Full text of "Fruit notes of New England"

University of
Massachusetts

Amherst

L I B R

jivl/Mor

Volume 67, Number 1
WINTER ISSUE, 2002

fleiJuCnaland

Table of Contents

Apple-pomace Compost and Pre-plant Monoammonium Phosphate for Improving the Growth of Newly Planted Apple Trees

R.E. Moran and ].R. Schupp 1

Development of a Model for Predicting Flyspeck Risks in Blocks of Apple Trees

A. Tuttte, C. Bergweiler, J. Hall, L. Reisner, S. Christie, W. Autio, and D. Cooley 5

Effects of Gibberellin Synthesis Inhibition on Feeding Injury by Potato Leafhopper on Apple

K. Leahy, D. Greene, and W. Autio 9

Food Quality Protection Act: An Organophosphate Update - February 2002

G. Morm 13

Food Quality Protection Act: Cumulative Risk Assessment for the Organophosphate Pesticides

R. Spitko 16

Commercial-orchard Evaluation of Traps for Monitoring Plum Curculio: 2001 Results

R. Prokopy, B. Chandler, and ]. Pinero 17

An Odor-baited "Trap-tree" Approach to Monitoring Plum Curculio

R. Prokopy 23

IMPORTANT SUBSCRIPTION RENEWAL INFORMATION 25

rleu/Cngiand

Editors:

Wesley R. Autio
William J. Bramlage

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Fruit Notes

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Apple-pomace Compost and Pre-plant
Monoammonium Phosphate for
Improving the Growth of Newly Planted
Apple Trees

Renae E. Moran

Department of Animal and Horticultural Sciences, University of Maine

James R. Schupp

Hudson Valley Laboratory, Cornell University

In many orchards in the Northeast, early yield is
limited by tree growth, and trees are typically not
cropped until the third or fourth season because growth
IS not vigorous. Management practices that encourage
rapid early tree growth and early fruit production result
in economic advantages to growers by hastening a
return on investment. Decreasing the time required for
trees to fill their space would allow growers to increase
early yields.

Increasing early tree growth can be accomplished
by adding organic matter or phosphorus fertilizer to
the planting hole. Adding compost as a source of
organic matter to planting holes affected young apple
tree growth in experiments in Massachusetts and
Maine. Organic matter is often low in many existing
orchard soils. Increasing soil organic matter improves
its water and nutrient holding capacities, which
enhances root regeneration and promotes overall tree
vigor, but the effects of planting-hole treatments are
most visible during the year of planting. As root
growth extends beyond the volume of the planting
hole, the effects of planting-hole treatments diminish.
If organic matter amendments were broadcast
throughout the orchard soil, perhaps the beneficial
growth response could be sustained for a longer
period. For pre-plant compost to be a feasible
management practice, an economical, local source of
compost must be available. University of Maine
Cooperative Extension developed an apple-pomace
composting project in cooperation with Chick
Orchards in Monmouth, Maine. Apple pomace from
the cider operation was mixed with leaf waste from the

local waste transfer station, and chicken manure from
a local egg farm at a 2:6: 1 ratio by volume. Wood ash
was used to adjust the pH to 5.8 prior to composting.
Composting reduced the volume of apple-pomace
waste by 50% and converted it into a soil amendment
with highly desirable characteristics.

Newly transplanted trees have impaired root
systems, so P fertilizer is often recommended for new
plantings. Since P is very immobile in soil, this
nutrient is more beneficial when it can be incorporated
prior to planting. Research in British Columbia has
shown that monoammonium phosphate (MAP 1 1-55-
0) fertilizer, incorporated into the soil used to fill the
planting hole, increased tree growth in the first 2years
after planting and increased flower production and
fruit set in the early years of the planting. The addition
of MAP to the planting hole has become a common
practice in B.C. orchards, especially when replant
problems are anticipated. It has been suggested that
root uptake or utilization of P may be more efficient in
the presence of ammonium. Moreover, MAP could be
influencing tree growth by providing N. This study
was performed to determine if pre -plant-incorporated
apple-pomace compost and MAP, either alone or in
combination, would improve early apple tree growth
and precocity.

Methods

This experiment was conducted at Highmoor
Farm in Monmouth, Maine, on land which had been
fallow for 6 years, but in continuous apple production

Fruit Notes, Volume 67, Winter, 2002

for the previous 37 years. The soil was a fine sandy
loam, with a pH of 6.8 and an organic matter content of
4.7% before the addition of fertilizer or compost.
Macoun/B. 9 apple trees were planted using a tractor-
mounted tree planter on May 1,1998 into plots that had
received one of the following combinations of pre-
plant treatments: 1 ) urea fertilizer without compost; 2)
MAP fertilizer without compost; 3) both compost and
urea; and 4) both compost and MAP. Each plot
consisted of three trees at a spacing of 6 feet between
trees and 18 feet between rows. Cortland/B. 9 trees
were planted as a buffer between plots. Prior to
planting, MAP was applied to the plots at a rate of 332
lbs. per acre and urea at a rate of 79 lbs. per acre, so that
each treatment received an equivalent amount of N
(1 .44 oz. per tree). Apple-pomace compost was spread

over the planting strip and leveled to a uniform
thickness of 4 inches. All plots were then roto-tilled to
a depth of 6 inches. The trees were unfeathered whips,
headed to a height of 28 inches at planting. The trees
were attached to a galvanized conduit stake supported
by a single wire at 7 feet. The trees were minimally
pruned, and trained to the vertical axis system.
Insecticides, fungicides, and herbicides were applied
as needed.

Results

Tree growth was increased by compost, but not by
MAP. Compost increased trunk diameter in the first
two seasons, but by the third season, trunk diameter
was similar in both plots (Figure 1). Annual shoot

;£ 0.8

"S 0.6

^ 0.4

.- 0.2 H

I I No Compost
H Compost

200

One"

Two'

Three

One*

Two Three

Two

Three* Four

Three'

Figure 1 . Tree growth characteristics with and without pre-plant-incorporated compost. * Indicates that
compost had a significant effect in the indicated year after planting.

Fruit Notes, Volume 67, Winter, 2002

Table 1. Orchard soil properties following
compost (year of planting).

soil incorporation of phosphorous or

apple pomace

Treatment pH

Organic P
matter (%) (lbs / acre)

K
(lbs / acre)

Mg
(lbs / acre)

Ca
(lbs / acre)

Urea 6.4
MAP 6.4
Compost-Urea 6.9*
Compost-MAP 6.8*

4.5
4.4
5.3*
5.6*

9.9
13.0
79.6*
86.8*

285
272
679*
612*

291
301
496*

457*

2144
2071
3258*
3093*

* Indicates a significant effect due to compost

at odds of 1 9 to 1 .

growth was increased by compost in the first
season, but not significantly in the second or third
season. By the third season, tree height was
greater with compost. Compost increased the
amount of bloom. MAP had no effect on trunk
growth, shoot growth, number of growing points,
or tree height in any season of the study. We were
unable to determine if the increases in tree size
and flowering were large enough to increase early
yield, because the trees did not attain sufficient
size to permit cropping until after the third
growing season. The trees in this study were on
B.9 rootstock, which is less vigorous than M.9
EMLA, and may be insufficiently vigorous for
spur-type varieties such as Macoun in northern
New York and New England.

