur

0.3 be

1.0 ab

1.0 be

4.4 a

6.7 a

1.72

29.5 a

Eastman

0.2 c

0.1 c

0.5 c

1.9 b

2.7 b

1.52

20.5 b

Gatzke

0.2 be

0.5 be

1.2 ab

4.3 a

6.3 a

1.88

abc

27.7 a

Rogers

0.3 be

1.1 ab

1.8 a

4.9 a

8.1 a

2.17

29.4 a

* Within

columns.

means not

followed

by the

same letter

are

sign

if icantly

different.

As fruit ripen their starch is converted to sugar which is observed easily
by staining the starch with an iodine solution. The pattern of staining
changes during ripening and can be categorized by comparing it to an index
chart. As the starch disappears the index value increases. For two harvests
in 1983, three in 1984, two in 1985, and one in 1986 starch index values were
determined with the starch-iodine test (Table 2). No consistent differences

were seen among the strains, suggesting that there were no differences with
respects to the time of ripening. However, the starch-iodine test is not very
sensitive for assessing small differences.

Table 2. Starch index values of fruit from different strains of Mcintosh
harvested in 198J, 1984, 1985, and 1986.

1983 198M 1985 1986

Strain 9-9 9-17 9-4 9-11 9-18 9-3 9-10 9-4

Morspur

1.9 ab*

2.5 a

2.6 a

3.2 abc

4.7

3.2 a

4.7 a

3.5 b

Marshall

1.9 ab

2.8 a

2.2 a

3.4 ab

4.1

3.2 a

4.1 a

3.8 a

Imperial

1.7 ab

2.7 a

2.2 a

3.2 abc

4.1

3.3 a

4.6 a

5.2 c

Macspur

1.9 a

2.6 a

2.2 a

3.6 a

4.5

3.4 a

4.7 a

3.6 ab

Eastman

1.3 b

2.8 a

2.5 b

4.0 a

3.1 c

Gatzke

1.8 ab

2.3 a

2.2 a

3.1 be

2.8 ab

4.4 a

3.1 c

Rogers

1.5 ab

2.i a

2.0 a

2.9 c

4,1

3.0 ab

4.1 a

3.4 be

* Within columns, means not followed by the same letter are significantly
different.

During the course of apple ripening the internal C2H4 concentration rises
dramatically, providing an accurate and sensitive means of monitoring ripening.
For three harvests in 1984 and 1985 the internal C2H4 concentration was
determined for Marshall and Rogers fruit (Table 3). We were particularly
interested in determining if Marshall fruit ripened earlier, since they colored
significantly earlier than the other strains. Rogers was selected as a
standard strain. In both years, Marshall fruit ripened significantly earlier
than Rogers fruit, showing higher internal C2H4 concentrations at each harvest.
In 1986 internal C2H4 concentrations were determined for all strains on
September 4 (Table 3). Marshall fruit had the highest levels, and over the
three years of the study comparison of concentrations suggest that Marshall
fruit ripen about 5 days before standard strains such as Rogers.

The primary factor in determining success when growing Mcintosh is red
color. For an orchard to be profitable, a large percent of the fruit produced
must have enough red color to meet the U.S. Extra Fancy grade, i.e. 50 percent
red color characteristic of the cultivar. Table 4 shows the percent of the
fruit meeting the Extra Fancy grade for each harvest in each year. In all
cases Marshall had the highest percent of fruit in the Extra Fancy grade.
Also, earlier coloring of Marshall fruit can be observed in those years where
multiple harvests were made.

Flesh firmness was measured at harvest each year (Table 5). Significant
differences were noted among the seven strains. However, these differences may
be attributed to differences in fruit size (Table 6). Generally, the smallest
fruit were the firmest.

Table 3. Internal C2Hi( concentrations of fruit from different Mcintosh strains
harvested in 1984, 1985, and 1986.

Strain

9-4

1984

9-11

9-18

8-27

1985

9-i

9-10

1986

9-4

Morspur

Marshall

Imperial

Macspur

Eastman

Gatzke

Rogers

0.12 a* 4.60 a 11.50 a 0.10 a 3.15 a 14.93 a

0.04 b

0.65 b 3.80 b 0.05 b

0.51 b

2.12 b

0.35 b
1.29 a
0.48 ab
0.40 b
0.46 ab
0.62 ab
0.28 b

* Within columns, means not followed by the same letter are significantly
different.

Table 4. Percent of fruit meeting the U.S. Extra Fancy grade harvested from
different Mcintosh strains in 1983, 1984, 1985, and 1986.

1983

1984

1985

1986

Strain

9-1

9-7

9-14

9-4

9-11

9-18

9-S

9-10

9-4

Morspur

17 b"

20 b

57 be

13 b

23 b

72 b

30 b

20 b

75 ab

Marshall

64 a

67 a

84 a

51 a

89 a

90 a

77 a

65 a

95 a

Imperial

15 b

23 be

68 ab

23 b

13 be

72 b

12 c

21 b

80 ab

Macspur

8 be

33 b

56 be

9 b

23 b

63 b

18 be

17 b

81 ab

Eastman

1 c

6 c

25 d

—

5 c

4 b

61 b

Gatzke

9 be

17 c

52 be

8 b

8 c

—

10 c

14 b

80 ab

Rogers

8 be

28 b

39 cd

7 b

8 c

67 b

7 c

14 b

73 ab

Within columns,
different.

means not followed by the same letter are significantly

In 1985 one bushel of fruit from each tree was kept in controlled
atmosphere storage for 7 months followed by air storage for 2 months. In 1986
one bushel from each tree was kept in air storage for 4 months, and one bushel
was kept in controlled atmosphere storage for 6 months followed by air storage
for 1 1/2 months. The incidences of storage disorders were not significantly
different among strains in either year (Table 7). However, some differences
existed with respect to fruit firmness after storage in 1986, but these
differences may be attributed to fruit size.

Table 5. Flesh firmness (lbs) of fruit harvested from different Mcintosh
strains in 1983, 1984, 1985, and 1986.

198i 198'< 1985 1986

Strain 9-9 9-17 9-4 9-11 9-18 9-3 9-10 9-4

Morspur 15.5 ab* 14.5 ab 16.6 a 15.3 ab 14.7 a 15.7 a 14.0 ab 14.8 a

Marshall 15.5 ab 14.9 a 16.3 ab 15.5 ab 15.3 a 15.8 a 14.4 a 14.8 a

Imperial 15.3 ab 14.4 abc 16.1 ab 15.5 ab 14.8 a 15.5 ab 14.1 ab 14.6 ab

Macspur 14.7 b 13.8 cd 15.7 b 14.6 c 14.2 b 15.0 be 13.1 c 14.3 c

Eastman 14.8 b 13.6 d 14.7 c 13.8 b 14.2 c

Gatzke 15.3 ab 14.0 bed 15.6 b 15.0 be 14.4 c 1j.3 e 14.4 be

Rogers 16.0 a 14.5 abc 16.5 a 15.7 a 15.3 a 15.7 a 14.3 ab 14.7 ab

* Within columns, means not followed by the same letter are significantly
different.

Table 6. Diameter (in.) of fruit harvested from different Mcintosh strains in
1984, 1985, and 1986.

1984 1985 1986

Strain 9-4 9-11 9-18 9-3 9-10 9-4

3.13 ab 3.10 b 3.22 b 3.04 b

3.03 b 3.04 b 3.10 c 2.95 c

3.16 a 3.13 b 3.22 b 3.15 a
3.16 a

Morspur

2.93 b*

3.01 b

Marshall

2.89 b

2.98 b

Imperial

2.97 b

3.03 b

Macspur

3.02 ab

3.11 al

Eastman

Gatzke

3.13 a

3.19 a

Rogers

2.89 b

3.03 b

3.09 b

3.25 b

3.05 b

3.27 a

3.29 ab

3.20 a

3.30 a

3.39 a

3.16 a

3.04 b

3.17 be

3.03 b

3.14 ab

* Within columns, means not followed by the same letter are significantly
different.

In summary, Eastman produced a small tree which yielded poorly. Other
strains produced trees of similar size and productivity. Marshall produced
fruit which colored earlier and to a higher degree and ripened earlier than
fruit from other strains. Fruit quality after storage was similar for all
strains in this study. Another Mcintosh strain trial was established in 1985
with a number of high-coloring strains, including Redmax. Results from this
study will be reported in future issues of Fruit Notes.

Table 7. Post-storage quality of fruit harvested from different Mcintosh
strains in 1985 and 1986. Fruit in 1985 were harvested September 10, kept in
CA (3% O2, 5% CO2) for 7 months and air for 2 months prior to quality
assessment. Fruit in 1986 were harvested September 4 and either kept in air
for 4 months or CA for 6 months and air for 1 1/2 months prior to quality
assessment.

Senescent

Bitter

Firmness

Scald

Decay

breakdown

pit

Browncore

Strain

(lbs)

(X)

(%)

(i)

(5t)

(%)

CA— 1985

Morspur

9.8*

0»

17*

14*

— —

Marshall

10.1

—

Imperial

10.3

—

Macspur

8.7

—

Eastman

10.0

—

Gatzke

9.6

—

Rogers

9.6

14
Air— 1986

Morspur

10.1

ab*»

6»

8«

11*

Marshall

10.0

—

Imperial

9.8

—

Macspur

9.2

—

Eastman

9.3

—

Gatzke

9.1

—

Rogers

10.3

CA— 1986

Morspur

10.7

^mm

Marshall

11.6

Imperial

10.8

Macspur

10.3

Eastman

11.3

Gatzke

11.2

Rogers

11.1

* No significant differences existed among strain for these parameters.

** Within column and storage treatment, means not followed by the same letter
are significantly different.

• • « » »

POTATO LEAFHOPPER IN HASSACHUSETTS APPLE ORCHARDS

Kathleen Leahy, Ronald J. Prokopy, and William M. Coli

Department of Entomology

University of Massachusetts

In 1986, many growers, private consultants, and Extension workers noted a
"new" type of injury on terminal leaves of apple, consisting of general off-
coloration as well as a strong marginal yellowing or burning of the leaves.
Since the injury was not particularly severe and no causative agent was found,
in most cases it went unremarked during the growing season. It was not until
the fall, when Extension workers and private consultants from the Northeast
gathered to share information, that the problem was recognized as a widespread
phenomenon, and the injury was definitively identified as caused by the potato
leafhopper, (PLH) Empoasca fabae . Over the decades, this insect is known to
have been an occasional pest of apples, but this has been the most notable
outbreak in recent years.

Nymphs and adults of PLH are pale green in color, and tend to move rapidly
(often in a sideways fashion) when disturbed. In contrast, nymphs and adults
of the white apple leafhopper (the only other leafhopper likely to be seen in
Massachusetts apple orchards) are pale yellow to whitish in color and move more
slowly when disturbed, usually straight ahead. An additional distinguishing
character visible with a hand lens is a rather distinctive whitish "H" pattern
on the top of the thorax of a PLH adult. And, of course, the location (new,
succulent terminal growth) and type of damage (yellowing and "burn" as opposed
to stippling) are also diagnostic.

PLH overwinter as adults in the South, and move northward in warm masses
of air, usually beginning in June. They fall out when the warm air collides
with cooler northern air. Eggs are laid in the veins and petioles of newly-
developing foliage of a variety of plants. Nymphs feed on tender terminal
leaves. There are two and possibly three generations of PLH here in the
Northeast. Luckily, apple is not the most favored host of this insect. It was
discovered in 1841, feeding on beans. By the late 1800's it had become a pest
of potatoes, its preferred host. Other favored hosts include clover, alfalfa,
and beets. Fortunately, most (but not all) PLH apparently leave apple trees
after completing the first generation. By that time, the growth of terminal
foliage in most orchards has hardened off to an extent where PLH prefer other
plants having more succulent foliage. However, in plantings of young trees or
on older trees producing vigorous mid- to late season growth, PLH can continue
to be a problem until August.

The first evidence observed in 1987 of PLH on apple in Massachusetts was
on July 8 in a Wilbraham orchard. Over the next few weeks, PLH continued to
disperse into most locations in Massachusetts. In general, infestations have
been heavier this year than they were last. To illustrate, in surveys during
July in 18 orchards participating in the second-stage IPM program, we found
about 10? of terminals of bearing trees in sprayed (control) blocks manifesting
signs of PLH injury.

In most cases observed in 1987, PLH injury first appeared as a general
off-coloration (partial yellowing) of new terminal growth. It was only after

some weeks that the diagnostic "hopper burn," or yellowing of leaf margins,
began to appear. In a few severe cases, particularly where trees were also
stressed by drought, leaves later became curled and somewhat browned about the
margins.

Since PLH has only been a sporadic pest on apple, the effects of this
injury on affected trees are not well known. Because PLH inject a toxin into
the plant, in many crops (such as potatoes) the threshold for these insects is
very low. It is likely, however, that fruit trees, because of their size and
the enormous amount of vegetative growth of which they are capable, can
withstand considerably higher numbers of PLH. Until we know better, we have
adopted a provisional threshold for PLH that is the same as that for white
apple leafhopper, 25 leafhoppers or signs of feeding per 100 terminals
observed.

PLH are extremely mobile, rendering monitoring and management decision-
making difficult. For one thing, PLH will take flight at a fairly slight
disturbance, so that moving terminals for examination may cause the leafhoppers
to fly off. (According to researchers working with PLH, ovipositing females
are much less easily disturbed than males. This fact may make it possible at
least to determine whether the insects are still present, but difficult to
assess actual population levels.)

It is also difficult to assess the susceptibility of potato leafhopper to
insecticides. In 1986 in New York, where PLH infestation was more severe than
it was in Massachusetts, PLH were observed on terminals in blocks which had
been treated with organophosphate insecticides. This observation led tree
fruit entomologists there to speculate that resistance had developed, but
vegetable specialists raised the possibility that reinfestation had occurred in
those blocks, and that no resistance was present. Vegetable specialists in
both New York and Massachusetts note that PLH are highly dispersed over a wide
geographic range and a variety of plant hosts, many of which are never exposed
to pesticides. These factors would tend to inhibit the development of
resistance in most cases.

Pesticide control results in Massachusetts in 1987 have been inconclusive,
but we can state with confidence that we have not seen any sign of continued
infestation of trees treated with organophosphate insecticides (OP's). In
fact, in the one monitored orchard where an OP was used against PLH,
infestation declined from ^7% of terminals the week before treatment to 0% the
week after. The reason that it is not possible to state definitely that this
decline was due to the OP treatment is that similar declines also occurred in
untreated orchards, over the same period of time, possibly because terminal
growth was beginning to harden off and PLH were moving onto other hosts.

Based on the recommendations of vegetable specialists, and the fact that
no obvious OP resistance has been noted on any crop in Massachusetts in 1987,
we are proceeding with the assumption that PLH are indeed susceptible to OP's,
including Imidan and Guthion.

Since it appears that potato leafhopper migration is determined primarily
by prevailing weather conditions in the southern U.S., it is impossible to
predict whether this insect will continue to be a problem on apples in
Massachusetts. However, since such outbreaks have happened in the past, we

hope to be armed with more information to handle the next one, whenever it may
occur. We are involved currently with assessing injury levels in heavily-
infested blocks in order to determine whether PLH injury affects premature
drop, fruit size or color, or fruit set the following spring.

« « « « «

ERRATUH

A Report of the 1986 Massachusetts Apple IPM Program

William M. Coli, Daniel R. Cooley, Kathleen Leahy, and Ronald J. Prokopy

University of Massachusetts

In the article on the Apple IPM Program results published in the Spring
issue of Fruit Notes [52( 2) : 1 1-16] , we neglected to acknowledge the
contribution of the Regional Fruit Specialists, Jim Williams in particular, to
the IPM program. In addition to being responsible for sending the twice-weekly
Pest Alert Messages, the Regional Specialists have shared information gathered
from their orchard visits with us. Jim also has done regular, weekly IPM
scouting in at least one orchard for the past 4 seasons, and his assistance has
been of great value to the IPM Program, allowing us to extend our monitoring to
parts of the state which University-based scouts are unable to visit regularly.
We regret having omitted Jim's name, as well as Dom Marini and Karen Hauschild,
from the list of credits for all who have helped the program.

• « • • »

REDFREE: A HIGH QUALITY, EARLY-SEASON, DISEASE-RESISTANT APPLE

Daniel R. Cooley
Department of Plant Pathology

and

Joseph Sincuk

Department of Plant and Soil Sciences

University of Massachusetts

Early season apples are often thought of as second-rate fruit, stop-gaps
until the real show begins with Mcintosh. Redfree may not change the attitude
we have about Mcintosh, but it may offer an excellent opportunity for high-
quality, early-season fruit. The disease resistant planting at the
Horticultural Research Center, Belchertown, MA, has two Redfree trees, both of
which fruited heavily this year. The fruit were ready to pick August 10, making
it harvestable at about the same time as Jersey Mac and approximately 1 week
earlier than Paulared. When the fruit were harvested, most had approximately

65i red color with a green ground color, while approximately 10J had greater
than 80% red color with a yellow-cream ground color. Later taste testing
showed that the fruit with the cream ground color were too ripe, though they
were sweeter (Table 1). The fruit with a greener background were more tart,
similar to Empire. These greener fruit were judged as good, comparing well
with any early-season fruit. The texture of the fruit was very good, and the
fruit were firm (Table 1).

Table 1. Flesh firmness and percent soluble solids of Redfree divided into
average and high-coloring lots and Jersey Mac. One group of Redfree fruit was
kept at room temperature for ^ days prior to assessment.

Red color Time at Flesh firmness Soluble Solids
Cultivar (.%) room temp. (lbs) (%)

Redfree 82% fresh 14.9 11.1

Redfree 63% fresh 18.1 10.5

Jersey Mac 61% fresh 15.5 10.2

Redfree 63% ^ days 17. 'i 10.3

Redfree comes from the Purdue-Rutgers-Illinois breeding program, and as
such is resistant to apple scab, cedar apple rust, fire blight, and mildew. It
may also be resistant to red mite. Among the named parents in Redfree 's
heritage are Rome Beauty, Jonathan, Red Rome, and Melba. It is an annual
bearer. Some descriptions suggest that it may require two pickings, though if
the fruit are harvested prior to peak color, this activity may not be necessary
and quality may be higher. Redfree presently is available from The Nursery
Corporation (Hilltop).

While the information we gathered this year is very preliminary, it looks
like Redfree could be an excellent early-season apple, regardless of its
disease-resistant characteristics. It is reported to keep for up to 2 months
in refrigerated storage, and we found no serious loss of quality in ^ days at
room temperature. However, it appears that the fruit should be harvested early
rather than at or near full ripeness, since both taste quality and keeping
quality are lower in the ripest fruit. When compared to Jersey Mac picked a
few days earlier (Table 1), Redfree were sweeter but less juicy. Soluble
solids and firmness were both somewhat higher in the Redfree. If this season
is typical of Redfree 's quality, then it could compete well with any of the
popular early-season cultivars.

» « « « «

EFFECTS OF FERTILIZATION ON APPLE QUALITY

William J. Lord

Department of Plant and Soil Sciences

University of Massachusetts

It is necessary to produce apples with high quality, and many orchard
factors can affect quality. However, one of the most important and easiest to
alter is nutrition. Below are presented some of the effects of fertilization
on fruit quality.

Calcium

Initially, the concern about low fruit calcium was directed at bitter pit
and cork spot, but today many other physiological disorders have been at least
partly related to low calcium levels in the fruit. In warmer fruit growing
areas cork spot and bitter pit remain the most serious effects of low calcium;
but in cooler areas various forms of internal breakdown are the most serious
calcium-deficiency problems.

Nitrogen

Excessive amounts of nitrogen in the tree and fruit can severely reduce
fruit quality. The vigorous growth that nitrogen encourages results in a lower
calcium level in the fruit. Moreover, the high nitrogen fruit tend to be
larger, greener, and softer; are more subject to preharvest drop; and have more
cork spot and bitter pit. These fruit also tend to develop greater am.ounts of
scald, bitter pit, internal browning, and internal breakdown during and after
storage.

Potassium

Potassium deficiency has only a mild effect on fruit quality, reducing the
acidity of the fruit and reducing red coloration. Excessive amounts of
potassium in fruit are a greater danger to fruit quality, since they lead to
increased scald, bitter pit, and internal breakdown after storage.

Magnesium

There is little evidence that either too little or too much magnesium
directly affects fruit quality. However, excess magnesium interferes with
calcium just as does excess potassium, so excessive amounts of magnesium may
produce calcium deficiency effects in fruit.

Phosphorus

Phosphorus deficiency can reduce tree growth and yield, and in several
parts of the world it also has been shown to cause increased amounts of

breakdown of apples during storage. However, in North America there has been
very little evidence of phosphorus deficiency in fruit. We recently have found
that high levels of phosphorus in apples, especially in combination with low
levels of calcium, greatly increases breakdown of apples during storage.

Boron

Boron deficiency can cause internal and external cork development in
fruit. Excessive levels of boron in fruit can cause earlier maturation,
increased amounts of water core at harvest, and increased amounts of breakdown
after storage. Thus, a moderate level of boron is important for good fruit
quality.

Boron also influences calcium movement in the tree. If boron is
deficient, less calcium moves to the fruit and calcium deficiency can result.
It therefore is important to maintain adequate boron levels as part of a
program to avoid calcium deficiency.

« K » « «

POHOLOGICAL NOTE

Rabbits in Orchards

William G. Lord

Plant Science Department

University of New Hampshire

Cottontail rabbits can be found throughout southern New England and often
cause serious damage to young apple trees. Damage generally includes extensive
bark removal and severe clipping of lateral shoots.

Habitat control is an effective population control measure. Overgrown
ditches, brushy fence rows, and stone walls provide rabbits with excellent food
and protection from predators. Elimination of these areas may be all that is
needed for adequate rabbit control.

Trees can be protected from rabbits by hardware cloth (1/2" mesh) tree
guards that extend 2' above the average snow depth. Orchard perimeter fencing
or 1" or 1 1/2" mesh wire that extends S' above the average snow depth is also
effective.

Taste repellents are another effective method of reducing rabbit damage to
orchards. Repellents containing Thiram have been effective when applied
according to label directions. Other commercial products such as Hinder also
provide effective control.

« « « « «

CRANBERRY IPM IN HASSACHUSETTS — WHAT IT HEANS AND HOW IT WORKS

Joan A. Lasota

Cranberry Experiment Station

University of Massachusetts

East Wareham, MA

Tn 1986 a record cranberry crop (1.8 million barrels) was produced in
Massachusetts, where the total earnings reached approximately $90 million.
This level is a 7 percent increase from the previous season, making the 1986
crop the largest in Massachusetts history and makes the state the leading
cranberry producer in the U.S. for the third consecutive year. Cranberries are
this state's most valuable agricultural commodity, accounting for 23 percent
of the total cash receipts in 1985. The average per acre harvest is currently
149.3 barrels, an increase from 70.1 barrels in 1975. The price per barrel
also has increased — from $13 in 1975 to $55 in 1985. This figure was between
$52 and $5^* in 1986. Ocean Spray Cranberries, which markets approximately 80%
of the fruit sold in Massachusetts, increased its sales from $361 million in
1982 to $541 million in 1985 and expects to continue this trend.

Results of a pesticide survey conducted for pesticide-treated cranberry
acreage in 1983. 1984, and 1985 indicated that greater than 60 percent of all
pesticides used on cranberries in Massachusetts were insecticides. Evaluation
of the period between 1981 and 1985 showed that the number of insecticide
applications for bogs in Massachusetts increased by a factor of 1.6 in 1984;
however, this figure decreased to 1.0 in 1985, making 1981 and 1985 equivalent
in terms of the number of insecticide application. Tn all cranberry growing
regions, parathion was the most widely used insecticide. It was used on at
least three times as many acres as any of the other insecticides. A gradual
decrease in the use of parathion in bogs has been noted and may be related to
an increase in the use of 'orsban, an insecticide which only recently became
registered for use on cranberries in Massachusetts.

Environmental contamination, hazards to human and other non-target
organisms, increased monetary costs of pesticide applications, and the
increased probability of resistance to pesticides demands that current and
future research efforts focus on an integrated approach to pest management,
emphasizing minimal use of chemical pesticides. Depressing the use of
chemicals is particularly important in highly residential areas, such as
southeastern Massachusetts, to help prevent environmental contamination.
Pollution of aquifers is of particular importance. Additionally, the proximity
of cranberry bogs to homes results in fear of pesticide drift on the part of
homeowners. Recently, growers have been faced with public hearings on
proposed bills requiring notice 60 days prior to pesticide application. There
also have been hearings to ban all aerial applications in certain towns.
Pressure from external sources is forcing growers to contemplate alternatives
to the standard, prophylactic, calender application of pesticides, a spray
schedule which has little or no regard for pest population levels.

Integrated pest management (IPM) means the judicious use of chemical
control measures while taking full advantage of cultural, mechanical, and
biological controls. With IPM, calender-based spray schedules are replaced by
chemical controls which are based on sampling and monitoring pest populations.

By first determining when and at what quantities pests are present, we can
time accurately chemical applications to coincide with damaging pest levels.
The intent of IPM rarely is the elimination of pesticides. It usually means
minimizing chemical use. The benefits of IPM are not only realized at the time
of implementation of the program but are also long-term. Ecological,
economic, and sociological concerns are paramount when considering development
or implementation of an IPM program.

Integrated pest management gives maximum consideration to the fine
ecological balances among all of the components of an agricultural system.
Attention is paid to the life cycles of the pests and the extent of their
interaction with the host plant. Host plant phenology, or the developmental
stages of plants, are investigated extensively together with the pest and
natural enemy life cycles.

Tn an IPM program, the decision whether or not to implement control
measures is based upon economic threshold levels. These levels are the lowest
pest population densities that will result in economic damage. Thus, it is
important to monitor pest populations throughout the growing season so that
control decisions can be made to prevent economic losses. It is also important
that the cost of control does not exceed the marketable value of the commodity.
Because pests and their population levels change during the course of the
growing season, threshold levels may be different for different plant parts and
at different times during the season.

Threshold levels are based on two types of pests: 1)direct pests - those
which affect the marketable part of the plant, for example, the berries of a
cranberry plant, and 2)indirect pests - those which attack the non-marketable
parts, for example, leaves, stem, and roots. Because the fruit are the parts
of cranberries which are marketed, the threshold levels for direct pests are
extremely low, especially if the berries are sold for fresh-market purposes.
Keep in mind, that the importance of attack on the different plant parts varies
from crop to crop. In the case of ornamentals where the entire plant is used
for aesthetic purposes, direct and indirect pests may be of equal importance
from an economic standpoint and the need to control.

The Cranberry IPM program (1983 to 1985) successfully sparked grower
interest in the concepts if IPM and demonstrated significant monetary savings.
As growers become increasingly aware of the benefits of IPM, they tend to
utilize information distributed via this program, regardless of whether of not
they are formal participants in the program.

1986 and 1987 Scouting Program

Fifteen growers were involved in the cranberry IPM program in 1986. This
figure more than doubled in 1987, with 33 participants. The total number of
acres in the 1986 program was 208, increasing to 450 in 1987. The largest
acreage contracted from an individual grower was 50 and the smallest was 0.58.
All growers were visited in early May by the cranberry IPM coordinator to
discuss specifics and procedures for the program. Also at this time,
recommendations were made for spring weed control.

Bogs were scouted weekly by the IPM coordinator and summer scouts, from
the beginninR of May until September. This scouting involved monitoring insect
pests with the use of sweep nets, pheromone traps, and vine and berry samples.
Diseases and weed pests were also identified and monitored. Growers were
notified via telephone or in person regarding the pest status of their bogs and
recommendations for control. Copies of weekly reports were given to growers.
In September, growers received graphs and reports for cranberry fruitworm and
pests which were monitored with pheromone traps. Also in September, bogs were
sampled for weed problems to aid in making spring and fall herbicide
recommendations. Berry and vine samples were collected to determine end-of-
season damage (particularly upright dieback, berry rot, cranberry fruitworm,
and cranberry tipworm damage).

Insect monitoring is related to host plant phenology. The following
pests are most prevalent in spring and early summer and are damaging to the
vine uprights. They are leaf feeders; however, they are most destructive when
they damage developing buds. Sampling with sweep nets (25 sweeps/acre) was
conducted weekly, from mid-May through the end of bloom.

gypsy moth blossom worm black headed fireworm

Sparganothis fruitworm cranberry sawfly false armyworm
yellow headed fireworm cranberry weevil spanworms

The adult flight activity of the following pests were monitored with the
aid of pheromone traps. Traps were set out in late May and were changed and
counted weekly, until early to mid August.

cranberry girdler
Sparganothis fruitworm
blackheaded fireworm

Southern red mite is a potential pest throughout the growing season,
although its populations are highest during the summer. It was monitored by
collecting and inspecting 10 to 15 uprights/acre for eggs, immatures, adults,
and damage. Large populations may also be seen during sweeping. Cranberry
tipworm is a potential pest during most of the growing season, damaging the
tips of uprights. Uprights were collected and inspected in the laboratory for
the presence of eggs, larvae, pupae, and damage. Following the first two
cranberry fruitworm sprays, which are timed depending on when the plant is 50%
out-of-bloom, 50 berries/acre were collected every five to seven days and
inspected for the presence of viable cranberry fruitworm eggs until there was
no longer the danger that viable eggs were being deposited. The percentage of
parasitized eggs was also determined at this time.

Just prior to harvest, 50 berries/acre and 10 vines/acre were collected
and brought into the laboratory for inspection. Insect, disease, and
mechanical damage were identified.

This article is intended to be an introduction to the Cranberry IPM
program, some of the cranberry pests, and the procedures used during pest
monitoring. More detailed results will be presented in future issues.

« « « « «

GROWTH REGUUTORS IN ORCHARD HAMAGEHENT

Duane W. Greene

Department of Plant and Soil Sciences

University of Massachusetts

Growth regulators are an important component of apple production. They
are used more intensively on apples than on any other horticultural crop, and
they can regulate important physiological processes, resulting in higher and
more consistent yields of high-quality fruit. Growth regulators include
hormones found naturally in the plant and similar synthetic compounds.

Chemical Thinning

The oldest, yet probably the most important, use of plant growth
regulators remains in the area of chemical thinning. Apple trees frequently
produce too many flowers, and if all flowers set fruit which develop to
maturity, the fruit will be too small and flower bud formation for the crop the
following year will be either reduced or eliminated. Chemical thinners can be
applied from shortly after bloom until about ^ weeks afterwards. Weather
conditions determine the exact length of time during which fruit can be thinned
chemically.

Carbaryl is the mildest and safest thinning agent, but it should not be
used at bloom time because it is especially toxic to honey bees. Some growers
also are reluctant to use this compound because of its possible adverse effect
on predator mites.

Naphthaleneacetic acid (NAA) is a more potent thinner and is used on the
more difficult to thin cultivars and on those cultivars that have a
particularly heavy bloom. Naphthaleneacetamide (NAAm or NAD) is milder than
NAA and is used when NAA could cause injury or leaf dwarfing. NAD is not
recommended for use on Delicious because of the possibility of producing many
small, seedless fruit called "pygmies." Promalin^M, applied with a surfactant,
has some thinning ability when used to elongate Delicious. Spray combinations
of carbaryl and NAA or NAD are becoming increasingly popular — especially where
growers want to get increased thinning, yet reduce the possibility of
overthinning or foliar damage seen with the higher rates of "AA or mad.

Preharvest Drop

Daminozide (Alar-85^^) is the most important compound used to control
preharvest drop. It is most effective when applied near harvest, but label
restrictions specify that it cannot be applied within 50 days of harvest.
Since daminozide is less effective when application is made earlier in the
season, it should be applied as close to harvest as the label will allow.
Daminozide is under review by the EPA and its future registration status is in
question.

NAA also retards preharvest drop. It becomes effective within one day of
application, and it can control drop for 7 to 10 days. If needed a second
application may be made. NAA has the negative effects of advancing ripening
and causing fruit softening.

Advancing Fruit Ripening

Ethephon (Ethrel^^) can advance the marketing season of most cultivars by
increasing red color and advancing ripening. Also, it will accelerate fruit
drop if applied alone. Therefore, this compound should either be applied with
NAA or on trees that received daminozide earlier in the season. If
temperatures are very high following application and the weather remains
cloudy, sufficient red color may not develop on treated fruit until ripening is
significantly advanced. Because of this potential problem, ethephon should be
used on young trees, since light penetration is usually very good and fruit on
these trees frequently is too large to have a long storage life. Ripening may
advance rapidly on ethephon-treated trees. They should be watched very
carefully so that harvesting can be done before excessive fruit drop occurs.

Growth Control and Flower Bud Formation

Frequently young trees grow too rapidly thus failing to flower and set
fruit. Also, older trees may become too vigorous due to over-fertilization,
excessive pruning, or the loss of a crop due to frost. Daminozide, ethephon,
or a combination of daminozide and ethephon may be used to retard growth and
increase flower bud formation. Treatments should be applied when terminal
shoot growth is 4 to 6 inches long. Concentrations of ethephon high enough to
reduce terminal growth will also cause excessive fruit thinning. Therefore,
ethephon must not be used on trees where cropping is desired the year of
application. Young trees should not be sprayed with daminozide and ethephon
until they are large enough to bear a crop.

Water Sprout and Root Sucker Control

Water sprouts are vigorous, upright shoots arising from any portion of the
above-ground part of a tree. They are most prevalent on vigorous trees
carrying a light crop. Heavy pruning encourages water sprout growth. It is
desirable to restrict growth of these shoots for two reasons: the shade they
produce retards red color development, and removing them adds to the pruning
costs. Tre-Hold Sprout Inhibitor A112^^ (ethyl ester of NAA) is used to
inhibit growth of these shoots. It usually is mixed with interior latex paint
and applied to pruning cuts. The paint allows the applicator to see the
treated areas, and the increased viscosity of the mixture reduces movement to
nontarget areas of the limb. It is important that the inhibitor be applied
during the dormant season, because volatilization of the NAA from applications
made after the buds start to grow can cause some leaf epinasty and fruit
thinning.

Root sucker control also may be achieved with Tre-Hold. Root suckers
should be pruned during the dormant season and the regrowth treated with a Tre-
Hold spray. Application should be delayed in the spring until four weeks after
bloom to reduce the possibility of fruit thinning. Thorough coverage is
essential for success. If there is tall grass or weeds on the orchard floor,
it may be useful first to spray under the trees with a contact herbicide such
as paraquat. Ten to fourteen days later, follow the herbicide application with
the Tre-Hold treatment. Extreme care must be taken to prevent drift since the
recommended rate of '''re-Hold is ^00 to 1000 fold higher than the recommended
rate of NAA for chemical thinning or drop control.

Lateral Branching

Many young trees, especially spur types, fail to branch adequately. This
lack of branching can limit the ultimate productivity of the tree, because the
allotted space will not be filled. To stimulate lateral branching, Promalin
may be applied in the spring when terminal growth is 1 to ^4 inches long. Only
vigorous, healthy trees should be treated, since Promalin will not overcome a
lack of branching due to poor growth. The high rate of Promalin should be used
only on diff icult-to-branch trees. High rates of Promalin on easily branched
trees can stimulate too many lateral shoots, all of which will be too short to
develop into good scaffold limbs. Promalin should be used only on nonbearing
trees, because the rates required to stimulate lateral branching will thin the
crop the year of application and inhibit flower bud formation for the following
year.

Elongate Delicious

The Delicious grown in New England normally are not as elongated as those
grown in the Pacific Northwest. To elongate Delicious fruit, Promalin may be
applied when the king flower is open. Promalin can thin, especially if a
surfactant is included and the highest rate of Promalin is applied (2
pts/acre). Promalin should not be used on young trees until they are old
enough and ready to be chemically thinned.

« « » » «

POMOLOGY GROUP HOVES

In the middle of August three members of the pomology group of the
Department of Plant & Soil Sciences at the University of Massachusetts moved
from French Hall to Bowditch Hall. The new addresses and telephone numbers for
Wesley Autio- William Bramlage, and Duane Greene are listed below. James
Anderson, William Lord, and Franklin Southwick will remain in French Hall.

Wesley R. Autio
205 Bowditch Hall
University of Massachusetts
Amherst, MA 01003
Tel. 413-545-2250

William J. Bramlage
308 Bowditch Hall
University of Massachusetts
Amherst, MA 01003
Tel. 413-545-2254

Duane W. Greene
304 Bowditch Hall
University of Massachusetts
Amherst, MA 01003
Tel. 413-545-2259

« « « « «

OBCHABD HICE AND VOLES

Alan Eaton

Department of Entomology

University of New Hampshire

Mice and voles are closely related rodents that can be distinguished from
each other on the basis of tail and ear size, among other minor differences.
In New England, mice are not a problem in orchards, but two species of voles
frequently cause serious damage. These pests are the meadow vole and the pine
vole. Meadow voles range throughout New England, but pine voles are known to
be present only from southern New England to southern Vermont, New Hampshire,
and the southern tip of Maine.

Meadow voles inhabit the orchard floor, developing a network of surface
trails through the groundcover and feeding primarily on grasses and fleshy
herbs. This species usually does most of its damage during the winter when
herbage is less abundant, but damage is possible at any time of the year. They
chew away areas of bark and cambium that can be reached from the ground or from
higher positions in or on snow cover. In some soils they will burrow and
sometimes are responsible for trunk girdling several inches below the ground
surface.

Pine voles travel either in surface trails or in burrows 3 or more feet
deep depending somewhat on soil conditions. In solid grass sods, they may be
almost totally subterranean; but where the groundcover contains a high
percentage of broadleaf herbs, pine vole may travel on the surface. During the
cold months, their activity is pretty much limited to the underground burrows.
When herbage is abundant, pine voles store caches in the tunnel system for
later use. They feed upon bark and cambium primarily below the soil line, and
chew off small roots up to about the diameter of a pencil. All commercial
apple cultivars and their seedlings, as well as the available rootstocks, are
very susceptible to vole feeding.

Identification of Pest Species

When vole damage is apparent, it is important to determine which species
is responsible. Some of the management practices used for meadow voles are not
effective against pine voles. Identification of the species may require
trapping. Use snap traps baited with rolled oats, or peanut butter, or a 50:50
mixture of these two. Fresh apple pieces are also a good bait. Place traps
across active runs, including those that lead into underground burrows if they
are present. Cover the trap with an apple box or a similar cover. This will
exclude birds and cats and help you locate the trap trees in the orchard. Set
enough traps to be sure of catching 5 to 10 voles from various locations in the
orchard. Check the traps after only one or two days. Tail length is useful
for identification. The pine vole tail is very short — about the same length as
the hind foot (not the leg!), measuring 3/^ inch or less. The meadow vole's
tail is about twice the length of its hind feet, reaching 1 1/2 to 1 3/^ inches
on adults. Both species have chunky bodies and small beady eyes, and their
ears are small and almost concealed in fur. The fur color is dark brown or
gray-brown. If you catch a long-tailed specimen, it is likely to be a white-

footed mouse. This mouse's tail is well over ? inches long, and all underpants
of this mouse are covered with white fur. It is reported to eat the bark of
young trees occasionally, but it is generally considered a non-pest species in
orchards. Your traps may also catch a shrew, which is a beneficial small
mammal, or a mole, which is neither harmful nor beneficial. A shrew can be
identified by its long, pointed snout and its needle-pointed front teeth.
Moles can be identified by their front feet, which are very large, with
prominent digging claws.

Orchard Floor Management

Prevention of vole population build-ups offers the most practical method
of reducing tree injury.

1. Mow orchard floor sod frequently during the growing season.

2. Maintain a vegetation-free area within at least '< feet of the tree trunks.
The use of herbicides may be necessary to accomplish this.

3. Eliminate brush and thick vegetative cover around orchard perimeters.
^. Completely remove all fruit drops from the orchard.

Tree Guards

Maintenance of proper tree guards is the most effective measure for
preventing tree girdling by meadow voles, unless snow depth exceeds the height
of the guard. Voles tunnel through snow to any depth. Also, trunk guards do
not prevent underground damage by pine voles.

Galvanized hardware cloth is one of the best materials for tree guards.
One-quarter-inch mesh in 2'4-inch width is preferred. The cloth is cut large
enough to completely encircle the tree and allow enough room for 10 or more
years of growth. The cloth is formed into a cylinder and fastened together so
that no gaps are left through which the mice can gain entry. Two or 3 short
pieces of wire may be necessary to secure the seam. The guards are embedded at
least 2 inches into the soil to prevent the rodents from burrowing underneath.
An annual check of the guards is recommended, preferably before the ground
freezes. The disadvantages of hardware cloth are that it is difficult to work
with and installation is time-consuming.

Several rigid, perforated polyethylene or plastic mesh products are being
promoted for use as tree guards. Each is used in a way similar to that of
galvanized hardware cloth to form a cylinder which is buried in the ground and
is of large enough diameter to give free circulation to air and to allow for
tree growth. These products are easier to handle than wire guards, but some
may be broken down by ultraviolet light and may have a limited life.

Wrap-around plastic guards are readily available, cheap, and easy to
install but are not recommended unless they are removed each spring and
installed again in the fall . Various borers seem to prefer trees with wrap-
around plastic or paper guards. Also, the bark beneath plastic guards remains

tender and hardens slowly, the plastic may become brittle when weathered, and
these guards are difficult to keep in place on trees with uneven trunks or
swollen graft unions.

Paper wrap-around guards are not recommended. They must be tied off with
string which can girdle the tree unless it is removed in the spring. Very high
populations of bark borers have been found in trees protected with this
material. The treated paper also weathers quickly, and the protected bark
remains tender and hardens slowly.

Rodenticides

Poison baits are of two types: zinc phosphide and anti-coagulant. Just
one or two fresh grains or pellets of zinc phosphide-treated bait can quickly
kill the vole that eats it, whereas it may take several days of feeding on
anti-coagulant baits to kill voles. Owing to the caching habit of pine voles,
poison baits that are taken by the species may not be consumed until much
later, or not at all. Zinc phosphide breaks down slowly in moist air, and it
loses its toxicity rather quickly if the bait becomes wet. To preserve the
toxicity of unused zinc phosphide baits, place the opened package within a
plastic bag and seal the bag tightly.

Rodenticide Techniques

Broadcast . Broadcast applications of baits can be effective against
meadow voles. However, they are usually not effective against pine voles.
Bait should be directed into live ground cover where meadow voles forage,
rather than into herbicide-treated strips. Most product labels limit
treatments to the postharvest, dormant period. The presence of dropped apples
can make baiting ineffective; however, as apples are a preferred food for
voles. All sound drops should be removed before bait is broadcast. If the
weather is wet and dark during the first few days after broadcasting, the
baiting effort will have been wasted. Wet weather and dark days discourage
vole activity, and wet bait loses potency and palatability. Try to bait just
before a mild, fair-weather period of several days.

Baiting in Artificial Trails . Mechanical trail-builder baiting machines
construct trails beneath the soil surface and supply baits at regular intervals
for meadow or pine voles that enter those trails. According to the U.S. Fish
and Wildlife Service, which can furnish plans to construct the device, this
technique can be effective against both pine and meadow voles. Sod cover and
reasonably moist soil are required at the time the machine is pulled through
the orchard. Generally, one trail is made along each side of the tree rows,
beyond the wheel tracks, beneath the drip line of the trees, and in sod.
Trails should be cut 2 to ^ inches deep, with bait placed at ^- to 5-foot
intervals.

Hand-baiting . Hand-baiting implies selective placement of baits where
vole activity is most likely or where active trails or burrows are located.
Bait is placed in quantities of one teaspoon, at the rate of 2 to 3 lbs per
acre. To greatly speed bait placement, bait stations such as asphalt roofing
shingles or split tires should be distributed beneath the trees in sodded areas

well in advance of baiting time. Over a period of weeks or months voles
develop trails under these bait stations — trails that can be baited quickly
after harvest.

Orchard Floor Sprays . Liquid Rozol^^ (chlorphacinone) is an anticoagulant
formulated for spray application. In order for it to be effective, it must
thoroughly wet and penetrate the ground cover. Before the spray is applied,
the ground cover should be dry and mown short enough for maximum penetration.
Voles are killed after repeated exposure to residues on the ground and cover
crop. Liquid Rozol will not be effective when there is no surface-feeding
activity.

Estimating Vole Activity

Vole activity can be estimated by placing apples in runways or tunnel
entrances. Place whole, firm apples, with a thin slice removed, at regular
intervals throughout the orchard where activity is suspected. After 24 hours,
look for small teeth marks in the apples. If such a check indicates voles are
present 2 to 3 weeks following a baiting, a second treatment may be needed.

Re-treatment with Baits

Where some voles have been sickened by a rodenticide treatment but have
survived, the acceptance of the same bait a second time within a few weeks will
be poor. This problem seems to be more common with zinc phosphide baits than
with anticoagulants. If a second treatment is needed, use a different bait
(e.g., if zinc phosphide was used in the earlier treatment, use an
anticoagulant for the follow-up). Obviously, the best way to deal with this
problem is to prevent it from occurring: do everything possible to kill all of
the voles with the first treatment.

Orchard Borders

In the brushy areas immediately adjacent to a vole-infested orchard, one
can generally find a relatively high population of the same species that is
present in the orchard. If these border areas are not baited, they will be a
source of reinfestation of the treated orchard.

Caution

Rodenticide baits may be attractive to domestic pets, wild birds, and
other nontarget wildlife. Exposed bait, and especially exposed piled bait,
increases the chances of nontarget injury. As with all pesticides, use good
judgment and take reasonable precautions to avoid problems.

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Fruit Notes

Prepared by the Department of Plant & Soil Sciences

University of Massachusetts Cooperative Extension,

United States Department of Agriculture, and Massachusetts Counties cooperating.

ISSN 0427-6906

f Editors: Wesley R. Autio and William J. Bramlage

1988

Volume 53, Number 1
WDSTTER ISSUE, 1988

Table of Contents

Apple Scald, A Complex Problem

Can M.9 Rootstocks be Used Profitably in
Massachusetts Apple Orchards?

Nine Years of Apple IPM Implementation at the
Horticultural Research Center

Dormant Pruning to Improve Packout of Mcintosh

Are Asian Pears for New England?

Variable Conditions in CA Storage Can Cause Fruit

Disorders After Storage

Publications Available from the University of Massachusetts

APPLE SCALD, A COMPLEX PROBLEM

William J. Bramlage

Department of Plant and Soil Sciences, University of Massachusetts

Symptoms . "Scald" is a term loosely applied
to a group of skin disorders of apples and pears.
It involves brown or gray discoloration of
irregularly shaped areas on the surface of the
fruit during or following storage. On apples,
Wilkinson and Fidler (5) described the following
forms of scald:

a. "Rugose scald": skin initially develops a faint
bronze color, but later these areas turn Ught
brown to very dark brown. The surface
layers of cells are dead and so they dry out
and collapse, leaving a brown, sunken
appearance. Usually, many lenticels remain
green, however, standing out prominently
from the sunken areas.

b. "Browning scald": the lenticels do not remain
green, the injury progressively invades deeper
into the flesh, and areas often slough off
because they remain moist.

c. "Lenlicel spot scald": the injury is
predominantly around the lenticels, so that it
appears as a spotting rather than a blotchy
disorder.

d. "Stem-end browning": the injury is primarily
on the shoulder, radiating from the stem-end
cavity, which remains relatively free of the
disorder.

It appears that all of these forms are
expressions of the same problem, with specific
cultivars being more prone to one form or
another. However, there are many other forms of
fruit injury that also may cause skin damage that
is similar to one of these forms of scald. For
example, we have noted frequently a large amount
of lenticel spotting after storage which is clearly
the result of field treatments, presumably
pesticides, even though there was no evidence of
damage at harvest. This spotting could easily be
mistaken for "lenticel scald". Especially on
Mcintosh, we often see "black scald", a clearly
defined black area almost always occurring on the
red side of the fruit. This injury is actually a
form of sun scald, even though it usually is not

present at harvest, and could be confused with
"browning scald". With very ripe fruit, friction
damage can cause injury that could be confused
with either "browning scald" or "stem-end
browning". On pears, "scald" is often a symptom
of over-storage. Thus, there is often much
confusion about what is being called "scald".

Nature of scald . True scald is an
expression of damage and death within the
surface layers of cells in localized regions. It
never occurs on the tree, only after relatively
long periods of storage. Its development is
believed to be divided into four stages: 1. The
first 6 to 8 weeks after harvest, when changes
occur in the fruit that create the potential for
scald development, although scald does not yet
occur; 2. The next 5 to 8 weeks when changes
continue so that scald can no longer be
prevented although it still has not appeared; 3.
The remainder of storage, when scald may slowly
appear; 4. Post-storage, when scald rapidly
develops. Thus, the first 6 to 8 weeks after
harvest are crucial for applying scald control
measures, and post-storage conditions can
determine how extensively the scald symptoms
will appear. For example, we have noted much
more scald under humid post-harvest conditions
than under dry ones.

An outstanding series of research papers in
the late 1960's and early 1970's, mostly from
Australia, established much of what we know
about the chemistry of scald development. It
was shown that early in storage fruit accumulate
a chemical called alpha-farnesene; being a
volatile compound, much of it can evaporate
from the fruit. As storage time lengthens the
alpha-farnesene is oxidized to a group of
compounds called conjugated trienes, which do
not evaporate and continue to accumulate as
long as the fruit are kept in storage. These
conjugated trienes apparently are toxic to the
cells, damaging them and eventually causing their
death, which is accompanied by their brown or
black discoloration, drying out, and collapse.
Since most of the alpha-farnesene is found in
the fruit peel, most of the conjugated trienes

are made in the peel, and therefore these arc the
cells that are killed.

Factors affecting scald . Different cultivars
vary greatly in scald susceptibility. For example,
Cortland is extremely susceptible and nearly was
abandoned until effective scald-control methods
were developed. On the other hand, Golden
Delicious has very low susceptibility. The huge
increase in production of Granny Smith worldwide
has intensified concern about scald, since this
cultivar is extremely scald susceptible.

Susceptibility of a given cultivar is not
constant, however. It is widely recognized that
immature fruit tend to be more susceptible than
over mature ones. Although this relationship is
not invariably true, it is strong enough that
growers should be much more concerned about
scald on early-picked than on latc-pickcd fruit.

Color is another important factor. Scald is
more likely to occur on a green area than on a
well-colored area of the fruit. This relationship
is probably indirect; good exposure to sun is
probably what reduces scald susceptibility, rather
than red pigments. Thus, the production of red
strains of susceptible cultivars largely obscures
the fact that shaded areas and shaded fruit are
more susceptible than exposed areas and exposed
fruit. Excessive tree vigor and inadequate

pruning (hence, fruit shading) probably increase
scald susceptibility, while summer pruning
probably decreases it.

Scald susceptibility varies considerably from
year to year for a given cultivar. To a large
extent this variability is the result of the
influence of weather on scald susceptibility.
Studies in England (2) showed that weather
conditions from late July to the beginning of
September were very important: hot, dry weather
increased scald susceptibility; cool, damp weather
decreased it. Indications were that water stress
may have been more important than temperature
in this relationship. Studies in New Jersey (3)
showed that hot weather shortly before harvest
increased scald susceptibility; when Stayman
Winesap apples had experienced 190 or more hours
of temperatures below 50"F they did not develop
scald, but as this total dropped scald
susceptibility increased. Thus, a cool moist
August and a cool harvest season should greatly
reduce scald susceptibility; whereas, a hot dry

August and a hot September should increase it.
How these two periods interact is not clear.
For example, 1987 had a hot dry August but a
cool September. Is one of these situations more
important than the other?

Control measures . Numerous approaches to
controlling scald have been developed, since
losses to the disorder can be devastating. Early
approaches recognized that scald was caused by
a volatile compound and were aimed at
maximizing evaporation of the compound from
the fruit during storage. These techniques
included use of air purifiers in the storage,
storage ventilation, and paper wraps that were
impregnated with mineral oil. These techniques
reduced the amounts of scald that developed, but
did not control it.

CA storage greatly reduces scald. Both low
O2 and high CO2 can be effective. However,
since CO2 is most effective at concentrations
above 5% and most cultivars are susceptible to
CO2 injury above 5%, for most cultivars the
greatest benefit from CA is from the low O2.
The low O2 impedes oxidation of alpha farncsene
to conjugated trienes, the toxic materials. This
effect is much greater at 1 to 2% O2 than at 3%
O2, and many researchers have shown that scald
can be nearly completely controlled at 1 to 1.5%
O2. However, in the Northeast we have
generally been unable to store fruit at less than
3% O2, so we are unable to take full advantage
of the scald control from CA. At our
recommended CA conditions, scald is still a
potential problem.

An important factor in scald control
through CA is rapidity with which CA conditions
are established. Delayed sealing or slow

generation of an atmosphere can greatly increase
the risk of scald development after storage.
Rapid CA is an excellent scald control measure,
especially where O2 cannot be reduced below 3%.

Ethylene-scrubbing during CA storage can
also control scald. In England, scald virtually
was eliminated from fruit taken from a
commercial ethylene-scrubbed storage (1).
However, the feasibility of ethylene scrubbing in
commercial storage for most cultivars is doubtful,
so this method seems to have limited application.

The most reliable scald-control measure is

probably the use of the antioxidant chemicals
diphenylamine (DPA) and ethoxyquin. In the mid-
1950's Smock (4) found that these materials
provided excellent control of scald, and following
their approval by the Food and Drug
Administration they became standard commercial
treatments as postharvest dips for fruit destined
for long-term storage. These materials interfere
with the oxidation of alpha farnesene to
conjugated trienes, as does low O2 in a CA
atmosphere.

Use of antioxidants is not without its
problems. The materials must be used with care,
since excessive dosage can cause severe fruit
injury. Even use at recommended dosage often
leads to injury due to entrapment of solution in
cavities, between fruit, or in wooden containers.
As this trapped solution evaporates, the
antioxidant concentrates to injurious levels.
There is also concern about the risks to
consumers from residual antioxidants; since these
materials are volatile, little or no residue should
persist at the end of storage if the material is
used properly. However, these materials have not
been approved in some countries, so treated fruit
cannot be exported to such countries.

Current directions . During the past 3 years
we have been conducting extensive studies on
scald. Our goal is to reduce dependence on the
antioxidant chemicals for control. Current

recommendations are generally based on a "worse-
case scenario," since growers simply cannot risk
scald development. However, as is described
above scald susceptibility is extremely variable
and maximum treatment is often (usually?) not
necessary. If we can better quantify the factors
affecting scald, we should be able to quantify the
potential for scald and adjust the recommended
treatment to the actual need. One approach to
this is through careful collection of climatological
data in relation to scald development. A
cooperative study involving a number of fruit
researchers and directed by Dr. David Blanpied at
Cornell University is in progress. We are

attempting a different approach: a search for a
chemical index of scald susceptibiUty in the fruit
that might signal the need (or lack thereof) for
chemical treatments at the time of harvest.

Scald was probably the single most
important postharvest problem for apples until
antioxidant chemicals were approved. For 20
years after approval little further attention was
given to this problem. Now interest is renewed,
largely due to the need to reduce the use of
chemicals wherever possible. Growers can expect
to hear much more about scald control measures
in coming years.

Literature Cited

1. Dover, C. J. 1985. Commercial scale
catalytic oxidation of ethylene as applied to
fruit stores. In: J. A. Roberts and G. A.
Tucker (eds.). Ethylene and Plant
Development. Butterworths, London. pp.
373-383.

2. Fidler, J. C. 1956. Scald and weather.
Food Sci. Abstracts 28:545-554.

3. Merritt, R. H., W. C. StUes, A. V. Havens,
and L. A. Mitterling. 1%1. Effects of
preharvest Jiir temperatures on storage scald
of Stayman apples. Proc. Amer. Soc. Hort.
Sci. 78:24-34.

4. Smock, R. M. 1957. A comparison of
treatments for control of the apple scald
disease. Proc. Amer. Soc. Hort. Sci. 69:91-
100.

5. Wilkinson, B. G. and J. C. Fidler. 1973.
Physiological disorders. In: Fidler, J. C, B.
G. Wilkinson, K. L. Edney, and R. O.
Sharpies (eds.). Tlie Biology of Apple and
Pear Storage. Commonwealth Agricultural
Bureaux, East Mailing, Kent, England, pp.
67-Dl.

^^ ^f^ ^t^ ^m^ ^m^

CAN M.9 ROOTSTOCKS BE USED PROFITABLY IN
MASSACHUSETTS APPLE ORCHARDS?

Wesley R. Autio

Department of Plant and Soil Sciences, University of Massachusetts

The title of New York Agricultural
Experiment Station Bulletin No. 406 (1915) is
"Dwarf Apples Not Commercially Promising." The
opinions expressed in that publication certainly do
not reflect those held by the current researchers
at the New York Agricultural Experiment Station,
Geneva; however, there is still much resistance
among growers to the idea of planting fully
dwarfed apple trees. In this article data will be
presented that show that fully dwarfed trees on
M.9 can be substantially more profitable than the
much larger trees on M.7, particularly during the
early fruiting years.

Figure 1

Size of Rogers Mcintosh trees

planted in 1979.

Feet

M.7 A

M.26 M.9 Post M.9 Trellis

M.9 was one of the earliest dwarfing
rootstocks available. It was selected as a chance
seedling in France in 1879 (2) and produces a tree
only 25 to 50 % of the size of a standard,
seedling-rooted tree. A number of dwarfing
rootstocks which produce a tree similar in size to
that produced by M.9 now are being evaluated and
some are available, but M.9 still is used more

extensively worldwide than any other very
dwarfing rootstock (2). In the U. S. the strain
of M.9 which is most commonly available is M.9
EMLA. It was originally propagated from a
virus-free strain produced by the cooperation of
East Mailing and Long Ashton Research Stations
in England, hence the EMLA designation. A tree
on M.9 EMLA is somewhat more vigorous than
one on standard M.9. In this study the size,
productivity, and profitability of trees on M.9,
M.26, and M.7 were compared.

Table 1. Trunk circumference in 1987, calculated
tree density, and approximate spacing of Rogers
Mcintosh trees planted in 1979.

Trunk

Calculated

Approx.

circum.

density

spacing

Rootstock

(cm)

(trees/acre)*

(ft)

M.7A

43.2 a**

101

17x25

M.26

30.3 b

145

14x22

M.9 Post

19.7 c

277

9x17

M.9 Trellis

19.7 c

277

10x16

^Calculated from 1987 tree spreads (Figure 1).
**Means within columns are significantly
different if not followed by the same letter.

In 1979 a replicated planting of Rogers
Mcintosh and Macspur trees on M.7A, M.26, and
M.9 was established by Dr. Franklin W.
Southwick at the Horticultural Research Center,
Belchertown, MA. Half of the trees on M.9 were
trained to individual posts and half were trained
to simple, 3-wire trellises. At the end of the
1987 growing season (ninth leaf) trees were
nearing their mature size. Figure 1 depicts the
height and spread of the Rogers Mcintosh trees,
and Table 1 reports trunk circumferences. As
would be expected, trees on M.7A were the

Table 2. Yield per acre from Rogers Mcintosh trees and the percent of fruit making the U. S. Extra
Fancy grade in 1987 from Rogers Mcintosh and Macspur trees planted m 1979.

Yield per

acre (hv)

mvear:

Total

U.S. Extra
Fancy- 1987

Rootstock

(%)

M.7A
M.26
M.9 Post
M.9 Trellis

67 b*
84 b
147 a
180 a

147 b
183 b
217 a
307 a

163 b
168 b
294 b
463 a

385 c
426 be
512 ab
548 a

152 b
165 b
202 b
335 a

388 b
441 b
667 a
669 a

1302 c
1467 c
2039 b
2502 a

30 b
55 a
59 a
50 a

•Means within a column are significantly different if not followed by the same letter.

largest, reaching nearly 15 ft in height, and trees
on M!9 were the smallest, not reaching 9 ft. The
1987 tree spreads were used to calculate tree
densities and spacings (Table 1) so that potential
yields per acre could be estimated. Please note
that these densities represent optimal spacings for
this planting site, and those used by growers
should be adjusted as to cultivar, site, and soil
conditions.

Table 2 shows yields from years 4 through 9.
Each year the trees on M.9 produced more fruit
than those on M.7A or M.26. Additionally, in
later years and on a cumulative basis trees
trained to trellises yielded more than those
trained to individual posts. This observation is
likely related to a higher fruiting surface per
acre because of the support given to limbs by the
trellis. Also in Table 2 are reported the percent
of fruit making the U. S. Extra Fancy grade in
1987. These percentages are particularly low
because harvest occurred prior to optimum
coloring (September 8). Trees on M.9, both
posted and trellised, and M.26 had similar
percentages but all had significantly more Extra
Fancy fruit than those on M.7A. These smaller
trees were more open and allowed more light
penetration and coloring than did the more
vigorous trees on M.7A.