Tree growth was increased by pre-plant-
incorporated apple-pomace compost, similar to
results of other studies that showed organic matter
added to the planting hole increased shoot growth
and trunk girth. In those studies, the effect of
planting hole treatments was no longer evident by
the second or third season, and this result was
attributed to roots growing beyond the planting
hole. In our study, the effect of pre-plant organic
matter on trunk diameter and shoot growth also
diminished with time. The diminished effects
observed in our study were possibly due to the
depletion of soil K, Mg, and Ca (data not shown).
Soil K in the compost plots was twice as great as in
non-compost plots, but this difference was much
smaller by the third season. Although trunk and
shoot growth differences diminished with time,

4
3.5

3
2.5

2 H
1.5

1
0.5

2.5

S^ 2

i 1.5

C/)
TO

CL '

N+—

^ 0.5

No Compost
Compost

One'

Two* Three'

One"

Two*

Three"

Figure 2. Leaf nitrogen and potassium with and
without pre-plant-incorporated compost. *Indicates
that compost had a significant effect in the indi-
cated year after planting.

Fruit Notes, Volume 67, Winter, 2002

the greater tree height and bloom were evident in the
third season indicating that the cumulative effect of
compost on tree size was not short-lived.

Soil fertility was enhanced by the addition of
compost, but little influenced by the addition of MAP,
as shown for the year of planting in Table 1. The
addition of compost resulted in higher soil pH and
cation exchange capacity in each of the three seasons
after planting, compared to the plots without compost
(data not shown). Compost increased both soil organic
matter and P, while MAP and urea had no effect.
Compost also increased soil Mg, Ca, and K.

Compost increased tree growth and flowering by
improving soil fertility and tree nutrient status, and
most likely, by increasing soil water holding capacity
and soil aeration. An increase in the water holding
capacity of the soil would have been advantageous in

1998, when the newly planted trees were generating
new roots to replace those lost in transplanting, and in

1999, a season in which little precipitation occurred
before September. Foliar nutrient status was favorably
affected by compost (Figure 2). Compost increased
leaf N and K compared to trees in plots without
compost in all three seasons after planting. Leaf P and
Ca were not affected by compost. There was no
difference between urea and MAP in their effect on
leaf N or K, or leaf P, Ca, or Mg. Compost decreased
leaf Mg in the first season after planting, but had no
effect in the second or third season. The large increase
in soil K following compost incorporation may have
interfered with Ca and Mg uptake, so that even though
soil Ca and Mg were greater, foliar levels were not.
Leaf micronutrients were not affected by any of the
pre-plant treatments.

Pre-plant incorporation of P fertilizer had no effect
on tree growth or flowering in this study. In British
Columbia, P fertilization previously has been shown to

increase flowering when it results in greater leaf P. In
our study the soil level of P was within the optimum
range before treatment, and was increased to above
optimum by compost. Although the level of P in the
soil was increased with compost, there was no increase
in foliar P. These results are consistent with most
previous studies in showing no benefit from P
fertilization for apple.

Conclusions

Pre-plant compost incorporation was more
effective than P fertilization for increasing tree growth
during the establishment years. The practice of adding
P to the planting hole may not be appropriate for
Northeastern sites, particularly those where the soil
test indicates that P is adequate before planting. Soil
incorporation of compost increased tree growth and
flowering into the third year after planting. This was
most likely due to improved N and K status of the trees,
and through improved soil aeration and water-holding
capacity. Our results suggest that trees planted in soil
amended with apple-pomace compost would poten-
tially fill their space more quickly and be able to
support more fruit growth in the first years of cropping.

Ackno H'ledgem en ts

This project was supported in part by a grant from
the New England Tree Fruit Growers Research
Committee. The authors wish to thank Chick Orchards
for supplying the compost, and the technical staff at
Highmoor Farm for their assistance with this research.
Special thanks go to John McCue, Sheri Koller, and
Michelle Handley for maintaining this project during
the transition between project leaders.

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Fruit Notes, Volume 67, Winter, 2002

Development of a Model for Predicting
Flyspeck Risks in Blocks of Apple Trees

Arthur TYittle, Christopher Bergweiler, James Hall, Lisa Reisner, Steven Christie,
Wesley Autio, and Daniel Cooley
University of Massachusetts

For several years, we have been working toward
the elimination of summer fungicide applications in
apple orchards. The positive economic and
environmental impacts of achieving this goal are
considerable. Unfortunately, in the absence of
fungicides, the severity of flyspeck disease, and to a
lesser extent sooty blotch, can be significant. In apple
trees which are not sprayed in the summer, flyspeck
incidence varies dramatically, from barely existing in
some blocks of apple trees to infesting more than half
the fhiit in others.

How do we decide which trees need spraying and
which do not in a given year or month? We know that
the flyspeck fungus needs very high relative humidity
(97-100 %) to develop. By tracking leaf wetness,
rainfall, relative humidity, and temperature we can
estimate when specks will first show up in unsprayed
trees in or near an orchard. We can also estimate when
spray residues will be removed from apple trees by
rain, thanks to studies performed by Dave Rosenberger
at Cornell University's Hudson Valley Laboratory. It
remains a challenge, however, to estimate severity of
symptoms at harvest for a given block of trees.

Certain characteristics of blocks of apple trees,
such as slope, relative altitude in the orchard, and
spacing of rows and alleys are likely to influence air
drainage and relative humidity in the blocks. The size
and openness of tree canopies will also affect the
humidity surrounding an apple. The consensus among
plant pathologists working with apples is that the
inoculum for flyspeck disease overwinters on the waxy
cuticle of alternate host plants like blackberry, oak,
grape, and maple in wooded or shrubby borders near
the apple trees. Within the orchard block, flyspeck
does not colonize apple twigs. Flyspeck that grows on
fruit is removed at harvest or decays over the winter
on drops. The orchard border is home to over 100
species that maintain waxy cuticle suitable for flyspeck

and sooty blotch over a 12-month period on first year
growth.

Many relationships involving the block and the
borders seem worthy of investigation. Number and
size of borders around a block, distance between a block
and its borders, density of alternate host plants in the
borders, and density of the fungus on those hosts might
all have significant impacts on summer diseases in fruit
at harvest. We study these factors and their
relationships to flyspeck disease development in order
to create a predictive model to help growers safely
reduce fungicide inputs.

We reported on the first part of this study in the
Spring 1996 issue of Fruit Notes. This experiment
took place in six orchards over the 1995 and 1996
growing seasons. In each orchard, pairs of similar
blocks of apple trees were chosen. Some orchards
dedicated as many as 13 pairs of blocks to this
experiment. At each orchard, one block received no
fungicide after primary scab season (approximately
June 15), while the other block was managed according
to the grower's preferences using standard first-level
IPM. Flyspeck incidence was recorded weekly by
examining 200 fruit in each block from late-July
through mid-September. For each block, the following
orchard site characteristics were evaluated and
compared statistically to the flyspeck incidence or
severity data: slope of the ground, relative elevation
of the block compared to other blocks in the orchard,
closeness of shrubby or wooded borders to the apple
trees, density of a major alternate host plant in the
borders (blackberry), severity of flyspeck infestation
on those host plants, and density of apple tree canopies.

Table 1 lists the orchard site factors that had the
greatest effects on the flyspeck counts that were done
in the in 2-week period leading up to harvest in 1995
and 1996. Unless otherwise noted, analyses for this
report were performed on data from the blocks which

Fruit Notes, Volume 67, Winter, 2002

Table 1. Characteristics of blocks of apple trees or adjacent wooded or shrubby borders that positively affected the

amount of flyspeck on apples: in

order of

significance.

August 20 through harvest

August 20 through harvest August 29 through harvest

1995

1996 1995, 1996, 1998, and 1999

1. Lack of slope of block

1. Density of flyspeck on 1. Density of flyspeck
brambles in border on border host plants

2. Low relative elevation

2. Lack of slope of block 2. Number of borders

within the orchard

3. Height of apple trees

3. Closeness of apples to
borders

4. Density of brambles in

4. Lack of slope of block

border

5. Closeness of apple

trees to a border

received no summer fungicide. First-level IPM blocks
did not have enough flyspeck to analyze. In 1 995, there
were more flyspeck symptoms in blocks that were
relatively flat than in steep-sloped blocks (r", or amount
of variation explained, was 0.17, or 17%), and the
amount of flyspeck was higher in blocks that were
relatively low in elevation within the orchard (r- =
0. 12). Other factors that had positive but less significant
impacts (r^ < 0.03) were height of apple trees, proximity
of apples to border areas, and density of host-plants in
the borders.

hi 1996, the significant site factors (Table 1) were
density of flyspeck on host-plants in borders (r^ = 0.13),
lack of slope of the block (r^ = 0.05), and height of the
apple trees (r^ = 0.04). The factors which contributed
only marginally to explaining the variability in flyspeck
incidence (r^ < 0.03) were number of borders adjacent
to a block of apple trees and proximity of brambles in
the borders to the apples.

In summary, the site factors that were the most
important during 1995 and 1996 (explained at least
10% of the variability) were slope and relative
elevation in 1995 and density of flyspeck on host-
plants in borders in 1996.

In 1997-1999, a different group of blocks was
evaluated for site factors and flyspeck infection. In
this experiment, two of the key factors were planting
density/tree size and IPM level. A main objective of
the study was to evaluate the effectiveness of the range

of IPM strategies that had been developed using fairly
large semi-dwarf trees on plantings that included dwarf
trees at high densities. Each of eight participating
orchards provided two blocks of low density/large trees,
two blocks of medium density/medium-sized trees, and
two blocks of high density/small trees. The blocks that
had the same planting density were divided into two
groups: half were managed with first-level IPM
strategies and half with "third-level" IPM strategies.
The progression to third-level IPM was marked by the
integration of advance pest-management strategies with
horticultural strategies at the level of the whole orchard.
The third-level blocks, which were seeded with
beneficial mites and were managed with biologically-
based third-level strategies for insects, received reduced
rates or frequencies of fungicide applications, little or
no EBDC fungicide, and only captan or benomyl after
June 15. The first-level blocks were managed with the
growers' choices of materials and frequencies of
application. The blocks within a pair were not
contiguous. They were often at either end of a long
section of 'Mcintosh' or 'Cortland' rows and were
bordered by a wide variety of habitats. Some of the 48
blocks were surrounded by other rows of apple trees,
some by grassy fields, others by dense woods or
shrubby hedgerows.

During each growing season, the blocks and their
surrounding borders were rated for static orchard
factors which had proved significant in the earlier study.

Fruit Notes, Volume 67, Winter, 2002

These included: number of borders potentially
influencing flyspeck development in an orchard block,
distance between the trees and the borders, severity of
flyspeck in alternate host plants in the borders, density
of host plants themselves, foliar density of trees, height
and diameter of tree canopies, slope and relative
elevation of the block with respect to the orchard as a
whole, and planting density of the block (no. trees/
acre). We examined all known host plants (from the
ground to 6 ft. above ground), not just blackberry.
Apples in the adjacent blocks were examined weekly
or bi-weekly from mid-July to harvest.

At the end of each growmg season we looked at
the effect of each of the above-mentioned site factors
(and all factors combmed) on the amount of flyspeck
on the apples, to begin deriving a predictive model for
flyspeck mcidence at harvest. Prelimmary stepwise
regression analyses done separately for each year
suggested the importance of four variables: density
of flyspeck on alternate host plants in ttie borders,
number of borders, distance from apples to border,

and slope of the block. The other site factors did not
explain substantial amounts of the variation in flyspeck
incidence.

Combining data collected from unsprayed control
trees from the years 1995, 1996, 1998, and 1999, we
conducted a preliminary assessment usingg flyspeck
incidence data from various dates. Data from 1997
were not used, because all blocks received summer
fungicide sprays. Dates at or near harvest varied from
year to year primarily due to cultivar and weather
factors. Ultimately, we decided on a range of dates
allowing maximum inclusion of orchards in the data
set. Data from harvest or near-harvest ranged from 29
August to 23 September for the 4 years used in the
analysis.

We concluded the static factor phase of model
building by combining these four independent variables
with the most inclusive range of harvest dates and a
fifth derived variable, inoculum index. Inoculum index
was expressed as the product of amount of flyspeck on
alternate host plants and the density of those plants in

t 60

a.
S-40

20 -

■O

flyspeck incidence=inoculum index+no. of borders+slope

R-=0.27

• •

•

/ * *

•

100

Actual flyspeck incidence (% apples infected) at harvest

Figure 1. Predicted versus actual flyspect at harvest in Massachusetts orchards, 2000.