Higher yields and better potential packout
suggest that there are significant advantages to
planting trees that have been budded to M.9.
However, this information is not adequate to
recommend M.9 over the other rootstocks, since
the costs of producing apples on fully dwarfed

trees exceeds those of growing larger trees.
Therefore, it is necessary to look more closely
at the costs of production for trees on these
rootstocks and compare that information with
the potential monetary returns.

Table 3. Estimated per-acre establishment costs
of a Mcintosh orchard on M.7, M.26, and M.9
rootstocks.

M.7

M.26

M.9

Activity

Post Trel.

Site prep.*

Layout

Trees

Planting*

Posting*

Trellising*

700

500

125

700
30
725
175
300

700 700

60 60

1400 1400

350 350

600

1200

TOTAL

1345

1930

3110 3710

*Includes cost of supplies, labor, and equipment.

Cost data presented in this article are
estimates based on information from several
sources, including observations at the
Horticultural Research Center and published data
from Cummins and Norton (1), Gerling (3, 4),
Hanlon et al. (5), Kimball and Autio (6), and
Norton (7). Plantings of trees on M.9 cost
significantly more to establish than plantings on

M.7. Table 3 shows estimated establishment costs.
The more dwarfing rootstocks required a higher
tree cost, since more trees were planted per acre.
They required more labor in layout and planting.
Also, the cost of posting or establishing a treUis
was quite high and neither is required for trees
on M.7.

Table 4. Itemized per-acre costs of growing
Mcintosh trees during their second season.

differences in the costs of maintaining
nonbearing and bearing trees on these
rootstocks. Table 6 gives the individual and
cumulative costs for 9 years for each rootstock.
The major differences among rootstocks related
to training requirements, with the trellised trees
requiring significantly more labor to maintain.
Also, equipment usage was higher with the
dwarfed trees because of the greater number of
rows per acre to travel. The amount of spray
material required was considerably lower for
trees on M.9 because of the lower tree volume

per acre.

Additionally, the pruning time was

M.7

M.26

M.9

less for the small trees.
Table 6. Estimated

per-acre cost of

Activity

Post

Trel.

growing

Labor

Mcintosh trees during years 1 through 9.

Pruning

Training

150

Spraying

M.9

Other

Year

M.7

M.26 Post Trel.

Equipment

150
140

200
140

250
140

Chemicals

Other

Yearl

400

450 500

600

TOTAL

435

520

610

710

Year 2
Year 3
Year 4

435
520
600

520 610
600 700
630 750

710
800

900

Year 5

650

670 800

920

Table 5.

Itemized

per-acre

costs of growing

Year 6

720

710 880

940

Mcintosh trees during their ninth i

season.

Year 7

800

760 880

950

Years
Year 9

840
845

800 890
805 900

950

960

M.7

M.26

M.9

TOTAL

5810

5945 6910

7730

Activity

Post

Trel.

The

costs of trees on M.9 trained

Labor

to posts

Pruning

195

130

and M.9 trained

on trellis, including

Training

100

estabUshment, growing,

and harvesting (Table 7),

Spraying

were 36%

> and 57%, respectively, greater

than for

Other

trees on

M.7. However, the returns (Table 7),

Equipment

250

300

450

accounting for yield differences and some

Pesticides

250

200

150

variation

in packout

during the later

seasons

Fertilizers

when the

trees were 1

larger, were 60% ;

and %%

Other

greater than for M.7

The net profit

for the

TOTAL

845

805

900

960

first 9 years (Table '

7) was $405 per

acre for

trees on ]

M.7 and $4780 for trees on M.9 trained

to a treUis.

Growing costs differed as the trees on the
different rootstocks matured. Tables 4 and 5
itemize the growing costs for the second and
ninth growing seasons, respectively, to illustrate

These data suggest that during the early
fruiting years Mcintosh trees on M.9 are
considerably more profitable than those on M.7.
As these trees reach full maturity the

Table 7. Total per-acre costs and returns from
Mcintosh trees during their first 9 growing
seasons.

they give a basis for some comparison of these
rootstocks.

M.9

Activity

M.7

M.26

Post Trel.

COSTS:
Establishment
Growing
Harvesting*

1345
5810
2900

1930
5945
3100

3110
6910
3700

3710
7730
4300

Total

10055

10975

13720

15740

RHIURNS:**

10460

12030

16720

20520

NET:

405

1055

3000

4780

*Based on a fixed per-acre cost related to
equipment, picker housing, picker travel, etc.
plus a per-bushel cost related to harvesting.
** Based on yields reported in Table 2.

differences in yield and maintenance costs may
decline; however, the differences in packout may
increase. Rough estimates comparing the costs
and returns for the first 20 years of the planting
suggest that trees on M.9 trained to a trellis can
net $10,000 per acre more than trees on M.7,
accounting for differences in training, spraying,
yield, and packout. It is important to note that
the cost estimates used in this study could vary
greatly from those for an individual farm, but

Literature Cited

1. Cummins, J. N. and R. L. Norton. 1974.
Apple rootstock problems and potentials. N.
Y. Food and Life Sci. Bui. No. 41.

2. Ferree, D. C. and R. F. Carlson. 1987.
Apple rootstocks. In: R. C. Rom and R. F.
Carlson (eds) Rootstocks for Fruit Crops.
John Wiley & Sons. New York. pp. 107-143.

3. Gerling, W. D. 1984. A survey of the cost
of growing and harvesting apples in eastern
New York in 1983. Fruit Notes 49(3):12-18.

Gerling, W. D. 1986.
costs. Proc. Annu.

Growers' Assoc. 92:28-35.

Grower production
Mtg. Mass. Fruit

5. Hanlon, W. L., C. E. Willis, and R. L.
Christensen. 1976. A framework for long
range apple varietal decisions. Mass. Agric.
Exp. Sta. Bui. No. 621.

6. Kimball, M. A. and W. R. Autio. 1987.
Rejuvenating Mcintosh apple orchards: A
response to Alar reduction. Univ. Mass.
Coop. Ext. Circ. C-187.

7. Norton, R. 1970. High density apple
planting using clonal rootstocks. N. Y. State
Hort. Soc. Newsletter 26(3): 1-16.

NINE YEARS OF APPLE IPM IMPLEMENTATION AT
THE HORTICULTURAL RESEARCH CENTER

William M. Coll, Ronald J. Prokopy, and Kathleen Leahy
Department of Entomology, University of Massachusetts

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

Anthony Rossi

Department of Plant and Soil Sciences, University of Massachusetts

Commercial fruit grower adoption of IPM is
well established in a majority of Massachusetts
orchards {Fruit Notes 51(2):11-16; 51(3):19-25), and
such orchards represent a change from pre-IPM
pest management — a single-minded focus on
chemical pest controls -- to a more hoUstic IPM
approach integrating techniques, and disciplines of
pest management. In the 1987 March Message, we
described a range of characteristics which we
believe represent a typical "first-stage" IPM
orchard. In addition, we have published results
(Can. Ent. 117:581-585,1985) from Prokop/s
Conway orchard of 50 disease-resistant apple
trees that show reduced pesticide use even below
first-stage IPM levels.

Since most commercial orchards will not
contain primarily resistant cultivars for the
foreseeable future, we believe it is important to
demonstrate "how low one can go" with pesticide
use in first-stage IPM blocks which contain the
usual commercial apple mix, without sacrificing
fruit quality or quantity. Consequently, we think
growers would be interested in data we have
collected in a test orchard that used first-stage
IPM practices for a number of years.

This article presents the results of 9 years
of IPM implementation at the Horticultural
Research Center (HRC), Belchertown, MA.
Although the HRC is operated in most respects
like a typical commercial orchard, it allows us to
test new approaches to pest management and be
somewhat less risk-aversive than growers whose
livelihood depends on successful pest management
year after year.

Since 1979, the authors have cooperated to
implement a minimum-spray program in Block C at
the HRC, a 2-acre interior block, west of Sabin

Street and just north of the cold storage
building. Composed of mostly Delicious strains
on M.7 rootstocks, with a few Mcintosh mixed
in, trees are well pruned and fertilized.

Because of the demands of other research
being conducted in Block C, fungicide programs
in the early years were moderately conservative,
but insect and mite sprays were applied only if
justified by observations or trap captures in
excess of economic thresholds. Over the past 3
seasons, the effort to reduce fungicide in the
block has been intensified, and has consistently
included pre-application consultations. Where
pesticide labels allowed a range of rates (e.g., 4
to 6 oz/100 gal), we used the low end of the
range, or lower. Anthony Rossi, the orchard
foreman, received weekly scouting reports and
sometimes recommendations. Final spray

decisions were always his, although he followed
IPM guidelines very closely. Wherever practical,
sprays were avoided deliberately, and we
attempted to avoid the use of predator-harsh
pesticides (e.g. pyrethroids, carbamates, etc.) as
a matter of course. When sprays were applied,
few were at full, labeled rates. Sprays were
applied with well-calibrated airblast sprayers and
whenever possible at the same time that the rest
of the orchard was being covered. Each year,
we performed harvest surveys and examined
closely 800 to 1000 fruit on the trees.

Pesticide use . On average, 2.9 dosage
equivalents (DE) of insecticide, 1.0 DE oil, 1.3
DE miticide, 6.0 DE fungicide, and 0.1 DE
aphicide were applied (Table 1). Insecticide,
miticide, and fungicide use were all below
statewide IPM averages {Fruit Notes 52(3):9-12).
For reasons that are unclear, the HRC has never
had a problem with apple leafminers, although

Table 1. Number of spray applications (A) and dosage equivalents (DE) of
pesticide used in Block C, University of Massachusetts Horticultural Research
Center, 1979-87.

Year

Insecticide

Miticide

Fungicide

Aphicide

Total DE

1979 -A

3.0

1.0

2.0

9.0

-DE

2.3

1.0

1.2

4.5

9.0

1980 -A

5.0

1.0

2.0

9.0

-DE

3.0

1.3

0.8

4.8

9.9

1981 -A

3.0

1.0

3.0

8.0

-DE

1.6

1.0

1.2

5.6

9.4

1982 -A

4.0

1.0

2.0

8.0

-DE

2.8

1.0

2.0

5.6

11.6

1983 -A

2.0

1.0

2.0

11.0

-DE

0.8

1.0

0.8

7.7

10.3

1984 -A

3.0

1.0

3.0

11.0

-DE

1.6

1.0

1.8

9.1

14.5

1985 -A

2.0

1.0

2.0

7.0

-DE

2.0

1.0

1.5

4.7

9.2

1986 -A

2.0

1.0

2.0

8.0

-DE

1.6

1.0

0.8

7.2

10.6

1987 -A

5.0

1.0

2.0

6.0

-DE

4.1

1.0

1.8

5.0

11.9

9- Year Average

-A

3.2

1.0

2.4

8.5

0.1

-DE

2.9

1.0

1.3

6.0

0.1

10.7

*Endosulfan used against green aphids but timed to coincide with first
summer generation LM adult flight.

they are present in the orchard (most noticeably
in the third generation) and a nearby orchard has
experienced severe leafminer outbreaks and injury.
Fortunately, this pest has never exceeded action
thresholds, and no carbamate or pyrethroid
insecticide has been used in Block C.

In addition to helping keep insecticide DE
below state IPM averages, the absence of
predator-harsh pesticide also has made mite
control relatively easy in this block, even though
Red Delicious predominate. The occasional late
outbreak of ERM, and resultbg egglaying, do not
appear to be something that annual oil
applications (Table 1), endemic mite predators,
and split applications of low miticide rates caimot
handle.

Only in one year was any pre-bloom
insecticide appUed against TPB. Typically, the
first insecticide was applied at petal fall against
sawfly and curculio. An average of 1.6 spray
appUcations (range 1-2) were directed against
curcuUo. It seems clear that in some blocks at
least the 3, 4, or even 5 insecticide applications
some growers use against PC are not required.

A likely contributing factor to the relative
ease of mite control in Block C is the relatively
low number of spray appUcations (avg. 1.6, range
1-3) used against AMF. In over half of the
years (57%), first capture of AMF on red sphere
traps was late enough, and trap captures low
enough, to enable excellent AMF control with
only 1 well-timed spray. Only once were 3
sprays needed, based on monitoring.

As mentioned above, the fungicide program
in Block C was moderately conservative and,
although partly based on hygrothermograph and
weather monitoring and spore maturity
determination, likely could be improved upon.
Fungicide use in Block C largely was driven by a
perception that the cost:benefit ratio for
fungicide use was low. To eliminate the
perceived risk, fungicides were often appUed with
insecticides and oil sprays. From a high of 11
appUcations and over 9 DE in 1984, fungicide use
was reduced in 1987 to the fewest number of
spray appUcations (6) and the third fewest number
of DE (5.0) since we began record-keeping in
1979. This situation was at least partly due to
the incorporation of a new sterol-inhibiting (SI)
fungicide into the program.

Aphicide use in Block C was essentially nil,
with predators providing control in most years.
If needed, Anthony Rossi has been able to
coordinate application of endosulfan against aphids
and first summer generation adult leafminers.

Harvest survey results (Table 2). Levels of
pest injury in Block C were well within
acceptable ranges for commercial orchards in
spite of the much lower than average i>esticide
program.

As noted in Table 2, disease injury in all
years was negligible, reflecting a consistently
successful fungicide program even when less than
full rates were used.

Tarnished plant bug was the most frequent
injury found in samples. A high infestation in
1983 drove average injury up to 2.4%. However,
most of the 1983 injury was of the severity and
type that would not have affected fruit grade.
In 1983, plum ciu-culio injury reached 1.6%.

In two years, we experienced late season
mite buildup. Red mite eggs in the fruit calyx
were observed, although this "injury" is not
considered serious by most growers and again
should have no effect on grade.

Table 2. On-tree harvest surveys: percent insect, mite, and disease injury,
Horticultural Research Center, 1979-87.

Other

ERM

Year

TPB*

EAS

AMF

insects

eggs-

BER

SCAB

1979

0.8

0.2

0.1

3.0

1980

1.8

0.3

0.4

.***

1981

0.2

3.7

0.2

1982

1.0

0.3

1.0

1983

11.5

1.6

1984

0.2

3.7

0.2

1985

1.5

0.5

1986

1987

0.3

0.1

9 Year

Average

2.1

0.3

0.2

0.9

0.1

0.4

(Average Injury 4

.1%)

•TPB, tarnished plant bug; PC, plum curcuUo; EAS, European apple sawfly;
AMF, apple maggot fly; ERM, European red mite; BER, blossom end rot;
SCAB, apple scab; FS, fly speck.
**Eggs in calyx of fruit at harvest.
***Data not available.

Table 3. Cost per acre
Research Center, 1980-87*.

of spray materials, Block C, Horticultural

Total

Year

Insecticide

Oil

Miticide

Fungicide

Aphicide

yearly cost

1980

$34.55

$25.94

$18.50

$48.91

$127.90

1981

$14.48

$26.16

$24.98

$48.73

$114.35

1982

$38.29

$21.60

$43.80

$67.96

$171.65

1983

$9.24

$21.60

$18.24

$72.67

$121.75

1984

$18.50

$21.60

$41.04

$82.01

$41.04

$204.19

1985

$18.48

$21.00

$40.77

$46.47

$126.72

1986

$18.50

$21.60

$18.24

$67.%

$126.30

1987

$43.61

$21.60

$27.51

$50.87

$143.59

8 Year

Average

$24.46

$22.64

$29.14

$60.70

$5.13

$142.06

*Based on 300 gal/acre dilute base and non-discounted chemical costs.

It is interesting to note that although apple
maggot flies were caught in the block, no AMF
injury was ever detected. In the case of mobile
pests like the AMF, which normally do not
establish resident populations in sprayed blocks,
orchard edges typically experience more pest
pressure than interiors. We have looked at
hundreds of fruit in Block C over the years, and
we have never seen a single fruit damaged by
apple maggot egglaying. While it is true that
Block C is an interior block, this points out the
possibility that growers may be applying more
insecticide than is needed in similar blocks
elsewhere. The protection afforded interior
blocks such as Block C by sprays applied to
surrounding sprayed blocks may allow some
growers to achieve signiHcant decreases in
pesticides required for acceptable pest control.

Pesticide costs and potential for further
reduction (Table 3). By better using spore
maturity and weather monitoring and by including
SI fungicides against apple scab, we believe that
fungicide costs can be reduced further. This past
year, Rubigan^"* allowed longer spray intervals
between appUcations during frequent wetting. It
also gave us the confidence to wait until after an
infection period had occurred before making an
application. Additionally, information was

available from both a Reuter-Stokes scab

predictor and a modified hygrothermograph.
Having reliable weather information and a
fungicide with 96 hours post-infection activity
reduced the perceived risk.

Without Isirge-scale use of red sphere AMF
traps, it is unlikely that further significant
reductions in insecticide use can be achieved, so
that Uttle additional cost saving compared to
pre-IPM levels is expected. However, simply
reducing the total pesticide load in an orchard
should enhance the survival of mite predators
and reduce the difficulty of mite pest
management. Because of the importance of
spider mite pests, oil is an essential component
of apple IFM, and will remain a more or less
fixed cost. Of course, fluctuations in the price
of oil could significantly increase the cost of
annual treatment, as in 1980-81. The use of
mite predator releases in the future may provide
a way to apply oil only every 2 or 3 years, and
hence reduce the cost of this material.

The cost of aphicide would not be expected
to increase in low-spray blocks, due to enhanced
survival of aphid predators. Proper tree pruning
and fertilization will help deter aphid buildup
beyond economic thresholds. However,

occasional outbreaks (rosy aphid) could require
aphicide use.

Conclusions . From our experience at the
HRC, we conclude that it is possible, using first-
stage IPM strategies and technologies, for some
commercial growers to further reduce amounts of
pesticide used, and consequently, reduce costs (at
least in certain interior blocks) without
sacrificing fruit quality. We urge growers to
consider a scouting/low-spray approach in a trial
block so that they can achieve the lowest possible
spray usage from first-stage IPM. As growers

move beyond pesticide management toward the
"Second-Stage" of IPM, pest management
potentially will include such techniques as
resistant cultivars, insect growth regulators,
predator/parasite release or enhancement,
trapping out pests, mating disruption, oviposition
deterrents, etc. We are hopeful that second-
stage IPM research (now under way) will result
in even greater savings in pesticide cost and
improvement in farm profitability.

0^ 4|k ^* ^p ^p

DORMANT PRUNING TO IMPROVE PACKOUT
OF MCINTOSH

Duane W. Greene and Wesley R. Autio

Department of Plant and Soil Sciences, University of Massachusetts

A U. S. Extra Fancy Mcintosh apple must
have at least 50% typical red color, and an apple
will develop red color only if it is exposed to the
sun. The higher the light intensity reaching an
apple, the earlier its red color will develop and
the more intense its red color will be. The type,
severity, and location of the pruning cuts
determine the extent to which fruit on a tree will
be exposed to adequate light for good red color
development. Therefore, it is important for all
growers to conduct dormant pruning that will
assure good light penetration into the tree canopy
and high packout.

Types of pruning cuts and their use . Three
basic types of cuts are used during the pruning of
apple trees. These are described below.

1. Tliinning-out. These are cuts that involve
removal of an entire shoot or branch at its
junction with another shoot, a branch, or
the trunk. This type is the most useful
pruning cut on mature trees. It can be
used to redirect branch growth and open up
the tree for greater light penetration.

2. Stubbing. This type of cut involves the
removal of a portion of a branch back into
2-year-old or older wood. Stubbing is

usually done to reduce the length of a
limb or to stiffen a limb so that it does
not bend down and shade branches below.
Lateral branching may be increased by this
type of a cut. Excessive regrowth from
stubbing can be reduced by cutting to a
weak sideshoot.

3. Heading. A heading cut removes a portion
of 1-year-old wood. On bearing trees
heading cuts are not recommended, because
they encourage the development of lateral
shoots clustered near the cut, which have
narrow, weak crotch angles. If heading
cuts are made on a tree over a number of
years, a mantle of bushy growth will
develop that will inhibit light penetration.
Since some of the most productive buds
are removed each year and others are
forced to grow into lateral shoots,
cropping potential on these trees is
reduced considerably.

Pruning the bearing tree . The goals of
dormant pruning of mature apple trees are to
remove unproductive wood, to encourage the
continued development of productive wood, and
to allow maximum light penetration into the tree
canopy. The types of pruning that are most

frequently performed to achieve the above goak
are listed below.

1. Eliminate branches that are crossing.
These branches shade fruit and result in
low quality and poor coloring.

2. Remove large branches in the tops of trees.
A conical tree allows the most efficient
interception of light. A program of limb
rotation in the upper 1/3 of a tree should
be conducted to assure that no large limbs
will develop that might shade fruit or
prevent the development of scaffold limbs
below. It is critical that these Umbs be
eliminated if summer pruning is to be
effective. They cannot be removed during
the summer and if present even severe
summer pruning will not be sufficient to
overcome the shading.

3. Eliminate large upright branches.
Extremely strong branches that compete
with the central leader will cause problems
until they are removed. They prevent the
development of good scaffold branches and
they frequently cause too much shading.

4. Remove branches growing toward the center
of the tree. Branches growing toward the
center of the tree will increase shading in
an area prone to low light.

5. Remove branches with narrow crotch angles.
Branches with narrow crotch angles are
weak and frequently break under a fruit
load or during ice or snow storms. It is
important to remove branches with poor
crop potential to allow the growth of better
limbs with greater potential.

6. Remove weak wood. Fruit that develop on
weak branches are characteristically small

and have poor quality. When fruit on
these branches begin to grow the branches
bend down and shade other fruiting
branches below.

7. Lower tree height. When trees get too
tall they become difficult to harvest and
spray, and the upper portions can shade
productive branches below. Trees on M.7
can be lowered to 10 to 14 feet without
appreciable loss of yield if they have been
trained to a central leader.

Don't try to do it all at once . If a tree
has not been pruned or only has been pruned
lightly for several years, extensive pruning may
be necessary. However, growers should not make
all of the cuts in one year if extensive wood
removal is necessary. Tree renovation should be
distributed over at least 2 years. If too much
wood is removed in one year poor fruit set and
excessive vegetative regrowth may occur. It is
important to make sure that there is adequate
fruit set so that the crop can help control
regrowth.

The recommended pruning approach . We
feel that the pruning approach most useful in
Massachusetts will involve a combination of
dormant and summer pruning. It is essential to
establish the tree shape and make major cuts
during the dormant season. Large cuts made
during July and August likely will result in
extensive fruit bruising caused by falling
branches. Pruning during the summer should
emphasize the reduction of shading by removal
of young, nonfruitful wood. Summer pruning is
not an expense that is added directly to your
dormant pruning costs. At the Horticultural
Research Center dormant pruning of trees that
were previously summer pruned required 40% less
time than trees that were not summer pruned.
Prepare your trees now for summer pruning.

*•!• »Sg ^f %fe
^P •P *•* ^r

ARE ASIAN PEARS FOR NEW ENGLAND?

James T. Williams

University of Massachusetts Cooperative Extension, Concord, MA

Asian pears that we see on the fruit
counters of local supermarkets are the cultivated
forms of Pyms serotina (pyrifolia) and Pyrus
ussuriensis. They are unique in flavor and are
sometimes called salad pears, apple pears, or
oriental pears. They are firm, crisp, crunchy, and
juicy when ripe. Unlike many of our domestic
pears {Pyrus communis), they obtain their best
quality when ripened on the tree.

The Asian pear found its way to the United
States m mid-1800's during the Gold Rush when
early Oriental miners brought seeds with them
from China where these pears were first grown in
693 A.D.

Cultivars . The most commonly grown

cultivars in California are: Shinseiki (early),
Kikusui (mid-season). Twentieth Century, Chojuro,
and Ishiiwase (late). Most Asian pear cultivars
are partly self-fruitful, but better crops can be
expected when two or more cultivars are planted
together.

Spacing, training, and culture . Asian Pears
can be planted anywhere standard pears can be
grown. They must have 400 to 900 hours of
chilling temperatures below 45°F. They are
planted in the spring as with standard pears. We
have little experience with spacing requirements;
however, in California spacings vary from 7.5 x 15
feet to 15 X 20 feet, depending on the rootstock
used. These trees can be maintained as free-
standing, central leader or modified-central leader
trees. Trellising in Japan using the Pergola
system gives a continuous, single-layer canopy
kept at approximately 5 feet off the ground.
High quality, large fruit are harvested without the
use of ladders. The Tatura or modified Tatura
systems, which are "V"-shaped, are established
with trees spaced 5 x 16 feet and with the two
main scaffolds sloped 60° from horizontal.
Fertilizing and other cultural practices are similar
to those for standard pears.

Rootstocks . Pyrus betulaefolia is the most
commonly used rootstock for Asian pears because
of its vigor, tolerance of wet and poorly drained

soils, and effect on fruit size. Most Asian pears
are severely dwarfed on P. communis rootstocks,
but a few such as TsuU and Ishiiwase are
compatible and have done well in California.

Fruit thinning . Thiiming of the fruit is of
prime importance because premium prices are
paid for large fruit. During the winter of 1986-
87 New England supermarket prices for Asian
Pears ranged from $2 to $3 per pound! Heavy
crops are frequently set, often with 6 to 8 fruit
per cluster. Thinning to one fruit per cluster
and to 5 inches apart will insure good-sized
fruit. Most growers hand-thin fruit 3 to 6
weeks after petal fall. When trees are not
thinned, alternate bearing can develop.

Pests. Pear psylla is the most serious pest
of Asian pears, but Asian pears appear to be less
attractive and suffer less damage than standard
pears. Codling moth and mites are lesser
problems but bear watching. Fireblight can be a
problem but so far has not seemed as severe as
with Bartlett and Bosc.

Harvest . Harvest times in our area have
not yet been established but there are several
cultivars available that Hkely will ripen in
September and October. (Note: To begin
obtaining some information, such as harvest
dates, the three regional fruit agents in
Massachusetts are establishing Asian pear
cultivar trials including about 10 to 12 trees on
a site. Growers who are interested in being
involved in this study are urged to contact one
of the regional agents.) When harvesting Asian
pears care must be taken, because scarring and
bruising can occur very easily. Fruit should be
picked into Hned baskets. Yields in California
range from 150 to 200 pounds per 8- to 10-year-
old tree.

Storage . Most Asian pears can be stored
for up to 6 months at 32°F, although some
cultivars store better than others. So far,
extended storage has not been required to a
great degree in California, since market demand
has remained high early in the season.

Market . A New England market for Asian
pears has already been established by Western
U.S. fruit marketers, but it is felt that a few
enterprising local growers could find a niche in
our markets for this group of fruits.

Information for this article came from
Fowler Nurseries, Newcastle, CA, and from
articles in HortScience (15:13-17) and California
Agriculture (W. H. Griggs and B. T. Iwakiri.
January, 1977).

*^k 4t ^t# ^b

*J* ^^ *(* •p

VARIABLE CONDITIONS IN CA STORAGE CAN
CAUSE FRUIT DISORDERS AFTER STORAGE

William J. Bramlage

Department of Plant and Soil Sciences, University of Massachusetts

We frequently receive samples of fruit after
storage which contain some disorder(s), and are
asked what caused the problem. Even when we
see a copy of the storage log, it is often difficult
to specify the problem. We can usually identify
the disorder, but pinpointing its cause is often
little more than a guess, because storage (and
prestorage) conditions often interact to produce
problems.

This interaction of conditions was addressed
in a recent paper by C. R. Little and I. D. Peggie
of the Horticultural Research Institute, Victoria,
Australia {HortScience 22(5):783-790). The paper
reported results from an extraordinarily complex
series of experiments that spanned 8 years and
included 7 cultivars of apples and 2 cultivars of
pears. All fruit were harvested preclimacteric and
were stored in small experimental chambers where
conditions could be carefully controlled.

The primary objective was to test various
I0W-O2 regimes. In this experiment, they

compared Conventional CA (2 to 5% CO2 and 2 to
5% O2, depending on cultivar). Ultra-low O2 (1%
CO2 and 1.5% O2), and Hyper-low O2 (0.5% CO2
and 0.7 to 1.0% O2). They also applied Initial
L0W-O2 Stress (less then 0.2% O2 and less than
2% CO2 for the first 10 days of storage), followed
by one of the other I0W-O2 systems. In addition
to comparing the various O2 regimes, they
examined the interaction of Rapid CA (at-
temperature 1 day after harvest and at-
atmosphere in less than 6 days after harvest),

Slow CA (at-atmosphere 14 to 20 days after
harvest), inappropriate temperatures, high CO2
levels, and ethylene scrubbing.

Results were judged in terms of the
percentages of disorders that occurred, primarily
scald, Hesh browning, and core flush (a disorder
somewhat similar to brown core in Mcintosh).
Most of the experiments were with Jonathan and
Granny Smith apples.

Among the findings of the study were these:

1. The lower the O2 level, the less scald
developed. However, below a certain O2
level (depending on cultivar), the percents of
flesh browning and core flush increased. At
these levels, off-flavor and purpling of the
skin were noticeable in some cultivars.

2. Very low levels of O2 at the beginning of
storage were effective when Rapid CA was
used, but caused disorders when Slow CA
was used. Also, the Initial L0W-O2 stress
caused disorders if it lasted more than 10
days.

3. If the atmosphere was changed part-way
through storage, it was beneficial if it
beoune less severe but was detrimental if it
became more severe. The change was more
consequential if it occurred at 100 days than
if it occurred later than this.

4. When temperature was kept either above or
below what was recommended for a cultivar,
greater amounts of disorders occurred. If the
incorrect temperature was combined with low
O2, the effect was made worse.

5. Disorders that were intensified by very low
O2 and by low temperature were made worse
when CO2 was too high. The worst situation
was when very low O2 was combined with
both too low a temperature and too high a
CO2 level. All 3 factors interacted to worsen
problems.

6. Ethylene scrubbing reduced disorders,
especially scald. However, either 6% CO2 or
extremely low O2 levels were just as effective
as ethylene scrubbing in controlling scald.

7. When CO2 was higher than O2 in a storage
atmosphere, disorders tended to be increased.
Low O2 and high CO2 interacted to intensify
disorders other than scald, but the presence
of ethylene did not make these problems
worse.

The technology involved in these studies
generally is not applicable in the Northeast fruit
industry today. However, the principles that are
seen in the results are meaningful.

Clearly, anyone wishing to modify standard
storage recommendations must do so with great
care. Lowering O2, increasing CO2, or lowering
temperature possibly can reduce fruit softening,
but any of these factors can also lead to
disorders: low O2 injury, high CO2 injury, or
brown core. Thus, each modification involves a
calculated risk. What is generally not recognized
but is made dear in these studies is that if one
factor is changed (e.g., O2 is lowered), the risk
of damage from the change is greatly increased if
temperature is also changed or CO2 is also raised,
or worst of all, if all 3 modifications occur.
Most often, these additional changes are not
intended but result from operator errors or
equipment malfunctioning. The less reliable and
accurate that storage operation is, the greater is
the risk of a detrimental result if a storage
condition is deliberately modified.

The corollary of this situation is: if a

storage operator wants to modify standard
recommendations, storage management must first
be made precise and accurate. It is hazardous
to modify storage conditions without fu-st making
certain that storage operations are precise. If
you want to modify one condition, you must be
able to control other factors so that a stressful
combination of factors can be avoided.

Should a storage operator discover that
adverse conditions have developed, he should
react by lessening the stress on the fruit. For
example, he may be operating at a less-than-
recommended O2 level when he discovers that
CO2 is creeping out of control. Since he is
losing control of CO2, he needs to increase the
O2 to avoid a double stress. The sooner this is
done, the less likely it is that damage will
result.

Little and Peggie concluded that percent
CO2 should not exceed percent O2 in a storage
atmosphere. We recommend 5% CO2 and 3% O2
for Mcintosh, which appears to violate their
conclusion. However, ours is a very conservative
recommendation for Mcintosh, recognizing the
lack of sophistication in operation of most of
our storages, and is outside the consideration of
these authors. Yet, it is probably a good rule-
of-thumb that should you lower O2 below the
standard recommendation, you should follow
Little and Peggie's advice: keep CO2 lower than
O2.

The results of this study emphasize that
storage operation is a system , in which O2, CO2,
and temperature are in balance. Preharvest
conditions, fruit maturity, speed of atmosphere
generation, and possibly ethylene enter into this
balance. Our standard storage recommendations
are deliberately conservative to allow for some
variability among these factors. If a storage
operator chooses to modify these
recommendations, he must be able to control the
other factors in this balance, so that multiple
stresses do not result. Unless he can provide
this control, he should not deviate from the
standard recommendations unless he is prepared
to accept possibly serious development of
disorders in fruit during and after storage.

*4f '^ *t> ^b

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Fruit Notes

Prepared by the Department of Plant & Soil Sciences - . ^^O'^Orr'^ /»

' ■ '■-■' . ■"C-

University of Massachusetts Cooperative Extension, " ' ^ O

United States Department of Agriculture, and Massachusetts Counties cooperating. ^PR ^ C) looq

ISSN 0427-6906

Editors: Wesley R. Autio and William J. Bramlage

SCitivjj^

^^^ti^iii

Volume 53, Number 2
SPRING ISSUE, 1988

Table of Contents

Summer Pruning is Important for
Early Harvest of High Quality Mcintosh

A Brief History of the Cultivated Strawberry

The Initiation of a New IPM Program in Strawberries in
Massachusetts: Accomplishments in the Pilot Year 1987

Benefits of Alar to Apple IPM Programs

Results of the First Year of Second-stage Apple IPM Practices

Singing in the Rain: The Effects of Weather on Plum Curculio

Spring Migration

A Comparison of Insecticidal Soap and Amitraz as Summer Sprays

Against Pear Psylla

A Report on the 1987 Massachusetts Apple IPM Program

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

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tion begins January 1 and ends December 31. Some back issues are
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addresses). Payments must be in United States currency and should
be made to the University of Ma.ssachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

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opportunity in programs and cntploynicnt.

SUMMER PRUNING IS IMPORTANT FOR EARLY
HARVEST OF HIGH QUALITY MCINTOSH

Duane W. Greene and Wesley R. Autio

Department of Plant & Soil Sciences, University of Massachusetts

Summer pruning is a useful technique for increas-
ing red color and allowing early harvest of Mel ntosh apples,
as we have previously reported (Fniit Notes 52(3):7-8).
Most researchers conclude that August is the best time to
summer prune. It is reasoned that at this time rcgrowth
following summer pruning will be minimal, there will be
little risk of encouraging winter injury, and it will not be too
late to enhance color development. The goals of our
research in 1987 were to confirm the benefits of summer
pruning and to evaluate the potential for expanding the
timing of summer pruning to include .inly.

Dormant Pruning is Neccss:irv . Previously we
emphasized the need for proper dormant pruning to
achieve the maximum benefits from summer pruning
(Fm/VA'oto 53(1): 12-13). Large branches in the tops of the
trees that cause shading must be removed during the
dormant season, because removal during the summer
causes too much fruit damage and drop as cut branches fall
through the tree canopy. A program of limb rotation in the
tops of trees should be conducted in the dormant season to
maintain a conically shaped tree and to assure that there
are no major obstacles to light penetration into the tree
canopy.

Summer Pruning Procedure . Summer pruning
cuts should maximize light penetration. (Jcneraliy, these
are made in the tops and on the periphery of the tree.
Specific suggestions are listed below.

1. Remove vigorous, upright branches that will not be
productive.

2. Remove weak, hanging branches that are shading
productive wood below them.

3. Remove watersprouts; however, leave a sufficient
number with wide crotch angles to serve as potential
replacements for large branches in a limb rotation pro-
gram.

4. Do not remove branches larger than 1 inch.

5. Use thinning cuts rather than heading cuts, since
thinning cuts generally will result in less unwanted re-
growth.

Research Results in 1987 . In June 90 mature
Mclntosh/M.7 trees were selected and distributed among
15 groups of 6 trees each. One tree in each group was not
summer pruned and served as a control. Each of the
remaining 5 trees in each group was summer pruned on
eitherJulyl, July 15, August 4, August 14, or September 1.

The first harvest in this block was on September
15. Twelve percent more fruit were picked from summer
pruned trees at this harvest (Table 1). A random sample
of fruit taken immediately before harvest showed why this
effect occurred: summer pruning resulted in 10% more red
color and 30% more fruit making the U.S. Extra Fancy
grade (Table 1). There were no detrimental effects ob-
served due to summer pruning. Additionally, it appeared
to make no difference when the trees were summer pruned,
i.e. similar benefits were obtained from all treatments.
However, it should be noted that it took longer to prune
each tree as the sea.son progressed, 11 minutes per tree on
July 1 and 16 minutes per tree on September 1.

The results reported here have important prac-
tical significance. The beneficial effects ofsummer pruning
on red color and packout again have been confirmed.
Additionally, more fruit may be picked in the early portion
of the harvest season when they have the maximum storage
potential. Furthermore, summer pruning may be done
equally well any time during the months ofJuly and August.
Therefore, growers may summer prune trees during slack
periods using existing help, or it may be advantageous to
bring in off sht>re labor early, specifically to summer prune
Mcintosh trees.

Table 1. Effect

s ofsummer

pruning in

1987.

Red

. S. Extra

First

color

Fancy

harvest

Treatment

(%)

Control

Julyl

July 15

August 4

August 14

September 1

A BRIEF HISTORY OF THE CULTIVATED STRAWBERRY

David T. Handley

Cooperative Extension Service, University of Maine

The cultivated strawberry, Fragaria ananassa
Duch., is a relative newcomer to agriculture. The cullivars
now grown arc the result of hybridization by humans, the
fruit being quite different from those of their natural
ancestors. The unique developmental nature of the fruit
has made it the center of much study. The plant itself also
presents features of interest in its vegetative reproductive
ability, and its response to environmental conditions. In a
more practical sense, the strawberry has become the basis
of a large commercial industry, and is considered to be the
most popular small fruit in the United States.

The exact origin of the modern cultivated straw-
berry is unclear, but the best evidence indicates that it is
derived from a cross between two native American species,
F. virginiana Duch., andF. chilocnsis Linn. The former is
a common inhabitant of the eastern coast of North Amer-
ica that greatly impressed early seventeenth century colo-
nists. The natives commonly used the fruit in breads, but
Roger Williams noted in 1643 that "the English have
exceeded and make good wine". The species was intro-
duced in England, and soon became a favorite in local
gardens.

Prior to these introductions, the prevalent
strawberry in England and Europe was F. vesca Linn.,
commonly known as the wood strawberry. This berry has
a history dating back to the Romans, who favored it served
with cream and sugar, or soaked in wine. It is doubtful,
however, that the plant was widely cultivated at that time.
Supplies were probably obtained from the plentiful popu-
lations growing wild. By the fifteenth century, large-scale
cultivation of this species was occurring, but it was eventu-
ally replaced by an early-ripening, bright red clone of F.
virginiana , developed from the slock originating in the
colonies.

In 1712, while gathering information about
Spanish fortifications along the west coast of South Amer-
ica for the French navy, Captain Amede Frezier was
impres.sed by the large-fruited strawberries cultivated by
the natives. Being an amateur botanist in addition to a spy,
he collected some plants for the voyage home. Two of the
few surviving specimens were given to the Royal ( Jarden in
Paris along with the .statement that they bore fruit "as big
as walnuts". Antoinc de Jussieu, director of the garden at
the time, must have been disappointed when the plants

produced only small, deformed berries if any.

The plants Frezier took back to France were F.
chilocnsis. This species is dioecious (requiring both male
and female plants for productivity), and unfortunately he
had collected only females. The problem was simply a
matter of pollination, but this fact apparently was not
realized until many years later. Fortunately, plants were
retained in some collections and the species was later
redeemed when in Brittany it was discovered that inter-
planting it with F. virginiana , a plentiful pollen producer,
resulted in excellent crops. F. cliiloensis, or the Chilean
strawberry, soon became the major species of commerce.
Brittany was the European center of production, shipping
fruit to Paris and London. Despite its impressive size,
however, this strawberry was pale, seedy, and faint of
Havor.

Probably as a result of the cross pollination
technique used to produce Chilean strawberries, seedlings
of F. chilocnsis x F. virginiana crosses began to appear in
European gardens. Some of this progeny bore fruit of large
size with a deep red ficsh. The Havor was somewhat
reminiscent of pineapple, and for this reason these plants
became known as the pineapple strawberry or pine straw-
berry. Although the origin was initially clouded, probably
by businessmen in hopes of high profits, Antoinc Nicholas
Duchesne published a hypothesis of its hybrid origin in
1766, based upon his experier.ce with strawberry breeding
and knowledge of the Brittany practices. The pine straw-
berry was named F. ananassa Duch.

In America, the early commercial strawberry
industry was dependent upon the European introductions
ofF. virginiana and F. ananassa. However, in 1838, Charles
Hovey, of Cambridge Massachusetts, introduced the
'Hovey' strawberry. This cultivar was the result of crossing
a European pine strawberry with a native F. virginiana.
'Hovey' is credited with being the first cultivar of any fruit
made from an artificial cross in the United States. The high
quality of both the fruit and plant stimulated a great new
interest in strawberries throughout the country. This
cultivar and later U. S. introductions such as 'Wilson' and
'Howard' provided the basis for future breeding programs
and led to the large and successful commercial industry we
know today.

References

Darrow, G. M. 1966. Vie Strawberry: History, Breeding, Hendrickson, R. 1981. Tlie Berry Book. BaWcnUnc. NY.
and Physiology. Holt, Rhincharl, and Winston. NY.

Wilhelm, S. and J. E. Sagcn. 1974. A History of the
Hcdrick, U. P. 1925. Tlie Small Fniits of New York. Rept. Strawberry. Univ. Cal. Berkley, CA.
N. Y. Agric. Exp. Sta. J. B. Lyons Co. Albany, NY.

*4fi 4fi ^fe ^^

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THE INITIATION OF A NEW IPM PROGRAM IN
STRAWBERRIES IN MASSACHUSETTS:
ACCOMPLISHMENTS IN THE PILOT YEAR 1987

Sonia Schloemann and Daniel Cooley

Department of Plant Pathology, University of Massachusetts

Strawberries are the most extensively planted
small fruit in Massachusetts. According to current esti-
mates by the Massachusetts Department of Food and
Agriculture there are approximately 500 acres of strawber-
ries grown commercially in the state. The estimated yearly
value of the crop is $5,000 per acre for an overall value of
approximately $2.5 million. An individual's actual crop
value is determined largely by the marketing methods used
and the price that he is able to obtain. It is clear, however,
that strawberries are a valuable crop and can provide
significant returns under the proper conditions.

Most Massachusetts growers do not produce
large acreages of strawberries. The average grower man-
ages 3.5 acres, which illustrates the fact that strawberries
are often used as a cash crop to augment the income from
other fruit or vegetable crops. Strawberries fit in well with
these other cropping systems in terms of land require-
ments, machinery needed, and timing of harvest.

Strawberry culture requires significant inputs in
production and pest control. The increased awareness of
the ecological risks and the rising costs of pesticide appli-
cation are putting a strain on Massachusetts growers and
are providing incentives for developing new management
strategies. Additional incentives include: the development
of resistance by pests and pathogens to certain pesticides;
the loss of registration of some pesticides because of
potential health hazards; and, the risk of exposure by the
public to the spray materials used in commercial straw-
berry production. This danger is enhanced by the fact that

most of the berries are sold on a pick-your-own basis, so
consumers may be exposed to pesticide residues in the
field.

With this situation as a backdrop, the Strawberry
IPM program embarked on its first season with a set of
objectives as stated in the Summer, 1987 issue ofFntit Notes
(6). To summarize these objectives, we sought to: (1)
identify the key pests causing economic injury to straw-
berries in Massachusetts; (2) establish consistent and
accurate sampling techniques for each key pest; (3) study
available management and control methods; (4) deter-
mine what the current pest control practices are and the
areas for potential change; (5) conduct trials using alter-
native fungicide spray recommendationsand evaluate their
efficacy; and (6) distribute a regular Strawberry Pest
Message. Efforts to address these objectives were made in
several ways: (1) surveys were conducted at 4 locations on
a weekly basis throughout the season to monitor pest
pressures; (2) observations were made at 10 additional
locations; (3) sampling methods for all pests were devel-
oped and evaluated at these locations; (4) scouting results
were reported weekly through harvest and occasionally
thereafter; (5) limited-fungicide spray recommendations
were made and evaluated; (6) literature searches were
conducted to determine the current stale of knowledge on
strawberry pest management; and (7) all Massachusetts
strawberry growers were surveyed to obtain information
on current practices and concerns. The results of these
efforts follow.

Strawberry Pests

Pest control in strawberries includes efforts in all
three pest groups: insects, diseases, and weeds. Key insect
pests, those which cause economic injury and concern to
the grower, include tarnished plant bugs {Lyf^ts Uncolaris),
strawberry bud weevils (clipper) {Anlhonoinus sigiwtiis),
and two-spotted spider mites {Tetranychus iirticac) (12).
Other insect pests exist but arc of lesser concern togrowers.

Important plant disease organisms include bacte-
ria, viruses, and fungi, with fungi being the most prevalent.
Fungal pathogens fall into four categories: berry rots, leaf
diseases, crown rots, and root rots. The two key diseases
of concern are a berry rot, grey mold {Botrs'tis cincrca), and
a root rot, black root rot {Rhizoctonia fragaria) (12). Red
stele (Phylophthora fragaria) is also a problem in the
Northeast but generally is managed successfully through
the use of resistant cultivars and soil fumigation.

Keystrawbcrryweeds vary widely throughout the
state but grasses and other perennial weeds are of most
concern. These weed problems include dandelion {Ta-
raxacum officinale), goldenrod (Solidago canadensis),
orchard grass {Dactylis gloinerata), quackgrass {Agropyron
repcns), and yellow wood sorrel (Oxalis siricta) (12). Heavy
weed infestations will affect yield, plant vigor, and bed
longevity.

Key Insect Pests

Tarnished plant bug causes misshapen berries
with the typical "cat-facing" or apical seediness. It is
ubiquitous and can cause severe losses of yield if not
controlled. The damage is caused by the feeding of adults
or nymphs on the newly developing fruit. Feeding prevents
individual achenes from developing, thus causing the de-
formity. The later in the development of the berry that
feeding occurs, the less significant the injury. However,
under heavy infestations, 30 to 50% crop reductions have
been reported (10). Current practices include 1 to 3 sprays
in the early season with malathion or thiodan.

Tarnished plant bugs overwinter as adults and lay
eggs in early May. Eggs hatch at approximately the same
time as the strawberries are approaching 10% bloom. The
nymphs cause the majority of the damage and must be the
target of a management plan. Sampling for these nymphs
may be done by shaking 25 flower trusses from a 2-foot
section of row individually over a dish at a number of
locations. The current threshold number usingthis method
is 1 nymph per 25 flower trusses (10). We were unable to
evaluate this method satisfactorily in 1987, because the

IPM program began at the end of the flowering period. A
second monitoring method that we tried was the use of
sticky traps to catch the adult tarnished plant bugs, as has
been shown in apple orchards (4). This procedure was not
satisfactory, because it was difficult to correlate trap
catches and damage and to set threshold levels. The use of
models for egg hatch and nymphal development according
to thermal accumulation has been studied in Quebec (1)
and may prove useful in combination with sticky traps for
determining first incidence of tarnished plant bug activity.
The Massachusetts Strawberry IPM Program will be using
the Hower truss/nymph method this year to make spray
recommendations based on threshold numbers. The ob-
jective is not only to reduce the number of sprays but also
to improve the liming of sprays and to fine-tune the rates
and materials used against tarnished plant bug.

Strawbcrrvbud weevil causes a reduction of yield
by laying eggs in the newly exposed buds and girdling the
pedicel of these buds, which then will not develop. This
pest, otherwise known as the clipper because of the nature
of the injury, is not as common in Ma.ssachusetts as is the
tarnished plant bug, but when it occurs, it can cause severe
losses; up to 90% damage has been reported in some states
(11). Current practices include 1 to 3 pre-bloom sprays per
season of guthion, parathion, or lorsban.

The strawberry bud weevil overwinters as an adult
in hedge-rows or woods and is active when temperatures
are above 60°F and buds are available. Sampling for this
pest is performed by counting the number of clipped buds
per 2 feet of row. Unfortunately, this procedure counts the
damage after the fact but is the only satisfactory method
available. The threshold number that we are currently
using is 1.2 clipped buds per 2 feet of row (11). Samples
should be taken from near the field borders, hedge-rows,
and woods since these arc areas where we expect to find the
clipper first, and we want to halt the invasion of it into the
field. When the threshold level is reached, we recommend
spraying with guthion at labeled rates. As with the tar-
nished plant bug, the objective not only is to reduce the
number of sprays but to improve effectiveness by improv-
ing the timing. Experiments are planned to aid in the
development of a trap or lure similar to that used for the
boll weevil, so that we can monitor populations before
damage occurs.

Two-spotted spider miles affect the yield of straw-
berries indirectly by sapping the vigor of the plants. These
tiny arthropods live on the underside of leaves and feed on
plant juices. Under heavy infestation (over 100 mites per
leafiet) two-spotted mites can have significant impacts on
yields and on the longevity of a bed (9). Many growers do
not spray for two-spotted mites because their heaviest

populations occur during harvest. Spraying during this
time is not recommended and growers can wait and get
adequate control simply with renovation when the foliage
is mowed off. However, for growers who feel they must
spray before harvest or after renovation one or two sprays
of kelthane or plictran may be used. Both of these
materials were removed from the market during 1987, but
some formulations of kelthane are available for use in 1988.

Two-spotted spider mites overwinter as adults
and become more active as temperatures increase during
the summer. Dry, hot weather favors these mites. There
is a danger that populations can explode in a very short
period of time. The strawberry 1PM program is refraining
from making recommendations for mile control based on
threshold numbers, because there is little agreement
among researcherson what population levels are tolerable.
We will, however, report levels to growers. The current
concern is the lack of availability of milicides for those
growers who want to control mites. We plan to explore the
use of biological control of two-spotted mites with the use
of indigenous predacious mites (Anihlysciiis fallacis) (8).
This type of control can be accomplished cither by encour-
aging the growth of natural populations of these predators
or by the release of artificially-reared populations to aug-
ment the naturally occurring ones. In addition, the use of
"soft" pesticides such as insecticidal soaps, which have
been successful in greenhouse settings, will be evaluated
for efficacy in strawberries during 1988.

normally used from bloom through harvest.

In Ontario, grey mold has been shown to overwin-
ter in the green leaf tissue under the winter mulch (2). This
fact, if it is also true in New England, has significant
implications for disease management. According to the
Ontario work, spores from infected crop residues land on
newly formed and expanding leaves in the fall. The spores
germinate and invade the leaf tissue and then enter a
quiescent state for the winter protected by the winter
mulch. At that time there are no visible symptoms of
infection. Then, in the spring when these leaves begin to
sencsce and die, the fungus grows and produces new spores
which are available to infect the tender blossom petals,
which then infect the fruit. Using this information, one can
protect the leaves from infection in the fall or knock back
the initial inoculum in the spring before the blossoms
appear. This treatment eliminates the need for numerous
sprays, and the potential for any fungicide residues on the
fruit. Since no developing fruit will be present at the time
of sprays, they cannot accumulate fungicide (13). Leaf
protection can be accomplished by applying fungicides to
the surface or by providing competitive organisms which
will inhibit the ability of the fungus to germinate or pene-
trate the surface of the leaf tissue (5). Two yeast species and
one bacterial species which occur naturally on the surface
of strawberry leaves and provide effective biological con-
trol of grey mold in Ontario have been identified (13). The
Strawberry IPM program is determining the efficacy of
these methods in Ma.ssachusetts.

Key Disease Organisms and Their Damage

Grey mold (Botrylis cinerea). This fruit rot is, by
far, the problem of most concern to Massachusetts growers
in terms of potential for yield reduction (12). The Botrytis
fungus infects the Hower petals or sepals and then prolifer-
ates in the developing fruit causing it to rot. The berries
may rot on the plant or shortly after they have been
harvested. Grey mold can cause very heavy losses in years
with damp wet weather in the spring, especially if it occurs
during bloom. If not managed, under these conditions a
nearly complete crop loss is possible. Even under a
fungicide spray program a significant yield reduction may
occur. Current practices include 1 to 12 sprays per season
with captan, benlate, captan/benlate, or ronilan.

During 1987 an IPM spray regime consisting of 3
bloom sprays of captan or ronilan was compared with a
typical spray regime. We found no significant difference in
the amount of berry rot found with either regime (12).
These results concur with work done by other researchers
(3) and suggest that 3 well-timed bloom sprays are as
effective for grey mold control as the 4 or more sprays

Grey mold management presents a major chal-
lenge to pesticide reduction strategies. We are targeting a
reduction in the number of sprays, adjusting spray timing
to early season, and exploring the potential for biological
alternatives to reduce the pesticide load on the environ-
ment. Our approach is especially timely since captan's
registration is under special review and grey mold has
developed resistance to benlate and ronilan in some areas.
Furthermore, benlate has been shown to adversely affect
populations of predacious mites in apples and may do the
same in strawberries.

Black root rot is a complex of organisms which
results in the decay and blackening of the perennial and
feeder roots. The causal fungus, RItizoctonia fragariae
(Ceratobasidium sp.), commonly is associated with straw-
berry roots. R.fragariac invades strawberry roots by direct
penetration, causing cortical decay and rootlet death. This
injury results in reduced plant vigor, and degeneration and
premature death of plants.

Black root rot is difficult to manage with existing
measures. In Massachusetts, we suggest planting in well-

drained soil, using "healthy" plants, mulching to reduce
winter injury (a contributing factor), and using soil fumi-
gants before planting. While these fumigants may help
black root rot management, traces of them may also end up
in underground water supplies.

The IPM program plans to evaluate the use of
reduced rales of standard fumigation materials, the effect
of certain cover crops for reducing inoculum in the soil, and
the possible use of biological control methods by inoculat-
ing the roots at transplanting with avirulcnt strains of
Rhizoctonia. This work has been initiated by Janice
Drozdowski and Dr. William Manning at the University of
Massachusetts (7).

Weeds in Strawberries

Weed control in strawberries poses one of the
greatest challenges to commercial strawberry growers.
Since strawberries are a perennial broadlcaf plant, man-
agement of other perennials, particularly grasses, is diffi-
cult. If weeds proliferate they can significantly shorten the
longevity of a planting, reduce yields, and discourage pick-
your-own customers from picking in certain areas. Sev-
enty-seven percent of Massachusetts strawberry growers
use herbicides, as compared to 70% who use fungicides,
64% who use insecticides, and 28% who fumigate (12). The
average number of herbicide applications for those who
use herbicides is 3.2 sprays per season. This use level is
more than that for most other crops.

This year the IPM program surveyed strawberry
plantings throughout the state to establish which weeds and
weed types posed the most problems to growers. This work
will continue in 1988 to provide a more complete picture of
the situation. The strawberry IPM program plans to
establish field plots to evaluate alternative weed manage-
ment .strategics using reduced rates of certain herbicides
and using certain mulching practices. The objective is to
develop a management program with fewer herbicide
applications without reducing yield and bed longevity.

Conclusions

Integrated pest management of strawberry has
great potential forseveral reasons. First of all, strawberries
suffer important damage from diseases, weeds, and insects.
Secondly, pesticide applications are expensive both eco-
nomically and ecologically. Also, several of the key pests
of strawberries are significant pests in other crops and have
been studied in the IPM context before, and this informa-
tion gives us a head start in strawberry IPM. In addition,

many of our Massachusetts growers are involved in or
familiar with other Massachusetts IPM programs, i.e. corn,
potatoes, or apples. The success of these programs has
paved the way for an enthusiastic reception by growers to
the Strawberry IPM Program.

The first season of the Strawberry IPM program
has been one of establishing baselines for current practices
and knowledge of pest control, testing our scouting meth-
ods and making some trial recommendations, and for
introducing ourselves to the Massachusetts growers. The
key to success of the strawberry IPM program is involve-
ment of the growers, because their input is instrumental in
directing the course of this program.

We will be expanding our grower base from 4 in

1987 to 15 in 1988. With a larger number of growers, we
hope to be able to generate more information. We are
particularly interested in how well the relatively untested
techniques described in this paper will work in the field.
Our new reporting forms will facilitate communication
with growers. These forms will be used to report togrowers
the scouting results for the week and recommendations
based on those results. We look forward to a successful

1988 season.

Literature Cited

1. Bostanian, N. J., G. Mailloux, and M. Binns. 1987.
Modeling tarnished plant bug, (Lygiis lincolaris), nymphal
populations in strawberry fields by thermal summation.
Paper delivered at the 1987 Entomological Society of
America Annual Meeting. Boston MA., November 29 -
December 3, 1987.

2. Braun, P. G. and J. C. Sutton. 1987. Inoculum
sources oi Botrytis cincrca in fruit rot of strawberries 8in
Ontario. Can. J. Plant Pathol. 9:1-5.

3. Bulger, M. A., L. V. Madden, and M. A. Ellis. 1987.
Infiuence of temperature and wetness duration on infec-
tionof ripe strawberry fruit by fiof/}'//.rc//i<?re(7. Can. J. Plant
Pathol, (in press).

4. Coli, W. M., T. A. Green, T. A. Hosmcr, and R. J.
Prokopy. 1985. Use of visual traps for monitoring insect
pests in the Massachusetts IPM program. Agric. Ecosys-
tems Environ. 14:251-265.

5. Cook, R. J. and K. F. Baker. 1983. Vie Nature and
Practice of Biological Control of Plant Pathogens. Amer.
Phytopath. Soc, St. Paul, MN.

6. Coolcy, D. R., K. Hauschild, and S. G. Schlocmann.
1987. A new program for integrated pest management of
strawberries in Massachusetts. Fniit Notes 52(3):16-19.

7. Drozdowski, J. L. and W.J. Manning. 1984. Straw-
berry disease survey report. Unpublished manuscript.

8. Oatman, E. R., F. E. Gilstrap, and V. Voth. 1976.
Effect of different release rales of Phylosciiilus persimilis
on the two-spotted spider mite on strawberry in southern
California. Entomophaga 21:269-273.

9. Oatman, E. R., J. A. Wyman, H. W. Browning, and
V.Voth. 1981. Effects ofreleascs and varying infestations
levels of the two-spotted spider mite on strawberry yield in
southern California. 7. Econ. Entomol. 74:112-115.

10. Schacffcrs, G. A. 1980. Yield effects of tarnished
plant bug feeding on June-bearing strawberry varieties in
New York state. J. Econ. Ent. 73:721-725.

11. Schaeffers, G. A. 1981. Pest management systems
for strawberry insects, pp. 377-393. In D. Pimentel (ed.)
Handbook of Pest Management in Agriculture. Vol.3. CRC
Press, Boca Raton, PL.

12. Schloemann, S. G. and D. R. Cooley. 1987. Straw-
berry IPM survey: 1987 program report. Report to the
Massachusetts IPM Program.

13. Sutton, J. C. and R. G. Braun. 1987. New Methods
for controlling gray mould fruit rot (Botrytis cinerea) on
strawberries. Proc. Ontario Hort. Crop Conference.

*^M fc^^ ^^ *^*

^K ^r ^^ ^t^

BENEFITS OF ALAR TO APPLE IPM PROGRAMS

Ronald J. Prokopy

Department of Entomology, University of Massachusetts

Based on highly equivocal, unsubstantiated evi-
dence, the U. S. Environmental Protection Agency (EPA)
in August of 1985 announced the intent to cancel the
registration of Alar^^ (daminozide). When the press heard
of the EPA's intent to cancel Alar, the issue quickly
received extensive national coverage, with ensuing strong
condemnation of the material by the press and the public.
Even though the EPA's ultimate decision was to reduce
permissible levels of Alar on fruit, rather than cancel
completely the use of Alar, the initial irresponsible an-
nouncement of intent to cancel use was sufficient to flag
Alar as a dangerous chemical in the mind of the public. The
Massachusetts Department of Public Health expanded
upon the original EPA announcement by phasing out
tolerances for Alar residues in processed products. As you
well know, the end result has been strong reluctance on the
part of brokers, processing firms, and supermarkets to
accept apples treated with Alar for fear that consumers
would refrain from buying them. In turn, many growers
were reluctant to use Alar in 1986 and 1987 for fear that
they could not sell their apples, even though it technically
has remained legal to use it. This nonuse resulted in
premature drop of nearly 30% of all Mcintosh and reduc-
tion in storability of those apples that were harvested.

This situation in itself is most unfortunate. But, an
equally great misfortune is the highly counter-productive
effect discontinued use of Alar has had on present and
potential integrated pest management (IPM) practices on
apples. In regard to present practices. Alar is frequently
used not only to positively affect fruit quality but also, when
applied in mid-or late-June, to slow the growth of water-
sprouts and terminals. A positive benefit of this use to pest
management lies in depriving aphids of rapidly-growing
foliar tissue. Hence, aphid populations tend to be lower in
blocks treated with Alar in June. Another benefit of Alar
to current IPM practices is associated with tolerable levels
of leafmincrs and spider mite populations. When present
in substantial numbers (and even in only moderate num-
bers in dry years), leafmincrs and mites can cause prema-
ture fruit drop, reduce fruit coloration, and diminish the
keeping quality of fruit. Without Alar, many growers have
had to use a greater amount of pesticide against leafmincrs
and mites to maintain these pests at levels lower than can
be tolerated in Alar-treated blocks. With Alar, we can
tolerate more leafmincrs and mites to maintain these pests
at levels lower than can be tolerated in Alar-treated blocks.
With Alar, we can tolerate more leafmincrs and mites
without ill effect.