Fruit Notes, Volume 67, Winter, 2002

orchard borders. The best flyspeck prediction model
included inoculum index, number of borders, and slope.
We applied the model parameters derived here to
flyspeck incidence at 1 3 orchards in 2000 and compared
the resulting predicted values with observed flyspeck
incidence. The best-fit regression for the data
(R^=0.27) is presented in Figure 1. Given the high
"background noise" of variability in this kind of
investigation (different years, orchards, blocks, sizes
of trees, cultivars, prunmg regimens, types of borders,
etc.), we were gratified to see almost 30% of the
variability in flyspeck incidence explained by these
three site factors.

We applied the same model in 2001 to predict
flyspeck in 1 1 of the same orchard blocks used in 2000.
The relationship between model-predicted flyspeck and
actual flyspeck in the apples was not close (only 2%
of the variability was explained). However, 2001 was
very dry during most of the growing season, and 2000
was a very wet year. Weather factors as well as
differences in blocks at the different sites may have
made a bigger difference in a drier year. We plan to
develop a more comprehensive flyspeck model that
combines static orchard factors with dynamic weather
factors such as leaf wetness and rainfall. It would be
useful to adjust for accumulations in moisture during
a growing season. We may find that we need different
models for wet years as opposed to dry years. The
starting point, however, and key factor in rating a block

for flyspeck risk will probably always be a measure of
how much inoculum is in the orchard border areas at
the beginning of the growing season.

This study identifies several factors which can
combine to produce an environment which supports
flyspeck: density of flyspeck on alternate host plants
in borders, number of borders, distance from apples
to border, and slope of the block. Modification of
this environment in a number of ways, such as summer
pruning, clearing-back borders or removing host plants
or inoculum, or using high-density dwarf plantings
could reduce flyspeck pressure considerably. The most
stable management plans will involve several
strategies, such as border management, orchard design,
aggressive pruning, monitoring weather components,
and careful fungicide selection and timing.

A cknowledgem en ts

We are grateful to the growers who participated in
the three phases of this study: Keith Arsenault, Gerry
Bieme, Bill Broderick, Dave Chandler, Dave Cheney,
Aaron and Dana Clark, Tom Clark, Don & Chris
Greene, Tony Lincoln, Wayne Rice, Dave Shearer, Joe
Sincuk, Tim Smith, Mo Tougas, Bob Tuttle, and Steve
Ware & the folks at Davis Farms. This work was also
supported by State/Federal IPM Funds, SAKE Grant
#97 LNE 97-90 (USDA 96-COOP-1-2700), and a
Northeast Regional IPM Competitive grant.

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Fruit Notes, Volume 67, Winter, 2002

Effects of Gibberellin Synthesis
Inhibition on Feeding Injury by
Potato Leafhopper on Apple

Kathleen Leahy, Duane Greene, and Wesley Autio

Department of Plant & Soil Sciences, University of Massachusetts

Overview

Although the gibberellin synthesis inhibitor
Apogee (prohexadione-calcium) was introduced in
apple primarily as a horticultural tool to reduce shoot
length and thereby decrease the amount of necessary
pruning and associated costs, the inhibition of
gibberellin synthesis has also shown beneficial effects
in controlling some important pests of apple. The most
dramatic effect has been seen on the shoot-blight phase
of the bacterial disease fire blight, but some effects
have also been seen on flush-growth-feeding insects
such as green apple aphid and obliquebanded leafroller.
To date, however, no studies have been published on
the effects of Apogee on potato leafhoppers Empoasca
fabae (Harris) (Byers et al., 1997; Paulson and Hull,
1999;Yoderetal., 1999).

Potato leafhoppers are occasional orchard pests in
the mid-Atlantic and Northeast. These insects are not
able to winter in the north. They overwinter in the
southern United States and migrate northward on storm
systems over the course of the spring and early summer.
In apple, they feed in vascular tissue in rapidly-
developing shoot tissue. In mature trees, this injury is
not generally considered serious, although in young
trees it may be necessary to apply control measures
for a moderate to severe infestation. There is, however,
some evidence that potato leafhoppers may play a role
in facilitating the shoot-blight phase of fire blight, by
introducing feeding wounds in susceptible tissue on
which Erwiuia amylovora, the bacterium which causes
fire blight, is growing epiphytically (on leaf surfaces),
allowing the bacteria to invade the leaf and cause
infection (Koehler, 2000; Pfeiffer et al., 1999).

Since potato leafhoppers feed directly on tissue

likely to be affected by gibberellin synthesis inhibition,
we thought that the possibility of suppressing or even
completely controlling these leafhoppers with Apogee
or a similar gibberellin synthesis inhibitor was strong
enough to warrant further study. This work was done
as part of a larger study looking at the interactions of
gibberellin synthesis and potato leafhoppers with fire
blight.

Materials & Methods

A 200-tree section of a block of 15-year-old
Mclntosh/M.7 at Scott Farm in Dummerston, Vermont
was used for the study. A randomized-complete -block
design was used, with ten replications and two trees
per treatment within each replication. Buffer trees were
employed within the row, and a buffer row was
employed between treated rows. Apogee was applied
at the rate and timings recommended for commercial
growers in this area, 12 oz per 100 gallons dilute at
early petal fall (May 12) and a second application at
the same rate when growth would have been expected
to resume, June 1 .

There were two levels of two treatments used in
this experiment: Apogee treated and non-treated, and
potato leafhoppers excluded or permitted. The
insecticide Provado (imidacloprid) was used for
exclusion, at the highly reduced rate of 0.5 oz per 100
gallons dilute recommended by researchers at the
Cornell Hudson Valley Laboratory (Scaffolds
newsletter, June 2001). Provado was applied when
potato leafhoppers began to appear in the orchard, June
22, and was re-applied when numbers appeared to be
resurging, July 20.

Shoot length was measured using a measuring tape

Fruit Notes, Volume 67, Winter, 2002

on five shoots per tree ( 1 shoots per tree for the first
two sample sessions) at 10-day intervals beginning at
petal fall to assess the effectiveness of the Apogee
treatment. Potato leafhopper injury was evaluated with
a spectrophotometer early in the season, but this method
became cumbersome and was eventually supplemented
with a visual rating scale of injury, with being no
visible injury and 5 being severe injury. Because of
the high mobility of potato leafhopper adults, which
were the predominant life stage, we did not succeed in
getting a reliable count of leafhopper numbers per
shoot, hi future studies a field-adapted vacuum cleaner
device may be used for this purpose.