In regard to future IPM practices, particularly
second-stage IPM practices, Alar (or another compound
that is equally effective) must play a major role or else most
second-stage practices will come to naught. In nearly all
orchards treated with Alar, few pests can survive within the
orchard itself because the fruit (and any pests the fruit may
harbor) are picked before they drop. Thus, the pests are
taken away with the fruit. When the fruit drop, however,
pests may remain in the orchard, overwinter there, and
pose an immediate threat to the crop next summer. The
low price paid for dropped apples does not usually warrant
investment of labor to pick them up, so many are left on the
ground to rot. Such a situation is not amenable to manage-
ment by a second-stage IPM approach of intercepting pests
at the orchard border, before they enter the orchard. Thus,
without Alar, growers are denied the opportunity of reduc-
ing pesticide use against pest insects and mites by using a
second-stage IPM approach, and are denied the opportu-

nity of producing healthier, more pesticide-free apples.

We feel the EPA and the Massachusetts Depart-
ment of Public Health did not consider the multiple bene-
fits of Alar to fruit growers and the environment when it
announced in 1985, without good evidence, that Alar was
a dangerous chemical. In truth, the EPA's decision not only
has caused a great economic hardship to fruit growers, but
also has been counter-productive to the EPA's own best
interest in providing for a healthier environment. The
EPA's 1985 announcement has and will continue to cause
greater use of more toxic (but nevertheless legally used)
pesticides than otherwise would be necessary with Alar.
We hope that the EPA and the Massachusetts Department
of Public Health in the future will consider more fully the
positive benefits of an orchard chemical when making a
cost/benefit analysis of the future use of a compound.

* * *

RESULTS OF THE FIRST YEAR OF SECOND-STAGE APPLE
IPM PRACTICES

Mary T. O'Brien and Ronald J. Prokopy
Department of Entomology, University of Massachusetts

Since 1978 we have conducted a program of
integrated pest management (1PM) in Massachusetts
apple orchards. The first-stage of this program, from 1978
through 1982, was funded by a 5-year federal Cooperative
Extension Service pest management grant to initiate a pilot
IPM program. A maintenance phase followed the pilot
program and has been ongoing since 1982.

Initially, there were 3 major objectives: to pro-
mote the buildup of natural populations of beneficial
predators, to reduce pesticide use, and to maintain or
increase the quality and quantity of fruit produced. The
overall entomological approach to achieving these objec-
tives was to intensively and carefully monitor abundances
of pests and beneficial natural enemies in participating
IPM orchards and to give advice to IPM growers as to the
need for, optimal timing of, and type of pesticide to be
applied.

The results of this pilot program were highly
encouraging. Compared with pesticide use before 1978,
there was a 37% reduction in insecticide use and was a 61%
reduction in miticide use during the pilot program, along
with a reduction in the loss of fruit due to insect damage.
The results were so encouraging, in fact, that 2 persons
trained in the program formed "New England Fruit Con-
sultants". Over the past 5 years (1983-87) they have been
hired by commercial growers to provide IPM scouting and
advisement services on more than one-third of the apple
acreage in Massachusetts.

Results of a recent survey indicated that about
two-thirds of Massachusetts apple growers now employ
IPM practices. Thus, over the past decade, this first stage
of IPM in Massachusetts apple orchards can be considered
a success, although this success must be tempered by the
knowledge that the uses of miticides as well as non-
selective insecticides directed against apple blotch leafmin-

ers and white apple leafhoppers have been on the rise in
IPM orchards over the past 5 years (partly due to develop-
ment of resistance to materials previously effective).
Having substantially achieved our goals, we initiated the
second stage of the apple IPM program in 1987.

Second-stage IPM employs behavioral, ecologi-
cal, and biological approaches to pest management as
substitutes for most pesticide treatments. The major goal
of the program is to eliminate use of insecticides and
miticides after the last curculio spray. This elimination
allows important predators and parasites of key foliage-
feeding pests (mites, aphids, leafminers, and leafhoppers)
to build up to numberssufficient to provide control of these
pests. To facilitate this goal, we emphasize the use, during
April and May, of those pesticides least likely to be harmful
to beneficial predators and parasites.

In the summer of 1987, 18 commercial orchards
participated in the second-stage IPM program comprised
of the following 4 elements:

(1) application of oil or other needed selective pesticides

(1) during April and May to control European red mite,
San Jose scale, tarnished plant bug, European apple sawfly,
plum curculio, green fruitworms, and early-season leaf-
rollers;

(2) no use of any insecticide or miticide following the last
plum curculio spray in May to permit buildup of beneficial
predators and parasites in a pesticide-free habitat (except
for fungicide use against diseases);

(3) removal of abandoned apple, pear, hawthorn, and
quince trees within 100 yards or more of the orchard
perimeter to greatly reduce or preclude immigration of key
mid- and late-season lepidopteran pests (codling moth and
summer leafroUers) attacking apple fruit; and

(4) intercepting apple maggot Hies (a key summer pest
attacking the fruit) before the great majority of flies can
penetrate the orchard interior, either by ringing the or-
chard perimeter with odor/visual maggot Oy traps (sticky
red sphercsbaited with synthetic apple odor) or by spraying
perimeter-row apple trees periodically to kill entering files.

Of the 18 blocks (2 to 4 acres each) there were 6
in which odor/visual traps for apple maggot files were
placed every 10 yards in the woods surrounding each block,
6 in which odor/visual traps were placed every 10 yards in
perimeter apple trees, and 6 in which perimeter apple trees
were sprayed every 3 weeks during June, July, and August.
We compared results in these blocks with a comparable-
size nearby block in each orchard sprayed by growers in

normal fashion during June, July, and August.

Table 1 shows that on average 1,062 maggot files
per orchard were intercepted in test blocks where traps
were put in the woods, compared with 2,054 where the traps
were placed in perimeter apple trees. One hundred
percent more files were caught on nonbaitcd monitoring
traps placed in interior apple trees in woods-trapped test
blocks than in grower control blocks, suggesting that twice
as many files were active in the interior of these test blocks
than in the adjacent control blocks. About 46% more were
caught on monitoring traps inside the apple-tree-trapped
test blocks and 65% more in the border-row-sprayed test
blocks than in the adjacent control blocks. Although none
of the 3 approaches to intercepting maggot files before fiy
penetration into the block interior was completely effec-
tive, the latter 2 types gave promising results.

Table 1. Apple maggot fiy captures per block.

Type of block

Interception Monitoring
traps* traps**

AMP traps in woods 1,062

Grower control

AMF traps in orchard 2,054
Grower control

Border row sprays
Grower control

352
176

123
84

104
63

*Odor-baitcd traps at orchard perimeter.
**Nonbaitcd traps on interior apple trees.

Table 2 shows the percent fruit damaged by each
type of fruit-injuring pest. For all 3 test block types,
combined injury by early season pests (plant bugs, sawfiies,
curculios, and fruitworms) was greater in the test blocks
than in the grower control blocks. These pests would have
been controlled by sprays applied during April and May
(prior to the start of the program). Hence, it appears that
pest pressure in and around the average test block was
greater than that in and around the average control block
(so the cards were partly stacked against us). Maggot files
caused about 4 times as much damage in woods-trapped
test blocks as in control blocks (9.3 vs. 2.3%), about 3 times
more damage in apple-tree-trapped test blocks as in con-
trol blocks (1.4 vs. 0.5%), and about the same amount of

Table 2. Fruit-injuring pests.

Injured fruit

(%)*

TPB.EAS,

SJS,CM,LR

Type of test block PC.GFW

' AMF

other

AMF traps in woods

14.0

9.3

2.4

Grower control

12.6

2.3

1.1

AMF traps in orchard

6.3

1.4

0.1

Grower control

2.3

0.5

0.2

Border row sprays

2.4

0.6

0.3

Grower control

1.9

0.8

0.3

*700 fruit sampled per block ir

July, August, and

September.

**Key:

AMF -apple maggot fly

PC -plum curculio |

GFAV -green fruitworm

SJS -Sa

n Jose scale

TPB -tarnished plant bug

LR -Jc;

frollcr

EAS - European apple

sawfly

CM -codling moth

damage in border-row-sprayed test blocks as in control
blocks (0.6 vs. 0.8%). Damage by other mid- and late-
season pests (scale, codling moth, leafrollers, and others)
was about twice as great in woods-trapped test blocks as in
control blocks (2.4 vs. 1.1%), but was no different in apple-
tree-trapped and border-row-sprayed test blocks com-
pared with control blocks. Although none of the test blocks
yielded all perfect fruit, we feel these results are encourag-
ing in terms of the potential effectiveness of either traps
placed in perimeter apple trees, or border row sprays (in
combination with removal of nearby host trees) as an
alternative approach to managing maggot fly, codling
molh, and leafrollers.

Table 3 shows populations of foliar-feeding pests
found during sampling in each block. Although popula-
tions of European red mites and two-spotted miles aver-
aged 37% higher in the test than in the control blocks,
populations of mile predators averaged 137% higher in the
test blocks. This result is precisely the sort of outcome we
were hoping to sec. If (he test blocks were to remain free
of inscclicidc and milicidc after May for the next 2 years,
wc would expect mite predators to increase even further to
a point where I hey alone (in conjunction wit hpre-bloom oil
sprays) might be able to control pest mites. Woolly apple
aphids were low in numbers in all blocks. White apple
leafhoppcrs averaged 57% more abundant in the test
blocks, but here again we expect leafhopper parasites to

Table 3. Foliar-feeding pests.

Type of test block

Leaves (or

terminals)

infested (%)*

ERM,**
TSM

Predatory
mites

WAA

WAL

ABLM

AMF traps in woods
Grower control

AMF traps in orchard
Grower control

Border row sprays
Grower control

23
20

20
13

24
16

11
4

7
4

1
3

2
2

5
5

17
10

9
10

23
12

10
14

5
4

*200 leaves (or terminals) sampled per block in July and August.

**Key:

ERM -European red mite WAL -white apple leafhopper TSM
PL -potato leafhopper WAA -woolly apple aphid ABLM

-two-spotted mite
-apple blotch leafm

iner

increase in future years. Potato leafhopper averaged 32%
more abundant in the test blocks, but we still have no solid
evidence that this insect is truly injurious to bearing trees.
Leafmincrs were 27% more abundant in the test blocks,
but we fully expect leafminer parasites to increase to
substantial levels during summer months in future years.

Second-stage IPM research for 1988 will concen-
trate on repeating the experimental designs for border row
sprays and apple maggot traps placed in perimeter apple
trees. The design which called for apple maggot traps in the
woods around an orchard will be eliminated.

In conclusion, results of the first year of implem-
entation of several second-stage IPM practices in commer-
cial orchards give us cause to be optimistic about the future
of these practices in preventing injury to apple fruit during
June, July, and August and in fostering buildup of impor-
tant natural enemies of foliar pests. In succeeding years, we
will work on refining our second-stage techniques (includ-

ing possible substitution of sticky spheres with insecticide-
impregnated non-sticky spheres), with the aim of being
able to recommend with confidence a truly integrated
behavioral, cultural, and biological approach to orchard
pest management.

Acknowledpements . We thank the Massachu-
setts Society for Promoting Agriculture and the Northeast
Regional Project on Integrated Management of Apple
Pests (NE-156) for supporting our work on second-stage
apple IPM. Special thanks go to Leslie White and Esther
Ruiz who worked on the 1987 studies. Bill Coli, Kathleen
Leahy, Sue Butkcwich, and Dave Stanley also participated
in this program.

Literature Cited

1. Butkewich.S.L.andR.J.Prokopy. 1985. Update on
the relative toxicity of orchard pesticides to the predator
mite, Amblyseius fallacis. Fntit Notes 50(3): 9-11).

*^f ^fi *il^ *it*

#n #n rn ^%

SINGING IN THE RAIN: THE EFFECT OF WEATHER ON
PLUM CURCULIO SPRING MIGRATION

Susan L. Butkewich and Ronald J. Prokopy
Department of Entomology, University of Massachusetts

The plum curculio (PC), Conotrachelus nenuphar
(Hebst), is a serious pest of stone and pome fruits east of
the Rocky Mountains. It is also one of the two most
important species attacking apples in the Northeast. Less
is known about the plum curculio than about any other key
apple pest. Several factors have been responsible for
Hmiting our success in understanding this insect. PCs are
cryptically colored and feign death when disturbed, making
behavioral studies difficult. In their northern range, PCs
overwinter in leaf litter outside the orchard and return to
host trees in the spring. The behavioral adaptations
involved in leaving the orchard in the fall, returning in the
spring, and locating a host, are complex and not well
understood.

From a control standpoint, detection of PC move-
ment into an orchard in the spring is critical since PCs can
crawl quickly throughout a host tree, causing significant
damage to fruit in a short time. To illustrate the rapidity

with which PC injury may appear, in 1987 unlrcatcd trees
in Conway, MA had 9% fruit injury on May 21 and 96% on
May 24! PC populations are difficult to monitor since they
usually are clumped rather than distributed. Presently,
control practices are initiated when feeding and cggiaying
scars on fruit reach economic threshold levels; however, by
the time fruit damage is detected, considerable fruit injury
already may have occurred throughout an orchard. More
effective techniques for monitoring PC appearance on host
plants in the spring would help us to overcome a major
stumblingblock in pest control within apple integrated pest
management programs in the Northeast.

Many researchers have felt that PC spring migra-
tion is infiuenced by environmental factors. Quaintance
and Jenne (3) developed the mean temperature "rule" as
an index of PC activity, where a mean temperature above
60°F for 3 or 4 days will result in large migrations. Snap(5)
agreed with these conclusions. Whitcomb (6) found that

55° was the minimum temperature for PC activity and that
75° for 2 or more consecutive days was optimum for
migration. Furthermore, he suggested that cool weather
following a warm period may reduce or suspend migration
until optimum temperatures are reached once again.
Lathrop (1) believed that other environmental factors
besides temperature may be important to springmigration.
Smith and Flessel (4) found that mass migration was
correlated with humidity as well as temperature. They
indicated that water loss during periods of low humidity
may reduce migration. McGiffen and Meyer (2) suggest
that low temperatures suppress PC activity and aid in the
conservation of resources until daily air temperature and
saturation deficits are conducive to flight. They believed
that temperature must be above the flight threshold, with
saturation deficit below the desiccation range, for migra-
tion to occur.

Because PCs attack border rows first before
moving toward the block interior, we recommend only a
border row spray early in the season, with a f uli-biock spray
at peak PC activity and a border row spray toward ihe end
of the PC season. Gulhion and imidan have been the most
effective materials against PC.

Timing of the first border spray is critical and
should commence as soon as PC damage is observed on
fruit, even if rain is predicted, because PC movement to
host trees is likely to commence as soon as the rain slows
or stops. The rain may reduce residue longevity, possibly
making another insecticide application necessary. How-
ever, delay of a spray may leave you with a heavily damaged
crop when you awake in the morning! Weigh your choices
carefully.

Over the past 4 years, wc have gathered data to
determine the influence of weather on the spring migratory
night of PCs from overwintering sites. Ourstudiesindicate
that PCs are especially likely to move into orchards during
late day or evening hours under humid, warm conditions
when the air is relatively calm. Heavy movement occurred
even during lulls between intermittent rainfall, especially
when the temperature was above 70°F.

Based on these findings we want to stress the
importance of careful daily monitoring of fruit for PC
feeding and egglaying, especially when weather conditions
are ideal for migration. Examine 5 or 10 developing fruit
per tree for fresh feeding or egglaying scars on several trees
along rows that border woods. Feeding injury appears as
a small round hole, often undercut so that the hole is larger
beneath the skin. Oviposition scars are crescent-shaped.

Our research indicates that during migratory
night into an orchard, PCs may use visual and olfactory cues
to locate a host tree. However, it appears that odor alone
is a stronger stimulus than vision alone. Furthermore, in
laboratory studies, we found that host odor aids PCs in fruit
location and actually "turns on" feeding behavior. PCs
readily locate and feed on sap exuding from cut or wounded
branches. We therefore wonder if PCs might be attracted
to recently pruned trees.

Literature Cited

1. Lathrop, F. H. 1949. Biology of the plum curcuiio in
Maine./. Econ. Entomol. 42:12-18.

2. McGiffen, M.E. and J. R. Meyer. 1986. Effect of
environmental factors on overwintering phenomena and
spring migration of the plum curcuiio, Coiiolrachclus
^^^(^/^/^/•(ColeopterarCurculionidae). Environ. Enloniol.
15: 884-888.

3. Quaintance, A. L. and E. L. Jenne. 1912. The plum
curcuiio. U. S. Dept.Agric. Bur. Entomol. Bull. 103:1-250.

4. Smith, E. H. and J.K. Flessel. 1968. Hibernal ion of
the plum curcuiio and its migration to host trees. J. Econ.
Entomol. 61:193-203.

5. Snap, O. \. 1930. Life habits of the plum curcuiio in
the Georgia peach belt. U. S. Dept. Agric. Tech. Bull. 1 88:4-
76.

6. Whitcomb, W. D. 1929. The plum curcuiio in apples
in Massachusetts. Mass. Agric. Exp. Sta. Bull. 49:26-52.

* a^ ^M ^» ^1^

^R ^R ^^ ^J^

A COMPARISON OF INSECTICIDAL SOAP AND AMITRAZ
AS SUMMER SPRAYS AGAINST PEAR PSYLLA

William M. Coli, Anthony Rossi, and Kathleen Leahy

Departments of Entomology and Plant & Soil Sciences, University of Massachusetts

The pear psylla (Psylla pyricola) is well known as
an important pest of pears, causing damage in the form of
reduced tree vigor and through the accumulation of excre-
ment (honeydew) and resultant sooty mold fungus on fruit,
foliage, and wood. In commercial pear orchards, psylla are
often difficult to control due to pesticide-induced resis-
tance to many registered pesticides. We frequently have
seen excessive psylla injury, giving trees a blackened ap-
pearance, even in blocks which received a regular spray
program, and a number of growers have reported increas-
ing difficulty with psylla control in recent years.

To some extent, psylla are a problem because
growers often do not recognize that a particular material
that had been effective in the past is no longer providing
control. For example, some growers may .still be able to use
azinphosmcthyl or phosalone against psylla, but in many
instances these materials will not adequately control the
pest. Synthetic pyrethroids generally still are effective, but
continued use, especially of multiple applications in a
season, will almost certainly result in the development of
resistance. For most pear growers, dormant oils will
suppress psylla in the early part of the season, but fre-
quently one or more applications of amitraz, a highly toxic
material, are required during the July through August
period.

Because of the potential for psylla to develop
resistance to amitraz and the negative effects of this and
other registered pesticides on beneficial arthropods, it is
imperative that alternative approaches to managing pear
psylla be developed and tested. For example, researchers
in Washington achieved limited success by washing honey-
dew from fruit with water sprays. In this article, we describe
a trial conducted in 1987 at a small commercial pear
orchard to determine if insecticidal soaps have any poten-
tial in commercial psylla control programs by "cleaning"
fruit, by direct psylla control, or by both. For more informa-
tion on pear psylla management strategies, see the 1988
March Message (University of Massachusetts Cooperative
Extension).

The trial was conducted in a 1 acre orchard of well-
pruned, 8-year-old Bartlett pear trees in Belchertown, MA.
Treatments were laid out in a randomized complete block
design, using 6 replications of 3-tree plots for each treat-

ment. Weekly sampling for all psylla life stages (eggs,
softshcll nymphs, hardshell nymphs, and adults), honey-
dew, and beneficial arthropods was conducted by observ-
ing the last four leaves on 10 succulent terminals from
throughout the canopy of the center tree of each plot.

Treatments were: (1) untreated check, (2) ami-
traz @ 2 pints per 100 gal. water, and (3) SaferTM soap @
2 gal. per 100 gal. water. All treatments were applied until
runoff with a motorized hydraulic handgun sprayer at 200
psi, after 30% of terminals were infested with active psylla
stages (July 28). Because trees were not cropping heavily,
at harvest fruit from all trees in each 3-tree plot were
combined and examined closely for signs of injury. Data
were analyzed using analysis of variance, and means were
separated using Duncan's New Multiple Range Test.

Data in Figure la indicate that both the soap and
amitraz treatments caused a significant reduction in num-
bers of all active psylla stages (softshell, hardshell, and
adult) compared to the check on August 7 and August 12.
By August 19, the quantity of active psylla stages on treated
trees did not differ significantly from those on the check;
however, treatment-related pest reduction allowed fruit to
be harvested with no further treatment and with no down-
grading of fruit from honeydew or sooty mold when soap
or amitraz was used.

When life-stage data were analyzed separately,
results indicated that neither treatment caused a significant
reduction in numbers ofsoftshell nymphs (Figure lb). This
result may be due to the protection afforded this stage by
drops of honeydew which they secrete and hide within.
Softshcll nymphs typically also are protected by their
tendency to feed in leaf axils where sprays may not ade-
quately reach. Also, since neither treatment was expected
to have an effect on eggs, undoubtedly a certain portion
hatched after the treatment date, resulting in higher
softshell nymph numbers. This finding suggests that there
is a need for back-to-back soap applications to prevent
nymph numbers from continuing to expand, which is
important because it is nymphal feeding and excrement
which sap the tree of its fluids and soil the fruit. Hardshell
nymphs were reduced by both treatments as of the August
7 sample date (Figure Ic). Although significant differences
disappeared by subsequent sample dates (as surviving soft

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Figure 1. Number of active stages of pear psylla on check, Safer soap-, and amitraz-treated Bartlett pear trees.

shells continued to develop), in practical terms, psylla
populations under both spray treatments likely were below
most growers' "visual action threshold" through harvest.
Nonetheless, in blocks where psylla build up earlier in the
season, further applications of soap and amitraz likely
would be required.

Numbers of psylla adults (Figure Id) also were
reduced significantly by both soap and amitraz. Because
adult numbers were significantly higher in amitraz plots on
July 23 (pre-treatment), it can be argued that amitraz
performed better than soap against this stage. The residual
effect of amitraz compared to non-residual soap could
account for this apparent difference.

Although check terminals were infested com-
pletely and showed honcydew and sooty mold growth as
early as August 7, at harvest only a few fruit from check
trees showed signs of honeydew. While no evidence of
spray toxicity to foliage was noted in this trial, 49% of Safer-
treated fruit were found to be injured at harvest. Phytotox-
icity consisted of dark-colored surface lesions about 1 cm
in diameter, apparently formed when soap concentrated at
the bottom of treated fruit. This injury might be avoided

by the use of spreading agents to reduce soap accumula-
tion, by use of a different rate, or by spraying when drying
conditions arc optimal.

We compared the cost of applying amitraz and
Safer soap using a price of $45 per gallon for amitraz and
$9 per gallon for Safer soap (retail price when purchased
in volume) and recommended rates. The use of Safer soap
($54 per acre using a 3(X) gal. dilute base) was 37% more
costly than amitraz ($34 per acre) under the conditions of
our test. However, the manufacturer reports that they arc
working on a second-generation material which is hoped
will be as effective as the present soap but at 30% to 50%
of the cost. Moreover, it is difficult to estimate the value of
reduced pesticide resistance, reduced outbreaks of secon-
dary pests (e.g., mites), and of reduced negative effects on
beneficial species that may result from the use of soaps.
Also unknown at this time is whether or not growers could
receive a premium price in specialty markets by growing
"low-spray" or even "organic" pears using dormant oils
and soap sprays as the basis of a spray program. Positive
results in these areas could easily affect the economics of
spray decision-making.

We conclude that insecticidal soaps may have a
role in future pear psylla control programs in spite of their
higher cost; however, more work needs to be done using
spray additives to reduce or eliminate fruit phytotoxicity.
Because insecticidal soaps arc non-selective, possible
negative effects on beneficial species (aphid predators,
spiders, minute pirate bugs, etc.) must be investigated.

Further, other than learning that defoamcrs arc essential
when applying soaps, we know very little at present about
their application through air-blast sprayers, or whether
they may be applied using low-volume techniques. Conse-
quently, we are not prepared at this time to recommend
insecticidal soap on a large scale, although growers are
encouraged to experiment in small blocks.

* *

A REPORT ON THE 1987 MASSACHUSETTS APPLE IPM
PROGRAM

William M. Coli, Kathleen Leahy, Daniel R. Cooley, Ronald J. Prokopy, and Mary T. O'Brien
Departments of Entomology and Plant Pathology, University of Massachusetts

Acknowledgements: We wish to thank Keith
Bohne, Alex and Charlie Dowse, Tony Lincoln, Frank
Parker, Jesse and Wayne Rice, Ed Roberts, Bill Rose,
Mike and Tim Smith, Tony Rossi, and National Park
Service staff, Ron Catudal and Gene Gabriel, for their
cooperation. Thanks also to New England Fruit Consult-
ants, Sue Butkewich, and Tom Green for information they
provided which we included in pest messages and reports.
Special thanks to Regional Fruit Agents, Jim Williams and
DomMarini, for performing weekly scouting ofacommcr-
cial orchard in their region and reporting their findings for
use in pest alert messages. Thanks to all Regional Fruit
Agents for speedy turnaround of pest messages.

Extension Program Activity

As in previous years, the apple 1PM program was
funded by a combination of state, federal, and grower
sources. Voluntary grower contributions totaled $3,200 in
1987, a 14% increase from last year. We greatly appreciate
this continued support, and we consider it further evidence
that Massachusetts apple growers, through hiring IPM
consultants and support of Extension programs, have
adopted IPM on a large scale.

Program activities were similar to those in 1986,
and continued to focus on grower and other group educa-
tion, information-transfer using newsletters, code-a-
phones, twilight meetings, and orchard visits, and on per-
forming appropriate adaptive studies. Eight commercial
orchard blocks, two blocks at the University of Massachu-
setts Horticultural Research Center (HRC) in Belcher-

town, and one at an historic orchard in Quincy were
monitored weekly for arthropods and pathogens affecting
tree fruits. Increased emphasis was placed on monitoring
peach and pear pests and including this information in pest
messages. Scab infested leaves which had been placed in
wire cages at cooperator sites in November, 1986, were
collected weekly and examined to determine apple scab
spore maturity. In addition, temperature and rainfall were
recorded at the HRC, and other pest information was
gained by occasional orchard visits, and by reports from
Sue Butkewich, Tom Green, growers, Extension workers
in other states, and private scouts and consultants.

Plant Pathology expanded the Vcnliiria iitacqiialis
(apple scab) ascospore maturity monitoring to cover more
effectively the range of development in the stale. As a side
benefit, it was possible to begin to model the development
of ascosporcs, and relate it to degree days. In New
Hampshire, such a model has eliminated the need for
frequent maturity sampling. However, discrepancies be-
tween the New Hampshire results and tests in other states
make it advisable for us to test the model in Massachusetts.

Cooperating growers were strongly encouraged
tobuy modified recording hygrothermographs, which were
made available at a bulk discount along with weather
shelters or plans for their construction. Weather data from
these stations, as well as from the HRC, were used to advise
growers on the intensity of the scab pressure.

Scouting information was used to reply to grower
calls and to write twice-weekly Entomology Pest Messages
from April 7 to August 25. Plant Pathology messages were

written weekly during the primary scab season, and in
response to observed problems thereafter. Messages were
transmitted via the INFONET computerized bulletin
board system (BBS). The 3 regional fruit agents again
distributed messages as weekly newsletters and via 24-hour
code-a-phoncs. Recorded code-a-phone messages contin-
ued to be used by growers at levels comparable to past
years. A few growers accessed the INFONET BBS directly
from their own computers.

Entomology and Plant Pathology staff members
made a combined total of approximately 150 orchard site
visits during the year, assessing pest problems faced by
large and small commercial orchardists. Staff assisted
pomologists with apple maturity assessments during har-
vest using the starch-iodine test, and this information was
disseminated via INFONET and newsletters. Maturity
alerts provided an important harvest management tool for
growers, especially when less daminozide (AlarTM) was
used.

Staff members gave a total of 28 talks at grower
and other group meetings and authored or co-aulhorcd 6
Fniit Notes articles, 20 journal articles, and 1 proceedings
article. Entomologyand Plant Pathologystaff also collabo-
rated with Dr. Rick Weires, Hudson Valley Lab, on the
annual March Message.

Table 1. Percent insect- and disease-inj

urcd fruit in

8 commercial blocks in 1987, compared to 1978-86.

Fruit infested (%) |

Injury type

1987

1978-86

Tarnished plant bug

1.30

1.64

European apple sawfly

0.20

0.36

Plum curculio

0.71

0.54

Apple maggot fly

0.89

0.06

San Jose scale

0.01

0.67

Leafrollers

0.08

0.03

Green fruitworm

0.02

0.07

Codling moth

0.00

0.01

Other insects*

0.00

0.01

Apple scab

0.32

0.83

Calyx end rot

0.28

0.20

Black rot

0.03

0.14

Fly speck

0.72

0.05

Other diseases**

0.07

0.12

*Othcr insects include:

white

apple

Icafhopper,

aphid honeydew and sooty mold

**Other diseases include;

sooty blotch, moldy core, |

white rot, and quince rust

In 1987 we completed year 2 of a cooperative
agreement with the U.S.Dept. of the Interior, National
Park Service, which seeks to implement IPM in historic
orchards at the Adams National Historic Site (NHS),
Quincy, MA, at the Roosevelt/Vanderbilt NHS, Hyde
Park, NY, and at the Morristown NHS, Morristown, NJ.
Under our direction, park staff pruned trees, monitored
insects, recorded temperature and leaf wetness, and ap-
plied pesticides based on scouting. The Adams Historic
orchard shows the most completely developed pest man-
agement plan, and produced a crop of good quality apples
this season for the first time in recent history.

A Training Workshop held at the University of
Massachusetts February 24-26, 1987, as part of the USDI-
-NPS cooperative agreement was attended by 22 National
Park Service staff from throughout the U.S., and provided
training in concepts and techniques of 1PM for historic
orchards, including lectures by several University faculty
and staff. Participants identified 26 historic fruil plantings
in the NPS system, the earliest site dating from 1752.
Evaluations indicated highly positive response to work-
shop structure and content.

Insect and Mite Status, 1987

Tarnished plant bug (TPB) was again the single
most important cause of fruit injury noted at harvest in
Massachusetts orchards (Table 1), and TPB remains a
difficult pest to manage. The goal of predicting the optimal
liming of TPB sprays still eludes us. However, we rarely
observe severe fruit distortion from TPB feeding in com-
mercial orchards. Thus, much of the injury we see has
comparatively little effect on grade.

European apple sawfiv (EAS) activity was very
high in 1987 throughout Massachusetts and in other parts
of the Northeast. Activity began shortly before bloom (5/
14 to 5/21) in most areas, although a few EAS were caught
on white plant bug traps a week before bloom. Record
captures of EAS were noted, especially in a Wilbraham
block wherein cumulative average captures exceeded 39
per trap by 5/14. The highest single trap capture was 89
EAS, a new "record" for us, although Lorraine Los at the
University of Connecticut has us beat, with her report of up
to 100 EAS per trap! Numerous EAS-scarred or -infested
fruit were seen in orchards in June, but most fell from the
tree, and harvest surveys showed only an average amount
of EAS fruit injury (Table 1).

A pple maggot fiv (AMF) was first reported on 7/
6 on a red sphere in Westborogh, and activity was early and

high. In some parts of the state, fly emergence and activity
followed normal patterns, but in others, where rain show-
ers were infrequent, AMF activity in August was below
normal. In one warmer block of Delicious peak nonbaited-
spherc capture (mean of 4.5 per trap) occurred during the
week ending 9/11. AMF fruit injury in 8 monitored blocks
averaged 0.89% (Table 1), and in an additional 18 grower-
sprayed blocks injury averaged 1.4%, unusually high levels
for sprayed commercial blocks. Overall, AMF trap cap-
tures were high, with an average of 25 flies per trap in the
18 aforementioned blocks from early July to early Septem-
ber.

European red mite activity also began early, with
up to 20 mites per leaf seen on 5/14 in a Granville block
which had received an oil treatment and which did not have
a history of using predator-harsh materials. Two moni-
tored blocks needed treatment for mites before the end of
May. Pcrhapsdue to early prey mite buildup, predator mite
activity was also very high later in the season. A.fallacis and
the Stigmaeid mite, Z. mali (yellow mites), were common
in some monitored blocks. Some orchards had as many as
20% of leaves with ^./a//ac/.y, and up to 40% with Z. mali
in August. In addition, some unusual predators, such as the
Conioptcrix, were noted in Granville on 7/ 14; however, the
Coccinelliid beetle, Stclhoris puncliim, an important mite
predator in Pennsylvania and parts of New York, was not
reported anywhere in Massachusetts this season.

Plumcurculio pressure began shortly after bloom
and continued for 3 to 4 weeks. Most growers maintained
an insecticide cover through the period, and PC damage
was not significant in monitored blocks.

Leafminers (LM^ showed unusually low activity
throughout the state. Overwintering generation LM emer-
gence was apparently affected by very cold weather and
snow during the time of emergence. Adults which had
begun to move from the groundcover to tree canopies may
have been "knocked down" by the cold. After that, visual
trap captures continued at a low level into bloom. The few
growers who had a leafminer problem had difficulty timing
sprays correctly, and few monitored blocks had 100%
leafminer control. Third generation LM injury (late sea-
son) was high in several blocks, which should also have
resulted in an increase in parasitism, normally highest in
that generation.

Potato leafhopp cr (PLH) was first spotted in a
commercial orchard in Wilbraham on July 8, and activity
continued in some parts of the state through August. By
harvest, "hopper burn", a yellowing of leaf margins, some-
times progressing to death of leaf margins, was widespread
in the state. A single azinphosmethyl spray appeared to

provide control at the HRC, and we have had no reports of
apparent PLH resistance to other organophosphates.

A pple grain aphids and green apple aphids both
reached high numbers before bloom in many instances.
Green aphids dispersed onto apple fruit early as well,
although absolute numbers of aphids on fruit remained
low. In monitored orchards, however, no significant honey-
dewand no sooty mold problems were noted during harvest
surveys in spite of aphid presence earlier. Cecidomyiid
predator larvae were present in overwhelming numbers (5
to 10 per terminal). Syrphid larvae were not really a factor
in biocontrol until near the end of aphid activity.

Japanese beetles were noted in unusually high
numbers in some commercial orchards in 1987. Although
one grower reported high enough defoliation to warrant
treatment, most problems were not that severe. Beetle
problems were typically localized and could have been
spot-treated.

Birds caused a significant amount of damage to
fruit this year. Cortlands continued to be a favorite target
of crows, bluejays and other species. Peaches also received
much damage statewide. It has been suggested that the dry
summer forced birds to look for moisture sources wherever
they could, and that recurrence may be reduced in similar
years by providing bird baths or other clean water sources.

Disease Status, 1987

Scab i ncidence wasgenerally light, but variable. In
the eastern part of the state, within 50 miles of the coast,
scab was heaviest. Early season rain in the eastern part of
the state lasted for longer periods, though temperatures in
both east and west were similar. Infection periods, there-
fore, occurred in the east when they did not in the western
areas. A dry summer meant that there was little, if any,
secondary spread after June. Fruit scab was generally
confined to the calyx end, indicating early season infections
which spread.

Blossom end rot w as heavier than normal in some
orchards. The same weather which promoted calyx-end
scab undoubtedly promoted end rot. The causative organ-
ism for this was not Sclerolinia but Allcmaria.

Powdery mildew developed into a more serious
problem than usual last year. We used the pest messages to
advise growers that the disease was becoming widespread,
and that fungicides which affect both mildew and scab
should be used.

Related Research and Adaptive Studies

An important part of 1987 activity involved cm-
barking on the second stage of apple IPM in a large number
of commercial orchards. Second-stage IPM projects focus-
ing on apple maggot fly (the key insect pest after May) and
key Icpidopteran pests and on phytophagous mites and
apple scab were initiated with funding from outside grants.
As part of the mite biocontrol project, groundcover surveys
of 36 second-stage blocks were undertaken. Results of
these surveys will enable us to establish orchard classifica-
tions (mowing vs. herbicide, hard vs. soft spray program,
and broadleaf vs. grass groundcover) prior to the start of
1988 mite sampling. We wish to acknowledge the signifi-
cant contribution of James Williams and Karen Hauschild
who assisted with these surveys, and Dr. Prasanta
Bhowmik, who provided training and assistance in orchard
weed identification. We will report more fully on all
second-stage IPM projects in other Fniil Notes articles.

Fungicide, insecticide, and insect growth regula-
tor trials again were performed at the HRC and at grower
sites in 1987. This activity involved testing chem icals which
may be or presently arc a component of commercial spray
programs. Evaluation of pesticide effects on mite preda-
tors continued, as did the evaluation of disease-resistant
apple cultivars. Monitoring continued in a commercial test
block of disease-resistant cultivars established at the Rice
farm in Wilbraham. This planting is intended to determine
the feasibility of using no fungicides and a minimum of
insecticides in a commercial setting.

A set of 5 ergosterol biosynthesis-inhibiting
chemicals (Si's) was tested at 10-day application intervals,
following delayed application (tight cluster was the first
application). This study was designed to test the feasibility
of increasing intervals and delaying the first fungicide
application using Si's. This work will be described in other
Fmil Notes articles.

IPM blocks at the HRC were treated with a
registered SI (RubiganTM) on a delayed application basis
under Plant Pathology supervision. Effective control was
obtained with 2 fewer fungicide applications than in previ-
ous seasons. Another experimental material (not an SI),
with potential for long-term residual fungicidal activity
combined with low environmental hazard, was tested. Two
applications of the material, made in early and late June,
effectively stopped scab development. Next season, the
material will be tested in a series to determine whether it
might offer a means for drastically reducing summer cover
sprays and possibly primary season sprays as well.

Two root fungicides and various planting hole

amendments were tested for effect on early tree growth.
This experiment is a continuation from 1986 and indicates
that a 50% peat amendment and one of the fungicide
treatments (AlietteTM) are the two most effective tech-
niques for promoting the growth of newly planted trees. A
further report will appear in a future Fruit Notes article.

Daniel Cooley began work on a regional IPM
project with Dr. William MacHardy (NH) and Dr. David
Roscnberger (NY), to determine if the scab inoculum dose
from the previous season will predict the length to which
the first application of fungicide can be delayed the follow-
ing season. One Massachusetts orchard was involved in
this study, and plans were to expand the project to second
stage IPM blocks last fall.

Cooley also developed a prototype expert .systems
(computerized decision support software) for apple scab
and apple root problems in conjunction with Dr. Paul
Cohen of the Computer and Information Science Depart-
ment, using Public Service Grant funding. We have been
exploring ways to integrate this technology into the overall
IPM program.

Disease-resistant apple cultivar evaluation con-
tinued, with emphasis on horticultural factors, such as
maturity and storability. Plans were made and funding
obtained for a major disease resistant block at the HRC.
Observation of an immature block planted in Wilbraham
continued, and bud wood was distributed to a commercial
grower, suggesting that such a program might promote
disease-resistant cultivars.

Related entomology research and adaptive stud-
ies in Prokopy's lab continued to focus on improvement of
monitoring traps for apple Icafminers and on the host-
finding behavior of the apple maggot fiy and the plum
curculio. Other related entomology studies involved a test
of insecticidal soap against pear psylla (Psylla pyricola), the
most important pear pest in most orchards. In cooperation
with Dr. Alan Eaton, University of New Hampshire, we
continued tosurvey the distribution, in New England, of the
European apple sucker, Psylla mail, potentially a serious
pest in commercial blocks in the future. Although not yet
found as a pest in commercial orchards, P. mali appears to
be present in abandoned orchards throughout the central
and western counties in Massachusetts, west into New
York's Hudson Valley and south into Connecticut.

Plans for 1988

We propose to continue most of the 1987 activi-
ties, including: monitoring weather, pathogens, arthro-

pods, and tree development in at least 8 commercial blocks;
writing twice-weekly pest messages; presenting 4 grower
training sessions in each of three regions; performing
adaptive studies and pesticide trials; authoring extension
and other publications; and obtaining outside funding.

Both second-stage projects will continue in 1988.
The apple maggot-lepidopteran pest project, aimed at
preventing immigration of these apple pests into an or-
chard, will utilize most of the same 18 orchards as in 1987.
The orchard understory work will begin its first full field
season, with extensive sampling of miles and mite preda-
tors in about 30 commercial orchards with different
groundcover characteristics and management regimes.
Beginning in mid-May, mite sampling in the tree and in the
row or aisle groundcover will commence. Sampling will
consist both of visual scans and sample collection at 10
locations within the block and at block borders. Patholo-
gists will measure leaf litter decomposition relative to
groundcover type, and isolate fungi and bacteria to deter-
mine their effectiveness in decomposing fallen apple
leaves. A complete description of this project will be
forthcoming.

Spore maturity and weather data will be obtained
on the same scale as in 1987, and Pathology staff will
continue to evaluate disease-resistant apples including a
new block to be planted at the HRC. We also will look at
the possibility of early season fungicide reduction in a
program which requires early-season estimation of scab
inoculum dose, and late-season estimation of infection.

This program could eliminate all fungicides up to tight
cluster or pink, and fits well into a second-stage IPM
program.

Work on expert system development will con-
tinue, hopefully in conjunction with others in the northeast
region. Expert systems arc highly relevant to the future of
IPM, since applications of this technology are a natural
outgrowth of the apple IPM program, and have the poten-
tial to make it even more effective. We plan to pursue
regional and University funding and cooperation in the
dcvelopmentofacomprehensiveapplelPM expert system,
which, when released, should be a valuable educational as
well as managerial tool.

Continued field tests of insecticidal soap against
psylla, aphids, and mites arc planned, contingent on fund-
ing from outside sources. An additional activity planned for
1988 is an update of previously-established economic
thresholds, taking into account price changes for fresh fruit
and pesticides and new data on pest severity.

This year will be the first of a new cooperative
agreement with the National Park Service, which will
involve a survey and inventory of historic orchards and fruit
tree plantings in the NPS system throughout the U.S.
Inasmuch as some NPS sites may contain examples of
historic fruit cultivars which are not available elsewhere,
this work is being carried out under a directive from the
Secretary of the Interior to conserve unique genetic re-
sources (in the form of apple cultivars).

* * *

COOPERATIVE EXTENSION

U. S. DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS

AMHERST, MASSACHUSETTS 01003 0099

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SET^IAL SECTION
UNIV. LIBRARY

01003

Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension,

United States Department of Agriculture, and Massachusetts Counties Cooperating.

Editors: Wesley R. Autio and William J. Bramlage

ISSN 0427-6906

BIOLOGICAL

JUL 15 1988

Volume 53, Number 3
SUMMER ISSUE, 1988

Table of Contents

The Economic Benefits of Summer Pruning

Effects of Rootstock and Interstock on the

Growth, Productivity, and Anchorage of a

Spur and Standard Strain of DeUcious

Prospects for Greater Use of Biological Control
Agents Against Pests of Apple in Massachusetts

Peach Brown Rot Fungicide Trial, 1987

Mauget Microinjection for Peach X-Disease Therapy

Reevaluation of NAA as a Preharvest
Drop Controlling Chemical for Mcintosh

Postharvest Apple Rots: Dr. Rosenberger's Approach

Electric Lift Trucks in Refrigerated Facilities

Potential for Explosions in CA Storage Facilities

An "Expert System" for CA Storage of Mcintosh

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

The costs of subscriptions to Fndt Notes are $4.00 for United States
addresses and $6.00 for foreign addresses. Each one-year subscrip-
tion begins January 1 and ends December 31. Some back issues are
available for $1.00 (United States addresses) and $1.50 (foreign
addresses). Payments must be in United States currency and should
be made to the University of Massachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POLICY:

All chemical uses suggested in this publication are contingent upon continued registration. These
chemicals should be used in accordance with federal and state laws and regulations. Growers are urged
to be familiar with all current state regulations. Where trade names are used for identification, no
company endorsement or product discrimination is intended. The University of Massachusetts makes
nowarrantyorguaranteeof any kind, expressed or implied, concerning the use of these products. USER
ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE.

Issued by the University of Massachusetts Cooperative Extension, E. B. MacDougall, Director, in furtherance
of the acts of May 8 and June 30, 1 914. The University of Massachusetts Cooperative Extension offers equal
opportunity in programs and employment.

The Economic Benefits of Summer Pruning

Daniel A. Lass and Martha A. Kimball

Department of Agricultural & Resource Economics, University of Massachusetts

Wesley R. Autio, Duane W. Greene, and Richard Clark
Department of Plant & Soil Sciences, University of Massachusetts

In previous Fm/fNoto articles [52(3) :7-8 and 53(2): 1]
Greene and Autio outlined some of the procedures and
benefits of summer pruning of Mcintosh trees. These
benefits included earlier coloring (allowing earlier harvest
and lower losses to drop) and a higher percentage of the
fruit making the U. S. Extra Fancy grade. In this article we
shall detail the economic benefits of summer pruning, to
give growers the necessary information to decide whether
or not to summer prune.

In 1986 and 1987 summer pruning studies were per-
formed on 25-year-old Rogers Mclntosh/M.7 trees at the
Horticultural Research Center, Belchertown, MA. These
trees can be considered the standard for the industry. Two
harvests were made each year. Data were collected on the
number of bushels harvested in each picking, the number
which were lost to drop, and the percent of a random
sample made at the first picking which were U. S. Extra
Fancy. Additionally, the fruit were observed after storage

and downgrading due to bruising and softening was esti-
mated. Most of these data are reported in the previous 2
articles.

A distribution of the packout was approximated from
various observations for the entire yield of trees which were
summer pruned and those which were not (Table 1).
Grades were divided into 3 groups: Extra Fancy/Fancy,
No. 1/Utility, and Processing. Drops were counted sepa-
rately and assumed to be usable for processing. The per-
bushel fruit values used in this study were $10.50 for the
Extra Fancy/Fancy, $6.00 for the No. 1/Utility, and $2.00
for the processing. One half bushel per tree was assumed
to be lost during the summer pruning activity. Pruning
labor was assumed to cost $6.00 per hour.

Summer pruning reduced the losses to drop and
downgrading due to bruising and softening, because it
allowed an earlier harvest of a larger percentage of the
crop. Summer pruning also resulted in more fruit making

Table 1. Comparison of returns and costs for summer pruned and control Mcintosh trees. 1

Not summer
(bu/acre)

pruned
($/acre)

Summer

pruned

(bu/acre)

($/acre)

A. Crop yields and values:

Harvested

755

802

Extra Fancy/Fancy
No. 1/Utility
Processing

581

113

$6101
678
122

683
63
56

$7172
378
112

Drop
Totals

444

888

360

720

1199

$7789

1162

$8382

B. Labor costs:

Summer pruning (hours)
Dormant pruning (hours)

Totals

$
126

17
13

$102
78

$126

$180

C. Net value

$7663

$8202

Table 2. Comparison of returns and costs for Alar-treated and

summer pruned trees.

Alar-treated,

Not Alar-treated,

Alar-treated, |

not summer pruned

summer pruned

summer

pruned

(bu/acre)

($/acre)

(bu/acre)

($/acre)

(bu/acre)

($/acre)

A. Crop yields and values:

Harvested

1019

802

1023

Extra Fancy/Fancy

815

$8558

683

$7172

871

$9146

No. 1/Utility

153

918

378

480

Processing

102

112

144

Drop
Totals

180

360

720

139

278

1199

$9938

1162

$8382

1162

$10048

B. Labor costs:

Summer pruning (hours)

$102

Dormant pruning (hours)
Totals

126

$126

$180

C. Alar application

$70

D. Net value

$9742

$8202

$9798

the higher grades on color because of the increase in light
penetration into the tree. Summer pruned trees had
slightly lower yields, but the overall fruit value was $8382
per acre compared to $7789 for trees that were not summer
pruned (Table 1). Seventeen hours of labor per acre were
added by summer pruning, but dormant pruning was
reduced by 8 hours per acre. Total labor costs were
increased by only $54 per acre. Summer pruning resulted
in an additional net value of $539 per acre; a value which
makes the activity very much worthwhile.

In these 2 years of study only trees which did not
receive Alar^^ were used, but we have made estimates
comparing Alar-treated trees with summer pruned trees
which did or did not receive Alar (Table 2). Note that these
estimates were approximations based on our experience
with Alar and summer pruning. The expected net returns
were approximately $1540 higher if Alar were used com-
pared to when summer pruning was practiced without Alar,
primarily because of the much lower percentage of fruit

lost to premature drop. Obviously, summer pruning can-
not compensate completely for not using Alar, but it does
reduce the losses by approximately one third. Table 2 also
shows an estimate of the costs and returns of Alar-treated
trees which were summer pruned, giving a comparable net
value to Alar-treated trees which were not summer pruned.
These results suggest that it likely would not be beneficial
to summer prune if you have already treated with Alar,
primarily because Alar would keep fruit on the tree long
enough for red color to develop and the fruit to be har-
vested. However, summer pruning still may be beneficial
since earlier coloring would allow earlier harvest, poten-
tially resulting in higher quality fruit for long-term storage.

Summer pruning can be a very beneficial procedure
which causes a small increase in pruning costs, but a
substantially greater crop value in cases where Alar is not
used. Growers should consider summer pruning all Mcin-
tosh trees which will not receive Alar. The economic
returns speak for themselves.

* »f» %£^ «X« mSfi
w^ ^fm a^ *{*

Effects of Rootstock and Interstock on the Growth,
Productivity, and Anchorage of a Spur and Standard
Strain of Delicious

Wesley R. Autio and Franklin W. Southwick

Department of Plant & Soil Sciences, University of Massachusetts

A number of studies have compared spur and standard
apple strains but commonly have not assessed the addi-
tional effects of rootstock and interstock. In this study we
compared the effects of M.7A, M.26, M.9/MM.111, M.9/
MM. 106, and MM.lll on the growth, productivity, and
anchorage of Starkrimson Delicious (spur strain) and
Gardiner Delicious (standard strain) trees.

Trees were planted in the spring of 1981 at the Horti-
cultural Research Center, Belchertown, MA. The experi-
mental design was a randomized complete block with 7
replications. Within each block 4 trees were planted per
strain-rootstock-interstock combination, and the two
middle trees were used for data collection. All rows were
20 ft apart, but spacing within rows varied with the combi-
nation. Starkrimson trees on M.26, M.9/MM.106, and
M.9/MM.111 were spaced 12 ft apart, and Starkrimson
trees on M.7A and MM.lll and Gardiner trees on M.26,
M.9/MM.106, and M.9/MM.111 were spaced 14 ft apart.
Gardiner trees on M.7A and MM.lll were spaced 16 ft
apart.

In 1983 bloom was assessed, and in 1984 bloom, fruit
set, and yield were measured. In 1985 tree height, spread,
trunk circumference, and yield were measured. The 1985
tree spread values were used to calculate theoretical tree

spacings and theoretical numbers of trees per acre. It was
assumed that the optimal distance between trees within a
row should be 50% greater than the 1985 tree spread and
the distance between rows should be 8 ft greater than the
distance between trees within a row. The value of 50% was
used because it resulted in approximately the accepted
densities for the 2 strains on M.7A, the most tested root-
stock in the study. These values were used to calculate the
theoretical yield per acre in 1984 and 1985.

In September, 1985 these trees experienced the effects
of Hurricane Gloria, which allowed an assessment of tree
anchorage of these strains on the various combinations.
The angle of lean from the vertical was used to measure
anchorage, since poorly anchored trees were partially or
completely blown over.

Tree Size

Tree height, spread, and trunk circumference, ob-
tained in November, 1985, are presented in Table 1. For
each measurement Gardiner trees were significantly larger
than Starkrimson trees. This relationship between a spur
and a standard strain has been shown many times. Signifi-
cant differences also existed among rootstocks within each

Table 1. Height, spread, trunk circumference, and calculated number of trees per acre in 1985 of
Gardiner and Starkrimson Delicious trees planted In 1981.

Height (ft)

Spread (ft)

Trunk
circum. (cm)

Trees 1
per acre 1

Stock Gard.

Stark.

Gard.

Stark.

Gard.

Stark.

Gard.

Stark. 1

M.7A 13.7 b^
M.26 11.4 d
M.9/MM.111 12.2 c
M.9/MM.106 12.6 c
MM.lll 14.9 a

Average 13.0 **''

12.3 a
10.1b
10.0 b
10.8 b
12.3 a

11.1

10.7 a

9.2 b

9.0 b

10.5 a

10.3 a

9.9

7.9 a
6.4 b
6.2 b

7.8 a
8.4 a

** 7.4

26.6 a

19.2 d

21.3 c

23.4 b
26.9 a

23.5 **

23.8 a
18.1 be

16.9 d
19.5 b

23.7 a

20.4

119 b 191 b
153 a 276 a
160 a 291 a
121 b 198 b
126 b 175 b

136 ** 226

'Means within columns not followed by the same letter are significantly different at odds of 19:1. 1
''Gardiner and Starkrimson are different at odds of 99 to 1. 1

Table 2. Flowering and fruit set of Gardiner Delicious and Starkrimson Delicious trees planted in

1981.

Number of blossom cluster

Fruit set

1983

1984

Stock

(/cm

trunk circ.)

(/cm limb

circ.)

(/cm limb (

:irc.)

Gard.

Stark.

Gard.

Stark.

Gard.

Stark.

M.7A

8.3 c'

9.9 c

4.0 b

3.5 b

16.8 ab

23.4 ab

M.26

11.8 b

10.6 b

5.6 a

4.3 a

16.6 be

11.8 be

M.9/MM.111

10.2 be

9.2 be

4.9 a

4.5 a

11.6 c

10.4 c

M.9/MM.106

13.6 a

12.4 a

5.3 a

4.0 a

22.6 a

25.5 a

MM.lll

2.0 d

0.8 d

4.0 b

2.9 b

9.6 c

13.4 c

Average

9.2

ns" 8.6

4.8 **

3.9

15.4

16.9

'Means within columns not followed by the same letter are significantly different at odds of 19 to 1.

''If **, thenGardinei

■ and Starkrimson arc different at

odds of 99 to 1

. Ifns,

then Gardiner

md Starkrimson |

are not significantly

different.

Table 3. Yield per tree

and theoretical yield per :

acre for Gardiner and Starkrimson Delicious

trees

planted

in 1981.

■

Stock

1984

1985

Cumulative 1

Gard.

Stark.

Gard.

Stark.

Gard.

Stark.

A. Yield per tree

(bu)

M.7A

0.4 b^

0.3 b

0.6 be

1.3 be

1.0 be

1.6 be

M.26

0.4 b

0.3 b

0.9 a

1.5 b

1.3 b

1.8 b

M.9/MM.111

0.1 c

0.9 ab

1.0 cd

1.0 c

1.1 c

M.9/MM.106

0.7 a

0.5 a

1.0 a

1.9 a

1.7 a

2.4 a

MM.lll

0.1 c

0.4 c

0.8 d

0.5 d

0.9 d

Average

0.3

ns''

0.2

0.8

1.3

1.1

1.6

B. Yield per acre

(bu)

M.7A

47 b

57 b

63 ab

250 b

109 ab

307 b

M.26

49 b

58 b

138 a

385 a

187 a

444 a

M.9/MM.111

20 c

24 c

144 a

312 ab

165 a

336 b

M.9/MM.106

79 a

94 a

123 ab

371 a

202 a

466 a

MM.lll

15 c

12 c

42 b

136 c

57 b

147 c

Average

102 **

290

144

340

^Means within columns not followed by

the same

letter are significantly different at odds of 19 to 1.

1f**,thenGardi

ner and Starkrimson are different at odds of 99 to 1.

If ns, then Gardiner and Starkrimson |

are not significantly different.

strain. Gardiner trees were tallest on MM. Ill, followed by
those on M.7A. The two interstem combinations were
similar in size, and trees on M.26 were the shortest.
Siarkrimson trees were tallest on MM. Ill and M.7A, and
the M.26, M.9/MM.111, and M.9/MM.106 trees were of
similar height. Tree spread was greatest for trees on
MM.lll and M.7A.

As expected, the size of the spur trees allowed for
significantly more trees per acre than for the standard
strain (Table 1). For both strains the M.26 and M.9/
MM.lll rootstocks resulted in the smallest trees and most
trees per acre. The M.7A, M.9/MM.106, and MM.lll
trees were of similar tree spread which resulted in similar
values for trees per acre. Differences in precocity may
cause inaccuracies in determining theoretical densities
using these young trees. For instance, the trees on M.9/
MM. 106 had the highest yields for 1984 and 1985, and as a
result their growth rate may have been slower than trees on
M.7A. When a similar formula is used to calculate ultimate
spread for trees on M.7A and M.9/MM.106, it would be
expected that either the density for M.9/MM.106 would be
underestimated or that for M.7A would be overestimated.
In this case it appears that the theoretical density for trees
on M.9/MM.106 maybe lower than the ideal density. The
situation may be the reverse for trees on MM.lll, where
the theoretical density was substantially higher than com-
monly recommended.

Flowering and Fruit Set

Table 2 shows the flowering and fruit set data for 1983
and 1984. No significant differences existed between
Gardiner and Starkrimson as to the quantity of bloom in
1983, but in 1984 Gardiner had significantly more bloom
than Starkrimson. These trees were in their fourth leaf in
1984 and the greater bloom on Gardiner, the standard
strain, may have been due simply to variation in these trees
which were just coming into production. In general the
interstem trees and trees on M.26 had more blossom
clusters than did trees on M.7A or MM.lll.

Fruit set in 1984 (Table 2) was similar for the 2 strains,
but trees on M.9/MM.106 had the highest set and those on
MM.lll and M.9/MM.111 had the lowest.

Yield

Yield per tree and theoretical yield per acre are
presented in Table 3. On a per-tree basis the cumulative
yield for 1984 and 1985 was significantly higher for the
Starkrimson than the Gardiner trees. Some studies have
shown a similar relationship, with the spur strain yielding
more than the standard strain; however, most studies have
shown the reverse. Cases such as this one, where the spur
yielded more than the standard strain, may reflect precoc-
ity rather than ultimate yield potential. As the standard

trees become Wger it would be expected that they would
yield more than the spur trees.

Theoretical production per acre was significantly
higher for Starkrimson. Since the spur strain was smaller
and more productive it had a much higher theoretical yield
per acre.

Yields per tree for the various rootstocks showed that
trees on M.9/MM.106 produced the most fruit, whereas
those on MM.lll produced the fewest. The MM.lll root,
with or without an M.9 interstock, appeared to confer a low
yield potential to the tree, or at least resulted in less
precocity. There also was a lower fruit set for trees with
these roots. It is particularly interesting to note the
difference between the two interstem trees. Trees on M.9/
MM. 106 had the highest theoretical yield per acre, fol-
lowed by those on M.26, M.9/MM.111, M.7A, and
MM.lll. These data suggest that the interstem trees and
those on M.26 can result in the highest productivity.

Table 4. Tree lean after Hurricane Gloria, |

1985.

Lean from vertical (°) 1

Stock

Gard.

Stark.

M.7A

53 d'

33 c

M.26

20 b

19 b

M.9/MM.111

16 b

20 b

M.9/MM.106

34 c

19 b

MM.lll

Average

ns" 18

'Means within columns not followed by the 1

same letter are significantly different at |

odds of 19 to 1.

>'Gardiner and Starkrimson are

not signifi-

cantly different.

Anchorage

Information already presented suggests that MM.lll
is a poor rootstock for Delicious, because first of all, it
produces the largest tree, and secondly, it has the lowest
yield per tree and theoretical yield per acre. However, it is
commonly thought to be well anchored. We were able to
measure anchorage easily in 1985 because of the effects of
Hurricane Gloria. Trees were subjected to winds in excess
of 65 miles per hour, and substantial tree movement
resulted. After the hurricane, several trees were leaning,
and the angle from vertical was measured (Table 4). The
poorest anchorage was seen with trees on M.7A roots,
where the average angle oflean was 43°. Treeson MM.lll

showed no signs of leaning and were by far the best
anchored. Granted, the lower fruit load on MM.lll trees
may have reduced somewhat the tendency to lean, but they
also h-^d the largest leaf surface and above-ground por-
tions, providing a larger area for wind action and more
potential for damage.

Trees on MM.lll were undesirable in terms of size
and yield but were much better anchored than any other
rootstock or rootstock-interstock combination. Under
certain conditions the better anchorage would make trees
on MM.lll much more desirable than other combinations.