Results & Discussion

Shoot length measurements showed that Apogee
had a highly significant effect on shoot growth (Figure
1), both in the presence and absence of potato
leafhoppers. Potato leafhoppers arrived later than usual

in New England and did not reach high numbers in
any location, leading to a fairly low damage level in
the control. Using the visual rating scale assessment
of leafhopper injury, Apogee and Provado, individually,
had a highly significant effect on reducing leafliopper
injury (Figure 2). Where both materials were used
together, leafhopper injury was singificantly lower than
where either material was used alone. On the last
assessment date, August 15, 200 1 , the average level of
feeding injury where Apogee was used alone was 0.83,
where Provado was used alone was 0.78, and where
both were used together was 0.3 1 . Untreated control
trees showed an injury level of2. 13 for this date. Thus,
there appears to be a substantial benefit to potato
leafhopper control using Apogee either alone or in
combination with insecticide.

The mechanism by which gibberellin inhibition
affects leafhopper feeding is not known and will be
investigated further. The enhanced effect of Apogee
plus insecticide may be due to the reduction in new.

40
35
30 -

§25-

g 20-

-1

15 -

■^■■-V ■ ,

Figur

Provado only No Treatment Apogee only Apogee + Provado

e 1 . The effects of Apogee and Provado on shoot growth of 15-year-old Mclntosh/M.7 trees.

Fruit Notes, Volume 67, Winter, 2002

2.5

0.5

Notrt

Apogee

Provado

Ap + Prov

Figure 2. Potato leatTiopper damage (0-5 scale, with being no injury and 5 being severe injury) on 15-
year-old Mclntosh/M.7 trees as affected by Apogee and Provado.

untreated leaf area where shoot growth is inhibited.
For Apogee alone, it is possible that visual or chemical
cues used by the insects are muted by the treatment, or
it could be that the leafhoppers begin feeding but find
the treated plant unpalatable. Behavioral studies of
potato leafhoppers exposed to Apogee-treated and
nontreated foliage separately and in choice situations
will be conducted to try to elucidate the nature of the
response.

Regardless of the reason, however, the fact that
injury appears to be reduced by the inhibition of
gibberellin synthesis is of significance for growers
needing to control this insect. Specifically, where
Apogee has been used and leafhopper numbers are not
exceptionally high, there may be no need for an
insecticide directed at the leafhoppers. In cases where
a severe fire blight outbreak is in progress and
leafhopper numbers are high, an insecticide may still
be warranted, and should hopefully have greater
efficacy in combination with the Apogee.

More work needs to be done to understand the
nature of the effects of gibberellin synthesis inhibition
on leafhoppers and on to understand the relationship
between potato leafhoppers and fire blight. In addition.

it would be enlightening to repeat the experiment under
higher populations of potato leafhopper and see
whether or not the effects continues to hold true, or
are muted or enhanced under such conditions.

References

Byers, R.E., Yoder, K.S., and Smith, A.H. Jr. 1 997. The
effect of BAS-125W on apple tree growth, fruit quality
and fire blight suppression . HortScience 32:557.

Hildebrand, M., Dickler, E., and Geider, K. 2000.
Occurrence of Erwinia amylovora on insects in a fire
blight orchard. Phytopathology 148:251-256.

Koehler, GW. ed. 2000. 2000-2001 New England Apple
Pest Management Guide.

Maredia, K.M., Whalon, M.E., Gage, S.H., and Kaeb,
M.J. 1998. Observations of first occurrence and
severity of potato leafhopper Empoasca fabae (Harris),
(Homoptera:Cicadellidae) in the North Central and
Eastern United States. Great Lakes Entomologist
31:73-84.

Paulson, G.S. and Hull, L.A. 1999. Influence of Apogee

Fruit Notes, Volume 67, Winter, 2002

on selected apple and pear pests. Proceedings, 75th
Cumberland-Shenandoah Fruit Workers Conference,
Winchester, VA.

Pfeiffer, D.G., Killian, J.C, and Yoder, K.S. 1999.
Clarifying the roles of whiteapple leafhopper and potato
leafhopper (Homoptera:Cicadellidae) in fire blight
transmission in apple. J. Entomol. Soc. 34:314-321.

Plurad, S.B., Goodman, R.N., and Enns, W.R. 1967.
Factors influencing the efficacy of Aphis pomi as a

potential vector for Erwinia amylovora.
Phytopathology 57:1 060- 1063.

Sterner, P.W. and Lightner, G.W. 1992. Maryblyte 4.2:
A predictive program for forecasting fire blight disease
in apple and pear. University of Maryland.

Yoder, K.S., Miller, S.S., and Byers, R.E. 1999.
Suppression of fire blight in apple shoots by
Prohexadione-calcium following experimental and
natural inoculation. HortScience 34:1202-1204.

*%3^ %3^ %JU %Si^
^f% #1^ ^lg% ^j^

Fruit Notes, Volume 67, Winter, 2002

Food Quality Protection Act:
An Organopliosphate Update -
February 2002

Glenn Morin

New England Fruit Consultants, Montague, MA

As the six-year anniversary of the Food Quahty
Protection Act (FQPA) approaches, EPA continues to
focus on the regulation of the organophosphate (OP)
compounds. The protocols for tolerance reassessment
mandated by the FQPA were previously not described,
and the methodology by which they are ultimately
evaluated will be used to review the other classes of
compounds in the future. Therefore, EPA has
proceeded cautiously, opened the procedure to public
review, and provided for stakeholder input at each step
of the six-phase review process.

This process allows for the development of risk-
management recommendations by EPA and, when
combined with the previously ongoing re -registration
process, ultimately results in the publication of a Re-
registration Eligibility Document (RED). The RED
finalizes the regulatory process and outlines the
conditions under which continued use of the product
may occur.

In the case of the organophosphates, which must
still undergo a cumulative risk assessment as a class of
compounds (see related article in this issue oi Fruit
Notes), EPA has issued Interim Re-registration
Documents (IRED). These documents may include
risk reduction measures and other label changes that
will take effect prior to the final RED, which will be
released once the cumulative risks of the OP's have
been considered fully. It is anticipated that EPA will
conclude its review of the organophosphates sometime
later this year.

All seven of the active ingredients most commonly
used in commercial tree fruit production are currently
in the final phase of the individual risk assessment
process. The following is a summary of EPA's findings
and actions as of February 18, 2002.

Azinphos methyl - Initial label amendments for
azinphos methyl (Guthion) that effected tree fruit

production were voluntarily put in place by the
registrants prior to the 1999 growing season primarily
in response to EPA's concerns regarding dietary risk to
children. Further discussions among the registrants,
EPA, and the stakeholder community directed at
reducing the risk to agricultural workers and the
environment have continued since the release of the
revised risk assessment in the summer of 2000.