*^f^ »£» mj^ «£•
Wgk Wg9 W^ *J*

Prospects for Greater Use of Biological Control Agents
Against Pests of Apple in IVIassachusetts

Roy G. Van Driesche

Department of Entomology, University of Massachusetts

A recent publication of the Massachusetts Agricul-
tural Experiment Station, Opportunities for Increased Use
ofBiological Control in Massachusetts by Van Driesche and
Carey (Bulletin 718), has reviewed the status of the use of
parasites and predators for insect and mite pest control for
all major crops in Massachusetts. This report is available
through the Bulletin Distribution Center, Cottage A, at the
University of Massachusetts at Amherst for $7.00. For
apples, several possibilities exist to expand the degree of
pest control provided by predators and parasites.

Little to no possibility exists for control of the major
apple pests (apple maggot fly, plum curculio, and the
tarnished plant bug). These species have few exposed life
stages suitable for attack by beneficial insects, and because
they are direct pests of the fruit, little tolerance exists for
their presence in commercial orchards. Certainly a few
parasites of these species do exist, but they offer no
reasonable hope for commercially acceptable levels of
control. The controls applied for these species do, how-
ever, play a key role in regard to the biological control of
those species for which effective biological control agents
do exist - namely aphids, scales, white apple leafhopper,
mites, and leafminers. All of these groups can come under
effective control by predators or parasites given favorable
orchard management.

The traditional use of continuous insecticide cover
sprays from early season through early to mid-August
frequently disrupts the control of these secondary pests.
The "Second-stage" 1PM program currently being tested
at the University of Massachusetts by the tree fruit ento-
mologist, Ronald Prokopy, and the IPM coordinator,
William Coli, however, has the potential to change this
situation. The strategy replaces insecticidal control of
apple maggot fly with a control system based on sanitation
and intensive trapping. Second-stage IPM may allow

routine, non-fungicidal sprays to be discontinued after the
end of May. The termination of these disruptive sprays is
expected to result in more mite predators and leafminer
parasites in orchards, and these are expected, based on
previous studies, to exert commercial-level control of these
pests in most orchards. Preliminary results for one field
season did show a substantial increase in predator mites
when post-May, non-fungicidal sprays were not applied.
We are, therefore, very likely to be at a major turning point
in orchard pest control, in which the termination of con-
tinuous cover sprays (the rule for at least 40 years) will
usher in a mixed chemical/biological control strategy in
which mite predators and leafminer parasites will provide
control of these pests.

There are a number of specific actions or studies that
need to be undertaken to reach this goal. The most
important is, of course, the second-stage IPM project itself,
as it is the foundation on which all else rests. This effort
currently is underway with primary funding from the
Massachusetts Department of Food & Agriculture and the
Massachusetts Society for the Promotion of Agriculture.
Other specific actions that will be needed include the
following.

Mites . The composition of predacious mite fauna in
Massachusetts apple orchards and their response to or-
chard pesticides is fairly well understood (Hislop &
Prokopy, 1981). The goal of increasing predator numbers
in orchards to levels high enough to control spider mites
can be reached by 1) earlier termination of cover sprays (as
in the second-stage IPM strategy); 2) introducing a strain
of the main pTcda\.OT,Amblyseiusfallacis, that has greater
resistance to common cover spray insecticides; 3) planting
and managing orchard floor vegetation that is most favor-
able to predator mite survival and reproduction; and 4)

avoiding the use of materials such as benomyl and the
pyrethroids that do greater damage to predator mites than
spider mites. Activity on point one is underway and
a^'ditional funding for this effort is being sought from the
Department of Food & Agriculture under the
Department's competitive biological control grants pro-
gram. A pesticide-resistant strain of Amblyseius fallacis
does exist and has been established in apple orchards in
Quebec where it has provided successful control of Euro-
pean red mite and two-spotted spider mite (Bostanian &
Coulombe, 1986). This resistant >1. /a//acw can be intro-
duced in Massachusetts orchards. The role of orchard
floor vegetation, the species of plants used and their
management, is not well understood. Such vegetation
influences winter survival of predators, the timing of their
spring movement back into trees, and their rate of repro-
duction, since plant pollens are used as food sources by the
predator. A project to research this topic in Massachusetts
has been funded by the Department of Food & Agriculture.
Work was initiated in 1987 and will continue this year.

Aphids and San Jose Scale . Generally, existing
predators appear to keep the three aphid species in Mas-
sachusetts apples under satisfactory control unless dis-
rupted by pesticide use. The cecidomyiid, Aphidoletis
aphidimyza, is one of the more important aphid predators,
but various coccinellids, syrphids, and chamacmyiids also
exist in important numbers. The apple aphid is the best
studied of the three aphid species, and its control is
predominantly by predators. The woolly apple aphid has
a specific parasite, Apheliniis malt, that is important in
regulating that species. Least is known about biological
controls of the rosy apple aphid, one of the main aphid pests
of apples. San Jose scale is attacked by a specialized
parasite, Prospallella pemiciosi, of Asian origin, as well as
various generalist predators. Future plans for control of all
these pest species are based on the judgment that existing
parasites and predators do exist that will control these pests
in most cases unless disrupted by pesticide applications. As
such, the second-stage IPM strategy should improve the
degree and reliability of such control in the future.

Leaftniners . The apple blotch leafminer is a classic
induced pest. In unsprayed areas its densities are kept low
by several efficient specialist parasites. In Massachusetts
the major species are Pholetesor (Apanteles) omigis, a
braconid, and the eulophid, Sympiesis marylandensis (Van
Driesche & Taub, 1983). Both species feed on older larvae
within mines. Under current orchard spray regimes these
parasites become common in orchards only late in the
season (August through October) after cover sprays are
ended. When limited to this short period, parasites cannot
suppress leafminers below economic levels. Terminating
non-fungicidal cover sprays after the end of May, as envi-
sioned by second-stage IPM, should create an opportunity

for substantial increase in control of leafminer populations
by parasites. Two additional parasite species have poten-
tial for increasing the degree of leafminer control, the
braconid, Apanteles pedias, from New Zealand and the
encyrtid, Holcothorax testaceipes, from Japan. Both have
been imported successfully into Ontario by fruit entomolo-
gists at the University of Guelph and are established in that
area. A. pedias also has been released in New York state.
Dr. Chris Maier of the Connecticut Agricultural Experi-
ment Station recently received funding to import and
establish these parasites in New England. Studies in
Massachusetts will be needed following releases to deter-
mine the degree of control resulting from the introduction
of these new species.

In conclusion, biological control, while not applicable
for plum curculio, apple maggot fly, or tarnished plant bug,
in the future will play the key role in suppressing mites,
leafminers, aphids, and San Jose scale. The principal way
in which this control will occur will be through better
conservation of existing predators and parasites by earlier
terminationofregular cover sprays. Certain newbiological
control agents, namely a pesticide-resistant strain of the
predator m\{c, Amblyseius fallacis, and two exotic species
of leafminer parasites, Apanteles pedias and Holcothorax
testaceipes, should be introduced. As controls become
increasingly based on predators and parasites, grower need
for information on the recognition and biology of the
specific beneficial species involved will increase. To meet
this need, new Extension literature discussing the details of
biological controls of specific apple pests will be required.
Plans to develop such materials exist and are being sup-
ported by funds from the Department of Food & Agricul-
ture.

References Cited

Bostanian, N. J. and L. J. Coulombe. 1986. An integrated
pest management program for apple orchards in south-
western Quebec. Can. Enlomol. 118:1131-1142.

Hislop, R. G. and R. J. Prokopy. 1981. Integrated
management of phytophagous mites in Massachusetts
(USA) apple orchards. 2. Influence of pesticides on the
predator Amblyseius fallacis (Acarina: Phytoseiidae)
under laboratory and field conditions. Prot.Ecol. 3:157-72.

Van Driesche, R. G. and G. Taub. 1983. Impact of
parasitoids on Phyllonorycter leafminers infesting apple in
Massachusetts, USA. Prot. Ecol. 5:303-17.

Van Driesche, R. G. and E. Carey (eds.). 1987. Opportu-
nities for Increased Use of Biological Control in Massachu-
setts. Mass. Agric. Exp. Sta. Bull. 718.

**f« •X* *£• ^«
^% 0^ #j» ^»

Peach Brown Rot Fungicides Trial, 1987

Daniel Cooley and James Mussoni

Department of Plant Pathology, University of Massachusetts

Joseph Sincuk

Department of Plant & Soil Sciences, University of Massachusetts

Two of the newer fungicides for peach brown rot Funginex 1.6 EC was used in 1 treatment at the lower

control are Ronilan^^ (vinclozolin) and Rovral^^ (iprodi- end of the standard rate range (12 oz/100 gal), Rovral

one). These materials are reported to be more effective 50WP was used at 0.25 Ib/lOO gal (1/2 the standard rate)

than most other fungicides on peach brown rot. However, and Ronilan 50 WP was used in 3 treatments at 0.75 lbs, 0.75

they are also more expensive than other materials. lbs plus the spray adjuvant X-77™, and at 0.5 lbs plusX-77

Ronilan and Rovral are labelled and recommended (standard rate for Ronilan is 1 lb/100 gal). Treatments
such that a lower rate may be used under low or moderate were scheduled at the discretion of the assistant orchard
brown rot pressure. That means that when the weather is manager, and were done on the following dates under the
relatively dry, then the lower rate may be used. We tested weather conditions listed: May 11-late petal fall (70°F,
these materials at the lower label rates (and in one case, light breeze); May 26--post shuck split (85°F, light breeze);
below the lowest label rate) in 1987, to see whether or not June 22--ripening fruit (85°F, humid, shower); July 6--not
the low rates would perform as well as a low rate of Harbinger (75°F, clear, calm); and August 5--Glo Haven
Funginex^^ (triforine), which has been an effective mate- only (80°F, clear, calm). Sprays were applied with a high-
rial against brown rot for a number of years. We examined pressure handgun sprayer at a rate of 250 gal per acre, and
the efficacy of the lower rates and analyzed it with respect trees were sprayed to the drip point,
to the costs. The block consisted of three cultivars: Harbinger,

Table 1. Treatments and rot ratings for
Massachusetts, 1987.

peach

brown rot

fungicide trial at the University of

Treatment

Harbinger

Garnet
Pre.

Beauty
(%)

Glo Haven 1

Pre.'

Post."

(%)«

Pre.

Post. (%)

Ronilan 0.75 lb
+ X-77 1% v/v

0.0 a"

1.3 a

0.1 a

0.0 a

0.3 a 13

Ronilan 0.75 lb

0.1 a

1.2 a

1.5 d

0.4 b

0.3 ab 28

Ronilan 0.5 lb

+ X-77 1% v/v

0.0 a

1.5 ab

0.5 b

0.0 a

0.4 b 20

Rovral 0.25 lb

1.0 b

2.4 c

1.1 c

0.5 b

0.6 d 39

Funginex 12 oz

1.3 b

1.9 be

1.9 d

0.5 b

0.4 c 23

Control

3.1 c

3.4 d

100

1.6 d

0.8 c

0.9 e 45

^Mean number of brown rotted peaches per tree immediately prior to harvest.

^Mean rot rating on to 5 scale (0 = no rot, 1 = < 10% rot, 2 = 10 to 25%, 3 = 26 to 75%, 4 = 76 to

90%, 5 = > 90%) of a random box of approximately 40 fruit after 3 to 4 days at room temperature.

"Percent of the harvested fruit showing any rot.

"Means in a column not followed by the same letter are significantly different at odds of 19 to 1.

Garnet Beauty and Glo Haven. There were 2 randomly
placed blocks of 4 trees of each cultivar in each fungicide
treatment, for a total of 8 trees per treatment.

At harvest, fruit on each tree were evaluated for the
amount of rot present. All trees were mature (10 years) and
were in adjacent rows in a block at the Horticultural
Research Center (HRC), Belchertown, MA. Each cultivar
was grown in two adjacent rows, 20 ft apart. Peaches were
harvested, yield recorded, and a subsample of approxi-
mately 40 random, apparently healthy fruit from each
treatment were placed in a box and kept at room tempera-
ture for 3 to 4 days. The fruit then were rated for the
number of peaches which showed rot, and for the average
intensity of the rot present, rated on a to 5 scale (0 = no
rot, 1 = < 10% rot, 2 = 10 to 25%, 3 = 26 to 75%, 4 = 76
to 90%, 5 = >90%). The postharvest ratings for rot
intensity were not made on the Garnet Beauty fruit.

All fungicide treatments had significantly less rot than
the non-treated controls (Table 1). Harbinger has been
particularly susceptible to postharvest brown rot at the
HRC,asindicatedbythe 100% postharvest rot. Even in the
treated Harbingers, there was some rot on between 70 and
93% of the peaches. Ronilan treatments at the higher rate,
either with or without X-77, significantly reduced rot
intensity and preharvest rot. The 0.5 lb rate of Ronilan was
slightly better than Funginex at reducing the rot intensity,
but not the percent of rotted peaches. The 0.25 lb. rate of
Rovral was equivalent to Funginex. Ronilan at either rate
was significantly better than Funginex or Rovral at reduc-
ing the preharvest rot. There was no difference between
Ronilan treatments for preharvest rot on the Harbingers.

In the other two cultivars, adding X-77 to the Ronilan
at either the 1/2 rate or 3/4 rate significantly reduced the
preharvest rot. Not adding X-77 depressed Ronilan's
performance compared to that of Funginex. The 1/2 rate
of Rovral was sometimes better and sometimes worse than

the standard rate of Funginex.

The best treatment for brown rot in this experiment
was generally the 3/4 rate of Ronilan with X-77. The 1/2
rate of Ronilan with X-77 also did reasonably well. The 1/
2 rate of Rovral was as good as the standard rate of
Funginex.

Does this mean that 3/4 or 1/2 rates of Ronilan may
be substituted for other fungicides? Not really. This
experiment indicates that in a season with moderate pres-
sure, such as last year, the 3/4 and 1/2 rates of Ronilan or
the 1/2 rate of Rovral will work as well as a standard rate
of Funginex. The question remains, does Funginexwork as
well as some of the older materials such as thiram and
captan? Research in other states indicates that Funginex
is at least as good as either captan or thiram, and that is why
we used a Funginex standard. However, without including
these materials in the test, we cannot be sure that captan or
thiram would not have done better. This year we hope to
repeat the test using captan or thiram.

However, if Funginex at 12 oz is a good standard, then
the lower rates of Ronilan not only did as well, but usually
did better. In that context, reduced rates of Ronilan can do
as well as or better than Funginex, and therefore might be
considered as an alternative to a full rate of Funginex.
However, the economics of the situation do not necessarily
favor even the reduced Ronilan, Rovral, or Funginex
treatments. For the season (given 3 applications for brown
rot), the cost of Ronilan at the low rate was $114.00/acre
more than captan; at the 1/2 lb. rate, Ronilan cost $66.00
more than captan (Table 2). Funginex at the 12 oz rate cost
$25.50 more than captan. Rovral at the 1/4 lb rate cost
$15.00 more than captan. Since 3 applications is a low
estimate, the cost difference in many cases would be
greater. In short, a full rate of captan is always much less
expensive than the newer materials. Among the materials
tested, Ronilan is more effective, yet it is also several times

Table 2. List of retail prices for fungicides at recommended and decreased rates (January, 1988).

Material

High rate^

Cost
per acre''

Low rate

Cost
per acre

Reduction
per acre"

Cost comp.
to captan

Ronilan SOW lib $192.00 3/4 lb $144.00 $48.00 +$114.00

Ronilan 50 W 1 lb $192.00 1/2 lb $%.00 $96.00 + $66.00

Rovral 50 W 1/2 lb $90.00 1/4 lb $45.00 $45.00 + $15.00

Fungmex 1.6 EC 16 oz $74.25 12 oz $55.50 $18.75 + $25.50

Captan SOW 21b $30.00 21b $30.00 $0.00 + $0.00

Ter 100 gal.

Iligh rate of material in 250 gal, 3 applications; January, 1988 approximate prices from retail source.

"Dollars saved by using the reduced rate for 3 applications.

as expensive.

If the increased control can more than pay for itself, it
is worthwhile. For example, if the material reduces the
number of rotted peaches by 1 peach per tree, it will
increase the production of an acre of peaches by approxi-
mately 1 bushel. This result will earn an extra $15.00 to
$20.00. Ifthepostharvestrotisdecreased, extramoneyand
extra customer satisfaction will be added. If this extra
money exceeds the extra material cost, obviously the treat-
ment is worthwhile.

By those criteria, our data from last year indicated that

the Ronilan treatments were not economically justified.
However, it is important to stress that this is only one year,
and that we do not know how well captan might have
controlled brown rot. In addition, this analysis does not
consider what might happen under heavy brown rot pres-
sure.

This year we hope to carry out the economic analysis
more completely and include captan treatments for com-
parison. Only by determining the ultimate Tmancial benefit
can we judge whether or not a more effective chemical is
indeed a more cost effective fungicide.

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Mauget Microinjection for Peach X-Disease Therapy

Julianne Schieffer, Terry A. Tattar, and Daniel R. Cooley
Department of Plant Pathology, University of Massachusetts

Introduction

Since the first report in Connecticut in 1933, X-disease
has become a serious disease of peach. Originally thought
to be caused by a virus, X-disease was shown to be caused
by a mycoplasma-like organism living in the phloem.
Infection occurs from chokecherry to peach through trans-
mission by leafhoppers.

An infected tree breaks out of dormancy with healthy
foliage and flowers. After seven to eight weeks, sections of
the tree begin to show a diffuse yellowing. Soon the leaves
become brittle, develop red spots, tatter, and curl upward.
Diseased leaves fall, often leaving a rosette of yellowed,
dwarfed leaves at the tip of each infected branch. This
process produces a "rat tailing" effect as the terminal bud
breaks prematurely. Diseased trees have reduced growth
and lower yields. Unaffected scaffolds within the same tree
may continue to grow and bear, but this fruit often lacks
flavor or is bitter. Death of the tree, or winter kill of
affected sections, often follows within one to four years.

Attempts to control peach X-disease have had mixed
results. Pruning diseased limbs is not successful, as the
disease appears on other limbs the following year. Chemo-
therapy of X-disease with oxytetracycline (OTC) has
shown much promise, but traditional injection methods
have a number of disadvantages. Injection techniques such
as gravity infusion, pneumatic pressure, and pipettes, have
proven labor intensive, ineffective, or detrimental to tree
health (Lacy, 1982; Rosenbergcr & Jones, 1977). Mauget
microinjection has been used widely to deliver effectively

chemicals to shade trees with little injury. The objective of
this study was to determine if Mauget microinjection of
oxytetracycline could be used in commercial peach or-
chards for remission of peach X-disease symptoms.

Materials and Methods

The Mauget microinjection system consists of a small
disposable capsule. In our research, these capsules con-
tained 4 ml of 4% OTC solution. Each capsule is attached
to a beveled feeder tube and pressurized with a mallet to
approximately 10 to 12 pounds per square inch. One or
more 3/16 inch holes, depending on tree diameter, are
drilled approximately 1/2 inch deep at the tree base with a
portable drill. The capsules are inserted immediately and
tapped with the mallet to break the internal membrane,
thereby forcing the OTC solution into the xylem of the tree.
The appropriate dose rate is one capsule per two inches of
trunk diameter. Most trees in this study received 2 or 3
capsules. The contents of most of the capsules was taken
up by the tree within a few hours. Empty capsules were
removed within a week.

Four Massachusetts orchards were chosen for injec-
tion in September, 1986. Each diseased tree and each
healthy control tree was rated with the following scale: =
outwardly healthy, 1 = foliar symptoms on 10% or less of
the canopy, 2 = symptoms on 10 to 50% or less of the
canopy, 3 = 50 to 90% affected, and 4 = over 90% affected
or dead. Approximately half the trees in each rating class
then were injected after fruit harvest.

Trees were observed throughout the following grow-
ing season for symptom remission, yield, and wounding. In
September, 1987, every tree was rerated to determine any
change due to treatment or to progress of the disease.

Results

As indicated by the rating changes shown in Table 1,
most X-disease symptoms on the OTC-treated trees were
either absent or less severe. Untreated controls either
remained at the same disease level, or grew worse when
compared to the previous year's ratings. Of the untreated
trees with an initial rating of (healthy), 47% showed an
increase in X-disease symptoms. Trees with initial disease
ratings of 1 or 2 responded well to the OTC treatments,
often bearing as much fruit as healthy trees. The severely
diseased trees with ratings 3 and 4 gave variable results.
Many treated and untreated trees of the 3 and 4 rating
classes became worse or died. Even among those trees
responding to the treatment, most had only one or two live
scaffolds bearing fruit.

Observations throughout the season showed that most
treated trees in rating classes to 2 had good fruit yields.
Untreated trees gave a wide range of yields dependent
mostly on the extent to which the crown was affected by X-
disease.

Some trunk damage associated with the drilled holes
was evident a year after treatment. Over 60% of the holes
inspected had small cracks or gummosis associated with
the injection site. A few trees had extensive cracks (from
6 to 10 inches) and decay. Fourteen percent of the holes
had callused over after a year and a half. The injection
wound alone did not cause the cracks and gummosis; they

were caused by the OTC treatment (Schieffer, unpublished
data).

Discussion

Mauget microinjection of OTC appears to be an
effective and simple technique for X-disease therapy de-
spite possible long-term drawbacks related to injection
wounds. Microinjection is not labor intensive and does not
require special equipment. Since most X-infected trees
decline quickly and eventually die, treatment of diseased
trees may at least prolong their productivity. However,
trees not more than half affected responded the most,
therefore, Mauget therapy appears to offer limited effec-
tiveness to trees in advanced stages of X-disease. Injections
will be most cost-effective where half of the tree or less is
affected by foliar symptoms at the time of treatment.

Mauget microinjection may prove especially valuable
in delaying symptom development in asymptomatic trees
on sites where high disease pressure from infected choke-
cherries is present. Treatment of healthy trees, on the
other hand, may need to be considered carefully because of
the possible long-term wound effects from OTC injection.

Research is continuing on the evaluation of risks vs. the
benefits of prophylactic use of this method in healthy trees,
and to determine how long treated trees remain in symp-
tom remission.

References

Lacy, G.H. 1982. Peach X-disease: Treatment site damage
and yield response following antibiotic infusion. Plant
Disease Reptr. 66:1129-1133.

Table 1. Changes in

X-disease ratings following OTC treatment.

Original rating

Treatment

Increase

(%)

No change

(%)

Decrease (%)

OTC

Control

OTC

Control

OTC

Control

OTC

Control

OTC

Control

100

Rosenberger, DA., and A.L. Jones. 1977. Symptom remis-
sion in X-diseased peach trees as affected by date, method,
and rate of appUcation of oxytetracycHne-HCL. Phytopa-
tholoQ> 67:277-282.

Acknowledgements

The authors wish to thank Hamilton Orchards in New Salem,
Westward Orchards in Harvard, Bolton Spring Orchards in Bolton, and
Green Acres Fruit Farm in Wilbraham for their cooperation during this
study. We also thank James Williams and Karen Hauschild for help with
injections, and the J. J. Mauget Company for supplying the Mauget OTC
capsules.

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Reevaluation of NAA as a Preharvest Drop Controlling
Chemical for Mcintosh

Duane W. Greene

Department of Plant & Soil Sciences, University of Massachusetts

For the past 20 years Alar^^ has been the primary
chemical used to control preharvest drop of Mcintosh fruit.
The superior performance of Alar essentially eliminated
the use of those compounds available prior to its registra-

tion. However, the registration of Alar is under review and
we still do not know what its future will be. More stringent
tolerance levels already have been set by the Massachusetts
Department of Public Health.

Cumulative drop (%)

100

.^-— «

-^ Control

-I- NAA (10 ppm)

^ft^"^^^

- -^ NAA (20 ppm)

cJ^^^^ ^x.———-

H — ' — *"

-B- Alar (750 ppm)

J^ j^^'^^^^

//y^

/Jj€^

itJTi 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 t

1 1 1 1 1 1

■ 1 1 1 t-

Sept 2 Sept 11 Sept 20 Sept 29 Oct 8

Oct 17

Figure 1. Cumulative drop from trees which received Alar, NAA (10 or 20 ppm
ber 8), or no drop-controlling treatment.

on Septem-

The only other drop-controlling chemical that is reg-
istered for use on apples is naphthaleneacetic acid (NAA).
If growers in Massachusetts must depend on this com-
pound, then a reevaluation of its effectiveness is necessary,
since most of the research on NAA was done prior to 1960.
Pruning and training systems, pest control programs, root-
stocks, orchard management practices, and fruit condition
requirements have all undergone significant changes since
that time.

A study was initiated in 1987 to answer several specific
drop control questions: 1. How effective is NAA at
controlling preharvest drop of Mcintosh? 2. How long
does drop control from NAA last? 3. Can growers first spot
pick then effectively control drop with NAA? 4. How much
drop occurs as a result of harvesting?

A block of 11-year-old Rogers Mclntosh/M.26 were
selected and divided into 8 groups of 8 trees each. Two
trees in each group were sprayed with 750 ppm Alar (2.25
lbs per acre) on July 17, 1987. When the first sound fruit
began to drop on September 8, NAA at 10 and 20 ppm was
applied to a tree in each group. This timing is recom-
mended on the NAA label. It was decided that September

14 was the day that a commercial grower would begin spot
picking these trees. All fruit that had sufficient color to
meet the U. S. Extra Fancy grade were harvested from half
of the trees in each block. On September 15 NAA at 10 or
20 ppm was applied to a portion of the trees that were
previously spot picked. Drops were removed from under
trees prior to and immediately after spot picking. All drops
were removed 3 to 4 times weekly from September 1 to
October 2 and then twice weekly until the experiment
ended on October 20.

The NAA label recommends that application should
begin as soon as the first sound, uninjured fruit begin to
drop. This timing occurred on September 8. Whenapphed
at this time 10 ppm NAA was as effective as Alar at
controlling drop for 8 days, and 20 ppm NAA was as
effective as Alar for 10 days (Figure 1). After 10 days Alar
was clearly the superior drop controlling chemical. Cumu-
lative drop on trees receiving NAA was significantly less
than on control trees, even as long as 6 weeks after
application. Although fruit quality was not evaluated in this
experiment, it was noticed that fruit receiving NAA were
noticeably softer and riper at the end of September.

Cumulative drop (%)

100

-e-

Control

-h

NAA (10 ppm)

NAA (20 ppm)

-B- Alar (750 ppm)

I I I I I I I I

Sept 2

Sept 1 1

I I I I I I I I I I I I I I I I I I I I I I I I I I

Sept 20

Sept 29

Gets

Oct 17

Figure 2. Cumulative drop after spot picking on September 14 from trees which received
Alar, NAA (10 or 20 ppm on September 15), or no drop-controlling treatment.

100

Cumulative drop (%)

Sept 13

Sept 22

Octi

Oct 10

Oct 19

Figure 3. Cumulative drop after September 14 from trees that were or were not spot picked
on September 14 and received Alar or no drop controlling-treatment.

Growers may wish to delay the appHcation of NAA
until they make their first harvest. This delay will allow the
filling of CA storages with fruit that has the potential for
long-term storage. When application of NAA was delayed
until trees were spot picked (September 14), it took ap-
proximately 6 days for drop control to be effective (Figure
2). During this period, over 25% of the fruit on NAA-
treated trees dropped. Once drop control was established,
NAA retarded drop for a long period of time. The results
of this experiment confirm the results of a similar experi-
ment done in 1986. In that study NAA was applied on
September 13 when drop exceeded 10%. It required 9 days
for NAA to slow drop significantly, and by that time over
20% of the crop had been lost.

Spot picking removed about 39% of the crop. Even
though these trees were relatively small and are not difficult

to pick, 6% dropped as the result of harvesting process. It
has been suggested that partial crop removal may reduce
drop. It is reasoned that the more mature fruit that are
prone to drop will be removed by spot picking. Also, the
snowball effect of one dropping fruit hitting another will be
reduced. Harvest did not reduce the amount of drop from
untreated trees (Figure 3). However, if trees were previ-
ously treated with Alar, crop removal did retard drop. The
reason for this is not clear.

Summary . If NAA was applied when the first sound
apples started to drop it retarded drop effectively for 7 to
10 days. If NAA application was delayed until trees were
spot picked and drop was proceeding, it took up to 6 days
to slow drop. Over 25% of the crop was lost before drop
control was established.

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Postharvest Apple Rots: Dr. Rosenberger's Approach

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

Dr. David Rosenberger of the Hudson Valley Lab,
Cornell University, has been studying postharvest rots on
apples for a number of years. In a recent talk at the
University of Massachusetts he discussed some of the key
points in the management of these problems, and these
points will be outlined in this article. Dr. Rosenberger
emphasized that the key to good management was an
integration of several techniques:

* Appropriate and sufficient summer fungicide applica-
tions;

* Good management of the harvesting process;

* Appropriate postharvest chemical use in the dip tank;

* Good sanitation in the storage facility and harvest proc-
ess; and

* Intelligent use of storage and marketing options.

Fungicide Applications During the Growing
Season

Good storage rot control begins in the field before
harvest. For example, last summer the wet harvest tem-
peratures, combined with a tendency to leave fruit on the
tree for color development, produced a larger than normal
amount of rot in storage. This situation occurred because
the wet weather during summer and harvest increased the
rot inoculum and unseen fruit infections.

There are a number of diseases, rots and others, which
can develop in storage:

Pin-point scab can be a problem. Late-season scab
infections on the fruit can go undetected, and develop in
storage into visible lesions. The best way to avoid a
problem is to maintain good scab management throughout
the season.

Sooty blotch and fly speck are late season problems that
may develop if summer weather conditions are humid.
Interestingly, the fungi which cause these diseases will not
grow at storage temperatures. However, unseen infections
on harvested fruit can develop in storage. The fungi grow
duringthe period when the fruit is cooling, before it reaches
the storage temperature. In a large storage room, where it
may take several days to reach the desired temperature, the
fungi grow well for a time. Rapid cooling after harvest
would help eliminate this problem.

Moldy core is another disease which develops in the
field, and lies undetected until the fruit has been in storage.
Moldy core can be caused by a number of fungi, but about
90% of the problems are caused by Altemaria. The
infections occur during bloom and petal fall. Unfortu-

nately, there do not seem to be any fungicides which control
the disease very well. The infections develop inside the
fruit, largely protected from fungicides.

Fungicides can help reduce many of the other posthar-
vest rots. A minimum program of 1 appUcation in early July
and 1 again in early August should be adequate to control
development of most of the late season fungal infections.

Management During Harvest and Packing

Wounded or over-mature fruit are more susceptible to
postharvest diseases. For example, a rough orchard road
can lead to significant quantities of wounding, which will
increase the fruit's susceptibility to rot. Taking the time to
smooth the orchard floor can reduce this problem. Avoid
storing over-mature fruit. Ingeneral, the most mature fruit
should be marketed first, and the less mature stored.

As mentioned above, rapid cooling can decrease the
time that rot fungi have to develop. In some cases, it will
stop development completely, while in others it will slow
the process. Rapid cooling slows down fruit ripening,
which slows down all forms of fruit rotting since fruit lose
their resistance to fungi as they ripen.

Another management practice which affects posthar-
vest rots as well as storability is calcium nutrition. Low
calcium in the fruit increases its susceptibility to rot organ-
isms. Perhaps other nutrients, such as potassium also can
affect rot susceptibility. Maintaining a calcium nutrition
program is advisable.

Sanitation

Attention to sanitation can be beneficial at all points in
the postharvest handling process. The basic aim is to keep
the inoculum for postharvest rots away from the fruit.

Old bins can contain bits of old, rotten fruit from the
previous year. Designating a single bin for culls can reduce
the spread of this inoculum. Soaking a bin with bleach
solution (10% in water) mixed with either detergent or a
standard spreader-sticker, and allowing the bin to air dry
also will reduce problems.

Dirt from the orchard fioor also can carry inoculum.
To counter this problem, keep bins on sod and away from
direct soil contact. Do not operate equipment so that it will
dig up soil when a bin is Ufted. In wet weather, rigging a
hose to wash trucks, trailers, and bins wiU reduce the
amount of soil which is carried into the drench solution.

Reducing the inoculum load in the drench solution is
very important, since it comes in contact with virtually all

the fruit. Besides using an equipment prewash, it is
advisable to change the drench solution frequently. Since
disposing of the solution is a problem, minimizing the
voluir; of solution used in the drench equipment can
contribute to overall efficiency. For example, it would be
better to develop a system using 15 gallons of rapidly
recirculating drench, and change it daily, than to use a 200
gallon system for weeks.

Given that you have a large volume system, the holding
tank should have rounded corners rather than square
corners. Square corners are "dead" areas, where fungicide
can settle out of solution. Keepingthe solution agitated and
the chemicals in solution is critical to maintaining proper
application rates. Placing rounded baffles in a square tank,
or using a rounded tank, can solve the problem.

Fungicides

There are only a few fungicides registered for posthar-

vest use. These include the following materials: Captan
SOW™, Captan SOW™, Benlate 50W^, Topsin 70W™,
and Mertect 340- F™. Captan is only moderately effective.
Benlate, Topsin, and Mertect ju^e very effective, but can
become ineffective when fungal resistance develops.
Rosenberger observed that these fungicides appeared to
control rot better when used in combination with DPA
(diphenylamine) than did either the fungicides or the DPA
alone. When he tested the fungicides and DPA against
benomyl-resistant Penicillium, he discovered that DPA
inhibited the fungus. However, benomyl-sensitive isolates
of Penicillium were inhibited only marginally by DPA.
Most Penicillium isolates were sensitive to either DPA or
fungicide. Hence, in a mixed set of resistant and sensitive
fungal spores, such as would be expected in natural condi-
tions, the majority of the fungi would be affected. Interest-
ingly, the DPA is effective at low temperature (about 35°F)
but not at room temperature.

* %t^ %t« «2^ »l#
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Electric Lift Truclcs in Refrigerated Facilities

James F. Thompson
University of California, Davis

New Battery Desig ns. Although electric lift trucks cost
60% more than equivalently sized propane-powered Uft
trucks, many cold storage and precooling operations are
buying electric lifts for work inside refrigerated areas. One
reason for the switch is that new battery designs allow
electric lifts to operate for a full 8-hour shift in these
operations. But, more importantly, the savings in energy
and maintenance costs will more than pay for the extra cost
of an electric lift over its economic life.

Energy Cost . A 5,000 pound capacity Uft truck will cost
$23,000 if battery-powered (this includes a charger and a
battery with a 6,000-hour life) . An electric lift uses electric-
ity for battery charging. But an electric lift produces less
waste heat than a propane lift, so refrigeration for remov-
ing lift truck heat is much less. Seven tons of refrigeration
capacity are needed to remove waste heat produced by a
propane lift, while only 2.5 tons are needed for electric lifts.
In addition, most of the electricity use for electric lifts is at
night when electric rates are often lower.

The net effect is that electricity costs are equal for the
two types and total energy savings for electric compared
with propane are equal to the cost of propane for the
propane lift. To estimate propane savings, assume a 5,000

pound lift truck uses about 1 gallon of propane per hour.

Low Maintenance . Electric lifts have much lower
maintenance costs than propane lifts. Lift truck manufac-
turers' estimate maintenance costs for propane powered
trucks to be $2.50 per hour of operation, while maintenance
costs for electric lifts trucks are an equivalent of only $1.00
per hour of operation.

For many operations, the energy and maintenance cost
savings of electric lifts will more than pay for the higher
initial and battery replacement cost of electric lift trucks.

No Ethylene Gas No Carbon Monoxide . An impor-
tant added benefit of electric lifts is that they do not produce
ethylene gas as propane lifts do. Ethylene can cause
premature ripening in some crops, and postharvest disor-
ders such as russet-spotting in lettuce. Also, electric lifts do
not produce the carbon monoxide which can be a safety
concern if a refrigerated, enclosed facility does not have
adequate ventilation.

Reprintedfrom Perishables Handling Newsletter, Coopera-
tive Extension, University of California. No. 62, October,
1987.

* %i» %t* •]« «x*
•2* ^* *^ *S*

Potential for Explosions in CA Storage Facilities

Henry Waelti and Eugene M. Kupferman
Washington State University

A certain amount of risk is involved when using
combustible gases to generate CA atmospheres. This risk
can be minimized if users understand the principles of
operation of CA equipment so that they can take the
needed precautions.

The common gases used in CA generators arc propane
and natural gas. Both fuels can be ignited by a spark or
flame if they are allowed to accumulate to certain concen-
trations and if sufficient oxygen is present.

Explosive Limits

The limits of gas-to-air ratios between which explo-
sions can occur are expressed as lower explosive limit
(LEL) and upper explosive limit (UEL). Outside of these
limits there is no danger of explosion. For propane they are
2.2% (LEL) and 9.5% (UEL). This means that if there is
less than 2.2% propane in a room, there is not enough fuel
to explode, or if there is above 9.5% propane in a room,
there is not enough oxygen present to allow an explosion.
(For natural gas, the LEL is 5.3% and the UEL is 14%.) In
addition to the gas, a minimum of 11% oxygen is required
to create an explosion with propane.

Open Flame Burners

In open flame burners, without catalytic converters, it
is essential that the correct amount of gas is used to obtain
complete combustion (4.2% propane in normal air). If the
ratio of gas to air is lower, or higher, incomplete combus-
tion occurs, resulting in production of carbon monoxide
and ethylene gas, which are detrimental to fruit quality.
Also, carbon monoxide may leak through walls, accumu-
late in work areas, and create a health hazard to workers.
Fortunately, there are few of these burners left.

Inert Gas Generators

Inert gas generators, such as Tectrol and Isolcell,
produce an inert gas by direct and catalytic combustion of
fresh air and propane or natural gas. As long as the fuel-
air mixture remains at the correct ratio and the catalyst is
working properly, complete combustion is assured.

Recirculating

In recirculating systems, such as the catalytic oxygen
burners (COB), the fuel is oxidized on a catalytic surface
without a flame. As in the open flame burners, enough

oxygen must be available to combine with ALL the fuel
present. Thus, as the oxygen level in a storage decreases,
the fuel supply must also be decreased. Although catalytic
oxidation of fuel may occur without a flame down to 0.5%
oxygen, these burners should not be operated below 3%
oxygen. With the proper gas-to-air ratio in the COB, the
operating temperature of the catalyst is 1100°F to 1300°F.
This temperature range will be maintained as long as the
fuel and air flow remain at the proper setting and the
catalyst remains functional. A properly designed and
operated catalyst allows the fuel to be oxidized completely
down to an operating temperature of 1000°F. If a minimum
operating temperature of lOOO'F cannot be maintained at
the recommended fuel and air ratio, then the catalyst may
be defective and may need to be replaced.

Accident Prevention

-Purchase a propane/methane monitor. They can be
installed on the burner to monitor the effluent stream.
Portable units can be used to monitor individual rooms for
combustible hydrocarbons and other gases toxic to workers
and detrimental to the fruit. It usually is NOT possible to
detect propane or natural gas by smell.

-In early summer, have a competent technician check
out all CA equipment so that there is enough time to make
the necessary repairs before the storage season. These
tests should include the use of portable gas analyzers to
monitor fuel/air ratios and combustion efficiency.

-CA generating equipment must be operated and
maintained according to manufacturer's instructions at all
times.

-Low temperature fuel cut-offs on recirculating burn-
ers should not be set below the manufacturer's recommen-
dations, which is usually 1000°F.

-Check all safety devices at the start of equipment
operation, including low and high cutoff thermostats, sole-
noid valves, fuel regulators, and air pressure switches.

-Do NOT turn on the fans and open the door when
bringing up the oxygen in a room if there is a suspicion of
gas in the room.

-A recommended procedure when opening a room is
to scrub out the combustible gases that may be present in
the room atmosphere using the COB catalyst. Bring up the
oxygen level in the room to 5%. Turn off the fuel supply to

the COB and set it on preheat. Run the temperature up to
600°F and recirculate the CA room atmosphere through
the generator. The temperature of the catalyst may rise,
and if ^vill remain hot until the combustible gas (propane
or natural gas) is down to a s£ife level.

-Some storage operators routinely use a COB to scrub
out any combustible gas which may have entered a CA
room during pulldown.

It is possible to reduce risks to a minimum. By
understanding the principles of CA generator operation,
maintaining the equipment and safety devices, and using
the available instrumentation, managers can maintain a
clean and safe storage atmosphere.

Reprinted from Postharvest Pomology Newsletter, Wash-
ington State University, March, 1988.

*9Sm »3^ %|» «£#
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An "Expert System" for CA Storage of Mcintosh Apples

William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

Our recent survey of CA storage operators in Massa-
chusetts indicated that many storages are not being oper-
ated at conditions that are most suitable for Mcintosh
apples. Factors that can contribute to this situation include
not recognizing the importance of certain conditions, or
overlooking details during the hectic harvest period.

To try to provide easy access for storage operators to
critical information, and to create a mechanism for self-
evaluation of storage operations, we are developing an
"Expert System" for CA storage of Mcintosh apples in
New England. This system is a series of questions, with
answers to be provided by the storage operator, followed by
advice about how long the apples reasonably can be ex-
pected to retain quality in storage, the potential for storage
disorders resulting from some adverse storage condition,
and corrections that might be made when an adverse
condition is recognized.

This "Expert System" is a computer program on a
floppy disk that can be operated on any IBM-compatible
personal computer. It will come with directions for activat-
ing and operating the program, and will require only the
availability of an IBM"^-compatible personal computer
with 640 kbyte memory capacity, and the rudimentary
knowledge for operating the computer.

This system was developed by A. Zubin Varghese, a
graduate student in our Department of Food Engineering,
through a series of intense interviews with the author. Mr.
Varghese worked with Ernest Johnson and Lester Whit-
ney, in the Department of Food Engineering, to convert the
information from these interviews into a computer pro-
gram. This Expert System depicts the author's best judg-
ment of CA storage conditions for Mcintosh apples in
Massachusetts, but in a broader sense provides informa-

tion about storage responses of apples to varying condi-
tions. Its format is a series of "If ... Then ..." situations and
its primary goal is to provide information to help reduce
losses of apples during and following storage.

The questions in this program first attempt to establish
the potential of a set of apples for storage based on maturity
at harvest, speed of cooling, time required to fill and seal a
CA room, and time required to generate the CA atmos-
phere. Then, the storage operator is questioned about the
conditions that are being maintained within the CA room,
including unintended deviations from recommendations.
Where less-than-desired conditions exist, suggestions for
"what might have been" are given. Where risks of physio-
logical disorders are recognizable, these risks are quanti-
fied, the potential disorder is described, and possible
corrective actions are recommended. The program is
accompanied by a printed text describing the kinds of
information needed to answer the questions, and the
recommended ways of obtaining this information.

This "Expert System" is new and needs testing to see
how useful it is and how it might be improved. It is primarily
intended as an educational tool, a readily available source
of information. We hope to have it available for trial by late
summer, and to offer it through the University of Massa-
chusetts Cooperative Extension for a small fee to cover
expenses.

We hope that some CA storage operators will be
willing to try the system and to help us evaluate its useful-
ness and possible improvements. If you are interested in
obtaining and evaluating this "Expert System" if it is
available by late summer, please contact the author or Dr.
Wesley Autio, at your earliest convenience.

* ^£# ^^ ^}i* *S*
v|* vjv v{* *»^

I New England

Apple Production Guide

Cost: $4.00 per copy.

Name:

Address:

City, State, Zip Code:

To order send this form along with a check to the
UNIVERSITY OF MASSACHUSETTS to:

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University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION

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Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension, ' *"' ' ' ' A O O .

United States Department of Agriculture, and Massachusetts Counties Cooperating.

Editors: Wesley R. Autio and William J. Bramlage

ISSN 0427-6906

BIOLOGICAL

OCT 06 1988

bCltNCES LiBKAHY

Volume 53, Number 4
FALL ISSUE, 1988

Table of Contents

Improving the Growth of Newly Planted Apple Trees

The Effects of Travel Speed, Nozzle Arrangement,

and Application Volume on Pesticide

Distribution in Apple Trees

Biological Control of Apple Blotch Leafminers
in Massachusetts Apple Orchards

Controlling Spider Mites in Massachusetts Apple
Orchards Through Conservation of Predator Mites

Comparing Costs of Rubigan^^ and Conventional Fungicides

Apple Bruising. I. Evaluating Grading Lines

An Assessment of CA Storage Operations in Massachusetts

A User-built System for Automated Monitoring
and Controlling of CA Apple Storages

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POUCY:

All chemical uses suggested in this publication are contingent upon continued registration. Thesechemicals should be
used in accordance with federal and stale laws and regulations. Growers are urged to be familiarwith all current state
regulations. Where trade names are used for identification, no company endoreemeni or product discrimination is
intended. The University of Massachusetts makes no warranty or guarantee of any kind, expressed or implied,
concemingthe use of these products. USER ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY
DAMAGE

Issued by the Unhrrsity ofMassachusells Cooperatiw Extension, E. B. MacDougoU, Director, in furtherance of the acts of
May 8 andJune 30,1914. The Unix-ersily ofMassachusetIs Cooperative Extension offers equal opportunity in prop-ams and
employment.

Improving the Growth of Newly
Planted Apple Trees

Wesley R. Autio and Duane W. Greene

Department of Plant & Soil Sciences, University of Massachusetts

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

It is well accepted that to be profitable an orchard
enterprise must receive returns from new plantings as
early in the life of those trees as possible. Rootstocks and
cultivars are major factors determining the age at which an
orchard begins to pay for itself. Site preparation and
cultural practices prior to, during, and after planting also
influence the age at which a tree comes into production.

At the University of Massachusetts Horticultural
Research Center in Bclchertown we generally do not
obtain a desirable amount of growth the year of planting,
and it must be recognized that to obtain early returns and
maintain high profitability throughout the life of a block it
is necessary for the trees to grow well and produce a good
fruiting framework in the years just after planting. Site
preparation techniques, such as cover cropping, organic
matter incorporation, and installation of irrigation or
drainage, are known to improve growth. We decided to
study planting and post-planting techniques which may
offer some benefit to tree growth.

Level of Nitrogen Fertilizer

In 1986 four plantings were established at the Horti-

cultural Research Center. The first planting (Marshall
Mclntosh/M.9) assessed the effects of different levels of
nitrogen fertilizer applied soon after planting. It was
postulated that additional growth could be obtained if
nitrogen was applied at higher rates than usually recom-
mended. In 1986 individual trees received either 0.5, 1.0,
1.5, or 2.0 pounds of ammonium nitrate in split applica-
tions two weeks apart approximately two weeks after
planting. Treatments were repeated in 1987; however, the
2.0-pound rate was decreased to 1.5 pounds because of
tree injury noticed in 1986. Trunk circumference was
measured at planting and after the 1986 and 1987 grovving
seasons. Total shoot growth was measured after the 1986
and 1987 growing seasons. Data are reported in Table 1.
In 1986, increasing the amount of ammonium nitrate
beyond the standard rate of 0.5 pound decreased trunk and
shoot growth. Even in 1987, the second leaf, growth was
decreased when the rate of application was increased. We
can postulate that root injury occurred in 1986 which
carried over to 1987, and that we cannot attempt to
improve tree growth with increasing nitrogen applications.
Furthermore, these results suggest that we should re-
examine our present recommendation of 0.5 pound of

Table 1. The effects of different levels of i
planted in 1986.

litrogen fertilization on the growth of Marshall Mclntosh/M.9 trees

Ammonium
nitrate
1986/1987
(lbs/tree)

Trunk circumference (cm)

Change in

trunk circ. (cm)

Shoot growth (cm)

At planting 1986 1987

1986

1987 1986 + 87

1986 1987 1986 + 87

0.5/0.5
1.0/1.0
1.5/1.5
2.0/1.5

3.2 * 3.6 ** 6.4 **

3.3 3.5 5.8
3.2 3.3 5.1
3.2 • 3.3 5.1

0.4 **
0.2
0.1
0.1

2.8 ** 3.2 **
2.3 2.5
1.8 1.9
1.7 1.9

114 ** 649 ** 763 **
93 524 617
78 350 428
89 378 467

*No significant differences existed.

**For these measurements there was a significant linear decrease between the 0.5/0.5 and 1.5/1.5 treatments.

There was no significant difference between the 1.5/1.5 and the 2.0/1.5 treatments.

Table 2. The effects of urea application technique on the trunk and shoot growth of Summerland Red
Mclntosh/Mark trees planted in 1986.

Trunk circumference (cm)

Application

treatment At planting 1986 1987

Change
1986

in trunk circ. (cm)
1987 1986 + 87

Shoot

growth (cm)

1986

1987 1986+87

Dry 3.8 * 4.2 *
Foliar 3.7 4.3
Drench 3.5 3.9

7.1 *

6.9

7.4

0.4 *

0.6

0.4

2.9 * 3.2 *
2.6 3.2
3.5 3.9

117 *

132

108

657 * 774 *
652 784
770 878

*No significant differences existed.

ammonium nitrate and determine if a smaller dose may be
appropriate for newly planted trees.

Nitrogen Application Technique

The second planting (Summerland Red Mcintosh/
Mark) established in 1986 studied the effects of nitrogen
application technique the year of planting on tree growth.
In 1986 trees all received 0.25 pound of urea, but it was
applied either dry to the soil on May 15, in solution as a soil
drench on May 8, or in foliar applications on May 25 and
June 8. In 1987 all trees received a soil treatment of 1
pound of ammonium nitrate. Tree growth was measured
as in the first planting. Data are reported in Table 2, and
they showed that application technique did not alter the
amount of tree growth during the first or second leaf.

Mulching and Vydate

In the third planting established in 1986 Gala/M.26

trees were either mulched with 0.5 bale of hay after
planting, treated with foliar applications of Vydate 2L^^ (2
quarts/100 gallons) just after leaf emergence and in mid-
July, mulched and treated with Vydate, or not treated.
Mulch was reapplied in 1987. Tree growth was measured
as in the first planting, and data are reported in Table 3.
Mulch was included in this planting because it often is
able to encourage better tree growth, even beyond its weed
control abilities. In this experiment weed control was
maintained with herbicides. Vydate was used to control
nematodes which may reduce growth. Neither mulch nor
Vydate treatments affected the growth of these trees.
However, mulch significantly increased the quantity of
bloom in 1988. It is clear that this response could signifi-
cantly improve early returns. Additionally, mulched trees
are less susceptible to extremes in water availability, so
that over a number of years plantings established with
mulch would be expected to have better growth even
though we did not see it in this planting.

Table 3. The

effects of hay mulch and Vyd

ate appli

cations on the trunk, shoot growth.

and bloom of Gala/M.26

trees planted

in 1986.

Trunk circumference (cm)

Change

in trunk

circ. (cm)

Shoot

growth (cm)

1988 Bloom

(clusters/

Treatment

planting

1986

1987

1986

1987 1986 + 87

1986

1987

1986 + 87

cmO

Control

4.4*

4.8*

8.0*

0.5*

3.1*

3.6*

290 *

906

* 11% *

8.5**

Mulch

4.3

4.8

8.3

0.6

3.5

4.0

308

927

1235

20.4

Control

4.3*

4.8*

8.1*

0.5*

3.2*

3.7*

282 *

868

* 1150 *

17.0*

Vydate

4.3

4.9

8.3

0.5

3.4

3.9

316

962

1278

12.8

*No significant differences existed.

**Significantly different at odds of 99 to 1.

Table 4. The effects of various planting treatments on the trunk and shoot growth of Royal Gala/M.26 trees

planted in 1986.

Trunk circumference (cm)

Change in trunk

z\TC. (cm)

Shoot growth (cm)

Planting

treatment At planting

1986

1987

1986

1987

1986 + 87

1986

1987 1986+87

Control

3.8 a*

4.9 be

8.5 ab

1.1 de

3.6 ab

4.7 ab

321 c

1054 b 1375 b

Topsoil

3.8 a

4.9 be

9.1a

1.1 cde

4.1a

5.2 a

321 e

1509 a 1830 a

Peat

3.8 a

5.4 a

9.2 a

1.6 a

3.8 ab

5.4 a

500 a

1298 ab 1798 a

Manure

3.7 a

5.1b

8.9 a

1.4 abc

3.8 ab

5.2 a

399 b

1184 ab 1583 ab

Tree planter (TP)

3.8 a

4.7 c

7.9 b

0.9 e

3.2 b

4.1b

259 c

998 b 1257 b

TP + Aliette (2#)

3.8 a

4.9 be

8.4 ab

1.2bcde

3.5 ab

4.6 ab

294 c

1137 b 1431 b

TP + Aliette (4#)

3.7 a

5.1b

8.4 ab

1.4 ab

3.4 ab

4.8 ab

313 c

1258 ab 1571 ab

TP + Ridomil

3.8 a

5.0 be

8.6 ab

1.2 bed

3.6 ab

4.8 ab

328 c

1107 b 1435 b

*Means within columns not followed by the same

letter are

significantly different at odds of 19 to 1.

Planting Techniques, Hole Treatments, and Root
Fungicides

The last planting (Royal Gala/M.26) established in
1986 studied the effects of planting hole treatments, plant-
ing techniques, and post-plant root fungicides. In this
experiment half of the trees were planted with a tree
planter and half were planted into an 2-foot augered hole.
The trees in the auger holes either were planted with the
soil that was removed from the hole, good topsoil from
another site, a mixture of 1:1 peat-to-topsoil, or a mixture
of 2:1 composted manure-to-topsoil. Trees planted with a
tree planter were either sprayed in 1986 and 1987 to the
drip point with Aliette^^ (at 2 pounds/100 gallons or 4
pounds/100 gallons) late spring, mid-summer, and early
fall; treated with a soil drench in 1986 and 1987 of 1 quart
of Ridomil^^ (at 1 quart/100 gallons) late spring, mid-
summer, and early fall; or were not treated with either root
fungicide. Tree growth was measured as in the first
planting, and data are reported in Table 4.

In 1986 the most prominent effect was caused by the
addition of peat to the planting hole. Peat-treated trees
had the largest increase in trunk circumference and the
most shoot growth. The addition of composted manure
also improved growth but not to the extent of the peat
treatment. In 1987 differences in growth rate began to
dissipate except for the topsoil treatment. Using good
topsoil in the planting hole did not have much effect the
first year; however, in 1987 those trees had significantly
more shoot growth than the controls. At the end of 1987
the largest trees, in terms of trunk circumference, were
those planted with good topsoil, those planted with the
addition of peat, and those planted with the addition of

manure. Trees planted in an augered hole seemed to grow
better than those planted with a tree planter; however, the
differences between the two were not statistically signifi-
cant. These results suggest that the use of some type of
planting treatment can significantly improve the growth
and development of the trees to be planted. However, it
may be difficult to apply these types of treatments in some
situations, such as when a tree planter is used. Therefore,
at times it may be more practical to use surface applica-
tions of organic material or the growing of cover crops with
subsequent plowing or tilling under to improve the soil.
When the soil has been prepared such as this before
planting the effects probably will last longer than if only an
augered hole is treated.

The use of root fungicides had only a small effect on
tree growth. In 1986 the high level of Aliette and the
Ridomil treatment resulted in more trunk growth but no
increase in shoot growth. In 1987 no growth differences
existed. One could conclude that these root fungicides give
little benefit; however, at some sites the pressure of root-
attacking fungi may be much greater than at this site at the
Horticultural Research Center and the effect may be much
greater.

It is clear from the results of these four experiments
that cultural treatments performed at planting or to newly
planted trees can have significant effects on tree growth.
The importance of early tree growth and the establishment
of a fruiting framework suggests that growers should
carefully prepare a site before planting, and consider the
use of some of these treatments during the planting year.
We shall continue to study improvements of tree develop-
ment with cultural techniques.

* * *

The Effects of Travel Speed, Nozzle
Arrangement, and Application Volume on
Pesticide Distribution in Apple Trees

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

Spraying recommendations may seem as though they
are based only on common sense rules of thumb, or worse,
nothing at all. So it is encouraging when scientific facts are
generated that support spraying recommendations.

Dr. Jim Travis and Dr. Turner Sutton, plant patholo-
gists at Pennsylvania State University and North Carolina
State University, respectively, recently completed studies
on spray deposits in apple trees. The usual recommenda-
tion to direct 2/3 of the sprayer output toward the top
1 /3 of the tree, and 1 /3 of the output at the bottom 2/3 of
the tree is based on work done in 1965. Since that time, in
spite of the significant changes in tree size and pesticide
formulation, that recommendation has continued to be
made. Travis and Sutton found that the recommendation
is still relatively sound, if trees are of medium size (ap-
proximately 13 ft high X 12 ft in diameter). However, as the
tree size decreases to 9.5 ft high x 9.5 ft in diameter, a 50:50
ratio (half directed at the top 1/3 and half directed at the

bottom 2/3) gives the best deposit throughout the tree, and
the lowest variability from one part of the tree to another.
Of course, there are many other factors which affect
spray deposition. Of those examined in the recent study,
the following were found to optimize spray deposition:

1. A tractor speed of 2 mph was found to be better than 1.5
or 2.5 mph;

2. A rate of 66 gal/acre was better than 40, 100, or 400 gal/
acre;

3. Well pruned trees were better than moderately to
poorly pruned trees.

Adhering to these guidelines could improve spray
deposition and distribution in fruit tree foliage, making
pesticide applications more effective and more efficient. It
is important to note that the tests were made under a
specific set of conditions, which may or may not have
relevance to each particular orchard. However, if these
practices can be tried, they can help control costs.

:(: * 4:

Biological Control of Apple Blotch Leafminers
in Massachusetts Apple Orchards

Roy G. Van Driesche, Ronald J. Prokopy, and William M. Coli

Department of Entomology, University of Massachusetts

T. Bellows

Department of Entomology, Division of Biological Control, University of California,

Riverside, CA, 92521

Introduction

The apple blotch leafminer (ABLM), Phyllonorycter
crataegella (Clemens) is a small (1/4 inch) moth in the
family Gracillariidae that has become a significant pest in
Massachusetts apple orchards since the mid 1970's. This
problem has occurred due to the development of resis-
tance to common orchard cover spray materials, such as

azinphos-methyl (Guthion™), which formerly suppressed
populations as a side effect, although there was no con-
scious effort on the part of the growers to do so.

Following the first detection of resistance in ABLM
populations in Massachusetts, resistance spread rapidly
throughout the region. Densities of mines rose sharply as
the pest was controlled neither by cover sprays (which no
longer affected the moth), nor, in commercial orchards, by

parasites, which were easily killed by orchard cover sprays.

A broader view shows that this same scenario of
pesticide-resistant leafminers and pesticide-susceptible
parasites has led to significant pest problems from a
number of other Phyllonorycter species on apple or other
tree fruits in many areas, including P. blancardella (F.) in
New York, Michigan, and Ontario (Dutcher & Howitt,
1978; Free et al., 1980; Weires et al., 1980), P. corylifoliella
(Hubner) in Holland (Van Frankenhuyzen, 1975), P. el-
maella (Doganlar & Mutuura) in Utah (Barrett & Jor-
gensen, 1986), and P. ringoniella (Matsumura) in Japan
(Sekita & Yamada, 1979). This repeated pattern high-
lights the vulnerability of single-factor chemical controls
which, once breached by pest resistance, leave pests free to
multiply unrestrained by natural enemies which typically
are slower to develop pesticide resistance (if ever) and
hence cannot attack the pest in the sprayed environment.

Because high density leafmincr populations can ad-
versely affect apple crops by increasing drop and reducing
flower bud formation (Reissig et al., 1982) and because
Phyllonorycter spp. have a high capacity to develop pesti-
cide resistance, it is important that orchardists in Massa-
chusetts broaden control systems immediately to protect
and encourage the specialist parasites that attack ABLM.
If this is not done, further resistance in the species likely
will occur to the specific carbamate and organochlorine
materials that are currently effective and used against high
density leafminer populations.

Major Parasites of ABLM in Massachusetts

Studies in Massachusetts (Van Driesche & Taub,
1983), Connecticut (Maier, 1984), New York (Weires et
al., 1980), and elsewhere have consistently shown that
Phyllonorycter species attacking apple are themselves ex-
tensively attacked by several species of parasites in the
absence of interference from pesticide applications. The
most important of these in Massachusetts at this time are
the braconid, Pholetesor omigis (Weed), and the eulophid,
Sympiesis marylandensis (Girault) (Van Driesche & Taub,
1983).

P. omigis is a black species, 1/4 inch long, that attacks
tissue feeding host larvae, laying its egg inside the body of
the host larva. The mature parasite larvae exits from the
host and spins a white cocoon inside the leaf mine. Detec-
tion of parasitism by P. omigis is easiest in old mines since
parasite cocoons are readily visible to the naked eye and
remain present even after the adult parasite has left the
mine. Parasite cocoons are easily separated from both live
and emerged moth pupae.

S. marylandensis, in contrast, is smaller (1/8 inch),
metallic blue-black in color, and attacks tissue stage larvae.
Its eggs are laid next to, but outside of, the host larvae and
are visible with a hand lens. Parasite larvae develop and
feed outside the host larvae and pupate in the mine, with no

cocoon. Parasitism by this species can be detected at any
time because of its position external to the moth larva. In
addition to killing hosts by parasitization, 5. marylandensis
adults directly attack and kill other tissue feeding larvae
which they pierce with their ovipositor and then partially
consume as a source of protein. Larvae killed in this
manner appear dried out and shriveled 2md are often
attached to the mine "skin" at a single point, where the
parasite formerly fed.