The results of these discussions were made
available for public comment on November 28, 2001
in the form of an IRED. This document proposes the
cancellation of 28 crop uses (including nectarines), a
four-year phase out of seven crop uses (including
peaches) and a 4-year, time-limited registration for
eight crop uses (including apples, pears, and sweet
cherries). Some highlights of the proposed label
changes concerning apple production are as follows:

limit of 3.5 lbs ai/acre per season east of the
Mississippi, 4.0 lbs ai/acre west of the Mississippi;

increase REI to 14 days for all activities;

require enclosed cabs or maximum personal
protective equipment (PPE) for applicators;

require closed mixing systems or water soluble
bags and closed transfer systems for mixing/
loading;

add 25-foot buffer zones for permanent surface
water;

add spray drift language; and

prohibit pick-your-own (PYO) usage or restrict
application to early season or establish 30 day pre
harvest interval (PHI) for PYO operations.

The public comment period for this document ended
on January 28, 2002. Questions concerning which label
amendments will ultimately be required, the timeframe

Fruit Notes, Volume 67, Winter, 2002

for implementing these changes, and the disposition
of product already in the distribution system remain
unanswered at this time. However, the registrant is
optimistic that no label changes will take effect for the
upcoming growing season.

Phosmet - EPA released its revised risk assessment
for phosmet (Imidan) at a technical briefing in February
2000. This document indicated that dietary risk was
not an issue for this compound and that exposure to
handlers could be managed satisfactorily with increased
PPE and engineering controls.

An IRED for phosmet was made public
simultaneously with that of azinphos methyl (AZM)
in the fall of 2001. Similar to AZM, EPA's present
concerns center around risks to agricultural workers
and ecological risks. Proposed agricultural use changes
that affect tree-fruit producers fall into two categories:
1) continued registration with new labeling
requirements for 33 crop uses (including sweet and
tart cherries) and 2) a 5 -year, time-limited registration
for nine crop uses (including apples, apricots,
nectarines, peaches, pears, and plum/prunes). Some
highlights of the proposed label changes concerning
apple production are as follows:

increase REI to 3 days;

require enclosed cabs or maximum PPE for
applicators;

require water soluble bags and closed transfer
systems;

add spray drift language; and

prohibit application during bloom period.

The registrant has reached an agreement with EPA that
allows for all product currently in the distribution
system or in possession at the farm level to be used
under the current label until all inventories have been
depleted. All product sold by the registrant after June
30, 2002 will reflect the changes mandated by the
IRED.

Diazinon - In December of 2000, EPA released its
revised risk assessment for this active ingredient. EPA
concluded this active ingredient posed significant risk
to birdlife as currently labeled and was a common
contaminant of surface water. Risk mitigation measures
center largely on phasing out, over the next three years,
most residential uses of products containing diazinon
(Spectracide) whether applied for structural or lawn-

care purposes.

Although agricultural uses contributed little in this
regard, risk to agricultural workers who apply these
products or harvest treated crops was of concern. When
the IRED IS made public, it is expected that EPA will
proposed the cancellation of about 30% of the current
agricultural uses and require "Restricted Use"
classification for the remaining uses so that applications
will be limited to trained, certified applicators.
Discussions with the registrant and other stakeholders
are ongoing.

Malathion - The revised risk assessment for
malathion was presented at a technical briefing in
November, 2000. Malathion is a lower priority for
regulatory action since it is used on less than 10% of
the nation's apple acreage. EPA's analysis suggested
that dietary risk, drinking water risk, and ecological
risks were of little or no concern. However, risks to
mixers/loaders/applicators and risk to workers entering
treated areas for post-application activities were cited.
Although the IRED has yet to be posted, additional
personal protective equipment (PPE) for handlers and
longer restricted entry intervals (up to 6 days) are
expected to be included.

Methyl parathion (Penncap-M) - EPA has
previously announced acceptance of the registrant's
voluntary cancellation of many of the significant food
crop uses for this material including apples, peaches,
pears, nectarines, cherries, and plums in order to
address the Agency's concern of dietary risk to children.

Chlorpyrifos (Lorsban) - EPA severely restricted
the use of this material on apples, tomatoes, and grapes
shortly after the release of the revised risk assessment
in August of 2000, again, due to dietary-risk issues.
Post-bloom use on apples has been prohibited since
December 31, 2000. The IRED was published in the
Federal Register on November 14, 2001 for which the
public comment period ended in mid January.

The first step of the review process mandated by
the FQPA is drawing to a close for the organphosphate
compounds. EPA will soon conclude the evaluation of
these active ingredients on an individual basis. This
initial evaluation contains a risk assessment that
considers all potential routes of exposure including
dietary, drinking water, residential, and occupational
means.

The second phase, cumulative assessment of the

Fruit Notes, Volume 67, 'Winter, 2002

risk posed by OPs as a class of compounds, has already
begun. EPA and USDA convened an advisory panel,
the Committee to Advise on Reassessment and
Transition (CARAT), to assist in this process in
February 2000. Dr. Robin Spitko of New England Fruit

Consultants is a member of this committee and has
been monitoring the proceedings for the tree-fruit
industry in the Northeast.

Further information can be found at http://
vvww.epa.gov/pesticides.

*^1^ ^If ^I^ ^t^
^{^ ^J^ ^J^ ^1%

Fruit Notes, Volume 67, Winter, 2002

Food Quality Protection Act:
Cumulative Risk Assessment for the
Organophosphate Pesticides

Roberta Spitko

New England Fruit Consultants, Montague, MA

The primary focus of EPA's Office of Pesticide
Programs activities over the past year has been the
development of a cumulative risk assessment for the
organophosphate pesticides (OPCRA). This risk
assessment is the most complicated, comprehensive
attempt to measure cumulative exposure to a particular
group of pesticides that has ever been undertaken.

The OPCRA final document exceeds 5,000 pages
in length. The methodologies developed by EPA to
collect and analyze the data are extremely sophisticated
and complex and have also been a source of much
controversy in the agricultural stakeholder community.
EPA is relying heavily on the advice of the FIFRA
Science Advisory Panel, a panel of expert scientists,
especially those in statistical modeling and toxicology,
for validation of the methods used. These
methodologies have been developed over the past 5
years, and represent a significant advance in EPA's
abilities to evaluate pesticides in a comprehensive
manner. It must be emphasized that the current risk
assessment, which was released in January 2002 for
public and scientific comment, is a preliminary
assessment. The Agency expects a large number of
comments to be submitted until the comment period
closes on March 8, 2002.

A cumulative risk assessment is the process of
combining exposure (the amount of pesticide to which
an individual is exposed) and hazard (the health effects
a pesticide could cause) from all substances that share
a common mechanism of toxicity. In assessing hazard
associated with the organophosphate pesticides, EPA
analyzed their common method of toxicity, inhibition
of acetylcholinesterase, as the means for assessing risk.