Other potentially important parasite species, not yet
found in Massachusetts, include the braconid, Pholetesor
pedias (Nixon), and the encyrtid, Holcothorax testaceipes,
both recently introduced to Ontario (Laing & Heraty,
1981) from New Zealand and Japan, respectively.

Management Options Available to Growers to
Promote Biological Control of Apple Blotch
Leafminer Populations

The major infiuence on parasite populations in apple
orchards is the pesticide regime, both in terms of its
duration and the particular chemicals selected for use. To
a lesser extent, proximity of wild or abandoned apple trees,
or wild cherry trees where parasite populations will be
found attacking various species of leafminers, can also
infiuence events within commercial apple orchards.

Pesticide Management . Attempts have been made to
identify pesticides more toxic to the pest leafminer than to
their associated parasites (Weires et al., 1982; Van Dries-
che et al., 1985). While somedegree of selectivity has been
found (e.g., for oxamyl; Van Driesche et al., 1985), in
general all materials which provide effective control of
leafminer adults or larvae also seriously harm parasites.
Low rates of low-residual materials are the least damaging
to parasites. Nevertheless, complete elimination of chemi-
cal controls of leafminers in favor of reliance on parasites
should be the goal of orchardists trying to establish biologi-
cal leafminer control systems, as currently available pesti-
cides for leafminer control are relatively incompatible with
parasite survival.

In addition to pesticide applications directly targeted
against leafminers, cover sprays against other insects also
represent a major obstacle to parasite effectiveness within
commercial orchards. While parasitism levels on non-
sprayed trees are high (often 60% or greater), levels inside
blocks sprayed for other insects are typically very low (less
than 5%), with some increase in the third leafminer gen-
eration in September after cover sprays have ended (Van
Driesche and Taub, 1983). It thus appears that the most
effective action growers can take to conserve leafminer
parasites in commercial orchards is to end regular cover
sprays as early in the season as possible, lengthening out
the insecticide-free period in which leafminer parasites
can increase in numbers. Currently, cover sprays are

maintained until mid-August or even into September to
protect fruit against apple maggot flies. A "Second-stage
IPM" strategy now being tested in Massachusetts may
offer a means to extend the length of the insecticide-free
period by terminating regular cover sprays at the end of
May after the period of plum curculio attack has ended.
Control of apple maggot fly in July, August, and Septem-
ber then would be based on intensive trapping using red
sticky traps developed by Prokopy and removal of wild or
abandoned apple trees adjacent to the orchards. While
initial data (1987) show that this system increases numbers
of predator mites, data are not yet available as to its effect
on leafminer parasites. Such data, however, will be col-
lected in future tests beginning in 1988.

Habitat Management . Abandoned or wild apple
trees, or wild cherries in forested areas near orchards
typically have Phyllonorycter spp. Icafmincrs (including
ABLM) that serve as hosts for P. omigis and 5. marylan-
dcnsis. Increased parasitism in commercial orchards in
late summer and fall results from both within-orchard
build up of the parasites that survived early season pesti-
cide applications and perhaps from immigration of para-
sites into orchards from hosts living on unlcndcd trees.
The relative importance of these two sources is unknown.
Wild hawthornc, wild apple trees, and abandoned apple
trees near orchards all serve as sources of apple maggot
flies that can enter orchards and hence such trees should
be removed. Various species of native cherries also serve
as possible breeding sites for ABLM parasites, but are
likely to be too few in number to do more than "re-seed"
orchards that have lost their leafminer parasites due to
extensive pesticide use. The size of mid- to late-season
leafminer parasite populations in commercial orchards is
therefore less likely to be determined by the habitat out-
side the orchard than by the pesticide application history in
the orchard itself.

State Actions of Potential Value in Promoting
Biological Control of the Apple Blotch Leafminer

Existing native parasites of ABLM, while fairly effec-
tive, are not necessarily the species with the highest poten-
tial to suppress leafminer populations. Because of the
problems that have arisen in various regions with other
Phyllonorycter species, much is known of the parasites
attacking a variety of leafminer species. Some species
seem to have potential to increase the level of control over
that provided by our native parasites. For example in
Ontario, the introduced parasite, Pholetesor pedias, has
produced levels of parasitism 2 1/2 times greater than the
native Pholetesor omigis (Laing & Heraty, 1987). This
parasite has been established in Ontario and more recent-
ly in New York (Weires, personal communication). An-
other parasite of potential value is the encyrtid, Holcotho-
rax testaceipes, which is the major parasite attacking P.

ringoniella in Japan (Sekita & Yamada, 1979). It has
recently been established in Ontario and is becoming the
dominant parasite there as well. A recently approved
Northeast Regional Apple Project has provided funds to
Dr. Chris Maier of the Connecticut Agricultural Experi-
ment Station to introduce both of these parasites to New
England.

How to Monitor Parasitism Levels in Your
Orchard

Leafminer populations can be monitored either by
counts of adult moths caught on red sticky traps, or by
counts of mines per leaf for each leafminer generation.
Thresholds currently in use in Massachusetts for the sec-
ond system are 0.13 mine/leaf for the first generation and
1 .00 mine/leaf for the second generation. These levels are
lower than thresholds currently used in other states to
account for compounding effects of mites or drought
stress. The use of 0.13 mine/leaf as a treatment threshold
is based on the concept that, given the 7 to 8 fold increase
typical from the first to the second leafminer generations,
more than 0.13 healthy mines in the first generation will
result in damaging populations (more than 1.0 mine/leaf)
in the second generation. This first generation threshold,
however, should be raised if levels of parasitism are high
(Figure 1). Parasitism levels can be determined by select-
ing one hundred old mines at the end of a generation and
opening them with needle-nose tweezers. Mines then can
easily be classified into ones in which moths have devel-
oped, ones in which parasitoids have developed or ones in
which the larvae were killed by feeding of adult parasites.
Percentage parasitism can then be calculated as number of
mines with dead larvae plus the number with parasitized
larvae or parasite pupae or cast parasite pupal skins
divided by the total number of leaf mines sampled. Levels
of parasitism can be taken into consideration only if
leafminer levels are assessed in the first generation and
required treatments are then made in the next generation
against leafminer adults. This strategy currently has the
drawback that available materials for killing leafminers
tend to make mite control problems worse. This effect
becomes increasingly more severe as the season pro-
gresses, and thus, given existing pesticides, treatments
made early against first generation leafminer larvae are
less disruptive to mite population dynamics than treat-
ments made for second generation leafminer adults.
Unfortunately, treatments targeted against first genera-
tion leafminer larvae cannot use thresholds modified by
levels of parasitism because parasitism occurs late in the
leafminer larval stage. If the insect growth regulator
difiubenzuron (Dimilin™) is registered for leafminer
control, it will be easier to utilize a strategy based on
assessing first generation mine numbers and levels of
parasitism at that time and then treating second genera-

o
o

80
70
60
50
40
30
20
10

T 1 I I

J 1 1 l_

-i 1 1-

-10 10 20 30 40 50 60 70 80 90

PERCENTAGE PARASITISM

Figure 1. Treatment thresholds for apple blotch leafminer.

tion leafminer adults if needed, because diflurbenzuron is References
not disruptive to biological mite control.

Converting Front Pesticide Management to
Biological Control of Apple Leafminers

Conversion from pesticide management of apple
leafminers to management based largely on conservation
of parasites is essential if growers are to reduce pest
management costs and the threat of ever increasing pesti-
cide resistance in leafminer populations. This goal can be
reached only as part of an integrated reduction in orchard
pesticide use to increase, to the greatest extent possible,
the insecticide-free period from mid- to late season.
Recognition of the principal parasite species and the
ability to tell a leaf mine that produced a parasite from one
that produced a moth are essential. Sharp tweezers and a
hand lens are the required tools for this determination.
Training can be obtained from regional fruit extension
agents. Regular assessment of proportions of mines para-
sitized can help growers remain aware of the status of
leafminer populations in their orchards and can be used to
modify recommended chemical control thresholds.

Barrett, B A. and CD. Jorgensen. 1986. Parasitoidsofthe
western tentiform leafminer, Phyllonorycter elmaella
(Lepidoptera: Gracillariidae) in Utah apple orchards.
Environ. Entomol. 15:635-641.

Dutcher, J.D. and JA. Howitt. 1978. Bionomics and
control oi Lithocolletis blancardella in Michigan. /. Econ.
Entomol. 71:736-738.

Laing, J.E. and J.M. Heraty. 1981. Establishment in
Canada of the parasite Apanteles pedias Nixon on the
spotted tentiform leafminer, Phyllonorycter blancardella
(Fabr.). Environ. Entomol. 10:933-935.

Laing, J.E. and J.M. Heraty. 1987. Overwintering of
Phyllonorycter blancardella (Lepidoptera: Gracillariidae)
and its parasites, Pholetesor omigis and Pholetesor pedias
(Hymenoptera: Braconidae), in southwestern Ontario.
Environ. Entomol. 16:1157-1162.

Maier, C.T. 1984. Abundance and phenology of parasi-
toids of the spotted tentiforn leafminer, Phyllonorycter

blancardella (Lepidoptera: Gracillariidae), in Connecti-
cut. Can. Ent. 116:443-449.

Free, DJ., Hagley, EA.C. and Simpson, CM. 1980.
Resistance of the spotted tentiform leafminer, Phyllon-
orycter blancardella (Lepidoptera: Gracillariidae), to or-
ganophosphorous insecticides in southern Ontario. Can.
Entomol. 112:469-474.

Rcissig, W.H., R.W. Weires, and CO. Forshey. 1982.
Effects of gracillariid leafminers on apple tree growth and
production. Environ. Entomol. ll:958-%3.

Sekita, N. and M. Yamada. 1979. Studies on the popula-
tion of the apple leafminer Phyllonorycler ringoniella
Matsumura (Lepidoptera: LithocoUetidae). IIL Some
analysis of the mortality factors operating upon the popu-
lation. Appl. Entomol. Zool. 14:137-148.

Van Driesche, R.G. and G. Taub. 1983. Impact of
parasitoids on Phyllonorycler leafminers infesting apple in
Massachusetts, USA. Prot. Ecol. 5:303-317. ^

Van Driesche, R.G., J.M. Clark, M.W. Brooks, and FJ.
Drummond. 1985. Comparative toxicity of orchard insec-
ticides to the apple blotch leafminer, Phyllonorycler cra-
taegella (Lepidoptera: Gracillariidae), and its eulophid
paTisitoid, Sympiesismarylandensis (Hymenoptera: Eulo-
phidae). /. Econ. Entomol. 78:926-932.

Van Frankenhuyzen, A. 1975. Phyllonorycler corylifoliella
(Hubner 1973) (Lep., Gracillariidae). Entomol. Ber.,
Amersterdam, 35: 1. VIIL

Weires, R.W., D.R. Davis, J.R. Leeper, and W.H. Reissig.
1980. Distribution and parasitism of gracillariid leafmin-
ers on apple in the northeast. Ann. Entomol. Soc. Am.
73:541-546.

Weires, R.W., J.R. Leeper, W.H. Reissig and S.E. Lienk.
1982. Toxicity of several insecticides to the spotted tenti-
form leafminer (Lepidoptera: Gracillariidae) and its "paxdi-
silc, Apanleles omigis. J. Econ. Entomol. 75:680-684.

Controlling Spider Mites in Massachusetts
Apple Orchards Through Conservation
of Predator Mites

Roy G. Van Driesche, Ronald J. Prokopy, and William M. Coli
Department of Entomology, University of Massachusetts

Introduction

Spider mites (European red mite, Panonychus ulmi
(Koch), and two-spotted spider mite, Tetranychus urticae
Koch) have become increasingly significant pests in apple
orchards due to destruction of predator mite populations
and development of resistance to some major milicidcs.
While spider mites are not direct pests of the fruit itself, the
cost of their control has increased relative to control costs
of other pests. Efforts to reduce production costs
therefore must include less expensive alternatives for
spider mite control. This article discusses how the strategy
of predator conservation may be employed by growers to
reduce their mite control costs.

The Predators

In New England the most important mite predator is
the phytoseiid m'ltc, Amblyseiusfallacis (Garman) (Table

1). A second species of importance is the stigmaeid mite,
Zetzellia mail (Ewing). In Western New York,
Typhlodromus pyri (Scheuten) rather than/l./o/Zacw is the
major phytoseiid predator and in Pennsylvania and New
Jersey, the coccincUid Stelhonis punctum (LeConte) is
important. 5. punctiim is most often seen as a predator
attacking high density mite populations (15 or more mites/
leaO; whereas, A. fallacis does well moderate mite
densities (4 to 7/leaO. T.pyri andZ. mali are able to persist
at very low mite levels (under 3/leaO because of their
abilities to utilize various alternative food sources such as
rust mites, pollens, and fungi. Predator mite biology for
, each species must be understood if management practices
are to be effective. For example, whereas T. pyri spends
the entire year in apple Uccs,A. fallacis overwinters in the
orchard groundcover. Management of orchard
groundcover thus infiuences both A. fallacis survival and
the timing of its recolonization of apple trees the following

season.

Table 1. Major species

of mite predators on apples in the Northeastern United States.

Area

Species

Family

New England

Amblyseius fallacis (Garman)
Zetzellia malt (Ewing)

Phytoseiidae
Stigmaeidae

New York

Typhlodromus pyri (Scheuten)
Zetzellia malt (Ewing)
Stethorus punctum (LeConte)

Phytoseiidae
Stigmaeidae
Coccinellidae

Pennsylvania

Stethonis punctum (LeConte)

Coccinellidae

Conservation Methods Available to Growers

Pcsticidal chemicals, nitrogen, and orchard
groundcovcrs are the three orchard components that can
be manipulated to promote biological mite control.

Pesticide Management . Growers can create an
orchard environment more
favorable for predator mite
survival and reproduction by 1)
selecting pesticides that are as
safe as possible to predator
mites and 2) ending orchard
cover sprays as early in the
growing season as possible.
Relatively safe pesticides that
may be used without damaging
greatly predators do exist
(Table 2). In part, the relative
safety ofsome materials, such as
azinphos-methyl (Guthion^^),
is due to a natural evolution of
pesticide resistance in predators
such as A. fallacis, subject over
many years to the use of these
pesticides as orchard cover
sprays. The relative safety of oil
to predator mites is due to
selective timing, in that A.
fallacis is not on the tree at the
time that early season
applications are made to kill
European red mite eggs. All
classes of pesticides, including
herbicides, fungicides, and plant
growth regulators as well as
insecticides and miticides,
should be reviewed as to their
harmfulness to mite predators

prior to use. For example, both lime sulfur and benomyl
are very harmful to A. fallacis, but for very different
reasons. Lime sulfur is directly toxic. Benomyl induces
sterility in female predator mites (Hislop & Prokopy,
1981) and thus, when used from June onward, destroys the
potential for the population to persist and grow. Miticides,

Table 2. Relative harmfulness of orchard pesticides other than acaricides |

to predator mites in

apple."^

Very harmful

Moderately harmful

Relatively safe

chlorpyrifos''

phosphamidon

oil"

methomyl

karathane

malathion

carbaryl

amitraz

phosmet

oxamyl

difolatan

azinphos-methyl

phosalone

dinocap

endosulfan

diazinon

dikar

methoxychlor

dcmeton

glyodin

dimethoate

dodine

pcrmethrin

maneb

fenvalcrate

thiram

ammonium sulfate

dichlone

paraquat

captan

glyphosate

ferbam

benomyl"

simazine

lime sulfur

dalapon

NAA

^Data from Hislop & Prokopy (1981) and Butkewich & Prokopy (1985) |

u&ing A. fallacis as test species.

''At low dosage, this material may be relatively safe.

"Oil does not affect A. fallacis because this predator overwinters off the |

tree in the groundcover and hence is not contacted by

oil applications

made in the very early periods of the growing season.

"Harmful because it sterilizes female predator mites.

although by definition directly toxic to mites, still offer a
spectrum of safety to predator mites, ranging from
dormant oil that is relatively safe to A. fallacis, to
formetanate hydrochloride (Carzol^^) which is extremely
damaging to predator mites. Miticides in current use are
arranged in terms of relative safety toA. fallacis, the major
mite predator in Massachusetts, in Table 3.

Second-stage IPM, currently being developed in
Massachusetts apple orchards, provides another approach
to pesticide management that aids in conserving mite
predators. Under this management strategy, regular cover
sprays are used only in the early portion of the growing
season (to approximately the end of May). After this
period only fungicide applications are made. Apple
maggot fly damage is prevented after termination of cover
sprays by intensive trapping (using red sticky spheres) and
removal of wild or abandoned apple and hawthornc trees.
Preliminary data on this strategy from 1987 tests show an
improvement of predator:prey mite ratios from 1:9 in
grower-sprayed control blocks to 1:5 in second-stage 1PM
blocks. At the 1:5 ratio predator mites can be relied on to
maintain spider mites under commercially acceptable
control in most cases.

Nitrogen Management . Apple foliage with elevated
nitrogen levels is a more nutritious food for spider mites,
resulting in more rapid development and a larger number
of eggs laid per female mite (van DcVric & Boersma,
1970). This more rapid build up of spider mite populations
makes control by any existing level of predator mites more
difficult. Nitrogen levels thus should be kept at the lowest
levels consistent with healthy tree growth. Nitrogen may
become available to trees either directly, in the form of

fertilizer applications, or indirectly from nutrients
released from groundcovers killed by herbicide
application or plowing. Growers should monitor actual
nitrogen levels in leaves and adjust their fertilization
practices accordingly.

Groundcover Management . Over and above the
indirect effects of orchard floor vegetation management
through leaf nitrogen levels, groundcover management
directly influences predator numbers. Because A. fallacis
overwinters off the tree, groundcovers can influence the
numbers of predators that survive, and can affect the
timing in the following growing season of predator
movement back into the trees. The timing of predator re-
entry into trees depends in part on the availability of two-
spotted spider mites and other food sources in the
groundcover. The ideal groundcover species and
management practices are not known, but are currently
the subject of research in both Massachusetts and New
York. In addition, herbicides are sometimes used to kill
strips of orchard floor vegetation. Certain of these (e.g.,
glyphosate, paraquat, and ammonium sulfamate, see
Table 2) are highly toxic to predator mites.

Other actions that growers can take to promote
biological mite control include encouraging development
of apple rust mite populations. These mites make apple
leaves less favorable for spider mites and serve as food for
predator mites when spider mites are scarce. Alternate
food sources moderate predator mite population declines
when primary prey species are low in number with the
result that more predators remain in the orchard to
suppress spider mite populations when their numbers
begin to increase.

Table 3. Impact of orchard

acaricides on predator mites.

Overall

Material

Trade name

impact^

Comments

oil

—

Use split application (half at
half inch green and half at tight
cluster or early pink)

propargite

(Omite™)

fenbutatin-oxide

(Vendex™)

clofentezine

(Apollo™)

hexythiazox

(Savey™)

oxythioquinox

(Morestan™)

For pre-bloom use only, do not
combine with oil

dicofol

(Kelthane™)

Very hard on predators

formetanate

hydrochloride

(Carzol™)

Very hard on predators

^Safety index, with 1

being most harmful and 5 being

safest

on A. fallacis.

In addition, growers whose orchards have few
predator mites (due to factors such as past pesticide use
practices) can "re-seed" their orchards by purchasing
predators, such asA.fallacis, from commercial sources
and releasing them on orchard trees to induce a more rapid
increase in predator numbers, which must then be
conserved by altered (i.e. reduced pesticide) management.
In some cases such purchased predators may possess
higher levels of pesticide resistance than is common in
native predator mite populations. Such resistance will
promote better predator mite survival and reproduction
for populations subjected to pesticide use.

State Programs to Enhance Biological Mite
Control

Most of the decisions that influence biological mite
control in apples are made by growers. Two areas exist
however where state (or University) programs could
contribute to this process: introduction to Massachusetts
of more highly pesticide-resistant strains of existing
predator mite species and introduction of new species of
predator mites not currently found in Massachusetts.
Higher levels of pesticide-resistance than exist in field
populations have been induced in A. fallacis and other
species of phytoseiid predator mites. Such a pesticide-
resistant strain of A. fallacis has been released and
established in apples in Quebec with good results
(Bostanian & Coulombe, 1986).

Existing native species of mite predators in
Massachusetts {A. fallacis etc.) are not necessarily the
most effective possible predator species. Some success has
occurred in establishing exotic predator mites in other
regions. For example, T.pyri has been moved successfully
to Austraha for control of European red mite (Thwaite &
Bower, 1980). Examples listed by McMurlry (1982) of
species that are of value against spider mites in apples in
other regions of the world \nc\\\de, Amblyscius potcntillae
(Garman) from Europe and Typhlodroimis arboreus
(Chant) from Oregon, among others. Attempts to
establish exotic mite predators on outdoor crops generally
have been inhibited by the widespread belief among
research acarologists that locally existing native species
likely are to be superior due to better adaptation to the
local conditions. However, given that apples, European
red mite and two-spotted spider mites all are recent
introductions in Massachusetts (i.e. a few hundred years at
most), there is little reason to hold this view. Successes in
other areas argue for trials of exotic species to test whether
or not more effective mite predators might not be
obtainable.

Assessing Predator Levels in Your Orchard

Decisions to apply or not apply miticides are made

based on evaluations of numbers of prey mites (not
counting eggs) per leaf in light of numbers of predators
(either per leaf or per prey mite) and the point in the
growing season. The simplest assessment system is a fixed
predatorrprey ratio. For example if on 50 leaves 50
predators and 500 prey are found, you have a 1:10
predator: prey ratio, or 10 prey per leaf and only 1 predator
per leaf. Massachusetts makes miticide recommendations
based on a threshold than varies with the season (i.e. spray
if there are 2 to 3 mites/leaf in June, but 3 to 5/leaf in July
and 5 to 15/lcaf in August). New York recommends
miticide applications if there are more than 5 prey mites/
leaf unless predators are numerous (1 or more per leaf). In
general a 1:5 predator:prey ratio seems to indicate good
prospects for biological mite control. A 1 : 10 ratio indicates
less prospect for control (but still possible). Ratios smaller
than 1:10 indicate biological mite control is unlikely to
occur.

Actually counting all the mites on each of 40 or so
leaves can be a difficult task. To simplify the process. New
York has developed a sequential sampling scheme in
which leaves are picked one after another and then each
leaf is classified as cither having or lacking spider mites and
having or lacking predators. A chart with curves then
allows the sampler to determine if predator:prey ratios are
such that biocontrol is likely to occur, if miticide
applications arc needed, or if more leaves should be
examined (Nyrop, 1987). This scheme has been developed
for T. pyri in New York. No similar scheme has been
developed yet (or A. fallacis in Massachusetts.

In Pennsylvania, a more elaborate decision making
process in the form of a question and answer "expert
system" has been developed that growers can use on home
computers. No similar system exists in Massachusetts.

Regardless of the exact thresholds used, growers who
wish to monitor predator:prey ratios in their orchards
must learn to recognize predator mites as distinct from
prey mites (i.e. spider mites). A hand lens is sufficient for
this task and training can be requested from the regional
fruit extension agents.

How to Convert From a Pesticide Mite Control
Program to a Biological Control Program

Growers who wish to change management strategies
from chemical to biological mite control should begin by
requesting an evaluation of their mite control situation
from an IPM specialist or extension representative.
Factors to consider include past and current pesticide use
(both amounts and specific types), orchard floor
vegetation management, nitrogen management, and
current spider mite and predator densities. IPM scouts
can as.sess probable influences of various actions on mite
populations and recommend specific actions to promote
mite biological control. Regular monitoring for the first

season is essential to determine if mites are responding as
desired, and to determine timing and choice of any
supplemental mite control treatments that may prove
necessary. A period of several years may be required to
convert from an intensive chemical control program to one
based on conservation of mite predators, as predator
populations will require time to increase in numbers. This
process may be shortened by purchasing and releasing
predator mites into orchards lacking predators after
predator conservation practices have been established
(see, for example, Field et al., 1979).

References

Bostanian, N.J. and LJ. Couiombe. 1986. An integrated
pest management program for apple orchards in
southwestern Quebec. Can. Entomol. 118:1131-1142.

Butkewich, S.L. and R.J. Prokopy. 1985. Update on the
relative toxicity of orchard pesticides to the predator mite
Amblyseius fallacis. Fruit Notes 50:9-10.

Field, R.P., W.J. Webster and D.S. Morris. 1979. Mass

rearing Typhlodromus occidentalis Nesbitt (Acarina:
Phytoseiidae) for release in orchards. /. Aust. ent. Soc.
18:213-215.

Hislop, R.G. and RJ. Prokopy. 1981. Integrated
management of phytophagous mites in Massachusetts
(U.S A.) apple orchards. 2. Influence of pesticides on the
predator Amblyseius fallacis (Acarina: Phytoseiidae)
under laboratory and field conditions. Prot. Ecol. 3:157-
172.

McMurtry,JA. 1982. The use ofphytoseiids for biological
control: progress and future prospects. In: Recent
Advances in Knowledge of the Phytoseiidae, MA. Hoy (ed),
Pub. 3284 of the Univ. Cal., 92 pp.

Thwaite, G. and C. Bower. 1980. Predators spell doom for
orchard mites. Agric. Gazette ofN. S. W. 91(4):16-19.

van dc Vrie, M. and A. Bocrsma. 1970. The influence of
the prcdaccous mite Typhlodromus (A.) potentillae
(Carman) on the development of/'a/i<?/i>'c/iwjw//m (Koch)
on apple grown under various nitrogen conditons.
Entomophaga 15:291-304.

* * *

Comparing Costs of Rubigan^"^ and
Conventional Fungicides

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

One of the most appealing features of the ergosterol
biosynthesis inhibiting fungicides (Si's) is that they offer
longer periods between applications than do conventional
fungicides. Rubigan 1 EC^^ at 6 oz/acre, when combined
with a half-rate of Dithane M45 80W™ (0.75 lbs/ 100 gal),
has performed well when used at 10 day intervals in tests at
the Horticultural Research Center, Belchcrtown, MA
(Table 1). It should be noted that the performance of
Rubigan at the 4-oz rate plus the half-rate of Dithane is not
as good, and generally would not be acceptable, at the 10-
day intervals. After looking at efficacy, we then examined
the economics of a complete-season Rubigan program.

At 10-day intervals, 6 Rubigan/Dithane applications
were used in primary scab season last year (Table 2). At 7-
day intervals, 9 standard applications would have been
necessary. Looking at fungicide costs, using retail cost

estimates, we found that the Rubigan/Dithane program
was more expensive than a standard program (Tables 2
and 3). (The standard program used was 1.5 lbs/100 gal in
all applications, plus 2 applications containing 3/8 lb/100
gal Cyprex 65W.)

However, fungicides themselves are only part of the
costs. Application costs, such as gasoline, equipment wear,
and labor, must also be considered. Since the Rubigan/
Dithane program requires fewer applications, then such
costs over a season will be lower. Estimates for application
costs vary: in Massachusetts they are estimated at approxi-
mately $5.50/acre/application, while in New York they
are estimated at $16.00/acre/application. When the non-
fungicide costs were varied, and applied to different types
of seasons, the following results were obtained (Table 4).

In a season similar to last season (9 standard sprays vs.

Table 1. Scab incidence under 10-day Rubigan/Dithane

programs at two rates, 1987.

Fungicide & Rate

Percent scab incidence

Cluster

Terminals

Fruit

Rubigan lEC 4 oz plus
Dithane M45 SOW 2.25 lbs

0.7 a'

0.3 a

1.7 a

Rubigan lEC 6 oz plus
Dithane M45 80 W 2.25 lbs

2.9 a

0.5 a

4.7 b

Dithane M45 80 W 2.25 lbs

13.1 b

1.5 b

5.7 b

Non-sprayed control

23.6 c

4.4 c

23.0 c

'Means within columns not followed by
odds of 19:1.

the same

letter

are significantly different at

Table 2. Comparison

of actual 10-day SI spray

applications with a

theoretical 7-day

urogram (based on

Horticultural Research Center data, 1987).

Mill's scab

infection period

Infection period

Growth stage

and severety

Standard

Rubigan/Dithane

April 16 - 18

1/4 to 1/2"

light

yes(4/15)

yes(4/19)

April 20 - 21

early TC

light

April 25

none

yes(4/25)

May 2

late TC

none

yes(5/2)

May 7 - 9

pink to bloom

heavy

yes(5/5)

ycs(5/12)

May 16 - 17

petal fall

heavy

yes(5/12)

May 21 - 22

late PF, set

heavy

yes(5/19)

yes(5/22)

May 22 - 23

late PF, set

heavy

May 27 -28

set

heavy

yes(5/26)

May 30 - 31

1/4" fruit

moderate

June 2 - 3

1/4" fruit

heavy

yes(6/l)

June 4 - 5

1/4" fruit

heavy

June 12 - 13

3/4" fruit

heavy

yes(6/8)

yes(6/ll)

June 13 - 14

3/4" fruit

heavy

yes(6/15)

Totals

Cost

$76.07^

$79.40"

'Dithane M45 80W, 1

5 lbs/100 gal, 4.5 to 3.6 lbs/A plus 2 applications in combination with Cyprex 65W, 3/

8 lb/100 gal., 1.13 to 0.9 lbs/A.

^Rubigan 1 EC 6 oz/A in combination with Dithane M45 SOW, 0.75 to 0.6 lbs/A.

Type of season
(Mills period)

6 Rubigan/Dithane), if ap-
plication costs exceed $13.00,
it would be less expensive to
apply Rubigan/Dithane than
a standard treatment. If
Rubigan is used at the 4 oz
rate, then application costs
need to exceed only $6.00 for
economy. (Note, however,
that our results with this rate
may not be commercially ac-
ceptable.)

When 6 standard sprays
are needed versus 4 Ru-
bigan/Dithane sprays, the
break-even points for appli-
cation costs are the same:
$13.00 at the 6 oz Rubigan
rate and $6.00 at the 4 oz rate.
If the season is such that the
numbers of standard and
Rubigan/Dithane applica-
tions are similar, the break-
even points increase. So, at 7
standard vs. 6 Rubigan/
Dithane applications, appli-
cation costs need to exceed
$30.00 (unlikely) for econ-
omy.

In fact, it is more likely
that the Rubigan/Dithane
applications will save 2 or 3
sprays, and that the number

of applications will be 9 vs. 6, or 6 vs. 4, or some combina-
tion in between. The IPM block at the Horticultural
Research Center has received an average of 8.5 dosage
equivalents of fungicide in each of the past 8 years, with a
range of from 6 to 11 applications. (Last year was the only
year in which 6 dosage equivalents were used, largely
because Rubigan was used for the first time in the block.)
Similarly, Dr. Robin Spitko of New England Fruit Consult-
ants reports an average of 8.3 dosage equivalents in or-
chards that they scout, with a range of 6 to 11. In view of
that, it may be important to calculate application costs, in

Table 3. Estimates of retail prices used

in the cost comparisons.

Material

Rate per acre^

Cost

Cost per acre
per application

Rubigan 1 EC
Dithane M45 SOW
Rubigan/Dithane
Cyprex 65W

6oz
4.5 lbs
6 oz/4.5 lbs
1.13 lbs

$1.99/oz
$1.74/lb

$2.49/lb

$11.94

$7.84

$15.86

$2.81

^Dilute rate, assuming

300 gal per acre

required.

Table 4. Break-even point for non-fungicide application costs under different
types of seasons and varying numbers of applications.

Number of Number of
standard Rubigan/Dithane
applications applications

Break-even point'

6 oz

4 oz

Heavy 10

Moderate - Heavy 9

Average 6

Light 4

7
6

4
3

$16.00
$13.00
$13.00
$22.00
none

$8.00
$6.00
$6.00
$10.00
none

Hf application costs are above the figure, the 10-day program is less expen-
sive; if application costs are below the figure, the standard program is less
expensive.

order to determine whether a 10-day program would be
cost-effective under a given farm's conditions.

Of course, the convenience of a 10-day program also
should be considered. And, there may be additional cost
efficiency when a 10-day schedule allows an insecticide to
be applied with a fungicide, but a standard program would
not. A 10 day schedule offers considerable flexibility, and
does not appear to cost a great deal, if any, more than a
conventional program, even without considering possible
convenience and additional savings.

* * *

Apple Bruising. I. Evaluating Grading Lines

William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

Bruising is responsible for downgrading large quanti-
ties of apples and other fruit. A single bruise larger than 5/
8 inch in diameter, or several smaller bruises with an
aggregate area of more than 1/2 inch diameter will elimi-
nate an apple from the U.S. Extra Fancy grade. Some
bruising may occur before harvest, but the great majority
of it occurs during harvest, transport to the packing house,
grading and packing, transport to the retail outlet, and
during retail marketing. A great deal of this bruising is
caused by the harvesting and packing operations, and is
largely preventable. While any knowledgeable fruit
grower knows that a ripe apple is easily bruised and can
identify some obvious sources of bruising, many sources
are difficult to identify and thus to remedy.

Personnel at the U.S. Department of Agriculture,
Agricultural Research Service and at Michigan State
University have been conducting cooperative research on
the sources and consequences of apple bruising, and have
published a series of reports on their findings that are very
helpful in identifying and correcting sources of bruising.
This article is the first in a series of articles in Fruit Notes
on their findings about this extremely important subject.

Apple packing lines offer many opportunities for
bruising, but identifying trouble spots is not always easy. In
a paper presented at the December 15-18, 1987 meeting of
the American Society of Agricultural Engineers, G. K.
Brown, C. L. Burton, S. A. Sargent, N. L. Schulte Pason, E.
J. Timm, and B. E. Marshall addressed this problem.
Their paper, entitled "Apple Packing Line Damage As-
sessment," examined bruise, cut, and puncture damage
incurred by Golden Delicious apples as they moved
through typical mechanical packing and grading lines.
Eight different packing lines were tested, representing the
widely-used equipment and the range of daily capacity of
commercial packing houses in Michigan. The lines were
all evaluated twice: mid-September to mid-October
(freshly harvested apples), and early-January to early-
February (ripe air-stored fruit).

Apples were sampled at 4 locations: input to the
washer, output from the dryer (after waxing), on the sizer,
and on the packing table. Additional samples were taken
after bagging. Bruises were all rated according to size
(diameter): "A" = 1/4 to 1/2 inch; "B" = 1/2 to 3/4 inch;
"C" = 3/4 to 7/8 inch; "D" = 7/8 to 1 1/4 inch; "E" =
more than 11/4 inch.

Sampling at the washer input measured bruising that
occurred in the flotation tank, the undersize eliminator.

and the inspection belt. Two-thirds of the apples sustained
bruises in these operations. Sampling at the dryer meas-
ured damage from the washer, dewaterer, waxer, and
dryer. More damage occurred in these operations than
anywhere else on the line. Sampling on the sizer showed
damage from the singulator and from transfer to the sizer,
and this was the second-most source of fruit damage on the
hne. Sampling at the packing table showed damage that
occurred from the sizer, and the conveyor, and here the
least amount of damage occurred. By the time the fruit
reached the packing table, 99% of them had been bruised
in the packing line. To evaluate damage in the bagging
operation, bruise-free fruit were bagged. This step was the
most damaging of all, bruising 91% of the apples.

These results are depicted in Figure 1, showing the
average number of bruises per fruit incurred in each of
these operations, for each of the 8 packing lines. The data
shown are for the late test.

Up to the bagging operation, over 90% of the bruises
were of the "A" size, less than 1/2 inch in diameter, and
less than 5% of the fruit were cut or punctured. However,
during bagging the damage was more severe; 20 to 25% of
the bruises were 1/2 to 3/4 inch in diameter, and 4 to 5%
of the fruit were cut or punctured.

There were few differences in results between the fall
and winter tests, meaning that ripening had little effect
when compared with the operations of the packing lines.
One difference that did exist was that freshly harvested
fruit were more likely to be cut or punctured than were
fruit out of storage.

As you might expect, there were great differences in
damage among the different packing lines, indicating that
much of this damage is under the control of the packing
line operator, and thus is correctable. This was demon-
strated clearly in that total number of bruises was reduced
by 50% in the late test, after operators saw the results of the
early test and began taking corrective actions.

The authors summarized their assessments of the
causes of damage as follows.

Sampling Point A:

l.RoUing fruit hit steel chains, rollers, plates, and other
fruit.

Sampling Point B :

1. High washer or waxer brush speed resulted in bounc-
ing and stacking of fruit.

o
<

tlJ

6.5
6.0
5.5-
5.0-
4.5
4.0
:5.5

i^ :3.o

^ 2.5^

r)
a:

"^ 2.0^

1.5

1.0

0.5-1

0.0.

PACXlNOfOUSE 1

OODE

AVERAGE

I 1

r/VA

K^^rt

^Z^

KSSSi

' — '

SAMPLING POINTS AND DAMAGE INCURRED BETWEEN
SUCCESSIVE POINTS ON PACKING LINE

Figure 1. Average number of bruises to Golden Delicious apples incurred between
points on eight grading lines. A = at input to the washer. B = output from the dryer.
C = on the sizer. D = on the packing table. E = bagging operation.

2. Unpadded or poorly padded braces and guides.
Obstructions in the line.

3. Mismatched transfers from washer to dewaterer/
waxer.

4. Fruit to fruit contact or impact required for fruit flow.

5. No partitioning between parallel-flow brushes.

6. Long resistance time in washer, dewaterer, and waxer
(low slope angle, fruit contact required for flow).

7. Fruit hit dryer rollers too fast after leaving the waxer.
Sampling Point C :

1. Unpadded plates and rollers.

2. Dried wax on padded surfaces caused surfaces to be
rough and hard.

3. Mistimed singulator to sizer transfer (fruit hit cup or
bounced).

4. No timing for transfer of fruit from singulator to sizer.

5. No transfer plate at singulator-to-sizer transfer.

6. Fruit-to-fruit impact.

7. Excess fruit on singulator fell onto hard surfaces in
recycling line.

8. Hard cup surfaces on the sizer.
Sampling Point D :

1. Excessive belt speeds or sizing cone speeds in sizer.

2. Excessive drop distance from sizer cup to cross con-
veyor.

3. Fruit-to-fruit impact.

4. No decelerator strips.

5. No padding in sizer.

6. Hard surface on sizing cones (metal, rubber).

7. Excessive recycling on the accumulation tables due to
fruit volume exceeding packing capacity.

Sampling Point E :

1. Fruit-to-fruit contact on the bagger feed-rolls.

2. Fruit-to-fruit contact as apples drop into the bags.

3. Excessive vertical drop height from the weight tray to
the bag.

4. Excessive fruit size for the bagger.

5. Dropping bagged fruit onto the conveyor.

6. Top apples in bags getting hit at the bag closer ma-
chine.

7. Bag tumbling at conveyor transfer corners and drops.

These findings show that many surfaces impacted by
apples should be padded, that fruit velocity (primarily as
they roll down transfer ramps) should be slowed, and that
drop angles (especially in the sizers and baggers) should be
reduced. Knowing what to look for should help the
operators of packing lines identify and correct problems,
thereby substantially reducing fruit bruising during the
packing operations.

In subsequent articles based on these Michigan State
studies, we shall describe other sources of fruit bruising
and some of its consequences.

* * *

An Assessment of CA Storage Operations
in Massachusetts

Katrin Kaminsky and William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

Development of controlled atmosphere (CA) storage
in the 1940's and 1950's revolutionized the Mcintosh apple
industry. This apple has an inherently short life in air
storage that is made worse by its susceptibility to brown
core development at temperatures below 37°F. In air
storage, its quality cannot be maintained beyond 3 or 4
months. However, in CA, it can be kept at a temperature
high enough to avoid brown core and, under proper CA
conditions, retain good quality for up to 8 or 9 months.
Thus, when done properly, CA can triple the length of the
marketing season for Mcintosh.

Current CA recommendations for Mcintosh in Mas-
sachusetts are 3% O^, 2 to 3% CO^ for the first month and
then 5% CO^, and 37°F. Some researchers have shown
that Mcintosh can be stored safely at much less than 3% O^
if the COj is also kept very low, but we have never
succeeded with low Oj storage for our Mcintosh and do
not recommend low-Oj storage in Massachusetts. The risk
of injury to the fruit is too high.

Every year we receive a number of samples of apples
showing symptoms after storage that strongly indicate that

storage operation was not correct. These symptoms in-
clude soft and broken-down apples due to over-ripeness,
Oj or COj injury due to an incorrect atmosphere compo-
sition, and core browning or freeze damage due to too low
a temperature.

To better understand why these problems occur, and
to help us in advising CA operators on how to do a better
job of managing their storages so as to maintain high
quality of fruit, we conducted a survey of CA operations for
Mcintosh during the 1986-87 season. A detailed question-
naire was sent to each of the 28 CA operators licensed by
the Massachusetts Department of Food and Agriculture,
and all of them responded to our request. From their
responses we can construct a reliable profile of CA opera-
tions for Mcintosh in Massachusetts. This information is
summarized and evaluated below.

Survey Results

Size of Facilities . The 28 CA facilities have a total of
83 CA rooms with a total capacity of about 590,000 bushels.

The average operation stored 21,000 bushels, but 50% of
the operators have a capacity of 15,000 bushels or less. The
average CA room size was 7,100 bushels, but the capacities
ranged from 600 to 33,000 bushels per room. Thirteen of
the CA storages have only 1 or 2 rooms, while 10 have 3 or
4 rooms, 4 have 5 rooms, and 1 has 7 rooms. All but 4
operators stored only their own fruit, yet 84% of the fruit
was destined for the wholesale market. Mcintosh com-
prised 77% of the stored fruit. These members all show
clearly that the CA industry in Mcintosh is dominated by
small storages where the operator stores only his own fruit.

Room Maintenance Characteristics . About two-
thirds of the rooms use freon as refrigerant, and the
remainder use ammonia. Only about two-thirds of the
operators test the rooms for leaks annually, a serious
oversight by the remaining operators. For pressure relief
in the room, 82% use breather bags, 21% use U-tubcs, but
7% apparently lack a designed relief system. (Percentages
may exceed 100% because some operators have different
equipment on different rooms.) In only two-thirds of the
rooms are floors covered with water before sealing, and
only 4 operators attempt to measure humidity in the
rooms. About 75% of the rooms use lime boxes to scrub
COj from the atmosphere.

Establishing CA Conditions . During precooling, only
one-fifth of the operators actually measure fruit tempera-
tures. Only 39% of the respondents typically fill a room
within 1 week, and 50% require 1 to 2 weeks for filling.
(When rooms are opened, 21% typically are emptied in 2
to 4 weeks, while another 21% require 8 to 12 weeks.)
Liquid nitrogen was used in 43% of the rooms to generate
an atmosphere, in most of which 5% O^ was reached within
3 days. However, one-third of the rooms utilize only fruit
respiration to generate the atmosphere, which requires
more than 7 days for 5% O^ to be reached.

Monitoring the Storage Atmosphere . In about one-
third of the storages, thermocouples or thermistors are
used to monitor temperature, and more than 2 locations
per room are monitored in one fourth of the storages.
However, nearly 50% of the rooms have only a thermome-
ter at the door for measuring temperature. Three-fourths
of the respondents calibrate their temperature-monitoring
devices annually.

All storages monitor O^ and CO^ with an Orsat. Only
8 storages use a pump to draw air from the room to the
Orsat. Only 7 storages monitor the atmosphere more than
once per day, and 3 reported monitoring it less than once
per day.

Desired storage conditions for Mcintosh varied
widely. Half of the operators did not state their desired
temperature, and of those who did, two-thirds set the
temperature at less than 37°F. For O^ levels, less than half
of the respondents try to keep the room at 3%. Eleven
operators try to keep Oj between 3 and 4%, and 5 try to

maintain Oj at 4 to 5% O^. Sbc operators run rooms at less
than 3% O^, but no one tries to go below 2%. Half of the
storage operators try to maintain 5% COj, and nearly half
try to keep CO^ at less than 5%.

Atmosphere Variations . Operators were asked to
identify typical atmosphere fluctuations in "good" rooms
and in "difficult" rooms. In good rooms, about half
reported temperature variations of no more than l°Ffrom
the set point, and about one-third reported that it varied no
more than 2°F. For Oj, about half reported variation of no
more than 0.5%, but 6 said that it typically fluctuated more
than 1% from the desired value. For CO^, responses were
almost identical to those for Oj.

One quarter of the operators reported no "difficult"
rooms. Of those who have such rooms, wide variations in
Oj or COj were more common than in temperature. When
asked what condition was most difficult to maintain in their
storage, half of the operators noted Oj and none noted
temperature, while one-fourth said there was no real
difference. When asked what kind of atmosphere injury to
fruit was most frequent for fruit in their storages, 7 identi-
fied freezing, 6 identified brown core, 2 identified COj
injury, and 1 identified low-O^ injury.

An Evaluation

This survey clearly show that some of the difficulties
with fruit quality that CA operators experience when the
fruit come from storage arise from the sizes of the opera-
tions. To optimize the benefits from CA, a room should be
at atmosphere within 7 to 10 days after the first fruit in the
room were picked.

Since half of the CA storages in Massachusetts consist
of only one or two rooms, and half require more than 1
week to fill a room, it appears that many operators lack the
volume to fill quickly enough to achieve full benefits of CA.
How much benefit these operators lose depends on how
ripe the apples become, how long it actually takes to
achieve CA conditions, and how well the storage operates.
Their problems are also compounded by slow pack-out
rates. Once the CA condition is broken, fruit begin to
ripen faster, and when 21% of the storages require 8 to 12
weeks for pack-out, much ripening occurs after breaking
the CA seal. These operations may benefit substantially
from division of the rooms, so that they can be both filled
and emptied faster.

Once a room is filled, it is critically important that it be
sealed and brought to atmosphere quickly. One-third of
the CA rooms still employ only fruit respiration to achieve
atmosphere pull-down, which takes more than a week.
Fruit condition is lost during this time — needlessly.
Liquid nitrogen is easy to use to generate rapidly a low-O^
atmosphere, and is especially applicable to small storages.
No storage should use fruit respiration to generate a CA

atmosphere with the technology that is readily available
today.

We recommend CA conditions of 3% Oj, 5% COj,
and 37°F for Mcintosh in Massachusetts. Many storages
are operated under conditions different from these.

Most operators set temperatures lower than 37°F,
thus risking brown core development in the fruit. Al-
though operators indicated that they thought temperature
was the easiest condition to maintain in CA, low-tempera-
ture disorders were the most frequently observed prob-
lems they reported. In part, these problems stem from too
many operators relying on a single thermometer on the
door to monitor temperature, but in part they also result
from deliberately operating at too low a temperature.

Over half of the storages operate at too high an O^
level. The recommended 3% Oj level is a very conservative
value, intended to allow for some difficulties in maintain-
ing control. When operators deliberately maintain O^
above 3%, they are wasting fruit condition needlessly. The
same can be said for CO^ levels. About half of the
operators deliberately maintain CO^ below 5%, often well
below it. In part this may be due to the practice of placing
lime in the room. However, when CO^ is less than 5% after
the first month of storage, fruit condition is being wasted.

Perhaps the wariness about maintaining recom-
mended Oj and COj levels arises from distrust of Orsat
readings. There is always some risk in relying on readings
from a stationary Orsat. These readings should be
checked weekly against readings at the door and or read-
ings with another instrument. We believe that Orsats
served their purpose in the past, but that it is time to
replace them with better equipment that is now available.
Electronic O^ and CO^ monitors offer many advantages
over the Orsat, and should instill more confidence in the
readings obtained.

Some fiuctuations in the storage atmosphere are inevi-

table, but they need not be large. Large fluctuations carry
two risks: when Oj is too high or CO^ is too low, fruit
condition is lost, and when Oj goes too low or CO^ goes too
high, there may be a risk of fruit injury. It is difficult to
evaluate how big this problem is in Massachusetts CA
storages, because our questions and many of the responses
were somewhat ambiguous. Yet, it is obvious that atmos-
pheres in many storages fluctuate excessively, and this
fluctuation too may be responsible for many of the storage
operators being too conservative in their desired Oj and
COj levels.

Excessive fluctuations can arise from many sources.
One is leakiness of the room, and all rooms should be
tested and leaks patched annually before filling. Another
source is infrequent sampling. Atmospheres should be
monitored once a day at a minimum, but more frequent
sampling is highly desirable. Another source is improper
means for adjusting the atmosphere. Letting in too much
air or using excessive scrubbing rates or times are two
examples of this problem.

Much can be done to improve maintenance of the
storage atmosphere. At the Horticultural Research Cen-
ter in Belchertown we established an automated system of
sampling and controlling the storage atmosphere. This
system is described briefly in an accompanying article. The
system provides improved atmosphere maintenance, and
results in conditions that better maintain fruit quality and
avoid injurious situations.

This survey of CA operations was of great value
toward an understanding of the problems that CA opera-
tors face. We are most grateful to all of our operators for
providing us with this information. The results of the
survey illustrate many different sources of fruit losses, and
hopefully they will be a great help in identifying and
correcting problems in CA operations that are causing
serious economic losses to many storage operators.

* * *

A User-build System for Automated Monitoring
and Controlling of CA Apple Storages

William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

The Orsat gas analyzer is used almost exclusively in
New England to determine the concentration of Oj and
COj in controlled atmosphere storages. Adjustments of
the Oj and the COj levels are then performed manually by
the storage operator. Use of the Orsat is subject to
considerable operation error. It also is time-consuming,
resulting in atmosphere sampling no more often than once
a day in most storages, which in turn can result in signifi-
cant atmosphere fluctuations, or in problems going unno-
ticed or uncontrolled for some time. Probably for these
reasons, CA operators tend to be very conservative in their
desired O^ and CO^ levels, thus forfeiting some of the
potential benefits to the fruit from the CA atmosphere.

To try to improve on CA management in New Eng-
land we have developed a demonstration system at the
Horticultural Research Center, Belchertown, that auto-
mates the CA control procedure. This idea is not new.
Numerous automatic control systems have been devel-
oped in other areas, and some excellent systems are
commercially available.

Our approach was to try to develop a system at
minimal cost to the storage operator, since many New
England storages are small and the operators are short on
investment capital. It is a system using off-the-shelf com-
ponents, in which the storage operator is involved from the
outset in developing a system to meet his or her specific
conditions and needs.

Our system was developed by Katrin Kaminsky, as
part of her M.S. thesis, in cooperation with personnel in the
Department of Food Engineering who have expertise and
experience in control systems and computer technology.
The project was funded by a grant from the Massachusetts
Society for Promoting Agriculture, with supplemental
funding from the Massachusetts Agricultural Experiment
Station.

The system is designed as a working demonstration of
automated sampling and control of a CA atmosphere. It is
in ongoing use at the Horticultural Research Center. To
provide storage operators with ready access to information
about the system, a University of Massachusetts Coopera-
tive Extension Publication has been prepared and is now
available. The publication provides a step-by-step descrip-
tion of the system we have developed, and a complete
listing of supplies and costs that were involved.

The publication, entitled, "A User-built System for
Automated Monitoring and Controlling of CA Apple
Storages," publication C-197, is available from William
Bramlage or Wesley Autio, Department of Plant & Soil
Sciences, Bowditch Hall, University of Massachusetts,
Amherst, MA 01003. We sincerely hope that CA opera-
tors will obtain a copy and carefully evaluate the applica-
tion of this system to their operation. We hope that many
operators will take the appropriate steps to upgrade their
storage operations with the technology that is now in hand.

4: :(: 4:

COOPERATIVE EXTENSION

U. S. DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS

AMHERST. MASSACHUSETTS 01003 0099

OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300

SERIAL SECTION
UNIV. LIBRARY

01003

BULK RATE

POSTAGE & FEES PAID

USDA

PERMIT No G?r)8

TCr

Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension,

United States Department of Agriculture, and Massachusetts Counties Cooperatmg.

Editors: Wesley R. Autio and William J. Bramlage

ISSN 0427-6906

Volume 54, Number 1
WINTER ISSUE, 1989

Table of Contents

Results of the Second Year of
Second-stage Apple IPM Practices

Apple Bruising. II. A "Mechanical Apple"
Measures Fruit Impact During Packing and Transport

Apple Bruising. III. Impact
Bruising Leads to Fruit Rotting

Blueberry Nutrition
Red Fuji is a Promising New Apple Cultivar

Apple Rootstocks for the 1990's

SCIENCES LlBKAtiy

Apple IPM Program: Delivery and Observations m 1988

JAN 17 1989

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POUCY:

All chemical uses suggested in (his publication are contingent upon continued registration. Thesechemicals should be
used in accordance with federal and state laws and regulations. Growers are urged to be familiarwith all current state
regulations. Where trade names are used for identification, no company endorsement or product discrimination is
intended. The University of Massachusetts makes no warranty or guarantee of any kind, expressed or implied,
concerning the use of these products. USER ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY
DAMAGE.

Issued by the University of Massachusetts Coopera/ive Extension, E. B. MacDougaU, Director, in Jiirtherance of the acts of
May 8 and June 30, 19} 4. The University of Massachusetts Cooperative Extension offers equal opportunity in programs and
empicymenL

Results of the Second Year of Second-stage
Apple IPM Practices

Ronald J. Prokopy and Susan A. Johnson
Department of Entomology, University of Massachusetts

In a previous issue ofFniil Notes [53(2) :8- 11], we re-
ported on results in 1987 from the first year of our second-
stage IPM program in commercial orchards. Second-
stage IPM employs behavioral, ecological, and biological
approaches to pest management as a substitute for all
insecticide and miticide treatments after the last spray
against plum curculio in early June. The intent of second-
stage practices is not only to provide an environmentally
safe, cost-effective approach to controlling summer pests
that directly attack apple fruit (apple maggot, codling
moth, summer leafrollcrs) but also to alleviate insecticide
toxicity to beneficial predators/parasites of important fo-
liar pests such as mites, aphids, and Icafminers. Allowing
more natural enemies of foliar pests to flourish reduces the
need for pesticide treatment against foliar pests and
thereby lessens the rate (currently very high) at which
several of these pests are developing resistance to pesti-
cides. To emphasize further this latter goal, a major facet
of second-stage IPM is use during April, May, and early
June of pesticides least likely to be harmful to beneficial
predators and parasites.

In the 1987 second-stage IPM tests, we compared 3
types of non-pesticidal approaches to intercepting apple
maggot flies before files penetrated the orchard interior.
These approaches were: (1) placing synthetic apple odor-
baited sticky red sphere traps every 10 yards in the woods
immediately surrounding a block of apple trees; (2) plac-
ing such spheres every 10 yards on perimeter apple trees
themselves; and (3) spraying perimeter (border row) apple
trees every 3 weeks from late June through August. In all
cases, abandoned apple trees within 100 yards of the or-
chard block perimeter were removed to preclude immi-
gration of codling moths and summer leafrollcrs.

In 1988, we repeated the second and third approaches
in the same blocks as in 1987. The first approach (placing
spheres in woods) failed to control apple maggot flies to an
acceptable level. It was replaced in a different set of blocks
by a treatment that received border row sprays every 3
weeks from late June onward and that also received
releases of mite predators into the block interior. Each of
the 3 approaches used in 1988 was carried out on 6 test
blocks averaging 2 to 4 acres. Each test block was matched
with a nearby block of comparable size that received a
normal amount of spraying during June, July, and August.

Apple Maggot Ffy Interception Traps on
Perimeter Trees

In 1988 we doubled the density of odor-baited sticky
red sphere traps in perimeter apple trees from 1 trap every
10 yards to 1 trap every 5 yards. Results (Table 1) show that
average apple maggot fly captures per block in 1988 were
about 50% greater than captures in 1987 (compare 3201 in
1988 with 2054 in 1987). Non-baited sticky red monitoring
spheres were placed in the interior of each test block and
grower-sprayed block to provide an estimate of maggot fly
populations in the block interior. In 1987, 40% more
maggot flies were caught on monitoring traps in test blocks
than in grower-sprayed blocks. In 1988, only 11% more
were caught in the test blocks than in the grower-sprayed
blocks, reflecting the greater effectiveness of the higher
density of interception traps in 1988. This greater effec-
tiveness is also borne out by the low amount of maggot
injury to fruit in 1988 (0.5% in test blocks vs. 0.2% in
grower-sprayed blocks). In sum, the higher density of
interception traps in 1988 did a very good job of preventing
apple maggot flies from penetrating the block interior.

Fruit injury by all other pests active after mid-June
(codling moth, red-banded leafroller, other leafrollcrs,
scale insects) was essentially the same (no greater than
0.2%) in test and grower-sprayed blocks in both 1987 and
1988. This result demonstrates the effectiveness of remov-
ing apple trees within 100 yards of the orchard perimeter
as a method of preventing movement of codling moths and
summer leafrollcrs into orchards (apple maggot flies move
over much longer distances and are little affected by the
tree removal method).

In both 1987 and 1988, total Amblyseius fallacis and
yellow mite predators were about double in frequency in
the test blocks compared with the grower-sprayed blocks.
In 1988, pest mites in the test blocks were effectively held
in check by predatory mites despite no use of miticide
other than pre-bloom oil. In the grower-sprayed blocks,
where miticide was usually used in addition to oil, there
was a much less favorable pest-to-predator mite ratio. A
similar pattern held true for aphid predators in 1988:
nearly double the frequency in the test blocks. Together,
the results point out the predator-fostering value of com-
plete elimination of insecticide and miticide use after the

Table 1. Effects from using AMF interception traps on perimeter trees.

Avg. no. AMF/block Avg. % fruit injury

by insect pests active

Inter- Interior after mid-June^*

ception monitoring

traps traps AMF CM RBLR Other

Year Block No.

1987 Trapped 6 2054 123

Grower-
sprayed 6 — 84

1.4 0.0 0.1 0.0
0.5 0.0 0.1 0.1

1988 Trapped 6 3201 117 0.5 0.0 0.1 0.0

Grower-
sprayed 6 — 105 0.2 0.0 0.2 0.0

Avg. % leaves (or terminals) infested/block"'*

Ratio of
pest to
ERM predatory

TSM AF YM mites WAA WAL PL LM GAAGAAP

1987 Trapped 6 20 4.0 3.2 2.8:1 2 9 17 10 -
Grower-
sprayed 6 13 1.5 2.3 3.4:1 2 5 10 14 -

1988 Trapped 6 12 1.3 1.2 4.7:1 3 27 3 11 14 6.7
Grower-
sprayed 6 11 1.1 0.1 9.3:1 4 18 2 11 16 3.7

"^500 on-tree fruit/block sampled during July, August, and September.

''AMF = apple maggot fly, CM = codling moth, RBLR = redbanded leaf roller, ERM

= European red mites, TSM = two spotted mites, AF = Amblyseius fallacis, YM =

predatory yellow mites, WAA = woolly apple aphid, WAL= white apple ieafhopper,

PL= potato Ieafhopper, LM= leafminer, GAA= green apple aphid, GAAP= green

apple aphid predators: cecidomyiids and syrphids.

"400 leaves (or terminals) sampled/block during July, August, and September.

last curculio spray in early June.

Woolly aphid and leafminer populations were similar
in abundance (both low) in test and grower-sprayed blocks
in both 1987 and 1988. However, both white apple Ieafhop-
per and potato Ieafhopper populations were greater in the
test blocks than the grower-sprayed blocks each year. This
result causes us concern. It indicates we must consider ap-
plying pesticides specifically against Ieafhopper nymphs in
test blocks in early- or mid-June.

We are most encouraged by the results of using apple
maggot Oy traps on perimeter apple trees. No grower will
want to hang hundreds of sticky spheres around his or-

chard each year and clean the spheres of maggot flies ev-
ery month or so. We have in mind a substitute plan
whereby a grower might purchase several hundred larger
spheres (5 to 6 inches or so in diameter) which could be
more attractive than the current 3-inch spheres. These
larger spheres could be hung in a permanent position on
perimeter trees for perhaps 10 years. Only tree pruning
would necessitate repositioning. In July, each sphere
would be sprayed with or dipped in a solution containing a
long-residual pesticide, a feeding stimulant for arriving
maggot flies, and an agent that would greatly lengthen
pesticide residual activity. Odor attractants would be

affixed on a nearby twig. Under this plan, there would be
no sticky and there would be minimal handling of the
spheres. We are trying to obtain grant funds to pursue this
idea.

Bonier Row Sprees Without Predator Releases

As in 1987, test blocks in 1988 received a spray of

Guthion™ or Imidan™ applied only to perimeter apple
trees every 3 weeks from mid-June through August. The
interior of the block remained free of insecticide or miti-
cide during this time.

As shown m Table 2, in both 1987 and 1988, there was
little fruit mjury caused by apple maggots, codling moths,
summer leafrollers, or other insects active after mid-June
in either border-row-sprayed blocks or the fully-sprayed

Table 2. Effects of applying border row sprays without mite predator releases in apple
orchard blocks.

Avg. % fru

it injury

Avg. no. AMF

by insect

pests

on interior
monitoring

active after m

id-June^''

Year

Block

No.

traps

AMF

RBLR

Other

1987

Brd-row-

sprayed

104

0.6

0.1

0.2

Fully-

sprayed

0.8

0.1

1988

Brd-row-

sprayed

101

0.3

0.1

Fully-

sprayed

0.2

Avg. % leaves (or terminals) infested/block'''*

Ratio of
pest to
ERM predatory

TSM AF YM mites WAA WAL PL LM GAA GAAP

1987 Brd-row-

sprayed 6 24 1.2 0.1 19:1
Fully-
sprayed 6 16 0.3 48:1

1988 Brd-row-

sprayed 5* 12 0.1 0.1 61:1
Fully-
sprayed 5 9 0.5 0.1 16:1

10.7

8.2

^500 on-tree fruit/block sampled during July, August, and September.

''AMF = apple maggot fly, CM = codling moth, RBLR = redbanded leaf roller, ERM

= European red mites, TSM = two spotted mites, AF = Amblyseius fallacis, YM =

predatory yellow mites, WAA = woolly apple aphid, WAL= white apple leafhopper,

PL= potato leafhopper, LM= leafminer, GAA= green apple aphid, GAAP= green

apple aphid predators: cecidomyiids and syrphids.

"400 leaves (or terminals) sampled/block during July, August, and September.

"Owing to a mistake on our part, data on foliar pests in one orchard had to be omitted.

blocks. This result demonstrates the effectiveness of bor-
der row sprays in preventing penetration of these fruit-in-
juring pests into the block interior.

Unfortunately, mite predators were low in frequency
in border-row-sprayed blocks in 1988, as they were in 1987.
Indeed, in neither year in neither type of block was the

ratio of leaves with predators to leaves with pest mites
better than 1 to 15. This result suggests a very low proba-
bility of achieving effective biological control via buildup of
predatory mites in border-row-sprayed blocks (assuming
the 6 blocks in which our tests were conducted are repre-
sentative). From recent work in our department on the in-

Table 3. Effects from using border row sprays with mite predators releases.

Year Block No.

Avg. no. AMF

on interior

monitoring

traps

Avg. % fruit injury

by insect pests

active after mid-June'*

AMF CM RBLR Other

1988 Brd-row-

sprayed 6
Fully-
sprayed 6

135 0.4 0.1

104 0.2 0.1

Avg. % leaves (or terminals) infested/block'''

Ratio of
pest to
ERM predatory

TSM AF YM mites WAA WAL PL LM GAA GAAP

1988 Brd-row-

sprayed 6 25 2.2

0.6 9.0:1

20 3

23 9

3.0

Fully-

sprayed 6 20 2.5

1.6 4.9:1

20 2

21 6

1.8

Avg. % leaves/

Avg. no.

orchard with

Tree predators released

trees

sampled under these trees

per orchard

ERM&TSM

July Yes

5.5

0.3

3.1

0.2

August Yes

4.5

1.2

3.1

0.8

September Yes

1.4

0.3

1.1

0.6

^500 on-tree fruit/block sampled during July, August, and September.
>'AMF = apple maggot fly, CM = codling moth, RBLR = redbanded leaf roller, ERM =
European red mites, TSM = two spotted mites, AF = Amblyseius fallacis, YM = predatory
yellow mites, WAA = woolly apple aphid, WAL= white apple leafhopper, PL= potato
leafhopper, LM= leafminer, GAA= green apple aphid, GAAP= green apple aphid preda-
tors: cecidomyiids and syrphids.
"400 leaves (or terminals) sampled/block during July, August, and September.

fluence of ground cover and orchard border area compo-
sition on mite predator abundance, it appears that a sub-
stantial number of predatory mites may be wind-blown
into orchards from plants surrounding the orchard. Possi-
bly such predators are being killed as they contact the
sprayed border row apple trees. Further work is planned
to evaluate this possibility.

All other foliage-injuring pests (woolly aphids, leaf-
hoppers, leafminers) were fairly low in abundance in both
1987 and 1988 in both border-row sprayed blocks and fully-
sprayed blocks.

In sum, we are pleased with the results of the border-
row spray program in virtually every respect except the
failure of predatory mites to build to effective numbers.

Border Row Sprees With Predator Releases

In 1988 6 bordcr-row-sprayed blocks and 6 fully-
sprayed blocks were established in which Amblyseiusfalla-
cis mite predators were released at the rate of 500 to 1000
predator eggs, nymphs, or adults under each of 6 to 7 trees
per block (every 4th tree of the block interior) in July.

As in the border-row-sprayed blocks without mite
predator releases, there was little difference between
border-row sprayed and fully-sprayed blocks in the
amount of fruit injury by apple maggots, codling moths, or
summer leafrollers or in populations of woolly aphids,
leafhoppers, or leafminers (Table 3).

Of prime interest is the result of the mite predator re-
leases. Amblyseius fallacis were about equally abundant in
both the border-row-sprayed and the fully-sprayed blocks
and were far more abundant in both than in comparable
blocks (Table 2) where no predators were released. The
released predators had genotypes largely resistant to
Guthion and Imidan. This situation may explain the much
greater abundance of this species in the blocks where they
were released than in border-row-sprayed and fully-
sprayed blocks where they were not released. These
results are encouraging in terms of released predator sur-
vival during summer in sprayed blocks. We collected data
in each block on the abundance of pest mites and Ambly-
seius fallacis on trees where the latter were released vs. im-
mediately adjacent trees where they were not released.

These data (Table 3) suggest that the numbers of released
predators were too few to have affected populations of pest
mites on the trees and that released predators were rather
slow to move away from the trees under which they were
released. This result suggests that in the future, much
greater numbers of predator mites should be released on
a greater proportion of trees in the orchard if such releases
are to provide meaningful biological control of mites.

Conclusion

In conclusion, we are highly encouraged by most of the
results of these past 2 years of second-stage IPM experi-
mentation. We have a few "bugs" to iron out to render the
second-stage approach more cost-effective and labor-
appealing (especially development of a system to replace
sticky as a method of killing apple maggot flies that arrive
on spheres). Presently, we see 2 alternative routes to
achieving potential second-stage IPM success on a practi-
cal level: (1) no insecticide or miticide used after early
June, employing baited, pesticide-treated, non-sticky
spheres around the orchard perimeter to intercept and kill
apple maggot flies, removing all apple trees within 100
yards or so of the orchard perimeter, and allowing mite and
aphid predators to immigrate into and build up in such
blocks in a pesticide-free atmosphere; or (2) using border
row sprays as a substitute for employing maggot fly spheres
and releasing very large numbers of pesticide-resistant
mite predators (possibly on an annual basis) on a high pro-
portion of trees.

Acknowledgements

We thank the Massachusetts Society for the Promo-
tion of Agriculture, the USDA Israel Binational Agricul-
tural Research and Development Fund (BARD) under
grant US-807-84, and the Northeast Regional Project on
Integrated Management of Apple Pests (NE-156) for sup-
porting our work on second-stage apple IPM. Special
thanks to Betsy Frederick, Esther Ruiz, Phuong Nguyen,
and Joseph Shepherd, who worked on the 1988 studies.
Bill Coli, Kathleen Leahy, and Bill Pyne also participated
in this program.

>t» kX* •!» •S« ^«

«{* «^ rg» ^» 0fm

Apple Bruising. II. A "Mechanical Apple"
Measures Fruit Impact During Packing
and Transport

William J, Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

A series of recent reports from Michigan State Uni-
versity describe results of an intense study of causes of
apple bruising. This research was cooperative between
personnel of the U.S. Dept. of Agriculture, Agriculture
Research Service, and the Agricultural Engineering De-
partment at Michigan State University. In the previous
article [Fruit Notes 53(4):15-17], we summarized their
study of bruising of Golden Delicious apples on commer-
cial grading and packing lines. Here we shall describe a
companion study of this situation that gives new insight
into the problems.

This study was reported in a paper entitled, "Bruising
Impact Data Acquisition and Analysis in Apple Packing
and Handling Systems, Utilizing the Instrument Sphere
(IS)." The paper was presented to the American Society
of Agricultural Engineers on June 26-29, 1988, by B. R.
Tennes, H. R. 2Lapp, D. E. Marshall, and P. R. Armstrong.

The "Instrument Sphere" used in this study is an
ingenious device designed to simulate an apple and to
record impacts it experiences as it passes through typical
commercial operations. It is the size of an apple and is a
battery-powered computer that senses impacts and rec-
ords them over times.

This device was passed 3 times through 5 different
packing lines along with the apples being graded on those
lines. Results are summarized in Figure 1, in which
maximum acceleration on any run is shown at 19 positions
on a generic packing Une.

As acceleration increases above about 50 g's, the risk
of apple bruising increases. In Figure 1 it can be seen that
high acceleration rates (rates of impact) occurred at many
points, especially from the initial water dumping through
the singulator after waxing, and in the automatic bagging
operation. These results generally substantiate the visually

^tti^

*^^

M-Q

1. WATER DUMPER = 67 g's

2. SUBMERSION TANK = 58 g's

3. UNDERSIZE ELIMINATOR = 73 g's

4. INSPECTION ROLLERS = 68 g's

5. WASHER/WAXER = 73 g's

6. DRYER TUNNEL = 130 g's

7. SINGULATOR = 54 g's

8. SIZER DROPOUT = 40 g's

9. TWO WAY CONVEYOR = 22 g's
lO.BAGGER AUGERS = 51 g's

< 1 J

1 1. WEIGH PANS = 48 g's

12. CONVEYOR TRANSFER = 29 g's

13. BAG CLOSER MECH. = 34 g's

14. CONVEYOR = 43 G

15. TRAY PACKS -25 g's

16. AUTOMATIC BAGGER = 120 g's

17. JUMBO PACK =34 g's

18. PACKING TABLE = 14 g's

19. BOX ONTO PALLET

20. PUT INTO BOX - 58 e's

Figure 1. A schematic drawing of a generic apple packing line, with points of fruit transfer nimibered
consecutively from input to the water dumper (1) to putting bags into cartons (20). The maximum acceleration
(g's) of the Instrument sphere is shown at each transfer point during 3 runs on each of 5 different packing lines.

determined bruising of Golden Delicious apples during
grading and packing that we described earlier.

The bagging operation is a point of special concern,
since it causes so much impact bruising. The high impacts
(Figure 1) resulted from bags being dropped onto a con-
veyor in front of the closing machine, the snapping action
of the bag-dosing mechanism, the transfer points on the
conveyors leading, and the hand placing of bags into
shipping cartons.

Much of this impact bruising during bagging can be
eliminated. The authors clearly showed this when they
placed a piece of shag carpet (facing up) between a
conveyor belt, onto which the bagged apples fell, and its
steel backing. The Instrument Sphere was dropped differ-
ent distances onto the belt, with and without the carpet
backing, and the padding reduced impact of the instrument
by nearly 75%.

Instrument Spheres were also used in a transportation
study. They were placed in the top tray of a tray-pack
carton, and into 3-lb. bags in a carton. The cartons were

transported from the packing house to a distribution
center, and then to a retailer, by a commercial semi-trailer.
As the trailer peissed over bridges under repair, impacts
were 3-times greater (54 vs. 17 g's) in the trays than in the
bags. Apparently, the tight fit in the bags provides protec-
tion to the fruit during rough transit. Note, however, that
velocities of these impacts during transport were much
lower than many of those experienced by apples on the
grading line (Figure 1).

The Instrument Sphere developed by these research-
ers appears to have much value in assessing the sources of
impact bruising on harvested fruit. This particular study
re-emphasizes the high potential for bruising apples dur-
ing the mechanical grading and packing processes, and the
fact that much of this bruising need not occur. We urge
readers to review the causes of fruit damaged outlined in
the previous article evaluate their own packing lines for
sources of impact bruising, and take corrective actions.
Bruising is preventable .

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Apple Bruising. III. Impact Bruising
Leads to Fruit Rotting

William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

In previous articles [Fruit Notes 53(4):15-17 and this
issue pp. 6-7], we have examined findings on sources of
bruising to apples from studies conducted at Michigan
State University. Here, we shall use their findings to show

a consequence of this bruising fruit rotting after

packaging.

This study was reported by C. L. Burton, Nancy L.
Schulte Pason, G. K. Brown, and E. J. Timm in a paper
entitled, "The Effect of Impact Bruising on Apples and
Subsequent Decay Development," presented to the
American Society of Agricultural Engineers on December
15-18, 1987. The authors are researchers in the Agricul-
tural Engineering Department and the U.S. Department
of Agriculture, Agricultural Research Service, at Michigan
State University, East Lansing.

Blue mold, caused by Penicillium expansum Lk. ex
Thorn, is responsible for 80 to 95% of the rotting of apples
that is seen in commercial markets in the U.S. Contami-
nation with spores of this fungus can occur in the orchard,

but most of it probably arises in the packing house, espe-
cially in water dumps and on grading and packing equip-
ment. Fruit contaminated during these operations may rot
quickly if the spores are able to penetrate the fruit surface.
Earlier studies showed that bruises can allow this penetra-
tion even though the skin is not broken. The study
reported here was conducted to see how blue mold rotting
related to impact bruising on apples. The authors con-
ducted a series of laboratory tests using Mcintosh, Deli-
cious, and Golden Delicious apples that were bruised on
surfaces contaminated with blue mold spores.

Fruit were carefully picked and handled so as to
minimize pre-storage injury, stored at 34°F for 0, 2, or 4
months, and warmed to room temperature before bruis-
ing. They were bruised by being dropped onto a steel plate
from different heights, which caused impact bruising of
different severities. The surface of the steel plate was
covered with blue mold spores to inoculate fruit as they
impacted on it. Following bruising, the apples were kept in

Table 1
bruise

. Effects
diameter

f drop height OB
on Mcintosh,

I average
Golden

Delicious, and Delicious apples after 0, 2,
or 4 months of storage at 34°F.

Drop

height

(cm)

Average

bruise diameter (mm)

months

in storage

Avg.

100

Avg.

moist plastic containers at 75°F for 5 to 7 days and then
inspected for rots.

Increasing drop height increased the average size of
impact bruises (Table 1). However, bruising was not
increased by storage time, even though the apples softened
during storage. Also, cultivar did not greatly influence
bruise size from a fall of a given height, so the data in Table
1 are the average values for the 3 cultivars.

Bruising greatly affected the amount of rotting that
occurred on these apples, as shown in Figure 1. Bruising
at harvest (0 months of storage) resulted in very little rot,
regju^dless of bruise size or cultivar. However, after 2 or 4
months of storage, bruising led to much rotting, and the
amount was greater for the apples stored for a longer time
before bruising.

Rotting increased as drop height (and bruise size.
Table 1) increased. A given drop height caused much
more rotting of Golden Delicious than of the other culti-
vars, and more on Mcintosh than on Red Delicious, even
though bruise size from a fall of a given height was about
the same for all 3 cultivars.

Since damage to the fruit from a given impact did not
increase with storage time, but subsequent rotting in-
creased greatly (Figure 1), the difference must be due to
ripening changes inside the fruit. It is well known that as

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60-
40-
20

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20 40 60 80 100

Impact drop height (cm)

Figure 1. Percent blue mold rotting that developed on 3 cultivars of apples dropped different heights onto a con-
tammated metal plate after 0, 2, or 4 months of storage at 34°F. After bruising, the apples were kept in a moist
environment for 5 to 7 days at 75°F.

they ripen, fruit lose their ability to fight-off invading
pathogens. Bruising, then, must in some way help the
fungus enter the fruit, and then advancing ripeness allows
that fungus to more easily rot the apples. Figure 1 shows
dramatically how the consequences of bruising worsen as
the bruising occurs on progressively riper fruit.

In earlier articles [Fruit Notes 53(4):15-17 and this
issue pp. 6-7], results of packing-line studies of bruising
were reported. In the study reported here, the authors
projected the amount of rot that likely would result from
the bruising incurred by Golden Delicious apples passing
through commercial packing lines.

They conclude that bruising of ripe apples on a con-
taminated packing line (and they all are contaminated)
would directly lead to 4 to 8% of the tray-packed apples
rotting within 5 days at 75°F, and that less ripe apples and

cultivars other than Golden Delicious probably would not
rot as badly. However, the projections of the authors show
what can happen and may help explain why some lots of
apples are rejected because of excessive rotting. Clearly,
bruising during the grading and packing operations can
lead to substantial rotting as well as to the direct quality
loss caused by appearance of the bruises themselves.

In their earlier studies [Fruit Notes 53(4):15-17 and
this issue pp. 6-7], the authors showed that much of this
bruising is preventable, and they described what packing-
line operators should be looking for, and gave some
suggestions for alleviating the problem.

The results described here also re-emphasize the
importance of practices to reduce build-up of fungal
spores on and around fruit. A recent article [Fruit Notes
53(3):15-16] examined this problem and offered sugges-
tions for controlling apple rotting.

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Blueberry Nutrition

Dominic A. Marini

University of Massachusetts Cooperative Extension, Hanson, MA

For high yields, blueberry bushes must be vigorous,
making at least 12 to 18 inches of new growth per year. The
most productive shoots are those with 15 to 20 leaves. Low
vigor can be the result of improper or no pruning, dry or
wet soil conditions, incorrect soil pH, or lack of nutrients.

Pruning must be done annually in late winter or early
spring. Mulching with sawdust or wood chips is ideal for
conserving soil moisture and preventing drought stress.
Many growers, particularly on light, sandy soils, are using
trickle irrigation to supply moisture during drought peri-
ods. Wet soil conditions can be corrected by soil drainage

m some cases.

Soil Acidity

Blueberries require an acid soil, the ideal pH being
between 4.5 and 5.5. If the pH is below 4.5, dolomitic or
high magnesium limestone should be applied to raise the
pH, while sulfur may be used to lower the pH. In addition,
fertilizers having an acid reaction should be used, such as
most complete fertilizers (10-10-10, etc.), ammonium
sulphate, and ammonium nitrate. Do not use fertilizers
having an alkaline reaction, such as sodium nitrate, cal-
cium nitrate, cyanamide, bone meal, and wood ashes,
unless the pH is 4.6 or lower.

Nutrients

It is generally agreed that nitrogen is the most impor-
tant of the major elements required by blueberries, the

ammonium form being preferred to the nitrate form.
Little or no response has been observed to phosphorus or
potassium applications although one Massachusetts
grower reports improved growth and production from
application of superphosphate. In the field, the only
deficiency symptoms observed are those of nitrogen, iron,
and magnesium. Symptoms of nitrogen deficiency include
stunted growth, yellowing, and, under severe deficiency,
reddening of older leaves. Iron deficiency appears on the
new growth with the leaves becoming bright yellow, while
magnesium deficiency usually becomes apparent at har-
vest as yellowing between the veins and of leaf margins of
older leaves while veins remain green. Both iron and
magnesium deficiencies are usually corrected by adjusting
pH to the optimum range. Environmental factors that can
be confused with nutrient deficiency symptoms include
drought stress, poor drainage, cool weather during the
growing season, insect or disease injury, fertilizer burn,
and injury from pesticides and herbicides. Therefore, a
soil test or leaf tissue analysis is advisable if a nutrient
deficiency is suspected. Soil samples should be taken in the
fall while leaf samples should be taken from July 15 to
August 15.

Fertilizer is usually applied in a ring around the bush
or in broad bands on both sides of the row. On newly-set,
young bushes a 6-inch ring around the bush 12 inches from
the crown is recommended when new growth starts. A
second application may be made in late June or early July
and a third in late November before the ground freezes.

On newly set plants the recommended amount of

fertilizer is 1 ounce of 10-10-10 or its equivalent. This
amount may be doubled each year to a maximum of 1
pound per bush at 5 years. Bushes low in vigor may be
fertilized again with 1/2 pound in late November. Fertil-
izer rates may be increased up to twice the recommended
amount where bushes are heavily mulched. Higher rates
are needed on sandy soils since nitrogen leaches readily.

especially in the nitrate form. Lower rates at frequent
intervals help to minimize leaching. Fertilizers containing
muriate of potash (potassium chloride) are not advisable
since the chlorine may be injurious, particularly to young
bushes. Well rotted manures may be applied in late fall or
early sprmg using half as much poultry as cow or horse
manure.

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Red Fuji is a Promising New Apple Cultivar

Duane W. Greene and Wesley R. Autio

Department of Plant & Soil Sciences, University of Massachusetts

There is increasing interest on a world-wide basis in
identifying and evaluating new apple cultivars. Significant
shifts are occurring, particularly in places such as The
Netherlands, New Zealand, China, and Japan, from the
traditional cultivars toward those that have better taste and
storage characteristics. Of the new cultivars, one of the
most promising is Fuji, a cross between Ralls Janet and
DeHcious. It is a medium-sized apple that is green with a
dull pink or red stripe or blush over a yellow-green ground
color. Red strains show considerably more, but not out-
standing, red color. The flesh is yellowish green, dense,
crisp, and sweet. Fuji is a high quality apple! Several red
coloring strains have been identified, and they are sold by
various nurseries. It is the most popular apple in Japan,
where 44 % of the production is Fuji (including its red
coloring strains). It is the most widely planted cultivar in
China and the most talked-about apple in California.
Growers in the Pacific Northwest also are giving Fuji
considerable attention.

At the University of Massachusetts Horticultural
Research Center, Belchertown, we propagated and
planted a strain of Red Fuji obtained from Roger Way at
the New York Agricultural Experiment Station in Geneva.
The first fruit from these trees were harvested this fall.
Here we report briefly on the first year's results with this
strain of Red Fuji.

Tree Characteristics

Fuji is a moderate- to high-vigor, non-spur tree. It is
easily trained to a central leader, and has scaffold branches
that appear to require no spreading. The tree may have
some bUnd wood at the base of 2-year-old wood, similar to
that of nonspur Delicious (one of its parents). It blooms
mid- to late-season. It is a diploid amd thus should have
viable pollen capable of pollinating other cultivars bloom-
ing in the same season. In 1988 it set more fruit in our
planting than similar Marshall Mcintosh trees. Because it

blooms and sets fruit at an early age, control of growth in
the orchard should not be difficult. Reports from else-
where suggest that it is susceptible to fire blight but may
have some resistance to apple scab.

Fruit Characteristics

Harvests of Red Fuji were made on October 20 and 24,
1988. At this time seeds were brown, and severe watercore
had developed in some fruit. Consequently, we feel that
the fruit could have been harvested some time prior to
October 20. Harvest was delayed because of the persis-
tence of a dark-green ground color. Fruit weight averaged
about 7 ounces. Because the trees are young, one could
expect fruit size on older trees to be smaller. Flesh
firmness was 18.5 pounds. Soluble solids (sugar) was over
15%, which is the highest that we have recorded for any
cultivar evaluated at the Horticultural Research Center.
The taste was sweet, fruity, slightly aromatic, subacid, and
pleasant. The fruit surface was slightly rough with raised
lenticels. The overall exterior appearance was very similar
to a well-colored Baldwin. We would rate the overall
quality of Red Fuji to be good but not exceptional. How-
ever, it is reported that Fuji does not produce a high quality
fruit on young trees. Fruit is now in air storage for periodic
evaluation of its storage potential.

We believe that Red Fuji is worthy of trial in Massa-
chusetts. Anyone who can mature Rome should be able to
mature Fuji. Based upon reports from other parts of the
country and from Australia, we believe that fruit color and
possibly taste of Fuji grown in Massachusetts may be as
good as, if not superior to, those fruit grown in other
regions. If the potential for Fuji is greater than that for
Granny Smith, as some have suggested, then Red Fuji is a
cultivar that growers in Massachusetts should be watching
very carefully.

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Apple Rootstocks for the 1990's

Wesley R. Autio and Duane W. Greene

Department of Plant & Soil Sciences, University of Massachusetts

The ideal apple tree is determined by fitting the
rootstock with the cultivar, site, training system, and the
orchardist's perception of what makes a good tree. The
introduction of a number of new rootstocks presents fruit
growers with many options for the future. Many of these
rootstocks are not tested, although research is being
conducted around the world to evaluate them. The
purpose of this article is to report on the results of 2 NC-
140 Rootstock Research Committee plantings in
Massachusetts that contain some of the most promising

new rootstocks.

The most thorough and extensive evaluation of
rootstocks in North America is carried out through the
NC-140 Rootstock Research Committee. This committee
is a group of approximately 50 pomologists from the U.S.
and Canada. Each year the group meets to share data and
observations on present plantings and to plan future,
cooperative, uniform plantings. At present 2 apple
rootstock plantings are in the ground, and 2 new plantings
are scheduled for 1990. The oldest of the two plantings was

Table 1. Trunk circumference

yield, yield efficiency.

and fruit we

ght of Starkspur Supreme

DeUcious on various rootstocks planted in

1980 and 1981

Cumulative

yields and yield efficiencies

represent data from 1983 and 1984 through 1988 for the 1980 and 1981 plantings, respectively.

Yield efficiency

Trunk
circumference

Yield per tree (bu)

(kg/

cm^)

Fruit

* 1_*

weight

Rootstock

(in)

1988

Cumulative

1988

Cumulative

(oz)

1980 Planting:

Ott.3

8.1 be'

1.2 be

7.6 b

0.68 a

4.15 be

8.0 ab

M.7 EMLA

11.9a

3.6 a

12.5 a

0.95 a

3.27 c

7.1 be

M.9 EMLA

6.4 cd

1.0 be

6.0 be

0.83 a

5.32 a

8.5 ab

M.26 EMLA

9.3 b

1.8 b

8.9 b

0.76 a

3.80 be

8.1 ab

M.27 EMLA

3.5 e

0.3 c

1.4 d

0.68 a

3.95 be

7.4 abc

M.9

4.7 de

0.3 c

2.6 cd

0.47 a

4.23 abc

7.9 ab

MAC 9

8.4 b

1.0 be

9.0 ab

0.49 a

4.54 ab

9.1a

OARl

9.6 b

1.2 be

3.8 cd

0.46 a

1.51 d

5.8 c

1981 Planting:

Ott.3

7.2 bed

1.5 ab

6.8 ab

1.15 abc

4.73 ab

8.4 ab

M.7 EMLA

9.9 a

2.1a

7.6 a

0.81 abc

2.85 cd

7.8 ab

M.9 EMLA

6.4 cd

1.6 ab

6.1 abc

1.45 a

5.38 a

8.5 ab

M.26 EMLA

8.3 abc

2.3 a

7.5 a

1.22 ab

3.98 abc

7.9 ab

M.27 EMLA

5.2 e

0.2 c

0.8 d

1.14 abc

3.45 be

7.2 ab

M.9

6.8 d

0.4 be

3.0 cd

0.48 be

3.93 abc

8.7 ab

MAC 9

6.8 cd

0.4 be

5.3 abc

0.33 c

4.15 abc

9.6 a

OARl

9.0 ab

1.4 abc

3.4 bed

0.61 be

1.49 d

6.5 b

'Means within

plantings and columns not

followed by the same letter are significantly

different

at odds of 19 to 1.

established at 27 locations in 1980 and 1981 and includes
Starkspur Supreme Delicious on M.7 EMLA, M.9 EMLA,
M.26 EMLA, M.27 EMLA, M.9, OAR 1, Ottawa 3, and
MAC 9 (the virus-indexed version of which is now being
sold as "Mark"). This planting was established as a
randomized complete block with 10 replications. Trees in
half of the replications (those planted in 1981) were staked
at planting, while trees in the other half (those planted in
1980) were staked only when they leaned more than 45°
from vertical. Each year the height, spread, trunk
circumference, and yield from each tree is measured.

The younger NC-140 planting was established in 1984
and includes Starkspur Supreme Delicious on Bud.9,
Bud.490, P.l, P.2, P.16, P.18, P.22, MAC 1, MAC 39, CG-
10, CG-24, M.4, M.7 EMLA, M.26 EMLA, C.6, Ant.313,
and domestic seedling in a randomized complete block
design with 10 replications. Trees have been staked only
when they have leaned more than 45° from vertical.

Table 1 presents the trunk circumference and yield
data from the 1980 and 1981 plantings. The discussion
here will focus on the 3 most interesting rootstocks in the
1980/81 planting: M.9 EMLA, Ott.3, and MAC 9 (Mark).

The EMLA designation refers to those rootstocks
derived from clones which have had the latent viruses
removed. They were developed by a cooperative effort of
the East Mailing and Long Ashton Research Stations in
England. In general, the EMLA series rootstocks are very
similar to the rootstock from which they were derived, e.g..

M.7 EMLA is very similar to M.7 or M.7A. In some cases
vigor may be slightly greater for the EMLA version;
however, M.9 EMLA is considerably more vigorous and
productive that M.9 (Figure 1). M.9 EMLA actually was
derived from a different strain of M.9 than we commonly
use. The trunk circumference after the 1988 growing
season of trees on M.9 EMLA was 28% greater than those
on M.9. The 1988 yield per tree was 308% larger, and the
cumulative yield per tree from 1983 through 1988 was
118% greater. Another way to look at yield is in terms of
yield efficiency (Table 1), which is given as yield per unit of
trunk cross-sectional area. This term accurately relates
tree size and yield per tree and allows a comparison of
potential productivity. On a cumulative basis through 1988
the trees on M.9 EMLA were 30% more yield efficient
than those on M.9.

In general, M.9 EMLA may result in a tree which is
too vigorous for a trellis; however, trees on M.9 EMLA
may be a superior tree on a post trained to a slender spindle
or a similar system. It is necessary to consider cultivar
when choosing between M.9 and M.9 EMLA and among
the various training systems. These observations are based
primarily on a low-vigor cultivar: Starkspur Supreme
Delicious. With a vigorous scion M.9 may produce an
excellent posted tree, and M.9 EMLA may result in a tree
too large for a high density planting. With a low-vigor
cultivar the vigor induced by M.9 EMLA may be necessary
to allow the development of even an adequate trellised

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Figure 1. Starkspur Supreme Delicious on M.9 EMLA (left) and M.9 (right) after 8 growing seasons (1981
planting).

tree.

Ottawa 3 (Figure 2) is a hardy rootstock which may
hold a great deal of promise. It results in a tree similar in
size to M.26 EMLA with a similar yielding potential. On
a cumulative basis through 1988 the yield efficiency (Table

Figure 2. Starkspur Supreme Delicious on Ott.3
after 9 growing seasons (1980 planting).

1) of trees on Ott.3 was second only to those on M.9
EMLA. Trees on Ottawa 3 appear to be sUghtly better
anchored than those on M.26 EMLA but in most cases will
require support. Ripening studies (data not shown)
suggest that Ott.3 may advance ripenmg.

MAC 9 (Mark) (Figure 3) is probably the most
interesting rootstock in the study. Tree size after the 1988
growing season was similar to that of trees on M.26 and
Ott.3 (Table 1), and it has been one of the most productive
trees in the planting. On a cumulative basis through 1988
trees on MAC 9 were 12% more yield efficient than trees
on M.26 EMLA. An inherently high level of precocity can
be a problem with MAC 9, especially with weak cultivars.
Excessive fruiting can result in very little growth and
"runting out" of the trees. Once growth has stopped due
to excessive cropping it is difficult to get trees to grow
again. Because of the limits of the uniform planting we did
not thin the fruit in 1987 when the crop was excessive, thus
fruit size and growth were reduced significantly in 1987 and
the crop was very light in 1988. Trees on MAC 9 (Mark)
in a commercial planting must be thinned early in their life
to maintain good growth and fruit size. Our observations
suggest that MAC 9 is only somewhat better anchored than
M.26 EMLA, so we feel that in most cases it will benefit
from support, at least during the first 5 years in the ground
when tree structure is being estabUshed. Ripening studies
(data not shown) suggest that MAC 9 delays ripening,
which may be a very useful tool for expanding the harvest

Figure 3. Starkspur Supreme DeUcious on MAC 9 (Mark) (left) and M.26 EMLA (right) after 8 growing
seasons (1981 planting).

season of a single cultivar in commercial settings.

The 1984 NC-140 planting is at this time too young to
make any accurate statement about specific rootstocks.
However, data on tree size and yield are presented in Table
2, and this information can be used to get some idea of the
basic relationships among these rootstocks. After the 1988
growing season the smallest trees were on P. 16 and P.22,
and the largest were on P.18, CG-10, Ant.313, and
domestic seedling. On a cumulative basis the most
efficient trees were on P.2, P.16, Bud.9, C.6, and P.22. The
rootstocks with the most promise are Bud.9, P.2, and C.6.
All are between M.9 and M.26 in their size controlling
properties, and all trees on these rootstocks will need
support. Representative trees on these rootstocks are
pictured in Figures 4, 5, and 6. We will be observing this
planting for the next 5 years to see where some of these new
rootstocks might fit into our production systems.

The next plantings of the NC-140 Rootstock Research
Committee are scheduled for 1990. One planting will look
at the interaction of rootstock and training system and the
second will study the interaction of rootstock and cultivar.
In the rootstock/cultivar planting we are trying to
eliminate the problem of evaluating a rootstock based

1 ^^'**«!
1

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■§:

Figure 4. Starkspur Supreme Delicious on Bud.9

after 5 growing seasons (1984 planting).

Table 2. Suckering, trunk circumference.

yield, yield efficiency, and fruit weight of Starkspur Supreme

Delicious on various rootstocks

planted in

1984. Cumulative yields anc

yield efficiencies represent data |

from 1987 through

1988.

Root

Yield efficiency

suckers

Trunk

Yield per

tree (bu)

(kg/cmO

Fruit
weight

per tree circumierence

Rootstock

(1984-88)

(in)

1988

Cumulative

1988

Cumulative

(oz)

Bud.9

0.0 c

4.7 efg

0.8 abc

1.2 abc

1.31 ab

2.04 ab

7.1 abc

MACl

3.9 abc

7.2 be

0.4 def

0.5 f

0.28 f

0.32 d

7.3 abc

MAC 39

0.0 c

4.7 efg

0.7bcde

0.8 cdef

1.08 abed

1.34 be

8.2 a

P.l

0.7 be

6.8 bed

1.1a

1.6 a

0.91 cd

1.31 be

7.7 ab

P.22

0.7 be

3.0 h

0.3 f

0.5 ef

1.02 bed

1.98 ab

6.8 be

Seedling

7.0 abc

8.4 ab

0.5 cdef

0.6 ef

0.25 f

0.31 d

7.1 abc

CG-10

9.2 a

8.1 ab

0.4 ef

0.4 f

0.28 f

0.34 d

7.2 abc

CG-24

3.9 abc

7.2 be

0.5 cdef

0.6 def

0.39 ef

0.44 d

6.8 be

M.4

0.8 be

7.2 be

0.6bcdef

0.8 cdef

0.48 ef

0.62 cd

7.1 abc

M.7 EMLA

0.4 be

6.3 cde

0.8 abc

1.1 abed

0.74 de

0.%cd

7.5 abc

M.26 EMLA

3.3 abc

5.3 def

0.8 abed

l.Obcde

1.00 bed

1.37 be

7.7 ab

Bud.490

1.0 abc

7.5 abc

0.7bcde

0.8 cdef

0.46 ef

0.55 d

7.6 ab

P.2

0.0 c

4.1 fgh

0.7bcde

l.Obcde

1.53 a

2.18 a

7.0 abc

P.16

0.6 be

3.4 gh

0.3 ef

0.6 ef

1.21 abc

2.20 a

6.3 c

P.18

0.8 abc

8.1 ab

0.7bcde

0.8 cdef

0.38 ef

0.46 d

7.9 ab

C.6

0.5 be

5.3 def

0.9 ab

1.4 ab

1.15 abc

1.83 ab

8.3 a

Ant.313

7.3 ab

8.4 ab

0.6bcdef

0.8 cdef

0.37 ef

0.48 d

7.7 ab

'Means within columns not followed by the same letter are significantly

different at odds of 19 to 1.

'•^^J:^r%^^"-~

Figure 5. Starkspur Supreme Delicious on P.2
after 5 growing seasons (1984 planting).

solely on data from one cultivar. It will contain 4 cultivars
(Golden Delicious, Jonagold, Empire, and Law Rome)
and 5 rootstocks (M.26 EMLA, M.9 EMLA, Mark, Ott.3,
and Bud.9) at ail cooperator locations. Cultivars to be
planted at some locations include Marshall Mcintosh,
Stayman, Red Yorking, Liberty, Jonathan, Chieftain,
Mutsu, Gala, and Granny Smith. Rootstocks which will be
planted at some locations include P.22 and M.27 EMLA.
With this planting we hope to evaluate cultivars of different
basic growth types on the most promising rootstocks to
give a better idea of how these rootstocks will perform.

Proper selection of a rootstock will be a significant
factor in apple production in the future. The choice of the
most appropriate rootstock will depend on a number of
factors including cultivar, training system, soil, and time of
ripening. An unprecedented number of new rootstocks
presently are under intensive evaluation. The prominent
rootstocks of the future likely are among those being
tested.

~.iyj^dQtei i^i T^fittiiaiiii til |-'>^ ^•H'^

Figure 6. Starkspur Supreme Delicious on C.6 (left) and M.26 EMLA (right) after 5 growing seasons (1984
planting).

•s* »s^ »s* »s* »s*

W^ W^ ^« ^% ¥^

Apple IPM Program:

Delivery and Observations in 1988

Kathleen P. Leahy, Ronald J. Prokopy, Susan A. Johnson, and William M. Coli
Department of Entomology, University of Massachusetts

Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

James T. Williams

University of Massachusetts Cooperative Extension, Concord, MA

Our thanks to the following cooperating growers in
the IPM monitoring program this year: Charlie and Alex
Dowse, Ed Jensen, Tony Lincoln, Tony Rossi, Don Sch-
licke, Steve Smedberg, Mike and Tim Smith, Mike Smo-
lak, and Denis Wagner. Special thanks to Sue Butkewich
for technical assistance.

Ovendew of the Program

The 1988 Massachusetts Apple Integrated Pest Man-
agement (IPM) Program was a mixture of "old" and new
approaches to orchard pest management. As always, we
monitored commercial blocks for insect and disease activ-
ity and reported the information to the state's growers, via
newsletters, recorded Code-A-Phone messages, and di-
rect grower access of INFO^fET, our computerized bulle-
tin board system. Some pesticide trials and other related
research was conducted at the University of Massachusetts
Horticultural Research Center, Belchertown. In addition
to these activities, however, we are now working toward
melding our more-proven, first-stage-IPM pesticide-re-
duction practices with some of the more-radical practices
involved in second-stage IPM into a unified "third stage"
of greatly reduced pesticide use without loss of crop quality
or profitability.

Monitored blocks (7 out of 9 blocks reporting pesti-
cide records) received an average of 4.3 dosage equivalents
(full-rate equivalents) of insecticide this year, 0.9 DE's of
miticide, and 8.5 DE's (range of 5.4 to 12) of fungicide.
This reduction in overall pesticide use did not result in any
loss of crop quality, premature fruit drop, or other prob-
lems in these blocks. One spray-related problem was
brought to our attention which had appe2ired in some
locations: a russetted ring towEwd the low-hanging end of
the fruit. This injury was tentatively attributed to Captan
applied on a hot (88°?) day under poor drying conditions.

Insects and Diseases in 1988

European Apple Sawflv . Captures were quite high in
blocks where sawfly was not well controlled last year; one
block even exceeded our record high trap captures of 1987
with an average of 73 per trap and a maximum of 126! Trap
captures were moderate in most blocks; however, sawflics
entered in such a way that many growers were unable to
protect earlier cultivars when later cultivars were still in
bloom. Sawfly damage was seen in blocks where pre-
bloom sprays were applied as well as where such sprays
were withheld.

Plum Curculio . Curculio activity also occurred in a
very concentrated period at bloom and petal fall. Injury
was exceptionally high in some blocks where controls
could not be applied in time. Very little fresh injury was
seen or reported in the 9 regular monitoring blocks after 2
to 3 weeks past petal fall. Some growers, particularly those
who often experience late curculio injury, did, however,
report serious problems with late curculio activity this
summer.

Pear Thrips . This insect became a major problem in
at least 3 orchards in western Massachusetts as well as in
Vermont, causing poor fruit set in infested blocks (ap-
proximately 75% yield reduction in one case). Thrips have
been present in low-spray orchards in this area since 1985,
but this year was their first major appearance in commer-
cial blocks in Massachusetts.

Leafminers . This year was another unusual year for
leafminer activity. Spring emergence seemed fairly stable
and predictable (unlike that of 1987, when cold and snow
made emergence highly erratic), and growers who had
leafminer problems, for the most part, were able to time
their sprays well. However, the second and third genera-
tions, increased to unexpectedly high levels, even where the
first generation appeared to be adequately controlled, or

where first-generation mines indicated that populations
were too low to worry about. Premature drop did not
appear to be a problem in any infested block, however.

Larvae of the apple-and-thorn skeletonizer (An-
thophilapariana) were present in one orchard in fairly high
numbers, but were completely controlled by an insecticide
directed against apple maggot fly in early August. Apple
leafminer (Lyonelia speculella) was also found in a few
locations this year, but no problems were observed.

Tarnished Plant Bug . Plant bug captures on white
rectangle traps were unusually low throughout the pre-
bloora period, not reaching cither the tight cluster or pink
threshold in any monitored block. For this reason, some
growers were able to withhold insecticides directed against
plant bug this year. Plant bug damage at harvest was less
than in previous years; of the injury that did appear, much
could have been either sawfly (calyx stings) or green
fruitworm/oblique-banded leafroUer (large russetted
dimples) injury.

Leafrollers . More oblique-banded Icafroller injury
was seen than is usual this year in monitored, first- and
second-stage IPM blocks, but still did not appear to be at
a level of concern. Early-season leafroller damage was
found in some blocks, especially low-spray blocks; this type
of injury is unusual in Massachusetts. Apparently the small
window of sawfly/curculio activity and control gave the
leafrollers a chance to move in after petal fall. Pesticide
resistance on the part of oblique-banded leafroller is also
a possibility, although damage was more notable in lightly-
sprayed blocks than in heavily-sprayed blocks. Overall
leafroller injury remained very low, however, amounting to
less than 0.2% of surveyed fruit.

A pple Maggot Fly . Overall maggot fly pressure was
low, and very little damage was found. There did not
appear to be a late-season flush of apple maggot fly
activity, as there has been for the last few years.

Aphids . Aphids were eventually controlled by preda-
tors, but populations tended to hang on longer than usual,
especially on water sprouts, where they could be found
until mid-July in some blocks. This delayed effect could
have been due to the presence of spiraea aphids in addition
to green apple aphids, or to some other factor. No
honeydew problems were seen in any monitored block. As
in 1987, cecidomyiid midge larvae were the predominant
predator, ably assisted by syrphid fly and camaemyiid fly
larvae, minute pirate bugs, ambush bugs, and ladybird
beetles.

Ladybird Beetles . Populations of ladybird beetles
were noticeably higher statewide this year than in previous
years.

Mites /Predators . Mite activity appeared to level off in

late summer; some growers who had originally planned to
treat decided to wait, and ultimately did not need a miticide
at all, or were able to use a low rate or spot treatment.
Once again, dormant oil appeared to be a highly effective
method of preventing mite buildup. Miticide use averaged
close to 1 DE in 9 commercial blocks, down from the usual
average of 2 DE of miticide (not including dormant oil).
Summer oil at 1 quart/ 100 gallons was used successfully in
one monitored block, with no apparent ill effect on fruit or
foliage. Predators continue to build in commercial or-
cha.r(is\Amblyseius fallacis and Zetzellia mali built up later
than usual, and were lower in number than in 1987, but
were still of value in several blocks. Rain in late summer
probably also helped wash mites off leaves.

Lcafhoppers . Potato leafhopper was not much in
evidence this year, except in one low-spray block of young
trees, where it disappeared entirely after an organo-
phosphate insecticide was applied. White apple leafhop-
per was at a problem level in one first-stage and a few
second-stage IPM blocks, but overall it did not present a
major problem this year.

Catfacing Insects . Activity was very low to moderate
in peach blocks this year. Many growers reduced insecti-
cide use with no noticeable ill effects.

Earwigs . Several instances of earwig injury to apples
in commercial orchards occurred, especially on Cortland
fruit. Injury was most often in the stem end and took the
form of chewing as well as substantial frass accumulation.
It was not possible to tell whether the earwigs had initiated
the injury or only moved in later and enlarged previous
wounds.

Scab . There were only 5 or 6 (depending on location)
actual scab infection periods, though the length of these
generally exceeded 36 hours. Frequent wetting periods,
which were not Mill's periods, occurred during primary
season. The timing of sprays was difficult due to the length
of the wetting periods, and windy weather. Growers who
missed a spray, or even missed a few trees, had some
trouble for the rest of the season which would have been
worse except for the dry summer weather. The average
fruit scab injury for IPM monitoring blocks was generally
low (0.47%) except for one block where mechanical break-
downs interfered with the scab spray schedule, and injury
was 5.5%.

Sooty Blotch and Flvspeck . These problems were
evident in a number of blocks, especially on Golden Deli-
cious apples.

Calyx End Rot. Black Rot, etc. Very little of any of
these problems were noted in monitored blocks, especially
when compared to the levels reported in previous years.
There were some instances of Botrytis-mAaceA end rot

>-
a:

1.500

1.000

^ 0.500 --

0.000

ES 1978-87
ES 1988

jaJ

Nixi

[^ R ^

PB EAS PC LR AMF GFW CM S,

S OTHER

Figure 1. Insect injury on fruit in 1988 (percent of 8000 fruit evaluated) compared with 1978-87. (TPB =
tarnished plant bug, EAS = European apple sawfly, PC = plum curculio, LR = leafroller,AMF = apple maggot
fly, GFW = green fruitworm, CM = codling moth, SJS = San Jose scale.)

1.500-

1.250-

1.000

0.750

0.500

0.250

0.000

ES 1978-87
ES 1988

SCAB CALYX BLACK SOOTY OTHER

END-ROT ROT BLOTCH/

FLYSPECK
Figure 2. Disease injury on fruit in 1988 (percent of 8000 fruit evaluated) compared with 1978-87.

which did not progress into the apple.

Fire Blight . Except for a limited occurrence on young
Gala and a block of exotic (British cider) cultivars, fire
blight was not a major problem on apples in 1988. This
observation was interesting, since 2 pear blocks had very
heavy fire blight damage, and other pear growers had
limited problems. Possibly growers are regularly using
dormant materials on apples but not on pears. Of course,
pears generally are more susceptible, but have not had

more fire blight than apples in recent years.

Bitter Rot . Isolated incidence of bitter rot at eco-
nomic levels (>5%) occurred in one Massachusetts or-
chard. This outbreak was probably related to the unusual
heat and humidity. Also, drops had not been removed
from the block for 2 years.

Figures 1 and 2 show the insect- and disease-related
fruit injury which occurred in 1988 compared with 1978-87.

»s* ^* ^« •$« »s^

0^ wgm ^9 «^ w^

COOPERATIVE EXTENSION

U S. DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS

AMHERST, MASSACHUSETTS 01003 0099

BULK RATE

POSTAGE & FEES PAID

USDA

PERMIT No G?r>8

OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300

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Y^h

Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension, n\ry\ OGICAL

United States Department of Agricultm-e, and Massachusetts Counties Cooperating. :

ISSN 0427-6906

Editors: Wesley R. Autio and William J. Bramlage

Volume 54, Number 2
SPRING ISSUE, 1989

Table of Contents

Life Without Alar

Apple Bruising. IV. Injury Occurring During
Harvest and Transport to the Packinghouse

The Effects of Summer Pruning on Insect
and Mite Populations in Apple Trees

New Trap-capture Thresholds for Tarnished Plant Bug and
European Apple Sawfly in Massachusetts Apple Orchards

Diagnosing Leaf Injury Symptoms

Integrated Pest Management for Commercial
Strawberries in Massachusetts

Planting Orchards in Massachusetts

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

Correspondence should be sent to:

Fniit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POUCY:

All chemical usessuggested in this publicalion are contingent upon continued registration. Thesechemlcals should be
used in accordance with federal and state laws and regulations. Growers are urged to be familiar with all current slate
regulations. Where trade names are used for identification, no company endorsement or product discrimination is
intended. The University of Massachusetts makes no warranty or guarantee of any kind, expressed or implied,
concemingthe use of these products. USER ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY
DAMAGE

Issued by tht University of Massachusetts Cooperative Extension, E. B. MacDougatt, Director, in furtherance of the acts of
May 8 and June 30, 19} 4. The Universilyof Massachusetts Cooperative Fjiensionoffersequalopportunit\'inprogramsand
employment.

Life Without Alar

Wesley R. Autio

Department of Plant & Soil Sciences, University of Massachusetts

In August, 1985 the controversy began regarding
the safety of Alar^*^ residues on apples. Since that time
many discussions and arguments have occurred. A
recent "60 Minutes" program fueled the controversy
by presenting claims made by the Natural Resources
Defense Council that Alar is a potent carcinogen. The
scientific data available certainly do not support that
view; however, the widespread publicity likely will
eliminate Alar-use as a hoilicultural practice. Apple
growers must look toward a future without Alar. In
this aiticle I shall present some of the ways that may
help reduce the need for Alar.

Before discussing specific activities, we must be
clear on what benefits are received from Alar. The first
and foremost function of Alar is to act as a "stop-drop."
This function allows a grower to harvest most of his
crop before it drops to the ground. By allowing fruit to
remain on the tree longer they are able to color more
fully, giving higher grade fruit. One reason why fruit
stay on the tree longer is that Alar delays the beginning
of fruit ripening, which results in less-ripe fruit for
storage, which then allows the fruit to retain high
quality for a longer time. In particular, the apples stay
firm for a longer period of time.

Alternative approaches to the use of Alar must
address these benefits that Alar provides. Approaches
will be divided into two types: short-term practices and
long-term changes. Short-term practices include sev-
eral activities, but in general these are practices which
may be undeilaken this season to reduce the losses
associated with the non-use of Alar. Long-term
changes require more time and capital to implement. It
must be understood that Alar provided a gi'eat deal of
benefit, and no practices are real alternatives: they only
assist in reducing the losses associated with non-use of
Alar.

Short-Term Practices

Pruning

Several Fruit Notes articles [52(3):7-8; 53(1):12-
13; 53(2): 1; and 53(3): 1-2] have discussed the effects of
pruning, particularly summer pruning, on the produc-
tion of high quality fruit. Removal of upright, hanging,
and shade-causing wood in the summer can result in a

dramatic increase in light penetration, fruit coloration,
and packout. Additionally, it causes earlier coloration
and thus allows earlier harvest, hopefully reducing
some of the need for Alar while not reducing average
fruit quality. Dormant pruning also is important,
specifically in improving light penetration to the fruit.
For more specific information about summer pruning
practices, see Fruit Notes 53(2):1, and for more infor-
mation about dormant pruning to improve packout,
see Fruit Notes 53(1):12-13.

Chemical Treatments

There are no chemical alternatives to Alar. How-
ever, there are two chemicals that can be used to
expand the harvest season: Ethrel and NAA. The
problem with both chemicals is that they may render
the fruit unusable for long-term storage by advancing
ripening. Ethrel is used to advance the hai^vest season
by breaking down to ethylene and triggering ripening.
Treatment with Ethrel results in marketable fruit
early in the season, but also fruit that probably must be
consumed immediately, because they are too ripe to
store. NAA is a "stop drop." It will significantly delay
premature fruit drop, but it also advances fruit ripen-
ing. NAA can expand the season, but treated fruit
must be sold relatively quickly. Details on the use of
both of these chemicals are given in the New England
Apple Spray Guide.

Harvest and Storage Management

Without Alar the fruit in storage probably will be
riper than what growers are used to. To maintain fruit
quality throughout the storage period, the fruit must
be handled with greater attention to details than if they
had been treated with Alar. This additional care in-
cludes more accurate attention to cooling and to the
rapid establishment and maintenance of optimal tem-
perature and atmosphere conditions, as well as to
application of the appropriate postharvest chemical
treatments. No longer will sloppy storage manage-
ment be acceptable, since the fruit will show the quality
of storage management more readily than before. In
addition to storage management, the intensity of har-
vest management must be increased. Growers must
accurately manage their harvest so that the most ap-

FruU Notes, Spring, 1989

propriate fruit are placed in long-term storage. This
practice may include the more frequent use of the
starch-iodine test for maturity assessment.

Increased Labor

Increasing harvest labor so that more fruit can be
picked in a shorter period of time is one way to reduce
the impact of the non-use of Alar; however, growers
must be able to handle the increased quantity of fruit.
Specifically, the orchard operation must be able to
move the fruit quickly from the orchard to the storage,
stack them in the storage, cool them quickly, and seal
the storage (if CA is used) if the increased labor is going
to pay off. Beside the availability of additional labor,
one problem which may prevent this practice from
being feasible is the size of the refrigeration plant. If
there is not adequate refrigeration to cool the high
quantity of fruit being placed in the storage per day
then the additional labor is not truly reducing the
impact of the non-use of Alar.

Long-term Changes

Changes in Cultiuars

One of the characteristics of the New England
apple industi-y which has increased the problems re-
lated to the loss of Alar is the large proportion (60 %) of
the production devoted to Mcintosh. A relatively
simple way of reducing the need for Alar is to replace
Mcintosh with other cultivars which allow an expan-
sion of the harvest season or do not require a chemical
"stop-drop." Several cultivars have potential in New
England, such as Gala, Mutsu, Libeiiy, Jonagold, and
Red Fuji. Older cultivars like Coitland and Macoun
also may deserve a greater role in the industry. Obvi-
ously, severed years are required to change cultivars,
and several years are required to develop markets for
new cultivars.

Changes in Strains

Several Mcintosh strains are now available.
Marshall Mcintosh has been the most planted strain
over the last few years, primarily because of its higher
coloring potential. Additional benefits which come
from Marshall Mcintosh are given by its earlier color-
ing and earlier ripening. It colors approximately 10
days prior to Rogers Mcintosh and ripens approxi-
mately a week earlier. These two differences allow an
advancement of the Mcintosh harvest season without
the kind of quality loss found with the use of a chemical
such as Ethrel. However, planting entirely to Marshall
Mcintosh will not reduce the losses associated with the

non-use of Alar, because the entire harvest season will
be earlier and just as concentrated as with a standard
strain of Mcintosh. Future orchards should have a mix
of Marshall Mcintosh with other strains to allow the
maximum expansion of the harvest season.

Pioneer Mac (recently named by Adams County
Nursery) technically is not a strain of Mcintosh but
actually is a seedling of Mcintosh and thus a new
cultivar; however, its fruit are virtually indistinguish-
able from Mcintosh and undoubtedly will be accepted
as Mcintosh. Its reported advantage over standard
Mcintosh is that it ripens 2 weeks later. In 1988 at the
University of Massachusetts Horticultural Research
Center we established a replicated trial to compare
Pioneer Mac to Marshall Mcintosh and Rogers Mcin-
tosh. When information is available it will be reported
through Fruit Notes. The benefits of Pioneer Mac may
be great, but as with Marshall Mcintosh it will be
necessary to include earlier-ripening strains of Mcin-
tosh to provide a true expansion of the hai-vest season.

Rootstocks

Changes in rootstocks must occur to give benefits
in two areas. First, more dwarfing rootstocks must be
used. Large plantings of Mcintosh as semi-dwaif trees
will not be feasible to maintain without Alar. Growers
must consider moving into the dwarf categoiy, using
M.9, M.9 EMLA, M.26, Mark, and possibly Ott.3 as
rootstocks. Trees on these rootstocks are much easier
to prune, require less spray material, and most impor-
tantly, in the context of this article, are much easier to
harvest than are semi-dwarf or standard trees. Nearly
all the fruit are harvestable from the ground, and the
harvesting process can be done more rapidly. Because
of high light penetration into the canopy, more of the
fruit are highly colored, making selective hai-vesting
less of a priority while improving packout. For more
general information on these dwarfmg rootstocks see
Fruit Notes [51(4):22-24; 52(l):l-4; 53(l):4-7; 53(3):3-
6;and54(l):ll-15].

The second potential benefit of a change in root-
stocks is their effect on ripening. For three years we
have been conducting research at the University of
Massachusetts Horticultural Research Center on the
effects of rootstocks on apple fruit quality and ripening
[see Fruit Notes 52(2):5-10], and have found that Mark
can delay ripening of Delicious and Mcintosh fruit by as
much as 5 days when compared to fruit from trees on
M.26 EMLA and Ott.3. The use of rootstock to expand
the harvest season should complement the use of dif-
ferent strains to expand further the Mcintosh hai-vest
season.

Fruit Notes, Spring, 1989

Conclusions

We do not have any easy answers to the question of
what an apple grower can do to reduce the losses
associated with the non-use of Alar. Short-term ap-
proaches, obviously, are stop-gap measures which may

somewhat reduce the losses. The long-term changes
will take time and capital to implement but should go
far to eliminate the need for Alar. The New England
apple industry has rough seas ahead, but if growers
look to the future and begin to make some changes, it
should be able to weather this storm.

mjs *t» »i» aS» ^A

^m vj« ^* w^ #2*

Apple Bruising. IV. Injury Occurring During
Harvest and Transport to the Packinghouse

William J. Bramlage

Department of Plant & Soil Sciences, University of Massachusetts

This is the fourth in a series of articles reporting
findings of a research gi'oup at Michigan State Univer-
sity on the causes and consequences of bruising to
apples. The previous articles examined bruising dur-
ing packing, grading, and subsequent transport [Fruit

Notes 53(4):15-17, 54(l):6-7, and 54(l):7-9]. Here we
summarize a report in which sources of bruising dur-
ing harvest and transport to the packing house are
examined.

This report is entitled, "Damage Assessment for

Table 1. Damage incurred during hand-harvest of Mcintosh apples for 6
Average damage for all orchards, and range of damage among the 6 orchards

Michigan orchards.
, are shown.

Location

in bin

Total bin

Bottom

Top

Avg.

Range

Avg.

Range

Avg.

Range

A. Fruit damage, %

Undamaged
Bruised
Cut
Punctured

5 to 24

76 to 95

0to5

2 to 7

77
1
3

7 to 41

59 to 92

Otol

lto4

6 to 29

71 to 94

0to3

1 to5

B. Bruise frequency, %

Bruise diameter
(inches)

1/4 to 1/2
1/2 to 3/4
3/4 to 7/8

74 to 93
7 to 24
Otol

81 to 94
6 to 18
Otol

87
12

77 to 93
7 to 21
Otol

Fruit Notes, Spring, 1989

Table 2. Cumulative damage to Mcintosh apples incurred during harvest and transport to packing
houses for 6 Michigan orchards.

Average

Range

A. Total damage in bin, %

Undamaged
Bruised
Cut
Punctured

Otoll

88 to 100

0to3

2to8

B. Bruise frequency, %

1/4 to 1/2 inch
1/2 to 3/4 inch
3/4 to 7/8 inch

91
8
1

88 to 95
5 to 11
Otol

C. Characteristics of orchard transport

Orchard

In the orchard

Orchard to packing house

1
2
3
4
5
6

Fork lift

Fork lift; bin trailer
Fork lift; bin trailer
Double fork lift
Fork lift; bin trailer
Fork lift

Truck, 4 mi. gravel road
Truck, 6 mi. paved road
Truck, 3 mi. paved road
Fork lift, 0.3 mile lane
Semi-trailer, 65 mile paved road
5th wheel trailer, 1.5 mile
gravel and paved roads

Apple Harvest and Transport," and was presented by
S. A. Sargent, G. K. Brown, C. L. Burton, N. L. Schutte
Pason, E. J. Timm, and D. E. Marshall to the American
Society of Agricultural Engineers December 15-18,
1987. It was a cooperative study by the U.S. Dept. of
Agriculture, Agricultural Research Semce, and the
Agi'icultural Engineering Department, at East Lan-
sing, Michigan.

This study examined damage to Mcintosh apples
in 6 commercial hand-harvested orchards in Michigan.
Fruit were sampled from bins when they had 2 or 3
layers of fruit in the bottom, and again when they were
full. Fruit in these bins were again sampled at the
packing houses as they were floated by water from the
bins, to assess damage that had occurred during bin
transfer operations.

All fruit were visually evaluated for bruises, which
were rated for size (diameter) as "A" = 1/4 to 1/2 inch,
"B" = 1/2 to 3/4 inch, "C" = 3/4 to 7/8 inch, "D" = 7/
8 to 1 1/4 inch, and "E" = greater than 1 1/4 inch. Cut
or punctured fruit were also recorded.

Overall, only 18% of the fruit in the bins in the
orchard were uninjured (Table 1). Eighty one percent
of them were bruised, 1% were cut, and 3% were
punctured. As expected, however, injury was more
prevalent in the bottom than on the top of the bins.
Most (87%) of the bruises were less than 1/2 inch in
diameter, and bruise size was about the same for fruit
in the bottom and at the top of the bin, indicating that
drop distance was about the same in both locations,
since bruise size increases with drop height.