The goal of the organophosphate cumulative risk
assessment (OPCRA) is to measure the probability of
exposure to more than one organophosphate pesticide
and to assess the effects of this combined exposure.
The assessment incorporates possible OP exposures

from structural, recreational, and drinking water, as
well as from OP residues in consumed food. Each
component of the risk assessment uses the best
available data: data from surveys of what people eat
and drink, of their activities involving pesticide use
around the home and workplace, and monitoring studies
of pesticide residues in these environments.

A comprehensive assessment of the
organophosphates may raise concerns with growers
about further restnctions on materials available for crop
production. However, the results of the OPCRA may
not have much effect on current OP use. Much work
has been done previously on the individual
organophosphates to reduce their risks as they go
through the FQPA-mandated tolerance reassessment
process.

The risks for the individual OPs will be factored
into the cumulative equation at these lower levels.
Most structural and home-garden uses have already
been cancelled or significantly curtailed. Routes of
exposure through drinking water have already been
determined to be negligible.

It must be noted again that the recently released
OP cumulative risk assessment is preliminary. EPA is
continuing to seek input from the scientific community
and stakeholders and is aware that revisions and
refinements will be necessary. Determining cumulative
exposure is a huge task, and this is the first time EPA
has attempted develop a comprehensive profile of
human exposure to a group of chemicals with common
modes of toxicity. It will be an evolving process that
will take years to refine.

Following the comment period closure of March
8, 2002, EPA will consider submitted comments and
plans to issue a revised risk assessment in the summer
of2002.

The preliminary OPCRA may be accessed at
www.epa.gov/pesticides/cumulative.

*%X^ %1> %i^ %9^
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Fruit Notes, Volume 67, Winter, 2002

Commercial-orchard Evaluation of Traps
for Monitoring Plum Curculio:
2001 Results

Ronald Prokopy, Brad Chandler, and Jaime Pinero
Department of Entomology, University of Massachusetts

In the 2000 issue oi Fruit Notes, we reported our
year 2000 tests in which we compared odor-baited with
unbaited traps of three types (pyramid, cyHnder, and
Circle) for monitoring plum curculios (PC's) m
commercial apple orchards. Results suggested that traps
baited with grandisoic acid alone (= synthetic male sex
pheromone) captured no more PC's than unbaited traps.
However, when grandisoic acid was combined with
any one of three different synthetic host fruit volatiles
(benzaldehyde, ethyl isovalerate, or limonene),
captures by baited traps were about twice as great as
captures by unbaited traps. Addition of the synthetic
fruit volatiles decanal, hexyl acetate, and trans-2-
hexenal to grandisoic acid did not enhance captures.

Here, we report results of 2001 studies in
commercial orchards in which we further evaluated the
best odor combinations found in 2000, again in
association with pyramid, cylinder, and Circle traps.

Materials & Methods

The three types of traps were: (a) black pyramid
traps (24 inches wide at base x 48 inches tall) placed
on the ground next to apple tree trunks, (b) black
cylinder traps (3 inches diameter x 1 2 inches tall) fixed
vertically onto horizontal branches within tree
canopies, and (c) aluminum-screen "Circle" traps
(developed by a grower named Edmund Circle in
Alabama for pecan weevil), wrapped tightly around
the base of tree trunks so as to completely encircle the
trunk and afford maximum chance of intercepting
adults walking upward.

The three synthetic components of host fruit odor
were benzaldehyde, ethyl isovalerate, and limonene.
Each was purchased from Aldrich Chemical Company
and was deployed in small polyethylene vials that fit
into the screen-funnel top of a boll weevil trap that

capped each pyramid, cylinder, or Circle trap. The
release rate of each compound was about 10 milligrams
per day (achieved by adjusting the type or number of
vials per trap according to compound volatility). Each
baited trap also contained a plastic dispenser of
grandisoic acid (obtained from Great Lakes IPM)
designed to release about 1 milligram of pheromone
per day.

Traps were deployed in four plots of apple trees in
each of 12 commercial orchards. Each plot consisted
of seven perimeter trees. Each tree (save one) contained
one baited or one unbaited trap of the above three types.
All three baited traps in a plot received the same odor.
In each orchard, each of three plots received a synthetic
fruit volatile in combination with grandisoic acid. The
fourth plot received grandisoic acid alone.

All traps were deployed at pink (May 2-4). Traps
were examined for captured PC's beginning at petal
fall (May 14-16) and every 3-4 days thereafter for 7
weeks until June 28-30. Vials of benzaldehyde and
dispensers of grandisoic acid were renewed on May
28-30 (about mid-way through the experiment). At each
trap examination, 10 fruit on each of the six trapped
trees per plot (= row 1 trees) and five fruit on each of
six corresponding but untrapped trees on interior rows
3,5, and 7 were examined for PC oviposition scars. In
all, 102,800 fruit were examined for PC injury. All plots
received two or three sprays of azinphosmethyl or
phosmet to control PC.

Results

Figure 1 shows that across the entire PC season,
Circle traps baited with benzaldehyde plus grandisoic
acid (GA) captured numerically more PC's than any
other type of baited or unbaited trap, although not
significantly more than unbaited Circle traps in the

Fruit Notes, Volume 67, Winter, 2002

2-5 1

I
i 2

L
I

: 1-5
; 1

a I

BEN+GA

IB baited
D unbajted

BC BC

2.5 -

EIV-KJA

. ■ baited
D unbailed

1 2 •

^_ AB

= 1-

^ 0.5 -

■

0.5

pyramid cylinder

LIM+GA

Circle

e baited
D unbailed

pyramid

cylinder

Circle

AB AB

•»H"-

2.5 •

@ baited
D unbailed

2 ■

1.5 ■

^■1

1 ■

HH BC

OS ■

n ■

«W

pyramid

cylinder

TRAP TYPE

Circle

pyrannid

cylinder
TRAP TYPE

Circle

Figure 1. Mean number of PC's captured by each type of odor-baited and unbaited trap placed on
perimeter-row trees. Among all bars in this figure, those superscribed by the same letter are not
significantly different from one-another at odds of 19 to 1 .

1 -

0.8 -
0.6 ■
0.4
0.2

BEN+GA

■ baited
D unbaited

I -\
0.8
0.6
0.4
0.2

pyramid cylinder

LIM+GA

Circle

■ baited
D unbaited

1 1
0.8
0.6
0.4
0.2

EIV+GA

@ baited
D unbaited

pyramid

0.8
0.6
0.4
0.2 ■

cylinder

Circle

B baited

D unbaited

BWP

|V*^J_

pyramid

cylinder
TRAP TYPE

Circle

pyramid

cylinder
TRAP TYPE

Circle

Figure 2. For each trap type, degree of correlation between total amount of PC captures on perimeter-
row traps and percent sampled PC injury to fruit on penmeter-row trees in plots having that odor. The
higher the R^ value, the greater the extent of the correlation. An asterisk (*) indicates a statistically
significant correlation at odds of 19 to 1.