In all orchards, bins were transported by tractor-
mounted fork lifts. In some cases, bins were moved to
other parts of the orchard for filling, and 1 orchard used
a double fork-lift to transport bins from the orchard to
the packing house. Three operators used self-loading
bin trailers with low-pressure balloon tires for trans-
port to roadside. Various trucks and trailers were used
to transport bins from roadside to packinghouse. Most
roads were paved, and distances ranged from 1/4 to 7
miles.

Following harvest and transpoil, only 6% of the

FruU Notes, Spring, 1989

Bruises/Fruit

Harvest Transport

Bruises Incurred During:

Figure 1. Average number of bruises incurred during harvest and
transport of Mcintosh apples in 6 Michigan orchards. See Table 2 for
descriptions of transport methods among the 6 orchards.

fruit were undamaged. Most of the increase in damage
during transport was from bruising, with very little
cutting or puncturing occurring after the harvest op-
eration. Most of the bruises incurred during transit
were the small, class A type. A high percentage of these
bruises appeared to be due to repeated vibrations from
trucks or trailers with "stiff' suspensions.

The relationships of orchard operation to bruising
can be seen in Table 2 and Figure 1. Orchard 4 had by
far the most bruising during harvest, an indication of
poor instruction and/or supervision of pickers. Or-
chard 6 produced the most bruising during transport.
Here, a trailer with "stiff" suspension was used to
transport bins from the orchard to the packing house,
a distance of about 1.5 miles over some gravel and some
paved roads.

The strikingfeature in Figure 1 is the relatively low
amount of bruising during transport in Orchards 2, 3,
and 5, all of which used bin-loading trailers to move
bins out of the orchard to the roadside.

Care in bin handling by fork-lift operators can
greatly reduce the amount of damage incurred when
settingbins on trailers and floors. In several operations
fork lifts had short tines which did not extend under
the entire bin bottom. This caused the bottom boards
to spring upward during transport, which can bruise
apples in the bottoms of the bins.

The authors conclude by recommending (a) gentle
harvest and placement of apples in bins; (b) careful
lifting, movement, and setting of bins during transport;
(c) a minimal number of handling steps, and (d) use of
appropriate equipment. They recommend use of long
tines on fork lifts, soft tires, and soft suspensions on
transport vehicles. Bin-loading trailers were of consid-
erable benefit in avoiding bruising.

Figure 1 clearly shows that much bruising during
harvest and transport is avoidable. The information
provided in this study should help growers to carefully
evaluate their operations to identify problems, and
help to correct them. This can substantially improve
fruit quality and pack-out.

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Fruit Notes, Spring, 1989

The Effects of Summer Pruning on Insect
and Mite Populations in Apple Trees

Susan L. Butkewich, Ronald J. Prokopy, and William Pyne
Department of Entomology, University of Massachusetts

Wesley R. Autio and Duane W. Greene

Department of Plant & Soil Sciences, University of Massachusetts

Summer pruning is one way to reduce setbacks in
apple production caused by the elimination of Alar^"^
from a grower's spray program. Without Alar, fruit
may drop before they become red enough to yield a high
marketvalue. In previousissuesofFrwi7iVo/es [52(3);7-
8, 53(2):1, 53(3): 1-2] the benefits derived from summer
pruning of Mcintosh trees were illustrated. An in-
crease in light penetration into the tree from summer
pruning resulted in 1) earlier coloring of fruit, 2) a
higher percentage of fruit making the U. S. Extra
Fancy grade, 3) earlier harvesting of fruit, and 4)
production of more fruit with a potential for long term
storage.

Little is known about the effects of summer prun-
ing on apple arthropod pests and predators. Pruning of
vegetative sprouts may remove a resource for pests
that prefer to feed on young succulent tissue (e.g.,
green apple aphid and spirea aphid), but wound exu-
date from pruning cuts may offer direct nutrient bene-
fits to pests like wooly apple aphid. Summer pruning
may also trigger a change in the level of tree nutrients
or defense compounds, and subsequently influence
phytophagous arthropod populations this way.

Two pruning experiments were conducted in 1988
on M.7 Mcintosh trees at the University of Massachu-
setts Horticultural Research Center, Belchertown. These
studies were undertaken initially to determine the
effect of summer pruning on fruit production. How-
ever, data on fruit yield and quality will be reported in
a future issue of Fruit Notes. Here, only data on arthro-
pod pest and predator levels are reported.

On August 26, 10 fruit cluster leaves and 10 non-
cluster leaves were sampled from the interior of each
tree at about head height. Within a cluster, the third to
the fifth leaf out was sampled. Non-cluster leaves were
picked from the interior part of a branch (not the
branch terminal) and were equivalent in size to cluster
leaves. The underside midrib area of each leaf was
evaluated for presence or abscence of European red
mites (ERM) and two-spotted spider mites (TSSM),
and also for presence or absence of the predatory mites

Amblyseius fallacis (AF) and Zetzelia mali (ZM). These
leaves were also evaluated for white apple leafhopper
(WALH) damage and apple blotch leafminer (ABLM)
damage (sap and tissue feeders). In addition, 10 prun-
ing cuts on the tree interior were sampled for the
presence of wooly apple aphid (WAA). In control (non-
pruned) trees, 10 pruning cuts from the previous year
were examined.

Experiment 1 was aimed at determining benefits of
summer pruning at various times after June. Three
rows of trees were randomly divided to accommodate 8
replications of 6 treatments. The treatments consisted
of trees pruned on July 1, July 15, August 1, August 15,
and September 1 and a control tree that was not
pruned.

Experiment 2 was conducted to determine effects
of summer pruning in combination with stop-drop
applications. In the same rows as Experiment 1, addi-
tional trees were chosen to provide 7 replications of
these treatments: 1) summer pruning, 2) summer
pruning plus NAA, 3) summer pruning plus Alar, 4)
NAA, 5) Alar, and 6) a control that received no treat-
ment. In this experiment all summer pruning occurred
on August 1 . Alar was applied on July 15. NAA was ap-
plied on September 18, after the first harvest (Septem-
ber 16). Note that NAA was applied after the arthropod
sample date. Data from treatments 2 and 4 thus will be
excluded.

Results from both experiments revealed that popu-
lation levels of WALH, TSSM, and the predator mites
ZM and AF were extremely low and not significantly
different among treatments. Low populations of ZM
and AF are typical of orchards where predator-harsh
pesticides have been used. Populations of TSSM are
often low in situations where ERM may have outcom-
peted them.

Population levels of other insects and mites sur-
veyed in Experiment 1 varied among treatments (Table
1). On most sampling dates, more ERM were found on
fruit cluster leaves than on non-cluster leaves. There
were no trends that may have suggested that pruning

Fruit Notes, Spring, 1989

Table 1. Effects of summer pruning of Mcintosh

apple trees on

European red

mite (ERM) and apple

blotch leafminer (ABLM) populations on

leaves, and on

wooly apple aphid (WAA) populations

around pruning cuts.

Percent leaves

Number of ABLM

with ERM

mines/leaf

Percent cuts
with WAA

I runing

Date Cluster

Non-cluster

Cluster

Non-cluster

Control 71

1.0

0.66

July 1 67

0.63

0.30

July 15 74

0.75

0.46

August 1 51

0.78

0.69

August 15 70

0.70

0.60

September 1 71

0.70

0.53

Table 2. Effects of summer

pruning on August ]

and of Alar application on European

red mite (ERM) and appk

blotch leafminer (ABLM) populations on

leaves, and on

wooly apple

aphid (WAA) populations around

pruning cuts.

Percent leaves

Number of ABLM

with ERM

mines/leaf

Percent cuts

Treatments

Cluster

Non-cluster Cluster Non-cluster

with WAA

Control

0.44 0.31

Alar

0.51 0.40

Summmer

pruning

0.40 0.41

Summer pruning

+ Alar

0.51 0.36

date had any substantial impact on ERM abundance.
Mines from ABLM likewise were more abundant on
fruit cluster leaves than on non-cluster leaves. In this
case, the fewest ABLM mines on both cluster and non-
cluster leaves were found on trees pruned on July 1.
Perhaps pruning on this date eliminated leaves that
otherwise would have been utilzed by second genera-
tion ABLM ovipositing at that time. The lowest WAA
populations were found on trees pruned on August 1
and August 15. Summer pruning on any date did not
appear to lead to buildup of either ERM or ABLM
compared with populations on non-pruned trees, al-
tough WAA on trees pruned July 15 and September 1
were slightly greater than populations on non-pruned

trees.

In Experiment 2 (Table 2), there were no apparent
differences in the numbers of ERM, WAA, or ABLM
mines among treatments. However, there did tend to
be more ERM and more ABLM mines on cluster leaves
than on non-cluster leaves.

These data are preliminary and should be com-
bined with results on fruit production to make sound
decisions about summer pruning. While further re-
search is needed to determine the influence of summer
pruning on pest and predator populations throughout
the summer, the results presented here do not suggest
that summer pruning has a major impact on foliar pest
populations.

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Fruit Notes, Spring, 1989

New Trap-capture Thresholds for Tarnished
Plant Bug and European Apple Sawfly In
Massachusetts Apple Orchards

Kathleen Leahy, Ronald J. Prokopy, and William M. Coli
Department of Entomology, University of Massachusetts

IPM trap-capture thresholds for tarnished plant
bug(TPB) and European apple sawfly (EAS) originally
were developed in 1980. Changes in input costs and
produce prices have reduced the reliability of these
thresholds. In this article we are presenting new
threshold values as well as a general format for estab-
lishing a trap-capture threshold. With this format
growers could use their own price and production
figures to calculate appropriate thresholds and update
them as their data change.

The new trap capture thresholds are as

follows:

Fruit market

TPB, silver tip to:

EAS (all)

Tight cluster Pink

Wholesale
Retail

3.5 5.5

5.4 7.7

9.0
9.0

The actual mechanics of how the new thresholds
were determined can be seen in the Table 1. Clearly, a
number of assumptions needed to be made about per-
acre fruit production, types and costs of chemicals
used, etc. Some of the assumptions used were:

- 15 minutes to spray one acre

- labor cost = $7/hr

- equipment cost = $8.68/hr, developed from
publications by New York agricultural
economists, updated by W. R. Autio

- use of an organophosphate insecticide

- per-acre production = 500 bushels

- average 80% Extra-Fancy packout

- fruit values = $15/bu U. S. Extra Fancy, $9/bu
U. S. Number 1, $7.50/bu Utility, $2/bu
Processing

In all cases, where a choice of assumptions was pos-
sible, we used the more consei-vative figure.

One obvious fact that emerged in calculating these
new thresholds was that the intended market for the
fruit made a difference in how much injury a giower
could tolerate. A gi-ower selling fruit through a farm-
stand, or who could otherwise market fruit graded less
than U. S. Fancy, can afford more injuiy than a gi-ower
for whom any fruit that does not meet the U.S. Fancy
gi-ade will be priced as processing fruit. Thus, we found
that wholesale growers need to be considerably more
conservative in their pest management decision-mak-
ing than retail gi-owers, a fact that probably will not
surprise most growers. In response to this situation,
we developed separate thresholds for the two situ-
ations.

Thus, we considered two possibilities for down-
graded fruit: first, U. S. Extra Fancy downgraded to a
mix of U. S. Number 1, Utility, and processing (20, 70,
and 10 %, respectively, of those fruit downgraded); and
second, U. S. Extra Fancy downgraded to processing
only (100 % of those fi-uit downgraded). We also used
data from a number of packout studies (e.g., Morin and
Bahn, Fruit Notes 1981) showing that only about 10%
of plant bug injury actually is downgraded at all, since
it tends to occur in the calyx of the fruit, hidden from
view.

Mostly what these new thresholds demonstrate is
that some gi-owers can tolerate more, and even a good
deal more, tarnished plant bug injuiy than had previ-
ously been assumed. In the case of sawfly, the tolerable
threshold likewise is slightly higher. But we do not
expect that growers will be able to save many sprays for
sav^y, since a petal fall insecticide would usually be
necessary for plum curculio or other insects even if
sawfly were not a problem. In ceilain years when
curculio adults begin attacking apples later than nor-
mal (e.g., a week after petal fall), sawfly trap captures
can indicate whether sawflies are sufficiently abun-
dant to spray at petal fall or not.

Fruit Notes, Spring, 1989

Table 1 . Calcxilating the trap-capture thresholds for tarnished plant bug (TPB) and European apple
sawfly (EAS) in retail and wholesale apple orchards.

I. The "break-even" level of injury is calculated related to the cost of the injury and the
cost of the treatment.

E + L + C

B =

where:

(P)P(F/100)[$XF-($NO)(NO/100)-($U)(U/100)-($P)(P/100)]

B = "Break-even" proportion of injury

E = Equipment cost per acre

L = Labor costs per acre

C = Chemical costs per acre

P = Total production per acre

XF = % U. S. Extra Fancy if no injun/ was to occur

$XF = Value of 1 bushel of U. S. Extra Fancy grade fruit

$NO = Value of 1 bushel of U. S. Number 1 grade fruit

NO = % of injured fruit downgraded to U. S. Number 1 grade

$U = Value of 1 bushel of Utility grade fruit

U = % of injured fruit downgraded to Utility grade

$P = Value of 1 bushel of Processing grade fruit

P = % of injured fruit downgraded to Processing grade

The following calculations were made with the assumptions used in this article.

For TPB in a retail operation:

B(retail-TPB) =

$2.17 + $1.75 + $8.55

(500 bu)(80%/100)[$15 - ($9)(20%/100) - ($7.50)(70%/100) - ($2)(10%/100)}

= 0.004 = 0.4 %

Fruit Notes, Spring, 1989

Table 1 , continued.

For TPB in a wholesale operation and EAS:

$2.17 + $1.75 + $8.55

B(wholesale-TPB) - B(EAS) =

(500bu)(80%/100)[$15-($2)(100%/100)]

= 0.0024 = 0.24 %

II. Some damage will occur regardless of treatment. For TPB 0.05 % should be added
to B, and for EAS 0.1 % should be added to B.

T= B + A

where:

T = Total % injury

A = % injury even with a well-timed insecticide treatment

With the assumptions used in this article:

T(retail-TPB) = 0.4% + 0.05% = 0.45%

T(wholesale-TPB) = 0.24% + 0.05% = 0.29%

T(EAS) = 0.24% + 0.1% - 0.34%

III. A portion of the total TPB injury is not downgraded. Data suggest that only 10 % of
the TPB injury actually is downgraded; whereas 100 % of the EAS injury is down
graded.

EIL = T/(D/100)

where:

EIL = Economic injury level

D = % of injury actually downgraded

10 Fruit Notes, Spring, 1989

Table 1, continued.

With the assumptions used in this article:

EIL(retail-TPB) = 0.45%/(10%/100) = 4.5%

EIL(wholesale-TPB) - 0.29%/(10%/100) = 2.9%

EIL(EAS) = 0.34%/(100%/100) = 0.34%

IV. The trap-capture threshold (TC) can be calculated from the EIL using relationships
presented by Coll et al. (1 985) Agriculture, Ecosystems and the Environment 1 4:251 -
265.

TC(TPB-before tight cluster) = (EIL + 0.0774) /0.8507
TC(TPB-before pink) = (EIL + 0.9981 )/0.71 07

TC(EAS) = (EIL + 0.3438)/0.0757

With the assumptions used in this article:
TPB before tight cluster

TC(retail) = (4.5 + 0. 077 4) /0. 8507 = 5.4 TPB/trap

TC(wholesale) = (2.9 + 0.0774)/0.8507 = 3.5 TPB/trap
TPB before pink

TC (retail) = (4.5 + 0.998 1)/0.7 107 = 7.7 TPB/trap

TC(wholesale) = (2.9 + 0.9981 )/0.71 07 = 5.5 TPB/trap
EAS

TC = (0.34 + 0. 3438) /0. 07 57 = 9.0 EAS/trap

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Fruit Notes, Spring, 1989 1 1

Diagnosing Leaf Injury Symptoms

Karen I. Hauschild

University of Massachusetts, West Springfield, MA

Growers often are faced with individual trees or
gi'oups of trees that show unusual leaf symptoms --
either color changes, shape or size differences, or in
some situations, leaves "just don't look right." It is
relatively easy to rule out insect and disease problems,
but often it is much more difficult to diagnose nutri-
tional or weather- related foliar damage. The purpose
of this aiticle is to help gi'owers determine the cause of
non-pest related foliar damage.

Herbicide injuiy is often confused with, or hard to
distinguish from, nutritional deficiency symptoms.
The best clue to herbicide injuiy is your knowledge of
application - how and when each herbicide was ap-
plied. Proper sprayer calibration, attention to label
directions, and attention to weather conditions when
applying materials all will help to minimize herbicide
damage.

Common Herbicide Injuries and
Their Symptoms

Terbicil (Sinbar^*^) -- Injury results in pronounced
differentiation of green and yellow areas of leaves.
Leaves also may appear deformed. Leaf veins may be
greener than normal.

Dichlobenil (Casoron^"^) - Injuiy results in yellow-
ing of the leaf margins. Leaves may be deformed.

Diuron (Karmex^*^) - Injury is similar to calcium
chloride injury and moisture stress. It is characterized
by browning of leaf margins that eventually progi-esses
throughout the leaf.

Simazine (Princep^") - Injury develops as necrosis of
the leaf margins, wdth a quick onset of necrosis of the
entireleaf. Leaves also may appear blotchy. With more
severe damage, leaves tear and veins become more
pronounced.

Weather-related Injuries

Drought - Symptoms originate at leaf tips, and mar-
gins then become necrotic. These symptoms usually
follow a period of dry weather.

Frost injury - Injury shows as a whitening of leaves.
Leaves become parchment-like in appearance. Symp-
toms are often confined to lower limbs.

Nutritional Deficiency Symptoms

Nitrogen (N) - The primaiy expression of deficiency
is the yellowing of leaves. Leaves also may be tinged
with red and the coloration may progi-ess to orange-red
with time. Leaves also can be small and deformed and
may abscise.

Potassium (K) - Deficiency is most often a problem
on young, fruiting trees. It starts as a loss of green color
followed by a water-soaked appearance in the older
leaves and progresses to leaf scorch.

Magnesium (Mg) - Older leaves are affected first.
Areas between leaf veins become yellow, and with time
become necrotic. By late summer, shoots may defoli-
ate, leaving tufts of green leaves at tips.

Manganese (Mn) - Deficiency appears first on older
leaves and is seen as fading of leaf margins. This fading
is inward progi-essing toward the leaf midrib. Green
veins may be sharply defined with white-yellow colora-
tion between them.

Zinc (Zn) - Deficiency may appear as rosettes of leaves
in early spring (dense cluster of narrow leaves above, or
at the end of, an othei-wise leafless twig). It also may
show as short, lateral spurs, or marginal intei-veinal
yellowing.

Although it often is difficult to diagnose the cause
of leaf injuries, knowledge of local weather patterns
and accurate, up-to-date herbicide and fertilizer appli-
cation records will help you make an accurate diagno-
sis. Where one or more nutritional deficiencies is
suspected, foliar tissue analysis can confirm your diag-
nosis. When leaf symptoms occur, the above symptom
descriptions should help you determine the tree's par-
ticular problem. Remember, however, that more than
one problem could be present, and that often one
symptom can mask another.

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Fruit Notes, Spring, 1989

Integrated Pest Management for
Commercial Strawberry Growers
In Massachusetts

Sonia G. Schloemann and Daniel R. Cooley

Department of Plant Pathology, University of Massachusetts

The strawberry IPM program began in 1987 with 4
cooperating growers. This number expanded to 14 in
1988. This e.xpansion provided a better sample of
grower practices and improved overall contact with
Massachusetts growers. We also expanded the geo-
graphic base of the progi'am to include a wider area of
the state. Cooperating growers were chosen from
among those who had responded positively to a ques-
tion on the 1 987 gi'ower survey asking if they would like
to become involved in the IPM program.

Fieldswere scouted for tarnished plant bug, straw-
beny bud weevil (clipper), and two-spotted mite.
Recommendations were also made for Botiytis gray
mold management. The sampling methods used for
monitoring insect populations were those generally
used by other IPM programs in New York and New
England. Relative yield impact due to pest injuiy was
monitored and comparisons were made between areas
under IPM management and ones under conventional
management.

Tarnished Plant Bug

For this insect, two scouting methods were com-
bined. It has been asserted that the immature stages
are the form of this insect that cause economic injury to
strawberries (Schaefers, 1980). Adults are present,
but in lesser numbers than nymphs, and are consid-
ered less of a threat. Nymphs are said to hatch around
bloom, the gi-owth stage most susceptible to TPB in-
juiy. White sticky traps were used for an indication of
adult activity (Coli, 1985). Thresholds are not available
for this method, because trap catches do not correlate
with resulting injury levels. However, traps can deter-
mine when adult tarnished plant bugs become active.
We are developing a database of trap catches over
several years to be used to develope thresholds. The
main sampling method used for making management
recommendations has been to assess nymph popula-
tions. This sampling is done by shaking flower trusses
and counting the number of nymphs that fall out. A
threshold number of 1 nymph per 25 flower trusses
was developed in New York (Schaefers, 1980) and has

been used by our program for two years. Additional
information suggests that the threshold perhaps can be
raised substantially to 1 nymph per flower truss
(Mailloux and Bostanian, 1988).

The situation is somewhat confounded by reports
that suggest that both nymphs and adults are causing
economic injuiy to strawberries in Massachusetts.
Adult insects cause much damage to strawberiy pro-
duction in Maine and New Hampshire, but are consid-
ered to be of little consequence in New York. New York
researchers consider nymphs to be the primaiy prob-
lem. Massachusetts may be at the inteiface of two
ecological regions, which suggests the need for further
research.

Among our cooperating growers the average
number of insecticide applications for tarnished plant
bug control in 1987 was 1.8 sprays per season. Under
IPM practices, these same growers made 0.9 insecticide
applications in 1988, a 50 % savings. This level can also
be compared to non-IPM areas on the same farms this
year where 1.4 insecticide applications were made.
Here, IPM recommendations resulted in a 35% savings
(Schloemann and Cooley, 1988). No significant differ-
ences in injuiy to fruit were obsei-ved.

Strawberry Bud Weevil

Strawberry bud weevil is an insect which destroys
individual buds before the strawberries can form. This
pest is of gi'eat consequence in mid-western states and
is becoming of greater concern in New England. Of the
14 cooperating growers in 1988, 11 sampled positive for
the presence of strawberiy bud weevil (clipper). Only
4 of these gi-owers had levels of clipper high enough for
concern, though 8 typically spray for them. The sam-
pling method for clipper involved counting the number
of clipped buds per foot of row. A threshold of 0.6
clipped buds per foot was used (Schaefers, 1972). The
problem with this method is that it evaluates damage
after the fact. Work has begun in New York to evaluate
the efficacy of boll weevil traps for clipper. This trap-
ping may be a valuable innovation for the future.

Fruit Notes, Spring, 1989

Two-spotted Mite

Two-spotted mites provided a very interesting case
for the strawberry IPM program this year. Late in the
1987 season, strawberry growers saw the removal of
cyhexetin (Plictran^'^) from use for mite control. This
loss left very few materials available to growers. Mite
infestations were early and heavy in some locations in
1988. Ordinarily, high mite levels do not occur before
mid-June. This time is approaching hai-vest which
makes spraying difficult due to harvest intei'val restric-
tions. This year, with such high levels early in the
season, gi-owers were concerned. The use of predators
for the control of two-spotted mites has been studied
(Croft et al., 1976; Penman et al., 1979; Waite, 1988).
These predators feed on all stages of two-spotted mite,
disperse rapidly in strawberry fields, and are indige-
nous to the Northeast. In many cases, the natural

Table 1. Two-spotted spider mite populations per
strawberiy leaf at first occurrence of the predator
mite Am6/ys/ews/a//ads, and for 3 weeks following
its appearance. No miticide applications were
made.

Average TSM population per leaf

Grower Weeks after 1st occurrence of A fallacis
site 12 3

1
2
3
4
5
6
7
8

Mean

0.5

2.0

2.2

0.9

0.4

1.5

0.4

3.2

1.1

6.5

0.3

33.8

12.5

30.0

1.6

16.2

2.5

1.0

0.2

5.3

21.6

13.6

1.8

0.4

1.0

27.5

0.2

1.9

13.0

7.5

0.2

7.8

6.6

11.2

0.9

populations are sufficient and appeared to be effective
in keeping two-spotted mite population levels low.
Releases of artificially reared populations can also be
made in locations where the natural populations are
insufficient for control. A local business, Biokon, has
emerged for the distribution of the predator Ambly-
sieus fallacis. In cooperation with Biokon, the straw-
berry IPM program monitored population levels of pest
and predator mites prior to and after releases of the
predators were made. The results were impressive. In
most cases the predators "cleaned up" the two-spotted
mites within 2 to 3 weeks, a result difficult to achieve

Table 2. Mean numbers of fungicide applications
and percent injured fruit at harvest for IPM and
non-IPM blocks in 1988.

Number of fungicide Injured fruit
Treatment applications at harvest (%)

IPM
Non-IPM

1.1 b-
3.8 a

5.6 a
6.3 a

•Means within columns not followed by the same
letter are significantly different at odds of 20 to 1.

with miticide applications. Data in Table 1 illustrate
these results.

Botrytis Gray Mold

Strawberry growers make more pesticide applica-
tions to control Botrytis cinerca, the fungus which
causes gray mold, than for any other single problem in
commercial strawberiy production in Massachusetts
(Schloemann and Cooley, 1987). In 1987 Massachu-
setts growers applied an average of 5.6 fungicide
sprays, ranging from to 15. These applications cost
growers about $140 per acre. Studies have shown that
the most susceptible gi-owth stage for the infection of
Botrytis is bloom, when the fungus infects the tender
blossom tissue (Devaux, 1987; Grove etal., 1985). The
infection remains latent until conditions of fruit devel-
opment and favorable weather conditions coincide.
Therefore, the IPM program in Massachusetts targets
bloom to prevent infection. Many growers have had
great success with this program of bloom sprays and
have saved several spray applications later in the sea-
son. Table 2 shows that under IPM recommendations
in 1988, cooperating growers made an average of 1.1
fungicide applications this year, compared to 3.8 in
non-IPM blocks on the same farms, a 70% savings.
Incidence of Botrytis in IPM vs. non-IPM fields was not
significantly different. However, disease pressure was
light this year. The progi-am's goal is to keep Botiylis
sprays to an average of 3 or less.

Inoculum causing blossom infections comes from
ovei^wintering Botiytis in the live leaf tissue of straw-
berries protected under the mulch (Braun and Sutton,
1986; Braun and Sutton, 1987; Sutton and Braun,
1987; Sutton, 1988). These leaves are infected in the
fall. As they senesce in the spring, they produce spores.
Efforts are undei-way to develop ways to inhibit the
ability of Botrytis spores to penetrate the leaf surface
successfully in the fall, thereby reducing the initial

Fruit Notes, Spring, 1989

inoculum available for infection in the spring. This
information is being incorporated into research efforts
to be conducted in the future.

Applied Studies

The strawberry IPM program has secured 2 acres
of land at the University research farm in South Deer-
field for applied studies of pest management practices.
Currently, studies of fumigation materials at different
rates and non-fumigant cultural practices are in prog-
ress. There is little doubt that fumigation provides
tremendous production benefits. However, its eco-
nomic and ecological costs are generally high. Alterna-
tively, certain cover corps have allelopathic qualities
which reduce pathogens, nematodes, and the viability
of weed seeds. They might also have some direct
economic value to the grower, as with Sude.x (a Sudan
X sorghum hybrid which is now used by some growers
as winter mulch) or pumpkins (which have been stud-
ied for their allelopathic qualities related to black root
rot control in strawberries). This work illustrates the
value of cultural practices in IPM systems. Additional
studies for improved and innovative management of
Botiytis gray mold, tarnished plant bug, and two-
spotted spider mites are planned for 1989.

References

Braun, P. G., and J. C. Sutton. 1986. Management of
strawberiy gray mould with fungicides targeted
against inoculum in crop residue. 19S6 British Crop
Protection Conference-Pests and Diseases. 8A-4. 915-
921.

Braun, P. G. and J. C. Sutton. 1987. Inoculum sources
of Botrytis cinerea in fruit rot of strawberries in On-
tario. Canadian J. Plant Path. 9(l):l-5.

Coli, W. M., T. A. Green, T. A. Hosmer, and R. J.
Prokopy. 1985. Use of visual traps for monitoring
insect pests in the Massachusetts 1PM program. Agric.
Ecosystems Environ. 14:251-265.

Croft, B. A., A. W. A. Brown, and S. A. Hoying. 1976.

Organophosphorus-resistance and its inheritance in
the predacious mite Amblyseius fallacis. J. Econ.
Entomol. 69:64-68.

Devaux, A. 1978. Etude epidemiologique gruse des
fraises et essais de lutte. Phytoprotection 59:19-27.

Grove G. G., L. V. Madden, M. A. Ellis and A. F.
Schmitthenner. 1985. Influence of temperature and
wetness duration of infection of immature strawberry
fruit by Borry'is cinerea. Phytopath. 75:165-169.

Mailloux, G. and N. J. Bostanian. 1988. Economic
injury level model for tarnished plant bug Lygus lline-
olaris in strawberry fields. Env. Ent. 17:581-585.

Penman, D. R., C. H. Wearing, E. CoUyer, and W. P.
Thomas. 1979. The role of insecticide resistant
phytoseiids in integrated mite control in New Zealand.
Proc. 5th Int. Cong. Acarol. 5:59-71.

Schaefers, G. A. 1972. Pest management systems for
strawberry insects. CRC Handbook of Pest Manage-
ment in Agriculture. Vol 111. Pimentel, ed.

Schaefers, G. A. 1980. Yield effects of tarnished plant
bug feeding on June-bearing strawberries in New York
state. J. Econ. Ent. 73:721-725.

Schloemann, S. G. and D. R. Cooley. 1987. Strawberiy
IPM survey. 1987 Strawberry IPM Program Report.

Schloemann, S. G. and D. R. Cooley. 1988. 1988
Strawberry IPM Program Report.

Sutton, J. C. 1988. Alternative methods for managing
gray mold fruit rot of strawberries. Proc. 1988 Annu.
Mtg., North American Strawberry Growers Assn.:120-
129.

Sutton, J. C. and R. G. Braun. 1987. New methods for
controlling gray mould fruit rot {Botrytis cinerea) on
strawberries. Proc. Ontario Hort. Crop Conf.

Waite, G. K. 1988. Integrated Control of Tetranychus
urticae in strawberries in South-East Queensland.
Experimental & Applied Acarology 5:23-32.

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Fruit Notes, Spring, 1989

From the editors:

The following is the first in a series of reprinted articles from Fruit
Notes of 50 years ago. This discussion by Professor Van Meter was first
published in the February, 1939 issue.

Planting Orchards in Massachusetts

R. A. Van Meter

Department of Pomology, University of Massachusetts

The average rainfall in Massachusetts is about 43
inches. This is more than the impoilant competing
apple regions get. We get our heaviest precipitation in
July and August when we need it most. Our climate
gives a finish to apples that has long been famous, and
its very severity holds insects like codling moth in
check to such an extent that we have less trouble with
them than any important competing section.

In the past 10 years Virginia has averaged about
45% of a crop each year. New York has averaged 53%,
New England 63%, and the Northwest about 70%. The
Northwest stands highest in average % of a crop and
New England comes next. The dependable cropping of
New England orchards is a real advantage. We are
rapidly becoming a one-variety section and that is a
disadvantage. Mcintosh is the most popular apple on
the market and we would not trade it for any or all the
others grown elsewhere, but we do need a good, high
quality variety to grow with it. Mcintosh probably is
the most difficult apple to handle that is grown any-
where and we still have much to learn about placing it
on the market in good condition.

We have some excellent orchard sites and soils,
many of which are not now utilized for orcharding.
Recent studies of the relation of subsoils to root devel-
opment have added much to our knowledge of what
soils to select.

Here in the Northeast we have a densely populated
area characterized by a high concentration of wealth.
This makes the best market on the continent. Its
nearness makes marketing costs veiy low and affords

advantages that many sections can never offset. This is
all reflected in the average per bushel price received by
Massachusetts growers. Table 1 will make this clear.

Table 1. Average farm

price paid for apples.

1934

1935 1936 1937

Massachusetts $1.26
Virginia, etc. 0.89
Northwest 0.73
United States 0.88

$1.02 $1.35 $0.90
0.72 0.99 0.60
0.60 0.96 0.69
0.71 1.05 0.70

The decline in the per capita consumption of apples
is not necessarily a calamity for the apple grower. The
per capita consumption is arrived at by dividing the
total crop (150,000,000 bu.) by the population
(125,000,000) to get the average consumed by each
individual (1 1/5 bu.). This is lower than it was a few
years ago--not because people refuse to eat apples for
they eat all you grow, but because fewer apples are
produced. Why are fewer apples produced? Cold
winters have destroyed millions of apples trees; in-
creasing difficulties in controlling pests have driven
many thousands of small orchards out of business, and
commercial orchards have not been planted fast
enough to take up the slack. Prices have not been high
enough to encourage large-scale planting-that is
where the decline in consumption operates.

Fruit Notes, Spring, 1989

People have not turned away from apples. In the
last 5 years they have eaten 3 times as many apples as
oranges and 6 times as many apples as grapefruit. If we
do plant more orchards in New England we shall not
wreck the market, for prices are affected by the supply
of all fruits in the country. We grow but about 5% of the
total apple crop. The last census showed about
6,000,000 apple trees in New England. If all these trees

lived 50 years we would have to plant 120,000 more
trees per year in New England in order to maintain the
number of trees. We haven't been doing that. Theman
who knows his business should plant in the right places
making a careful choice of varieties and plant acreage
enough to give him a satisfactoiy living. There is still
a chance for apple glowing in New England as a sound
conservative industry.

•S* »i» tjA •!• •$*

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Fruit Notes, Spring, 1989

COOPERATIVE EXTENSION

U. S. DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS

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Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension,

United States Department of Agriculture, and Massachusetts Counties Cooperating.

Editors: Wesley R, Autio and William J. Bramlage

ISSN 0427-6906

7% >/5

JUL 24 1989

bClENCES UBRARY

Volume 54, Number 3
SUMMER ISSUE, 1989

Table of Contents

A Critical Time for Change

Storage of Marshall Mcintosh: Some Cautions for 1989

Some Experience with Use of A Hollow-fiber
System for CA-atmosphere Generation

Seed Number in Apples Can Affect Calcium
Accumulation and Keeping Quality

Items from Here and There

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POUCY:

All chemical uses suggested in this publication are contingent upon continued registration. Thesechemicals should be
used in accordance with federal and state laws and regulations. Growers are urged to be familiarwith all current state
regulations. Where trade names are used for identification, no company endorsement or product discrimination is
intended. The University of Massachusetts makes no warranty or guarantee of any lund, expressed or implied,
concerning the use of these products. USER ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY
DAMAGE

Issued by the University {^Massachusetts Cooperative Extension, E. B. MacDougaU, Director, in furtherance of the acts of
May S and June 30, 1 91 4. The University of Massachusetts Cooperative Extension offers equal opportunity in pro-ams and
employment.

A Critical Time for Change

Duane W. Greene and Wesley R. Autio

Department of Plant & Soil Sciences, University of Massachusetts

Renewed adverse publicity has increased the like-
lihood that Alar^** will not be available for orchard use
in the future. Even if results of current tests show that
Alar is a safe chemical, registration may be cancelled
because of public pressure. The loss of Alar will influ-
ence growers of Mcintosh and Stayman most, so these
growers must not waste time in making the long-term
decisions required to cope with growing apples without
Alar. In a previous Fruits Notes article [54(2): 1-3] a
number of options were put forth as alternatives to
using Alar. The option that we will discuss here is the
replacement of Mcintosh with different cultivars.

There are many new, excellent-quality apple culti-
vars now available, and many others are in the early
stages of evaluation. The loss of Alar may be ablessing
in disguise since there is now incentive to plant new
and better-tasting cultivars. Selection of the cultivars
to plant may be the most important management
decision growers will make in the 1990's. Consistent
and sustained increased per capita consumption of
apples will not occur with continued planting of Mcin-
tosh, Delicious, and Golden Delicious. Itwill only occur
when we provide consumers with a wider choice of
better-tasting apples that have a longer shelf life than
is presently available. In this article we will describe
the most viable alternatives to growing Mcintosh.

Cultivars of Proven Superior Quality

Where New England Growers May

Have a Competitive Advantage

Gala

Gala is an apple cultivar introduced in New Zeal-
and in 1962 by Dr. Donald McKenzie. We previously
reported that this cultivar showed promise in New
England [Fruit Notes 51(1):12-14]. The planting of
Gala is no longer a gamble but a good business decision.
It is being planted extensively in the Pacific Northwest
and in many other areas in the country. It is estimated
that nearly 25% of all apple trees planted in Washing-
ton in 1990 will be Gala. In Massachusetts the fruit
characteristics and storage potential of Gala were
evaluated and compared to Mcintosh in 1988. Taste
panelists consistently preferred Gala over Mcintosh.

Gala is precocious and has shown early, heavy

production. Trees at the University of Massachusetts
Horticultural Research Center (Belchertown) on M.26
yielded over 8 bu/tree in their 7"" leaf. Based on a 12-
X 22-foot plant spacing there was a potential yield of
1386 bu/acre in the 7^ leaf with a cumulative yield of
about 3150 bu/acre. Gala is a "grower-friendly" tree
with few cultural problems. Limb spreading is proba-
bly not necessaiy. However, thinning is necessaiy
since Gala fruit size is not large, but trees have not had
any apparent tendency toward biennial bearing.

There are several red-coloring strains of Gala
available, and they are described below. Replicated
strain trials were established in 1988 at the Horticul-
tural Research Center and at Honeypot Hill Orchard
(Stowe, MA). We will be reporting on these studies as
soon as the trees come into production.

Kidd'sD-8 . This strain is the original one released
in New Zealand in 1962. Based on grower comments
from other parts of the country, the flavor of this strain
may be better than that of other red-coloring strains.
Kidd's D-8 colors well in New England. In our 1988
trials it developed red color on up to 80% of the surface.
Unlike other cultivars, the nonred portion of Gala
turns from green to yellow and finally to a very attrac-
tive orange-yellow color, providing a striking feature
for customer identification. Based on its appearance
from Australia, Italy, and other portions of the USA, we
believe that New England may produce the reddest and
most attractive Kidd's D-8 Gala. We may have a
distinct advantage in grovdng this strain.

Royal Gala . This strain is the most widely planted,
red-coloring strain of Gala. We fruited Royal Gala at
the Horticultural Research Center in 1988. It has a
distinct red stripe and is much redder than Kidd's D-8.
The yellow-orange background color is lacking on this
strain. Only time will tell what strain the consumer or
marketing chain buyers will prefer. In our estimation
the quality and taste of Royal Gala was at least compa-
rable to that of Kidd's D-8 in 1988.

Regal Gala . This strain is ablush type. It has been
suggested, but not confirmed, that Regal Gala is more
vigorous than Kidd's D-8 and may have superior color,
larger fruit size, better flavor, and less firm fruit [Good
Fruit Grower 40(7):7, 1989].

Imperial Gala . This striped strain is veiy similar to
Royal Gala in fruit appearance.

Fruit Notes, Summer, 1989

Scarlet Gala . This strain produces a striped red
fruit that may have better flavor than other red-color-
ing strains.

Spur Gala-Go-Red . This striped strain is the only
spur-type Gala that has been identified. It is reported
that Spur-Gala-Go-Red may produce larger, earlier-
coloring, and brighter fruit than Royal Gala. This
strain is not included in our trial but it is on order for
delivery in 1990.

Galaxy . It is a well-colored, solid-blush strain with
a dark overstripe. Trees of this strain are not presently
available.

Jonagold

This cultivar was released in 1 968 by the New York
Agricultural Experiment Station in Geneva and is a
cross between Golden Delicious and Jonathan. It has
become very popular in Europe, especially in Belgium
and Holland. Jonagold consistently receives high rat-
ings for flavor. Last year Jonagold was the best tasting
(except maybe for Gala) of all apples evaluated at the
Horticultural Research Center. However, it may not
have a long storage life. By the end of November acid
levels had declined to the point where the taste was
bland. Previous to that point, it was a superior and
outstanding apple.

Jonagold is a large yellow apple with a red blush or
cheek. It requires at least as much if not more direct
sunlight for red color to develop than Mcintosh. It is
reported to ripen with Golden Delicious. We feel that
it should have been harvested between October 4 and
8 at the Horticultural Research Center. It is a triploid,
so the trees are vigorous and cannot be used as polliniz-
ers for other cultivars. There are many red-coloring
strains of Jonagold, but these have not been evaluated
extensively.

There was intense interest in Jonagold in the
Pacific Northwest until recently. However, two abnor-
mally warm growing seasons exposed the susceptibil-
ity of Jonagold to sunscald and reduced fruit quality.
Consequently, Jonagold probably will be grown only in
the cooler areas in the Northwest. The cool nights and
sunny days in September and early October, climatic
conditions which make New England an ideal place to
grow Mcintosh, may also make New England the best
place in the United States to grow Jonagold. The
quality of this apple is excellent at harvest. The biggest
question about Jonagold is how long can it be kept in
storage before becoming bland and unappealing.

A number of red-coloring strains of Jonagold have
been identified, but few are presently available. We
will attempt to keep growers in New England updated
as these strains become available and reliable informa-
tion is generated.

Cultivars That Show Considerable

Promise That Are Worthy of at Least

Limited Planting

Red Fuji

We reported in an earlier article [Fruit Notes
54(1):10] on the Red Fuji apples grown at the Horticul-
tural Research Center. We have observed some of
these fruit periodically from regular storage. Of the
apples that we grow, these fruit appear to maintain
flavor and firmness in regular storage much longer
than any other. Pressure tests made on March 28, 1989
after 22 weeks in regular storage, revealed that flesh
firmness averaged over 16 lbs. Fruit harvested with a
green ground color averaged over 18 lbs and their
flavor was still very good. Fruit that were hai-vested
with a yellowish-green giound color were somewhat
bland and flesh firmness averaged about 14.5 lbs.

This cultivar is being planted extensively in Cali-
fornia and the Pacific Northwest. Fuji normally has a
red or pink cheek on a greenish yellow ground color.
Even the red-coloring strains do not develop the in-
tense red color characteristic of red-coloring strains of
other apple cultivars. However, growers in the North-
east may have an advantage growing it since red color
and desirable acid levels should develop more in our cli-
mate. In 1988 it ripened at about the same time as
Rome Beauty. It is a vigorous tree and we feel that it
should be grown on rootstocks no more vigorous than
M.26.

There are several red-coloring strains available but
all are largely untested in this country. We currently
have 4 strains of Red Fuji under evaluation at the
Horticultural Research Center.

Liberty

Of the disease-resistant cultivars available, Lib-
erty is clearly the one with the highest fruit quality.
However, Liberty should not be considered as a spe-
cialty cultivar to be gi-own only in situations where no
fungicides are used. Liberty is an apple that should be
grown on its own merits. In taste tests conducted in
Oregon and Washington and reported by Bob Stebbins
at the most recent New England Fruit Meetings, Lib-
erty was rated equal to or higher than Empire. It is a
medium-sized, oblate fruit with red color over a yellow
ground color, veiy similar in appearance to Empire. It
is crisp and juicy, and qualities of one of its parents,
Macoun, are quite apparent. It ripens with Empire.
Trees are semivigorous and productive. It is likely that
Liberty trees will require thinning to the same degree
as Empire to obtain adequate fruit size.

Fruit Notes, Summer, 1989

Cultivars That May Be Worthy But
Further Testing Is Required.

Braebum

Braeburn is a chance seedling that originated in
New Zealand. It is firm, crisp, veiy juicy, sweet, and
aromatic with light-green flesh and oval shape. Fruit
are medium to large in size and green overlaid with
red. Fruit are not attractive; however, the eating
quality of this apple has been rated excellent. Probably
the biggest question about Braeburn is whether or not
our season is long enough to mature it. The maturity
date of Braeburn has been compared to that of Granny
Smith. However, the 1988 Apple Variety Progress
report from Oregon State University by Bob Stebbins
et al. indicates that Braeburn ripens a week later than
Delicious and a week before Fuji. Braeburn appears to
store well. The tree is moderately vigorous, precocious,
and has a standard type grovvrth habit. It appears to be
a "grower-friendly" tree [Pacific Northwest Fruit
Tester's Association (PNFTA) Fact Sheet, James K.
Ballard, 1 101 West Orchard Street, Selah, WA 98942].

Criterion

This cultivar originated as a chance seedling in an
orchard near Parker, Washington. Criterion is a yel-
low apple with a shape similar to Delicious. Like
Golden Dehcious, color is determined largely by the
nitrogen status of the tree. It is a firm, sweet, aromatic
apple with creamy flesh and excellent flavor. Criterion
bruises easily. It is not prone to russet, and near
harvest it develops a red cheek. Its storage potential is
good. It is reported to ripens with Rome Beauty,
although there are indications that it may not mature
properly in western Washington and in British Colum-
bia. It is a very vigorous tree which may not be as
precocious as other cultivars (PNFTA Fact Sheet).

Elstar

This cultivar is one of the most attractive and
promising of the new cultivars available. It is also one
of the most heavily planted cultivars in Northern
Europe. Elstar resulted from a cross between Golden
Delicious and Ingrid Marie (a seedling of Cox's Orange
Pippin) made at the Institute for Horticultural Plant
Breeding at Wageningen, Holland. It is medium to
large in size and round to conical in shape, with white
flesh. It is a firm and somewhat-tart, yellow apple with
a very attractive orange-red stripe that matures in late
September. It may require a period of storage to
develop acceptable flavor (PNFTA Fact Sheet).

AceyMac

Acey Mac is a selection from trees vegetatively
propagated from a seedling tree discovered over 20
years ago by Art Burrill in the Champlain VaUey of
New York. It is very similar to Mcintosh in appearance,
taste, shape, flesh color, and flesh texture. It is reported
that Acey Mac is larger and firmer, has less preharvest
drop, and ripens about 5 days later than Rogers Mcin-
tosh. Red color development appears to be better than
Rogers Mcintosh, and it may be comparable to
Marshall Mcintosh. Acey Mac is a nonspur tree with
growth and bearing characteristics similar to Mcin-
tosh. Nine-year-old trees of Acey Mac are growing in
the orchard of Bob Sodoma, Brockport, New York (Carl
Perleberg, Columbia Basin Nursery, Quincy, WA and
Dick Norton, Spencerport, NY).

Buhr Mcintosh (Wafler Nurseries, Wolcott, NY)
was originally propagated from the same tree as Acey
Mac. We are unsure at this time if there are distin-
guishable differences between Acey Mac and Buhr
Mcintosh.

Pioneer Mac

Pioneer Mac is very promising, Mclntosh-type cul-
tivar. It was discovered as an open pollinated seedling
of Mcintosh at Ernest Greiner's farm in Marlboro,
New York. It appears to have fruit characteristics very
similar to those of Mcintosh, although it is reported to
have better color than the Roger's strain. Taste and
external appearance are close if not identical to Mcin-
tosh. Preharvest drop does not appear to be a problem.
It is a nonspur tree that may be less vigorous than
Roger's Mcintosh (Phillip Baugher and Tom Callahan,
Adams County Nursery, Inc., Aspers, PA).

Cultivars of High Quality That May

Have Local or National Market

Acceptance

Akane

Akane ripens 7 to 10 days before the start of
Mcintosh harvest. The fruit are firm, medium sized,
and red with white, dense flesh. Fruit hang on the tree
for an extended period of time without dropping or
losing appreciable fruit quality. It has a distinctive
spicy flavor. It appears to hold up better in storage than
other late-summer apples. It has been reported to be
somewhat resistant to scab. The largest fault that we
find with Akane is that fruit set may be light. It is one
of the shyest producers that we have at the Horticul-
tural Research Center.

Fnut Notes, Summer, 1989

Paulared

This cultivar is one of the most attractive and best
tasting apples that ripens before Mcintosh. Fruit size,
red color, and productivity have been very good at the
Horticultural Research Center. It can be stored for
several weeks without excessive softening. Since it is
an attractive and early-coloring apple, the tendency is
to harvest this cultivar too early, before its true flavor
develops. Sufficient Paulareds should be planted so
that they can be harvested at the appropriate time and
sold with the fine flavor and quality that Paulared is
capable of developing.

Empire

The popularity of this apple is increasing, espe-
cially where it is difficult to color Mcintosh adequately.
It is a high-quality, firm, red apple that stores excep-
tionally well. In our estimation it is only rivaled by
Mutsu for its ability to store in CA. It has not developed
the popularity in New England that many thought that
it would. Since it ripens between Mcintosh and Deli-
cious, it is not always harvested at the proper time.
Although its storage capability is exceptional, once
removed from CA it appears to soften more rapidly
than other cultivars. There does not appear to be the
customer acceptance of a moderately soft Empire as
there is with other cultivars with similar firmness. It
may be difficult to obtain good fruit size in all areas, and
it appears to be particularly difficult to size Empire in
colder areas (a characteristic that it may have inherited
from Delicious).

Macoun

The popularity of this old and difficult-to-grow
apple appears to be increasing. The flavor and crisp-
ness of Macoun is exceptional and makes this fruit a
much sought after apple in the fall. Its many faults
make it unpopular to grow. It may be very biennial, and
hand thinning is frequently required. Red color may
develop slowly, and preharvest drop may occur before
adequate color. Fruit lose firmness rapidly in storage
although they will store well in CA. This apple is not for
everyone, but for those who can grow it, there is good
customer demand.

Mutsu (Crispin)

The quality of Mutsu is among the highest of the
apples that we can grow here in New England. It is a
firm, juicy, and very large, yellowish-green apple that
matures after Golden Delicious. It holds up very well in
regular storage, but its regular storage potential is not
exceptional. However, in CA storage fruit come out in

almost identical conditions to that when they were
placed in storage. Mutsu has not developed the popu-
larity that its quality and CA potential warrant. It is
susceptible to Pseudomonas or blister spot, and unless
this problem is controlled, packout will be poor. We
have found that 3 weekly sprays of Polyram'r", starting
at bloom, control mostof the blister spot. Mutsu is also
very susceptible to excess nitrogen. Mutsu is a yellow
and not a green apple and frequently is picked too early.
Like Granny Smith, if it is picked too early it v^rill have
only mediocre flavor. For people who have roadside
stands, this apple should attract considerable return
business if grown properly and harvested at the time
that will assure the quality that Mutsu is capable of
developing.

Melrose (and its red strains)

This cultivar is the result of a Jonathan x Delicious
cross. Fruit are large, firm, crisp, juicy, and red with a
yellow background. It is a high quality apple that
ripens with Golden Delicious and keeps well in storage.
It is a very popular apple in Ohio.

Idared

Idared has been planted extensively in New York
where it is suitable for fresh market or processing. It is
a very easy tree to grow and maintain. It is a medium-
sized red apple with good flavor. Idared ripens after
Golden Delicious and it benefits from a period of stor-
age following harvest. Although the quality of Idared is
not as high as that of some of the other cultivars
mentioned, its regular and CA storage potential are
excellent. Long after other cultivars have lost firmness
and flavor, Idared remains a good and saleable apple.
People who grow this apple will have quality apples to
sell from regular storage, prior to opening of CA stor-
ages, and at the end of the apple marketing season.

Growing of new, superior-quality apples will be
successful only if the apples can be grown and sold at a
profit high enough to stay in business. Growers who
sell directly to the public through roadside stands have
a distinct advantage since they can introduce to cus-
tomers specific cultivars at the appropriate time to
provide the customer with the best possible product.

Growers who wholesale market their product will
have a more difficult time but it is not impossible.

1. Growers must insist and ensure that their product
is sold at the proper stage of maturity. For example.
Granny Smith is a high-quality apple that at proper
maturity is yellowish green. Unfortunately, it is nearly
impossible to buy a good Granny Smith in the grocery

Fruit Notes, Summer, 1989

stores, because all were harvested when still too green,
before proper flavor developed. Idared has been sold
for the past 2 seasons by local grocery chains in mid-
September, fully 3 weeks before it should be harvested.
It seem ludicrous to harvest an apple so early that you
unjustifiably tarnish the name of that apple and also
jeopardize sales of other apples.

2. Grower groups may volunteer time to pass out
apple samples in the grocery stores. Anyone who has
shopped recently has been offered free samples of
pizza, hotdogs, and cheese. Why not apples?

3. In a recent address to the Washington State Horti-
culture Society, Frieda Caplan, Chairman of the Board
of Frieda's Finest Produce Specialties, Inc., made sev-
eral suggestions to Washington State Growers to in-
crease sales of their apples. She suggested that refrig-
eration of apples in grocery stores should be the grow-
ers' number one imperative. Taste, appearance, stor-
age life, more rapid rotation, and increased sales would
all be improved. It is time that we communicated to the
public the conditions under which apples should be
stored.

4. There is a need for growers to become involved
with cultivar testing. Jim Ballard, a prominent Wash-

ington State pomologist and former Washington State
University Elxtension specialist, has organized the
Pacific Northwest Fruit Testers Association. This
group is comprised of growers and nurserymen who
have agreed to test and share results and observations
of new apple cultivars with other members. Although
the membership is changing rapidly, in December,
1988, there were 180 members in 22 states and 12
countries. This organization is providing an invaluable
service to the industry by speeding up the testing
process and providing the most current information on
appropriate cultivars, especially those adapted to grow-
ing conditions in the Pacific Northwest. Recent evalu-
ations emphasize that environment plays a dominant
role in determining the suitability of a cultivar for a
particular location. Evaluations conducted in the Pa-
cific Northwest provide a good first screening. How-
ever, they provide only rough indications of suitability
for the Northeast.

Is it time to establish an evaluation organization in
the Northeast? If you feel that this approach is appro-
priate contact Duane Greene (413-545-4733) or Wesley
Autio (413-545-2963).

^* «f« ^« m9^ ^3

*f» *f» •{• wj* wj*

Fruit Notes, Summer, 1989

storage of Marshall Mcintosh:
Some Cautions for 1989

Wesley R. Autio, William J. Bramlage, and William J. Lord
Department of Plant & Soil Sciences, University of Massachusetts

Marshall Mcintosh is presently the most widely
planted strain of Mcintosh in the Northeast. In a
previous issue of FruzYATofes [52(4): 1-5] we reported on
tree, fniit, and storage characteristics of Marshall in
comparison with 6 other strains. Marshall trees were
similar in size to Morspur, Imperial, Macspur, Gatzke,
and Rogers trees and yielded similar amounts.
Marshall fruit colored earlier and to a higher degree
than other strains, and Marshall fruit ripened 3 to 5
days earlier than the other strains. Marshall trees
produced relatively small fruit, but in most years they
were not significantly smaller than Rogers fruit.

We also evaluated the storage potential of Marshall
and found no consistent differences between it and
other strains with regard to softening or the develop-
ment of storage disorders in refrigerated (32°F) or
controlled atmosphere (CA) (37°F, 3% O2, 5% COg)

storage. However, when commercial CA's were
opened in 1988 a number of growers reported off-
flavors and other injuries only with Marshall, which
suggested that Marshall may be more sensitive to low
O2 levels than other strains. To test these observations,
we harvested 2 bushels of fruit from each of 8 Rogers
and 8 Marshall trees (planted in 1979 in a replicated
trial) . One bushel from each tree was kept in 3% O2 and
5% COj, and the other bushel was kept at 2.25% O^ and
5% COj. After 6 months of CA, 1 month of refrigerated
storage, and 6 days at room temperature, the incidence
of I0W-O2 injury was assessed.

L0W-O2 injury can manifest itself in a number of
ways including presence of off-flavors, purpling of the
skin, and development of brown sunken patches on the
surface. The most common symptom noted in this
study was internal browning as shown in Figure 1. The

Emit Notes, Spring, 1989

20 -

Low oxygen injury (%)

***

^H Roger*
IZZ Marshal

2.26% 3%

Oxygen concentration

Figure 2. The incidence of low-O^ injury in Marshall
and Rogers Mcintosh fruit stored at 3% and 2.25 % O2
after the 1988 harvest.

flesh browning characteristic of I0W-O2 injury has a rim
of normal, white tissue outside of the browned tissue
and under the skin. With further development, this
white rim disappears.

Figure 2 shows the levels of low-Oj injury found in
Marshall and Rogers fruit. Even at 3% Oj (the recom-
mended level for CA storage of Mcintosh in New Eng-
land) Marshall fruit developed some internal I0W-O2
injury. At 2.25% O2, 32% of the Marshall fruit exhib-
ited internal I0W-O2 injury, while only 4% of the Rogers
fruit were damaged. This increased level of damage

would represent a significant loss by a storage operator.
Storage operators must monitor their O2 concentra-
tions carefully and not allow O^ to drop below the
recommended value if they are storing Marshall Mcin-
tosh fruit.

Because of its early coloring and ripening,
Marshall Mcintosh will undoubtedly be of great value
to the New England Mcintosh industry if Alar'''" is not
used in the future. However, we stress that it is not safe
to store Marshall fruit in CA with O2 concentrations
below 3%.

•X» «!• ai» •S* •S*

*j» •]« *f» *{* ^*

Fmit Notes, Summer, 1989

Some Experience with Use of A
l-lollow-fiber System for
CA-atmosphere Generation

William J. Bramlage and Joseph E. Sincuk

Department of Plant & Soil Sciences, University of Massachusetts

Controlled atmosphere (CA) storage of apples
requires a method of reducing oxygen (Oj) concentra-
tion in the storage atmosphere from that of air (2 1%) to
the level desired for apple storage (usually 3% or less).
Originally, the process used fruit respiration to "pull
down" the O2, but at low storage temperatures this
reduction usually requires 14 to 21 days or more. We
now recognize that this length of time results in signifi-
cant loss of fruit quality, and recommend that the at-
mosphere be pulled down to 5% in no more than 3 days
after sealing the room. This reduction cannot be done
by fruit respiration alone.

Rapid pull-down can be achieved by either displac-
ing most of the storage air with nitrogen (N2), as tank
gas or as liquid N2, or by using an external generator to
create a I0W-O2 atmosphere that is piped into the room.
Several types of generators were developed that mixed

propane gas with air to produce carbon dioxide (CO2)
and water either by open-flame burning or by catalytic
chemical reaction. However, a series of storage explo-
sions have made both storage operators and generator
manufacturers wary about using these machines, and
they rapidly are becoming obsolete.

In New England, many CA storage operators re-
cently have adopted use of liquid N, for CA pull-down,
a practice that we have advocated (Proc. 92"'' Annu.
Meet. Mass. Fruit Growers' Assoc. 1986:102-105),
because it requires little capital investment and
achieves a CA atmosphere rapidly and withoutbuildup
of CO2, which would have to be removed. Liquid Nj
also provides some cooling in the CA room. However,
use of liquid N2 is not problem-free. Some freezing of
fruit near the manifold outlets often occurs, and some
storage operators have difficulty obtaining timely de-

Jt' «r I--- ... ^

> V i

*■ /

Mfi* H2* He, H^, CX)2, O?. Ar, CO. Ns, CH4

pl^$t*' "Slow"

'"' ' Relative Permation Rates

Stream

S , •> ijf^O j- / •.' X. V '-. AC ..>

Figure 1. Relative permeation rates for the Prism Alpha™ hollow-fiber system.

Fruit Notes, Summer, 1989

tnriched

Oxygen

Outlet

Heater'

Compressed

Air

intake

w>«w»»wi»y»y»»wwN<»<ww»wi»y^wwy» jM >»w««w*ff

i^phj

Figure 2. A schematic representation of the hollow-fiber system used at the HRC.

livery of liquid Nj. Also, cost of liquid N2 to different
operators can vary considerably.

We are interested, therefore, in the development of
new types of atmosphere generators which remove the
O2 from air in ways other than by using propane. Two
types of these "air separator" generators now are avail-
able commercially: "pressure-swing" units that re-
move O2 by adsorption, and "hollow fiber" systems
that remove it by diffusion.

Pressure-swing adsorption binds O^, water, and
some other gases onto a Carbon Molecular Sieve
(CMS), leaving nearly-pure N^ that then enters the CA
room. It is called "pressure-swing" because (a) the air
entering the unit must be under high pressure, and (b)
it consists of two columns of CMS, and alternates
("swings") between them . . . the column not adsorbing
gases is being regenerated so that it can be used again.

The hollow-fiber membrane system is a unit filled
with tiny plastic tubes, through which air is forced
under pressure. The plastic is much more permeable
to some gases, such as O^, CO2, water, and ethylene,
than to others such as N2- Thus, as the air passes
through the long tubes, the more permeable gases pass
out through the plastic, and at the exit port the remain-

ing gas is mostly N2, which then enters the CA storage.

Through a lease agreement with Permea, Inc., a
subsidiaiy of Monsanto Company and manufacturer of
a hollow fiber system (Prism Alpha''""), we obtained a
unit in September, 1987, for use at the University of
Massachusetts Horticultural Research Center (HRC),
Belchertown. This unit was designed to generate an
atmosphere of 2 to 8% O2 and 98 to 92% N2 at a flow rate
of 125 to 535 standard cu. ft. per hour, at a pressure of
150 PSl.

We immediately encountered a major problem.
We had been assured that the 5 horsepower (HP) air
compressor at the HRC would adequately power the
unit, but it did not. Through aging it was inadequate,
ran constantly, and overheated. As a result, we were
unable to use the N2 generator to pull down our CA
rooms.

In January, 1988, we rented a 15 HP air compres-
sor (which was oversized but available) so that we
could use the Nj generator to regenerate a CA atmos-
phere in a room that had been opened, partially emp-
tied, and re-sealed. We were pleased with its operation,
so in August, 1988, we purchased a new 5 HP genera-
tor. Later, it was attached to operate in tandem with

Fmil Notes, Summer, 1989

the existing compressor to provide the pressure and
volume of air needed to operator the N^ generator
efficiently.

In September, 1988, two 600-bushel CA rooms
filled with Mcintosh apples were sealed. One was
pulled down with liquid N2, and the other one was
pulled down with the Nj generator. With liquid Nj the
room was at 3% O2 in 1 hour. With the generator, the
other room reached 5% O^ in 26 hours, although at that
time the unit was being powered by only the new air
compressor.

After the two air compressors were operating to-
gether, the Nj generator was used to pull down a 2500-
bushel CA room filled with a mixture of "hard" culti-
vars. The generator pulled the room down to 13% O^ in
6 hours, and to 3% O^ in a total of 30 hours.

At various times, the generator was used to purge
O, from the storage atmosphere, to observe its opera-
tion. For example, at one point it reduced O2 from 3.7%
to 3.4% in 4 hours. The unit is effective for scrubbing
COj, since COj diffuses rapidly through the plastic
tubes, but in our system we maintain constant CO^
levels by adjusting continual flow through lime boxes,
so we did not use the generator for COj scrubbing.

In January, 1989, the 2500-bu room was opened,
800 bushels were removed, the room was resealed, and
the generator was used to pull down O^. In this partly
empty room, the unit required 24 hours to reduce O^ to
11%, and a total of 48 hours to reduce it to 7%. It then
took an additional 48 hours to reach 3% O2.

The hollow-fiber N^ generator exhibited a number
of attractive features during these operations. Once
the operator becomes familiar with its operation, the
unit requires Uttle "tinkering" and does not have to be
watched, so the operator is free to attend to other

duties. The unit has no moving parts, so it should
require very little maintenance and have a very long
operating life. It can maintain both O^ and COj in an
atmosphere as well as generate an atmosphere, al-
though we chose to use it for little more than genera-
tion. Also, it wiU combine with a computer-operated
CA system very easily, although we chose not to do this
due to other research objectives.

The two problems we encountered were first, the
high initial cost of the unit, and second, the absolute
need for adequate air compressor capacity. Operating
costs are limited to the power needed to operate the
compressor and to maintain the temperature of the
generator at 110°F.

The hollow-fiber generator will not pull down a CA
room as fast as can be done with liquid N2. However,
the pull-down rate is sufficient to optimize CA condi-
tions for apples, and the fact that the unit is always
ready to operate as soon as the room is sealed may save
time that would be spent obtaining liquid N, or prepar-
ing for its use. In the short-run, use of liquid N^ is the
less expensive method, but since the N2 generator
should have a long, trouble-free life, in the long-run the
costs may be comparable.

In summary, while our experience with the hol-
low-fiber, N2-generating system is not extensive, it has
been very positive. These units should have a secure
place in CA storage operations. While we have had no
experience with a pressure-swing adsorption unit, a
number of these are in use throughout the United
States and in other countries, and experiences with
them also have been positive. Thus, it appears that CA
storage operators have a number of effective options for
achieving CA atmospheres rapidly. The choice from
among these options will depend on personal and local
considerations.

•i^ ftf# «fA «f# 9S3

^« vj^ *^ *^ *4^

Fruit Notes, Summer, 1989

Seed Number in Apples Can Affect Calcium
Accumulation and Keeping Quality

William J. Bramlage, Sarah A. Weis, and Duane W. Greene
Department of Plant & Soil Sciences, University of Massachusetts

Apple growers are well aware of the importance of
pollination and seed development for fruit set. How-
ever, the importance of seeds continues throughout
fruit development, affecting not just the fruit but also
the tree. During experiments designed to test other
questions, we have observed some of these relation-
ships between seed number and fruit quality, which we
shall describe briefly here.

In a study of effects of growth regulators on Mcin-
tosh apples, we found that vdth increasing concentra-
tions of gibberellins A^^, and benzyladenine, an in-
creasing number of seedless fruit remained on the
trees and ripened. However, during and after storage
the amount of senescent breakdown that occurred
increased as growth regulator concentration that had
been applied to the fruit increased. When the fruit
were examined and analyzed, we found that the senes-
cent breakdown was mostly in seedless fruit, and that
the treatments were depressing fruit calcium concen-
tration at the same rate that they were increasing the
numbers of seedless fruit that matured. This result
suggested that calcium was much lower in seedless
fruit than in ones with seeds.

In a later study of effects of growth regulators on
Delicious apples, we again noticed large differences in

seed numbers among fruit, so samples from all of the
treatments were examined for size, seed number, and
mineral composition. The results are summarized in
Table 1.

There was a significant linear relationship be-
tween seed number and fruit diameter: the more seeds
in the apple, the larger the apple. This relationship has
been seen before with a number of different kinds of
fruit, so one effect of abundant seed development ap-
pears to be larger fruit size.

It is well known that increasing fruit size reduces
the amount of calcium in apples, yet as can be seen in
Table 1 there was a significant increase in fruit calcium
with increasing seed number. Thus, the extra calcium
drawn into the apple as a result of increased seed
number was greater than the dilution effect that the
increased size had on fruit calcium concentration. The
end result was larger fruit with more calcium in them.
In the case of magnesium, the data on Table 1 show that
it was reduced by seed number, but statistical analysis
showed that this reduction was merely the dilution
effect of larger fruit size. For potassium, seed number
had no effect. Therefore, the effect of seed number was
specific to calcium — increased seed number attracted
extra calcium into the fruit.

Table 1. Relationships of seed number per fruit in Delicious apples
concentrations.

to fruit size (diameter) and mineral

Seed number
per fruit

Average

diameter

(mm)

Mineral concentration'

Calcium

Magnesium

Potassium

0-1
2-3
4-5
More than 5

Significance^

67
70
71
72

*•

174
208
215
223

284
278
279
280

6700
6600
6600
6600

'Parts per million dry weight in outer cortical tissue.
''•*,significantly different at odds of 99:1; ns, not significantly different.

Fruit Notes, Summer, 1989

Percent of Total

without Breakdown
With Breakdown

to 1

2 to 3 3 to 4 5 to 6

Seeds per Fruit

7 to 8

Figure 1. Seed numbers for Mcintosh apples that did or did not develop senescent
breakdown after 6 months of storage in 32''F air plus 1 week at room temperature.
"Percent of total" is for each population — those that developed breakdown, and
those that did not develop the disorder.

In this experiment we did not determine the occur-
rence of disorders after storage of fruit, because there
were not enough fruit for a meaningful test. However,
in another experiment we had the opportunity to relate
seed number to keeping quality.

Bushel samples of Mcintosh apples had been col-
lected from 50 different blocks in commercial orchards,
and all had been stored at 32°F in air at the Horticul-
tural Research Center for 6 months. They were then
kept at room temperature for 1 week, and each fruit
was cut open, its seed number counted, and it was
recorded as to whether or not senescent breakdown
had developed.

The results are shown in Figure 1. We examined
the results as two populations of fruit — those that had
breakdown and those that did not have it. In the
population that developed breakdown, a high propor-

tion of the fruit had 3 seeds or less. In the population
that did not develop breakdown, most of the fruit had
5 or more seeds. A statistical analysis showed that a
real difference in seed number did exist between the
two populations. Thus, in these Mcintosh from com-
mercial orchards throughout Massachusetts, low seed
number appeared to be a contributing factor (though
certainly not the only factor) in development of senes-
cent breakdown, a disorder caused by calcium defi-
ciency.

These results demonstrate that low seed number
probably contributes to low calcium concentrations in
Mcintosh and Delicious apples, and also contributes to
calcium-related disorders during and following stor-
age. This means that one approach to maintaining
adequate calcium levels in apples is to pay careful
attention to pollination conditions in orchards. Seeds
are important contributors to fruit quality.

*i0 •{# ^0 «f« miM

w^ 0^ ^% «2^ «{%

Fruit Notes, Summer, 1989

The following "Items from Here and There" are reprinted from
Fruit Notes, June and Augfust, 1939.

Items From Here and There

William H. Ties

Department of Pomology, Massachusetts State College

Granville Grower Solves
Deer Problem

Karl Hanson, who owns an orchard in the town of
Granville, has constructed a wire fence which seems to
exclude deer in a section where much damage has been
done in previous years. Mr. Hanson had to replace
many of the trees in his orchard and found it impossible
to get satisfactory tree growth before the deer were
fenced out. The construction is briefly as follows. A
barbed wire is stretched along the ground to prevent
deer from getting underneath, and about 4 inches
above that is stretched a section of woven wire, 39
inches high. The top and bottom strands are number
10 wire and the rest number 13. Above the top of the
woven wire are 4 strands of heavy wire such as is used
in growing covered tobacco, these strands being spaced
as follows. The first, 8 inches above the top of the
woven wire, the others 10, 12, and 14 inches, respec-
tively. This makes a fence about 7 feet high. Mr.
Hanson has found no evidence of deer jumping such a
fence, although other growers have reported them
jumping as high as 8 or 9 feet. There are still plenty of
deer in that locality, although this orchard has been
unmolested since the fence was built 4 years ago.

Two Interesting Gadgets

Yankee ingenuity is still fairly common in Massa-
chusetts. Lee Rice of Wilbraham has devised a spray
tank filler by mounting a small pump, similar to that
used by the telephone company, on the front bumper of
his truck which carries a supply tank. The pump is
attached to the truck motor and makes possible the
filling of the tank from a brook or pond in short order.
Raymond Fiske of Lunenburg, instead of using a
wooden frame or barrel for support in spraying from
the top of the tank, has mounted an automobile tire at
that point, thus providing a rubber bumper effect for
weary bones.

A Square Deal Without
"Square Apples"

A campaign is underway in the Wenatchee district
to do away with "unnecessary and unwarranted mash-
ing of apples in the packing shed." An attempt is being
made to prevent a higher and higher bulge as the fruit
leaves the packing house. The contention is made that
there isn't the slightest reason for putting 45 lbs. of
apples into a box and then stamping them with a 40 lb.
stamp. Veiy often apples are not of uniform firmness
and when they are squeezed together in the lidding
process, the harder ones make virtually square apples
out of the softer ones.

Mcintosh Color Requirements
are Too Low

The color requirements for Mcintosh are too low,
according to Cornell Memoir 220, "Joint Correlation
Applied to the Quality and Price of Mcintosh Apples,"
published in March, 1939. After a detailed study of the
various factors which surround a Mcintosh apple and
of their relation to market price, the author, J. R.
Raeburn, says, "The relationships of color to price
indicated that apples with less than 67% of their skin a
good red characteristic of the variety should not be
permitted in the United States Elxtra Fancy grade, and
those with less than 33% should not be permitted in the
United States No. 1 grade."

Red Sports are Often Picked
Too Early

W. E. Piper reports a well known Boston dealer as
saying "A green Red Grav is worse than a green Green
one." This seems to suggest a tendency among growers
to pick red sports too early. If we harvest a Red Grav,
Richared or other red sport as soon as it takes on a red
color, we are sure to have a less edible apple than the
color would indicate and about the only thing worth
less than an immature, rubbery apple is two such
apples.

Fruit Notes, Summer, 1989

COOPERATIVE EXTENSION

U. S. DEPARTMENT OF AGRICULTURE

UNIVERSITY OF MASSACHUSETTS

AMHERST, MASSACHUSETTS 01003 0099

BULK RATE

POSTAGE & FEES PAID

USDA

PERMIT No G?r)8

OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300

SEPTAL

UNIV.

SECTION
LIBRARY

01003

Fruit Notes

Prepared by the Department of Plant & Soil Sciences.

University of Massachusetts Cooperative Extension,

United States Department of Agriculture, and Massachusetts Counties Cooperating.

Editors: Wesley R. Autio and William J. Bramlage

ISSN 0427-6906

B'OLOGfCAL

^^'^^ 1 7 1989

Volume 54, Number 4
FALL ISSUE, 1989

Table of Contents

The Use of Soil Applications of Gypsum to
Increase Calcium Content of Apples

Comparison of Slender Spindle and
Vertical Axis Tree Training

News from Other Areas

Trends in the New England Apple Industry

Advancements in Second-stage Apple IPM: Improving
the Attractiveness of Baited Red Spheres

Fruit Notes

Publication Information:

Fruit Notes (ISSN 0427-6906) is published the first day of January,
April, July, and October by the Department of Plant & Soil Sciences,
University of Massachusetts.

Correspondence should be sent to:

Fruit Notes

Department of Plant & Soil Sciences

205 Bowditch Hall

University of Massachusetts

Amherst, MA 01003

COOPERATIVE EXTENSION POUCY:

AJI chemical uses suggested in this publication are contingent upon continued registration. Thesechemicals should be
used in accordance with federal and stale laws and regulations. Growers are urged to be familiar with ail current state
regulations. Where trade names are used for identiHcation, no company endorsement or product discrimination is
intended. The University of Massachusetts makes no warranty or guarantee of any kind, expressed or implied,
concerning the use of these products. USER ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY
DAMAGE

ksuedby the University ofMassachusetts Cooperative Extension, Stevenson W. Fletcher, Acting Director, in furtherance <^
the acts of May 8 and June 30, 1914. The University ofMassachusells Cooperative Extension offers equal opportunity in
proffoms and employmenL

The Use of Soil Applications of Gypsum to
Increase Calcium Content of Apples

William J. Bramlage, Sarah A. Weis, and John H. Baker

Department of Plant & Soil Sciences, University of Massachusetts

The problem of calcium (Ca) deficiency in apples is
well known to our readers, as is the fact that we have
researched various ways of alleviating this problem for
many years.

There are four ways of improving Ca content of
apples:

1. Orchard practices to reduce competition between
leaves and fruit for available Ca.

2. Soil applications of materials to increase uptake of
Ca by apple tree roots.

3. Foliar sprays of Ca-containing materials.

4. Postharvest treatments with Ca-containing mat-
erials.

In general, soil treatments have been the least
effective method of improving fruit Ca levels, because
apple roots are very poor at absorbing Ca, which is one
of the most abundant minerals in soil. This problem is
increased by the very slow movement of Ca in an apple
tree, resulting in slow and perhaps diluted responses to
whatever improvement in Ca uptake that may have
been achieved.

Despite these problems, we have found that soil
applications of gypsum (hydrated calcium sulfate) can
increase apple frait Ca levels. An experiment begun by
Mack Drake and John Baker in 1976 first showed these
benefits, and another one begun by Bill Lord in 1980
expanded on those findings. Since the retirements of
Dr. Drake and Dr. Lord, we have assumed these experi-
ments and established a series of new ones designed to
answer questions raised by results from the original
experiments.

Research with soil treatments to influence apple
nutrition progresses very slowly. First, trees respond
slowly to soil treatments, and second, the soil is a very
complicated system and when you change it, you must
look at long-term effects of these changes. In 1987, we
reported the promising results from the studies of Dr.
Drake and Dr. Lord, and described some of the ques-
tions that needed to be answered (Fruit Notes 52(2):1-
4). Here, we have updated those earlier findings with
what we have recorded during the past two years.

In our 1987 article, we showed that 8 years of
annual gypsum treatments to soil beneath mature.

seedling- rooted Cortland trees had raised fruit and leaf
Ca levels, decreased fruit and leaf Mg levels, and had no
effect on fruit and leaf Klevels. The treatments had no
effect on fruit firmness at harvest or after storage, but
reduced the occurrences of bitter pit and senescent
breakdown after storage. A second experiment applied
to young Delicious trees also showed that gypsum
increased Ca, decreased Mg, and had no effect on K, but
no consistent effects on fruit quality were yet apparent
at that time. We pointed out that we did not know what
effects the treatments were having on soil propeities,
that we did not know what the optimum application
rate was, and that we did not know the economics of
gypsum treatments.

Currently, we have three long-term gypsum ex-
periments in progress. The first is a continuation of the
experiment begun by Dr. Lord in 1980, using a block of
Sturdeespur Delicious trees on MM. 106 planted in
1972. Trees in this block were given 0, 50, or 100 lbs. of
gypsum (0, 0.3, and 0.6 lbs. per sq. ft.) each April
through 1985, v^ath the gypsum spread beneath the
tree canopy. By 1985, it was apparent that both 50-lb.
and 100-lb. application rates were having the same
effect, so the 100-lb. rate was discontinued to deter-
mine how long effects would last after a gypsum treat-
ment was ended.

The second experiment was established in a block
of mature Cortland trees on M.7 rootstock planted
about 1962. These trees have a severe Ca deficiency,
and their fruit always develop high rates of bitter pit
and senescent breakdown. The objective was to see
what role gypsum treatments might play in trying to
control a chronic Ca-deficiency situation. Annual
applications of 0, 40, or 80 lbs. of gypsum (0, 0.25, and
0.5 lbs. per sq. ft.) beneath the tree canopy are made in
April or May. The experiment was begun in 1986 and
thus is in its fourth year.

The third experiment was established in 1987 in a
block of Cortland trees on M.7a rootstock planted in
1981. Trees received applications of 0, 8, 16, 24, 32, 40,
or 48 lbs. of gypsum (0, 0. 1, 0.2, 0.3, 0.4, 0.5, and 0.6 lbs.
per sq. ft.) in April, in an attempt to learn the optimum
rate of application.

FmU Notes, Fall, 1989

Percent of control

125

120

116

110

106

101

Percent of control

Fruit

High rate
diaoonllntMd

-^<-

Ca-

60# oypMim/lr**

-A-

Ca-

100# gypaum/tra*

-*-

Ma-

ao# sypaum/traa

-B-

Mo-

100# gypaum/traa

76'—
80

81 82 83 84 88 88 87 88

Year

Figure 1. Effects of low (50 Ibs./tree) and high (100 Ibs./tree) rates of gypsum, applied annually, on leaf
and fruit mineral composition of Delicious. The high rate was discontinued after 1985.

The soil type in these blocks is generally a Scituate
fine sandy loam, although depth to hardpan and spe-
cific soil characteristics varies somewhat among the
blocks.

Effects on Leaves and Fruit

In the Delicious experiment, we continue to see the
effects of gypsum on leaf and fruit mineral composition
that we repoi-ted earlier, that is, gypsum significantly
increases leaf and fruit Ca and decreases leaf and fruit
Mg (Figure 1), but has no effect on leaf and fruit K (data
not shown). The effects were quite consistent from
year to year, with about a 20% increase in leaf Ca and
a 10% increase in fruit Ca, and a 20% decrease in leaf
Mg and a 5% decrease in fruit Mg each year after
responses were established. This means that the re-
sponse is very reliable, and also that you can get only so
much response from a gypsum treatment: once the
response is established, it does not get bigger as you
continue to apply gypsum from year to year. It is also
clear that it takes time for the tree to respond to
gypsum treatments — in this case, it took 3 years after
treatments began before the responses were estab-
lished.

In the trees where gypsum applications were dis-
continued in 1985, it can be seen that levels of leaf and

fruit Ca and Mg continued to show the gypsum effect
for at least two years. In 1988, the third year, it
appeared that levels might be starting to change, but
we should have a much better picture of this after the
1989 analyses are completed. It may be that 3 years
represents the time needed for Ca to move from the
roots to the fruit in these trees, since it took this long to
see benefits of gypsum treatments, and perhaps this
long to see any result of ending the treatment.

The gypsum treatments had a very consistent ef-
fect on the occurrence of bitter pit in these fruit (Figure
2). Once the treatment effects were established, 5 to
10% less of the crop has developed bitter pit after
storage in the samples taken from gypsum-treated
trees, except in 1986 when no bitter pit developed in
any fruit. Again, as with the mineral analyses, it is
clear that only so much could be done to alleviate Ca
deficiency through gypsum treatments. They did not
work magic!

In the experiment with mature, Ca-deficient Cort-
land trees, leaf Ca wtis increased and leaf Mg was
decreased in the third year of treatment (Figure 3), as
with the Delicious. However, there was no effect on
fruit Ca or Mg, or on fruit quality, during the first three
years. Since these trees were larger than the Delicious
trees at the time their experiments were established, it
may be taking longer for the Ca to travel from root to

FmifAtoto, Fall, 1989

% Bitter pit

10-

— •— No oypaum

~A 100# gypsum/tr»«

High
rate
discontinued

Year

Figure 2. Effects of annual applications of
gypsum on the percent of fruit having bitter pit
after 6 months of storage in air at 32°F. Effects
were significant in 1985, 1987, and 1988.

Percent of control

110-
105;

- ^^'^^^'^^^^^^^^

<[>^^^'" *-^^

lOOlt- -^ _ ^~~'"^.^,__^_^

---. ^

»b-

-^ Ca- 401 gypHin/tiM

-^ C<- Mf gypiun/IrM

90-

-^ Mg- 40# oypMii/lr«e

-B Mg- lOf gypwn/lrsa

— \

86 87 B8

Year

Figure 3. Effects of low (40 Ibs./tree) and high
(80 Ibs./tree) rates of gypsum applications on
leaf mineral composition of Cortland. There
were no significant effects on fruit mineral
composition.

Table 1. Effects of different rates of gypsum application on leaf and fruit mineral

analyses. 1988. Treatments

were begun

in 1987 beneath 6-year-old Cortland trees |

on M.7a rootstock

Leaf

Fruit

Treatment

(Ibs./tree)

Ca (%)

Mg (%)

K(%)

Ca (ppm)

Mg (ppm)

K(%)

1.23

0.26

1.34

122

388

0.54

1.82

0.25

1.28

138

320

0.51

1.40

0.25

1.40

147

334

0.55

1.35

0.22

1.34

142

313

0.50

1.46

0.25

1.30

155

337

0.53

1.46

0.24

1.31

144

330

0.52

1.43

0.23

1.34

147

325

0.52

Significance

*••

•

Significance: ***,

odds of 999:1; *, odds of 95:1;

ns, not significant.

Fruit Notes, Fall, 1989

finiit in these larger trees. We should have a better
picture of effects when 1989 samples are analyzed.

A key experiment for us is the one in which differ-
ent rates of gypsum are being applied, as it will help
considerably in determining practical treatments. In
only the second year of application to these young trees,
results have begun to emerge (Table 1). Both leaf and
fruit Ca levels were higher in the gypsum treatments
than in the controls, vdth the hint that 16 lbs. per tree
might be as effective as 48 lbs. per tree. Both leaf and
fruit Mg were suppressed by gypsum, and neither leaf
nor fruit K was affected by it. It will require several
more years of data to establish response levels, but
these results suggest that much lower rates of gypsum
application than we have used in our previous experi-
ments may be just as effective. These results also add
to our view that tree size influences response time:
fruit on these small trees responded in two years, while
on the large Cortland trees, fruit did not respond in
even the third year of treatment.

Effects on Soil Properties

It is important to know what effects the treatments
are having on soil properties in order to judge long-
term effects of gypsum applications.

In 1988, we analyzed soil samples taken to hardpan
in April in both the Delicious block and the mature
Coitland block. Only the results for the Delicious block
are presented here (Figure 4), since the results from
the mature Cortland block were nearly identical.

Gypsum greatly increased the exchangeable Ca in
the soil throughout the entire soil profile. Thus, a huge
reservoir of exchangeable Ca has been created on the
treated soil. However, a shocking reduction of ex-
changeable Mg and K also occurred. It is surprising
that the suppression of leaf and fruit Mg has been so
small (Figure 1), and even more surprising that neither
leaf nor fruit K has been affected by gypsum treat-
ments. Apparently, in this soil, before treatment there
was much more exchangeable Mg and K than was
needed to feed the apple roots, but less Ca than is
desirable for optimum Ca uptake.

There was no consistent effect of gypsum treat-
ments on soil pH beneath the Delicious trees (Table 2).
Similarly, there was no effect on pH beneath the ma-
ture Cortland trees (data not shown).

Discussion

In 1987 we cautiously concluded that gypsum
treatments could improve fruit Ca levels and fruit
quality. Two more years of data remove some of the
caution from our conclusions.

It is evident that under our soil conditions, gypsum

Depth (cm)

2 4 a 8 10

meq Calcium/100 g soil

Depth (cm)

0.2 a4 oj as 1

meq Magnesium/ICO g soil

Depth (cm)

02 0.4 0.6 OJ 1

meq Potassium/lOO g soil

Figure 4. Effects of 8 years of annual applica-
tions of gypsum (501bs./tree) on exchangeable
Ca, Mg, and K at different depths of Scituate
fine sandy loam soil.

Frmt Notes, Fall, 1989

Table 2. Effects of eight years of annual appli- |

cations of gypsum

(501bs./tree)

on pH of soil at 1

different depths beneath Delicious apple trees.

Depth

(cm)

Control

Gypsum

0-10

5.4

5.8

10-20

5.4

5.5

20-30

5.4

30-40

5.5

5.4

40-60

5.3

60-80

5.2

Mean

5.3

5.4

treatments can improve fruit Ca levels and fruit qual-
ity. It is also clear, however, that benefits are limited.
Figures 1 and 2 convincingly demonstrate that only a
relatively modest improvement can be achieved, but
these Figures also show that a fruit grower can count
on this level of benefit once treatment responses are
established. Thus, it appears that gypsum treatments
have a role in trying to control Ca deficiency in apples,
but they are not a solution to Ca deficiency, a problem
that is a part of modern apple production.

We are still far from knowing what is the optimum
treatment of gypsum. It appears that we have applied
much higher rates than needed in our experiments to
date, but several more years of data will be needed to
clarify this. Likewise, we cannot tell yet whether or not
annual treatments are needed. Even though treat-
ments greatly increased exchangeable Ca in the soil,
one cannot assume that trees can continue to benefit
from this after annual treatment ceases.

It is clear from these data that there is a long delay
after gypsum is applied until the fruit begin to show
increased Ca levels and improved quality. Results
presented here suggest that at least two years are
required, and that in large trees even three years may
not be a long enough time. Responses of finiit to
gypsum come slowly!

It is also clear that a price is to be paid for improved
Ca levels in fruit: the reduction in leaf Mg. In the
results shown here, the reduction was small and did
not increase over time, although in Dr. Drake's original
gypsum experiment, the reduction in leaf Mg became
greater each year of treatment. The severe reduction in
soil exchangeable K is also troubling. Perhaps in other
orchards, leaf K might be reduced. There is also the
possibility that some other element, such as manga-
nese might be influenced by such large effects on soil

chemistry. Thus, it is imperative that an orchardist
who tries gypsum treatments employ a careful leaf
analysis program to monitor the mineral nutrition of
the trees.

It should be noted that gypsum is well known to
improve the physical properties of soil, and in particu-
lar to improve water penetration. Thus, gypsum may
help maintain good soil properties, especially in herbi-
cide strips where soils can lose their structure over
time.

It should be pointed out also that gypsum is not a
substitute for lime, and vice versa. As seen in Table 2,
gypsum did not change pH, so it did not change the
liming needs of the soil. Gypsum is much more water
soluble than lime, and quickly penetrates through the
soil profile (Figure 4). Lime, in contrast, quickly affects
only the soil area where it was applied, moving only
very slowly down through the soil. If an orchardist is
using gypsum, then liming should be done with only
dolomitic limestone, to help offset the loss of soil Mg
due to gypsum (Figure 4).

We cannot judge the economics of gypsum treat-
ments from our experiments. At this point, we do not
know what is the optimum rate of application, or
whether or not annual treatment is required. Also, we
do not know what is the most economical materied to
apply.

In our experiments, we have used mined, ground
white gypsum, which is relatively expensive. There are
other grades of mined gypsum, which, because they are
not white, cannot be used in wallboard and thus are
less expensive. Also, there are vast quantities of mate-
rials available at many power plants that are the result
of purging smokestacks of sulfur emissions. A series of
studies have suggested that these materials may be as
effective as mined gypsum when applied to the soils.
We have not used any of these materials, but they may
be available at little or no cost other than transporta-
tion. Indeed, use in orchards may be a desirable way of
disposing of such waste materials.

Clearly, many questions about use of gypsum or
gypsum-like materials to improve fruit Ca levels re-
main to be answered. However, our results strongly
suggest that treatments can produce consistent, albeit
modest, improvements in fruit Ca and quality. Such
treatments will not solve the Ca-problem in apples, but
may be a part of the program needed to cope with Ca
deficiency, which is such a general part of modern apple
production.

Acknowledgement

We wish to thank Agway, Inc., Syracuse, New
York, for their financial support during the course of
these experiment.

•S» *3* »i* *i* •!•

*{• 0g» *{* 0^ *g»

Fruit Notes, Fall, 1989

Comparison of Slender Spindle and Vertical
Axis Tree Training

Kathleen Williams

Washington State University

As the Pacific Northwest tree fruit industry moves
into the 2P' century, there will increasingly be an
emphasis on improving orchard labor efficiency and
fruit quality, as well as promoting early production.
Labor for pruning and harvesting operations is, and
will continue to be, the most expensive aspect of pro-
ducing fruit. Improved labor efficiency depends on
improved orchard design.

Large trees of the Pacific Northwest (PNW) cen-
tral leader system pose significant problems in terms of
orchard labor efficiency and fruit quality. We as an
industry are looking to other orchard systems, primar-
ily from western Europe, to improve our orchard effi-
ciency.

Two promising systems, the slender spindle from
the Netherlands and the vertical axis from France, are
currently under test in Washington State. Both of
these systems use a central leader tree with a support-
ing framework of laterals.

However, there are significant differences in prun-
ing and training techniques for producing trees in
either of these orchard systems in comparison with, the
PNW central leader system.

Slender Spindle

The slender spindle orchard system was developed
in the Netherlands in the mid 1960's and has been
refined throughout the past 20 years. The system was
developed to optimize light interception and distribu-
tion throughout the tree canopy under the low-hght
conditions in the Netherlands. Furthermore, the trees
had to be physically easy to train, prune, and maintain,
because the Dutch labor supply depends on the local
people. The trees also had to begin producing early to
repay the high initial capital expenditure required and
allow growers the option of replanting their orchards to
newer, more profitable cultivars.

The slender spindle and vertical axis systems were
developed and continue to be utilized primarily in the
management of non-spur cultivars such as Golden
Delicious.

The slender spindle tree is a pyramid-shaped tree
that is always planted on a dwarfing rootstock, mainly

M.9. Trees are supported with either a post or stake.
Tree height is maintained at 6 to 7 feet, and tree spread
is generally restricted to 3 to 3.5 feet in a single row
design. Tree density is 1,000 trees or more per acre,
depending on the tree spacing. (See Table 1.)

Training the Slender Spindle Tree

Year 1—At Planting

A branched or "feathered" nursery tree is always
preferable to a non-branched "whip" as planting stock,
because production wall occur at least one year earlier.
The branched tree is headed 10 to 15 inches above the
highest retained branch. If there are upright branches
present which cannot be trained to a more horizontal
angle, they are removed. Branches below 18 inches
above the soil line are removed, because they will
interfere with herbicide applications, and the fruit will
be too low for convenient and clean harvest. If a whip
is planted, it is headed 33 to 30 inches above the soil
line.

Year 1 - Summer (First Leaf)

Vigorous branches are tied or weighted down to
the horizontal with non-spur cultivars. For spur types,
a less extreme horizontal angle is appropriate, e.g., 45
to 60 degrees. It is important with spur types not to
train weak branches to a horizontal angle; the branches
will be devigorated by fruiting and will eventually
"runt out".

The optimum time for limb positioning, if tying or
weighing down, is mid July to mid August. However,
earlier improvement of branch angles v«th young
shoots three to six inches in length can be achieved
with clothespins or toothpicks.

Care must be taken to keep the terminal ends of the
branches at a horizontal or slightly vertical angle; they
should not be allowed to bend down, as this can cause
excessive vigor in the lower portions of the branch. On
spur types, extreme downward bending can be too
devigorating.

The first summer is when most of the pruning is
conducted on the young slender spindle tree. Vigorous

FruU Notes, Fall, 1989

Table 1. Comparison of central leader training systems for non-spur apple cultivars (after Barritt, 1984).

,4^

V&.

PNW Head & Spread

Vertical Axis

Slender Spindle

Tree height

10-15 feet

10-14 feet

7-8 feet

Tree spread

7-10 feet

4-6 feet

Spacing of single
rows

16-20 feet

13-16 feet

10-12 feet

Tree density

200-400 trees/acre

450-800 trees/acre

700-1100 trees/acre

Rootstocks

M.26, M.7, MM.106
MM. Ill, seedhng

M.9, M.26, M.7

M.9, Mark

Tree support

None

Pole & wires

Post or stake

At planting
head the tree

Yes

Select 3-5 permanent
lower scaffolds

Yes

Head leader in
dormant season

Yes

Pruning of central
leader after
year 1

Head into 1-yr-old

wood. To maintain

height, cut to lateral.

No heading. To maintain

height, cut to

replacement leader.

Head to competing

lateral on older

wood.

Remove central
leader to weaker
side shoot in
each dormant season

Yes

Head scaffolds in
dormant season

Yes

Spread or tie down
branches

Yes, 45°

Yes

Yes, to horizontal

Control limb length
by cutting back
into older wood

Yes

Yes, lower tier

Control limb length
by removal to trunk

Yes, upper limbs,
leaving a stub.

FmU Notes, Fall, 1989

upright branches which compete with the leader are
removed. The desirable branches to leave are weak and
horizontal.

Year 2 — Dormant Pruning
(First Dormant Season)

If summer training and pruning operations were
conducted during the first growing season, very little
dormant pruning is required. However, if vigorous
branches or upright grov^h were not removed, now is
the time to do this operation.

Vigorous growth should not be allowed to remain
for two seasons; the growth and vigor of the leader and
other lateral branches vdll be unbalanced.

The central leader is removed by heading into two-
year-old wood to a competing lateral. An alternative
method of central leader vigor control is to bend over
the central leader the previous summer, then return
the leader to the other side of the supporting post the
following spring (May or June).

In this method, no heading cuts are made during
the second winter. The leader of a non-spur cultivar
should not be headed into one-year-old wood.

The scaffold branches for the lower permanent tier
are selected; there are generally three to five perma-
nent lower branches. Scaffold branches are NEVER
headed into one-year-old wood, as this type of pruning
cut is too invigorating. Also, heading cuts into one-
year-old wood delay fruiting.

Year 2 — Summer Training and Pruning

As in year 1, limb positioning of lateral branches
should be continued and undesirable growth removed.
Proper limb positioning is critical for flower bud initia-
tion and development. Growth which competes with
the leader or is excessively vigorous should not be
allowed to develop during the growing season.

Timing and techniques for training and pruning
are the same as those for year 1 summer.

Years

The tree should be in commercial production by
year 3 (third leaf), if a branched nursery tree was
planted. Dormant and summer pruning utilize the
same techniques as employed in the first growing
seasons.

However, lower scaffolds will need to be shortened
with the use of stubbing cuts into two-year-old wood.
The leader v^all continue to be pruned to a replacement
lateral or tied over as in previous years.

Continued pruning of the central leader to a com-
petinglateral, which is then trained upwards results in

a central leader with a zigzag shape. This zigzag
configuration helps to reduce excessive growth in the
top of the tree as the tree matures.

Year 4

By the fourth leaf, maintenance pruning is con-
ducted. There are three major steps to remember:

1. Renew upper scaffolds: after a branch has fruited,
it is generally removed completely, leaving a short
stub.

2. Shorten lower scaffolds: head to aweak lateral on
older wood. This is used to restrict the tree to its
allotted space.

3. Control central leader growth: use either replace-
ment pruning or tying down. After year 5, the
central leader is generally controlled by cutting to
a competing lateral on two-, three-, or four-year-
old wood. Bending over the leader is not recom-
mended.

The same principles as outlined above are em-
ployed throughout the life of the mature slender
spindle orchard. Special caution is advised concerning
the vigor of the tree, particularly at the top of the
canopy. The growth MUST remain weak and must be
continually renewed after fruiting.

If the top is allowed to become vigorous and domi-
nant, the fruiting portion of the lower third of the tree
is eliminated. All parts of the tree must receive light.
Shading also reduces fruit quality.

The slender spindle system as described above is
the "pure" system. Modifications wall be devised to fit
Pacific Northwest growing conditions. The higher
light incidence and longer growing season in a desert
climate, as compared to the Netherlands where the
system was developed, will certainly mean that we
must adapt the slender spindle tree for our needs and
purposes. A taller slender spindle tree (eight feet)
would utilize light efficiency under Pacific Northwest
growing conditions.

It may be necessary to use more heading into one-
year-old wood than the original slender spindle system
allows. Treatment of the leader may be modified to
light tipping on varieties such as Granny Smith, which
may require more feathery growth at the top of the
canopy, and tying, rather than heading, for devigora-
tion.

Vertical Axis

The "axe centrale" or vertical axis tree training
system was developed by Lespinasse in the 1970's. It is
a central leader tree trained to a three- or four-wire

FmU Notes, Fall, 1989

trellis. Modifications of the trellis have heen success-
fully employed, such as a one-wire trellis with bamboo
stakes for individual tree support.

Generally, trees are 10 to 14 feet high, depending
on the rootstock used, and about five to six feet wide.
Rootstocks range from M.9 to MM. Ill under French
conditions, with MM. Ill recommended for severe re-
plant sites. Tree density ranges from 500 to 600 trees
per acre.

Trees are usually planted in single rows, as op-
posed to the multi-row bed system used frequently
with the slender spindle. The tree has a narrow
pyramid shape, with an open (sparse) top. (See Table
1.)

Training The Vertical Axis Tree

Year 1 - At Planting

If unbranched trees ("whips") are planted, it is
advisable to head the tree 30 to 33 inches above the

Figure 1. Do not allow vigorous growth to remain on the vertical
axis tree. The most desirable wood to retain is weak and horizon-
tal.

ground to force lateral branching. Preferably,
branched or feathered trees are utilized. As originally
described, heading of the central leader is not done. It
may be advisable to head the leader 10 to 12 inches
above the highest retained branch. This type of head-
ing cut encourages the development of a strong, perma-
nent lower tier of branches. As with the slender
spindle, branches that have poor angles, or that are
lower than 18 inches above the soil line, are removed.

Year 1 — Summer

Limb positioning is an important aspect of tree
training for the vertical axis. Weights and strings are
most commonly used. In a non-spur cultivar, branches
can be trained to the horizontal. For a spur type, a more
moderate branch angle, i.e. 45 to 60 degrees, is advised.
Early summer pruning is an essential part of tree
training. Branches that are overly vigorous with nar-
row angles are completely removed (thinning cuts) in
May and June, when three to six inches long. In fact,
if rigorous summer pruning is con-
ducted, little or no dormant prun-
ing is required the subsequent
winter. (See Figure 1.)

The leader must be supported
by tying it to the supporting pole.
Plastic tubing and tape are com-
monly used. Nylon string is not
advised, because of risks of girdling
the leader.

Year 2 — Dormant Pruning

No dormant pruning is re-
quired if summer pruning has been
utilized. If no summer pruning
was done, remove competing later-
als, vigorous upright growth, low
branches, and poorly placed
giowth. Do not head the leader.

Year 2 — Summer Training
and Pruning

Tree training and pruning
techniques are identical to those
used for year 1. Caution: do not
allow vigorous growth to remain on
the tree. (See Figure 1.) The most
desirable wood to be retained is
weak horizontal growth.

Year 3 — Dormant Pruning

Remove uprights and vigorous
branches. Do not head the leader.
Vei7 little pruning is required.

Fmit Notes, Fall, 1989

Year 3 - Summer Training and Pruning

As in the previous two summers, special attention
must be paid to eliminate overly vigorous fruiting
branches. In addition, the vigor of the top of the tree
must be controlled. One of the easiest methods of
controlling top vigor is to let the leader bend over above
the point of central leader support with the weight of
cropping. Later, the portion of the central leader above
the support that has become pendulant is removed
entirely. This process will likely be repeated in subse-
quent years. It is important to remove strong upright
growth at the top of the tree; this growth can interfere
with fruit bud formation in the bottom poilion of the
tree.

Year 4 — Dormant Pruning

The lower scaffolds are permanent branches and
must eventually be shortened. Shortening to lateral
branches is used to contain the lower scaffold branches
to their allotted space. Also, the weight of the crop
bends the branches downward, and so branches are
pruned to promote a more horizontal growth habit.
(See Figure 2.)

Vigorous growth is removed and replacement
branches selected in the upper poition of the tree. If a
branch has been fruited and requires replacement, an
angled stub is made. (See Figure 2.) A new branch will
emerge from adventitious buds and can then replace
the old branch.

Pruning the mature vertical axis tree employs the
same techniques as that of the slender spindle:

The lower permanent scaffold branches are short-
ened to weak lateral branches (preferably, fruiting
laterals) to contain their length.
The upper two-thirds of the canopy receive re-
newal pruning. Fruitinglaterals are not allowed to
remain in the tree for more than three or four
years. Constant renewal of the fruiting wood is
critical to keep the mature vertical axis tree pro-
ductive.

Light must reach every portion of the tree. If light
islimiting, production will be affected. Special care
must be taken to keep the top of the tree weak to
prevent shading in the bottom section of the tree.

Summary

Both the slender spindle and the veilical axis train-
ing systems are central leader systems. There is a
dependence on summer pruning for tree training (limb
positioning) and a lack of heading into one-year-old
wood. Renewal pruning and limb shortening are criti-

Figure 2. Vigorous growth is removed and re-
placement branches are selected in the upper
portion of the vertical axis tree.

cal to the success of these systems.

The systems differ in how the central leader is
handled. With the slender spindle tree, the centred
leader is headed into two-year-old wood (or older) to a
replacement lateral which is tied upward to continue
the central leader. In contrast, the vertical axis leader
is never headed, except at planting.

Both the slender spindle and vertical axis systems
will produce more quickly - if handled correctly - than
the traditional PNW central leader system. In addition
to earlier production, there is the advantage of im-
proved labor efficiency.

Changing to high density systems in the Pacific
Northwest will not be a matter of "if," but "when."

This article was reprinted from Good Fruit
Grower, June, 1989.

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FruU Notes, Fall, 1989

News from Other Areas

Editors' Note: The following two items are reprinted from "Garden," the Journal of the
Royal Horticultural Society, London, England in their August, 1989, issue.

Hope for National Fruit Collection

There is now more than a ghmmer of hope about
the future of the National Fruit Collection at the
Brogdale Research Station in Kent, which is under
threat from Government cutbacks. Having held the
collection in the past, the Royal Hoiticultural Society is
deeply concerned that the threatened closure of
Brogdale may mean the loss of the world's largest col-
lection of apple cultivars - an incomparable treasure
trove of genetic material for breeders and nurserymen
the world over.

Government ministers have now given a commit-
ment to secure the future of the collection for a few
years. What this entails is still uncei-tain and it is likely
that the Collection will need to be moved over the next
five years.

The Royal Hoiticulture Society was approached by
the Ministry of Agriculture, Fisheries and Food to
consider housing the Collection (apple cultivars in
particular) at the Wisley RHS Garden in Surrey, and
indicated that "it would be prepared to do this if the
source of funding for the maintenance was secured."
The Society already has 700 apple cultivars in cultiva-
tion at Wisley - a third of the Brogdale Collection.

Wye College, in Kent, offers another possible site
and the College is keen to take responsibility for the
National Fruit Collection - again provided adequate
funding is available. Wye is remarkably well placed for
the purpose. It is in the right location, has appropriate
soils and has the space and expertise to maintain the
Collection. The RHS would be happy to support the
College in its application.

There remains the problem of raising the one
million pound (about $1.5 million) endowment fund
estimated to be required to safeguard the future main-
tenance of the Collection. It is vital to the future of the
fruit-growing industry that this unique collection of
world-wide importance is saved.

Survey of Old Apple Cultivars

The National Council for the Conservation of
Plants and Gardens (NCCPG) is making a survey of old
cultivars held in small collections and as individual
trees in private gardens.

When completed it will be possible to assess which
cultivars are in the gieatest danger of becoming lost
and where the greatest effort must be made to save
them.

Initially all culinaiy and dessert cultivars (not ci-
der) produced before 1900 are being listed. This list
will be extended if necessaiy.

The NCCPG is asking for information from anyone
who grows old cultivars. The information they need is:

1. The names and numbers of each cultivar held in
collections or as individual trees.

2. Their approximate age.

3. The location.

If 'local' names only are known, please give these
with a brief description of the fruit and its season of
ripening.

As the Council anticipates a large number of re-
plies it regrets that letters cannot be answered. How-
ever, if the survey reveals that certain cultivars are in
a parlous state, the owners will be contacted with a
view to providing propagating material.

Please send details to: Mr. S. F. Baldock, Fruit
Collator for the NCCPG, Costrels, Eaton Bishop, Here-
ford. HR2 9QW. England.

Fruit Notes, Fall, 1989

Trends in the New England Apple Industry

Wesley R. Autio

Department of Plant & Soil Sciences, University of Massachusetts

New England fruit growers produce 7.8 million
bushels of apples on 24,000 acres of land. Figure 1
shows the acreage planted to apples in each of the New
England states. The size of individual orchards is
generally larger in northern New England (ME, NH,
VT) than in southern New England (MA, RI, CT)
(Figure 2). In northern New England 75% of the crop
is grown for a wholesale market; whereas, only 47% of
the southern New England crop is sold wholesale
(Figure 3).

In 1989 a survey was conducted to study the New

Acres (Thousands)

Figure 1. Total acreage of apple production in each
New England state.

Average acreage per farm

Figure 2. Average acreage per farm in apple pro-
duction.

Percent wholesale

62% for New England

Figure 3. Percent of the annual production sold in
a wholesale market.

England planting trends. (RI data are not included due
to insufficient returns.) Figure 4 shows the percentage
of each state's 1989 acreage planted before 1980, be-
tween 1980 and 1984, and between 1985 and 1989. The
least planting has been done in Maine, vnih only 18% of

100

Percent of total

Year ot planting:
^H Before 1980
^S 1980-84
1966-89

Figure 4. Percent of each state's total apple acre-
age planted before 1980, between 1980 and 1984,
and between 1985 and 1989.

FmU Notes, Fall, 1989

Mcintosh

Cortland

Delicious

Macoun

Paulared

Empire

Golden D.

Baldwin

Jersey Mac

N.Spy

\ ■> ^ V

■«+'

m 1970

IZ2 1976

■ 198d

)

^N 1994

I >

15 30 45 60

Percent of total

Mcintosh
Cortland

Vl'IVi'Vi'l'i

W#^

Delicious
Paulared

Macoun

Empire

Mutsu

Rome

)

Qolden D.

Baldwin

15 30 45

Percent of total

Mcintosh

Delicious

Macoun

Cortland

Empire

Golden D.

Idared

Rome

Paulared

Mutsu

^r^^ffg

15 30 45 60

Percent of total

Mcintosh

'i'['ivri'('iviV('tYtri^u

Delicious
Cortland

Golden D.

Paulared

N.8py

Macoun

Vista Bella

Jersey Mac

Empire

)

15 30 45 60

Percent of total

Mcintosh
Cortland

*w*

Delicious
Empire
N.Spy

Paulared

Spartan

Macoun

Qolden D.

Rome

1 1

15 30 45

Percent of total

Figure 5. The percent of the total acreage
planted to the top 10 cultivars. Data from
1970, 1976, and 1989 are included, as well
asprojections for 1994. The 1970 and 1976
data are from the New England Crop Re-
porting Service's 1970 and 1976 New
England Fruit Tree Surveys.

FniU Notes, Fall, 1989

Percent of total

^1980-84
■ 1990-94

Mdnto Cortia Empire Macoun Paular Libert Delici

70
60
50
40
30
20
10

Percent of total

■ • /

- /

1 IJ

J Fl^ B:^

Mclnto Libert RedFre Gala Cortia Empire Delici

Percent of total

r Jn P l JLFL -

Mclnto Cortia Jonago Empire Macoun Golden Delici

Percent of total

4^ 13-^

Mclnto Empire Cortia Libert Macoun Delici Paular

Figure 6. The percent of the total planted
acreage devoted to 7 different cultivars in
1980-84, 1985-89, and proposed for 1990-
94.

Mclnto Cortia Macoun Rome Mutsu Empire Delici

Fruit Notes, Fall, 1989

100

Percent of total

60 -

DJ 1970

■I 1989
.E3. 1994 .

.Ml

rJ-ru-l □ n

100

Sding MM lit MM 106 M.7 M2B M9 Mark lntr«tm

Percent of total

_□_

100

SdIng MM.111MU.106 M.7 M.26 M.g Mirk Intrttm

Percent of total

60 -

20 -

2 '

- ,

rfr

Sdlng MM.111MM.106 M.7 M.2e M.9 Mark Inlralm

100

Percent of total

JE^

_fi_Jfi

100

Sdlng MM.111MM.106 M.7 M.26 M.9 Mark Inlralm

Percent of total

■-^

^^n

-o S.

SdlfM] MM.111MM.106 M.7 M.26 M.9 Mark Inlralm

Figure 7. The percent of the total acreage
planted to various rootstocks. Data from
1970, 1976, and 1989 are included, as well
asprojections for 1994. The 1970 and 1976
data are from the New England Crop Re-
porting Service's 1970 and 1976 New Eng-
land Tree Fruit Surveys.

FmU Notes, Fall, 1989

'ercent of total

Percent of total

70
60
50
40
30
20
10

Sding MM.tt1 MM.106 M.7 M.26 U9 Mark Intritm

Percent of total

, Dbx.

y
-/
-/
:/
-/

/
/

WjI--

Sding MM.111 MM.106 M.7 M.26 M.9 Mark Intralm

Percent of total

60-

xfi

SdIng MM.111 MM.106 M.7 M.26 M9 Mark Intntm

Percent of total

SdIng MM.111 MM.106 M.7 M.26 M.9 Mark Inlratm

Figure 8. The different rootstocks that
have been planted during the periods 1 980
through 1984 and 1985 through 1989, and
are projected by growers for the period
1990 through 1994.

Sdino MM.111 MM.106 M.7 M 26 M.9 Mark Intratm

Fruit Notes, Fall, 1989

the acreage less than 10 years old. Vermont, on the
other hand, has 39% of its acreage less than 10 years
old. Based on the intent of growers, as expressed in the
survey, it is estimated that 16% of the acreage will be
replanted in the next 5 years.

The primary intent of the survey was to determine
cultivar trends. Figure 5 presents the top 10 cultivars
in 1989 for each state. Also included are data for 1970
and 1976. A projection for 1994 is given, assuming that
70% of the trees removed will be Mcintosh, 15% will be
Delicious, 5% will be Cortland, and the remaining 10%
will be small amounts of various other cultivars.

Mcintosh alone accounts for about 58% of the
acreage in New England and will continue to be the
primary cultivar; however, it is likely that the acreage
of Mcintosh will dechne in the next 5 years. Other
important trends in these data are the dramatic decline
of Delicious that has occurred and will continue to
occur, and the increases of Cortland, Macoun, Empire,
and Paulared.

Since a relatively small portion of the total acreage
is planted each year, the data presented in Figure 5 do
not give an accurate estimate of trends. Figure 6 gives
the planting which occurred during the last two 5-year
periods and is projected to occur during the next 5-year
period. It is clear that in all but Connecticut the per-
centage of trees planted which are Mcintosh will de-
cline over the next 5 years. Delicious has declined
dramatically as a percent of the total planting and will
continue to decline. Liberty, Jonagold, Redfree, and
Gala planting will increase substantially in the next 5
years. The disease-resistant cultivars alone will ac-
count for 10% of the planting during this time.

The percentages of the acreage planted to trees on

various rootstocks are presented in Figure 7. In 1970
approximately 90% of all of the trees in New England
were on seedling rootstocks. Now only 42% are on
seedling roots, with M.7, MM. 106, and MM.lll ac-
counting for 47% of the acreage. The 1994 levels were
projected eissuming that 90, 2, 3, 4, and 1% of the trees
removed in the next 5 years will be on seedling,
MM.lll, MM.106, M.7, and interstems, respectively.
The amount of the acreage devoted to trees on seedling
rootstocks will continue to decline, and the full dwarf-
ing rootstocks (M.26, M.9, Mark, etc.) will account for
significant portions of the acreage by 1994.

As with cultivars, overall levels do not give an
accurate picture of trends, since only small portions of
the acreage are replanted each year. Figure 8 shows
the planting which has occurred over the last two 5-
year periods and will occur over the next 5-year period.
Since 1980, most trees have been on M.7, MM. 106, and
MM.lll, accounting for 82% of the total. However, a
dramatic change will occur during the next 5 years,
with dwarfing rootstocks accounting for 62% of the
planting. Mark and M.26 will account for 28 and 22%
of the total, respectively.

The New England apple industry is experiencing a
great deal of change. The decline in Mcintosh and
increase in other cultivars is certainly related to the
loss of Alar^". An increase in the planting of disease-
resistant cultivars is likely related to the broader con-
cern about pesticides. The increased use of dwarfing
rootstocks is somewhat due to the loss of Alar, but also
may be related to an increasing interest in a smaller
tree vdth the potential for higher profitability. It is
clear that the New England apple industry is bracing
for the future vnth these important and necessary
changes.

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Fruit Notes Founder Dies

Wilbur H. Thies, Professor Emeritus, University
of Massachusetts, died July 29, 1989. He was born in
Leland, Michigan, October 24, 1892. He graduated
with a B.S. degree in 1919 and a M.S. degree in 1925
from Michigan Agricultural College (now Michigan
State University). In 1924 he joined the Horticulture
Department at Massachusetts Agricultural College

(now University of Massachusetts) as Extension Hor-
ticulturalist. In July, 1935 he founded Fruit Notes and
continued to write for and edit it until his retirement
from the University on February 1, 1955. Memorial
services were held September 30, 1989 at the North
Congregational Church of Amherst, Memorial gifts
may be made to one's favorite charity.

Fruit Notes, Fall, 1989

Advancements in Second-stage Apple IPM:
Improving the Attractiveness of Baited Red
Spheres

Ronald J. Prokopy, Jian Jun Duan, Patricia Powers,
and Max P. Prokopy

Department of Entomology, University of Massachusetts

We previously reported [Fruit Notes 54(1): 1-5] on
results of the second year of our pilot second-stage
apple IPM program in Massachusetts commercial or-
chards. One of the major elements in second-stage IPM
is the use of red spheres baited with synthetic apple
odor for intercepting immigrating apple maggot flies at
the orchard perimeter. We concluded that before such
an interception system for maggot fly control could be-
come broadly successful on a commercial level, some
improvements would be needed. One improvement
might be enhancing the attractiveness of spheres to
apple maggot females, to ensure better capture of a
high proportion of females flying from border areas
onto apple trees at the orchard perimeter. Here, we
describe results of 2 studies conducted in 1989 toward
this goal.

The first study involved evaluating different sizes
of unbaited red spheres. More than a decade ago [Fruit
Notes 41(6):6-9], we found that spherical shape (mim-
icking apple shape) was more attractive to maggot flies
than cubical, cylindrical, or rectangular shape. We also
discovered that red and
black spheres were equally
attractive as colors and
more attractive than
green, orange, yellow, or
white spheres. We chose to
use red spheres over black
ones to permit better vi-
sion of a captured maggot
fly. Finally, we found that
8-cm-diameterred spheres
were more attractive than
spheres of 4,6,15,23,30, or
45 cm in diameter. Here,
we wondered if there were
any sphere size between 8
and 15 cm that might be
more attractive than the 8

We purchased softballs (10 cm), toy balls (14 and
18 cm), and volleyballs (23 cm), painted them the same
red color as our standard 8 cm croquet balls, coated
them v^ath sticky, and hung them in non-sprayed fruit-
ing apple trees harboring a low population of apple
maggot flies. Foliage and fruit within 10 cm of the
sphere surface were removed. Periodically, the
spheres were rotated to provide equal time for each size
at each position.

Although the low fly population precluded sub-
stantial fly captures, the results (Table 1) do nonethe-
less indicate a consistent pattern of greater captures of
females on 8 cm spheres than on spheres 10 cm or
larger in size. Other recent studies we have carried out
indicate that apple maggot female response to fruit of
different sizes is partly under genetic control and partly
a learned response based on recent experience with
fruit of a particular size. From our results here, it
appears that if an apple or a red sphere mimicking an
apple is larger than 8 cm, neither genetic-based nor
learned behavior of females confers strong attraction.

cm size.

Table 1. Total apple maggot females captured on unbaited sticky red
spheres of different sizes hung in unsp rayed fruiting apple trees (July 27-
August 8, 1989).

Size of

sphere (cm)*

Experiment 1

Experiment 2

Experiment 3

7 a

9 a

11 a

7 ab

1 b

•No. replicates per experiment: Expt. 1 = 5; Expt. 2 = 8; Expt. 3=8. Values
not followed by the same letter are significantly different at odds of 19 to
1.

FmU Notes, Fall, 1989

Perhaps apples and red spheres increasingly larger
than 8 cm decreasingly have the appearance of fruit in
the eyes of flies whose native host is hawthorn fruit,
which are only 1.5 to 2.0 cm in diameter.

The second study involved evaluation of different
numbers of vials containing synthetic apple odor
placed at different distances from 8 cm sticky red
spheres. At the New York Agricultural Experiment
Station in Geneva, where Anne Averill, Harvey Reis-
sig, Wendell Roelofs, and others showed butyl hex-
anoate to be the principal component of apple odor
attraction to apple maggot flies, liquid butyl hexanoate
has been used to monitor fly populations by putting it
into small (2-dram) polyethylene vials seated in wells
drilled into 8 cm red spheres. The liquid is absorbed by
the wall of the vial, which then releases about 700 apple
equivalents of the odor per hour. In the first 2 years of
our pilot second-stage apple IPM program, we placed
such a polyethylene vial containing butyl hexanoate
about 15 cm to the side of each 8 cm sticky red sphere
hung on perimeter apple trees. However, recent re-
search conducted by graduate student Martin Aluja of
our laboratory suggested that a polyethylene vial re-

Table 2. Total apple maggot females captured on 8 cm
sticky red spheres hung in fruiting apple trees in a com-
mercial orchard and baited with different numbers of 2-
dram polyethylene vials containing attractive apple odor
(butyl hexanoate) at different distances from the side of a
sphere (July 21 - August 3, 1989).

Distance of vials
from sphere (cm)*

Number of vials around each sphere

47 b 70 b 92 b 78 b

67 b 66 b 149 a 92 b

70 b 83 b 96 b 101 b

leasing 700 apple equivalents of butyl hexanoate per
hour may arrest or even repel apple maggot flies that
move too close to the vial. We were therefore interested
in determining the optimum density and distribution
of polyethylene vials (containing butyl hexanoate) that
would confer high fly attraction to the vicinity of a red
sphere but not adversely affect the propensity of an
arriving female to alight on the sphere.

Our test was carried out in Clarkdale Orchard,
West Deerfield, MA, which harbored a moderate popu-
lation of apple maggot flies on a mixture of Early
Mcintosh and Gravenstein test trees. We placed no
more than 1 sphere in each tree. Using wire, we posi-
tioned either 0,1,2, or 4 2-dram polyethylene vials of
butyl hexanoate 15,30, or 60 cm to the side of a sphere.
Where more than 1 vial per sphere was used, vials were
distributed evenly around the sphere. Periodically, the
vials were rotated from tree to tree to provide equal
time for each treatment at each position.

The results (Table 2) indicate that 2 vials of odor
placed 30 cm to the side of a red sphere gave rise to a
50% greater capture of apple maggot females than vials
at any other density or distribution. Use of 2 or 4 vials
per sphere invariably led to greater fe-
male captures than vials or 1 vial at an
equivalent distance. Thus, butyl hex-
anoate used in conjunction with red
spheres led to increased capture of apple
maggot females, but too great an amount
too close to a sphere reduced fly captures,
possibly through arresting or repelling ef-
fects.

For future employment of red
spheres to intercept apple maggot flies on
perimeter apple trees under second-stage
IPM, we will continue to use 8 cm spheres
but will now bait each sphere with two 2-
dram polyetheylene vials of butyl hex-
anoate 30 cm from (and on opposite sides
of) each sphere, instead of a single vial 15
cm from a sphere.

• Four replicates per treatment type. Values not followed
by the same letter are significantly different at odds of 19
to 1.

ACKNOWLEDGMENT. We thank
the Northeast Regional Project on Inte-
grated Management of Apple Pests (NE-
156) for supporting this work.

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Fruit Notes, Fall, 1989

Fruit Notes

University of Massachusetts

Department of Plant & Soil Sciences

205 Bowditch Hall

Amherst, MA 01003

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