Fruit Notes, Volume 67, Winter, 2002

0.8
0.6
0.4
0.2

BEN+GA

■ baited
D unbaited

1 -l

EIV+GA

■ baited
D unbaited

0.8 -

0.6 -

0.4 -

0.2 -

■H 1

^=r^ .

pyramid

cylinder

LIM + GA

Circle

@ bailed
D unbailed

pyramid

cylinder
TRAP TYPE

Circle

1
0.8
0.6
0.4
0.2

cylinder

Circle

@ baited
□ unbailed

J I

pyramid

cylinder
TRAP TYPE

Circle

Figure 3. For each trap type, degree of correlation between phenology (time during the season) of PC
captures on perimeter-row traps and phenology of mjury to fruit on perimeter-row trees m plots havmg
that odor. The higher the R^ value, the greater the extent of the correlation. There were no statistically
significant positive correlations.

same plots, or Circle traps baited with ethyl isovalerate
plus GA, limonene plus GA, or GA alone. For each
type of odor bait, pyramid and cylinder traps captured
numerically fewer PC's than Circle traps.

Figure 2 shows, for each odor and trap type, the
degree of correlation between the total (season-long)
amount of PC captures and the percent sampled
perimeter-row fruit injured by PC's in plots having that
odor and trap type. A significant positive correlation
would indicate that orchards which showed
comparatively many captures for a given odor and trap
type also showed a comparatively large amount of PC
injury, whereas orchards which showed comparatively
few captures also showed a comparatively small
amount of PC injury. Among all odors and trap types.
Circle traps baited with benzaldehyde plus GA showed
the highest degree of positive correlation (0.75)
between trap captures and injury. What this means is
that after the PC season has ended, one can look back
and say with high confidence that the extent of PC
captures by Circle traps baited with benzaldehyde plus
GA reflected quite well the extent of PC injury that
occurred on trapped and other trees in the same plot.

Figure 3 shows, for each odor and trap type, the

degree of correlation between the phenology (time of
season) of PC captures and the phenology of PC injury
to perimeter-row fruit in plots having that odor and
trap type. A significant positive correlation would
indicate that a sampling period during which
comparatively many trap captures occurred also was a
sampling penod in which a comparatively large amount
of injury was initiated, whereas a sampling period
during which comparatively few (or no) trap captures
occurred was a sampling period in which comparatively
little (or no) fruit injury was initiated. Among all odor
and trap types, no trap showed a significant positive
correlation between phenology of captures and
phenology of injury. In fact, the highest degree of
positive correlation for any trap type was only 0.20,
and the correlation for Circle traps baited with
benzaldehyde plus GA was a mere 0.01. What this
means is that during the PC season, one could not have
any confidence whatsoever that the extent of PC
captures during any particular 3- to 4-day period
reflected the amount of PC injury that was initiated
during that period, even for the best-performing trap.
A deeper look into the phenology of captures by
Circle traps baited with benzaldehyde plus GA and the

Fruit Notes, Volume 67, Winter, 2002

1.2 1

r ^

1 -

\ '*

- 5

MEAN No.

0.8 -

\ - -•- - INJURY

- 4

MEAN %

PCs
TRAPPED

0.6 -

\ *

. 3 FRUIT
INJURY

0.4-

Vii^---^-^'*'"^---^^ -

- 2

0.2 -

A .

* *
*

- 1

U n

r U

PK-PF 0-2 WK AFTER 2-4 WK AFTER 4-6 WK AFTER

PF PF PF

Figure 4. For Circle traps baited with benzaldehyde plus GA, a graphic display of PC captures and |

amount of PC

injury to fruit during each of four 2-week periods from pink (PK) to 6 weeks after petal

fall (PF).

160

■ Gab, Fuji, Jonagokd
D Mcintosh, Empire

■ Gala, Fuji, Jonagokd
n Mcintosh, Empire

TRAP CAPTURES

FRUIT INJURY

Figure 5. Total captures of PC's on perimeter-row traps and PC injury to perimeter-row fruit in six
blocks of apple trees comprised of Gala, Fuji, or Jonagold as perimeter-row cultivars versus six blocks
comprised of Mcintosh or Empire as perimeter-row cultivars.

phenology of PC injury is helpful in understanding the
lack of relationship between these two entities. As
shown in Figure 4, PC captures were greatest during
the period of pink to petal fall but were low during
each 2-week period thereafter. Conversely, PC injury
to fruit was low (about 1 .5%) during the first 2 weeks
after petal fall, but increased in essentially a linear
fashion until 4 to 6 weeks after petal fall, when it
reached about 5.3%. Thus, the trends depicted in Figure

4 show clearly that the steady rise in PC fruit injury on
perimeter-row trees from petal fall to 6 weeks thereafter
was not accompanied by a rise in PC captures by
perimeter-row Circle traps baited with benzaldehyde
plus GA, accounting for the lack of correlation between
these variables.

Figure 5 shows that PC captures by all perimeter-
row traps combined and PC injury to perimeter-row
fruit were about 60% and 140% greater, respectively,

Fruit Notes, Volume 67, Winter, 2002

140 1
120-
100

■ woods
D hedge
Dopen

TRAP CAPTURES

.2, *

= 9

5 1

■ woods
D hedge

4 •
1 .

Dopen

2 ■

1 -
■

FRUIT INJURY

Figure 6. Total captures of PC's on perimeter-row traps and PC injury to perimeter-row fruit in blocks
of apple trees whose front rows bordered woods, hedgerow, or open field (four blocks of each type).

in blocks having Gala, Jonagold, or Fuji as perimeter-
row cultivars, compared with blocks having Mcfritosh
or Empire as perimeter-row cultivars. The average
number of insecticide sprays applied against PC was
the same in each case (2.7).

Figure 6 shows that PC captures by all perimeter-
row traps combined were greatest for blocks bordered
by woods, intermediate for blocks bordered by

hedgerows, and least for blocks bordered by open field.
However, PC injury to perimeter-row fruit was greatest
for blocks bordered by open field. The average number
of insecticide sprays applied against PC was about the
same in each case (2.8, 2.8, and 2.5, respecfively).

Figure 7 shows that season-long PC injury to fruit
on perimeter-row trees (row 1) averaged about 12 times
greater than on trees of interior rows 3, 5, or 7.

ROW

Figure 7. Mean percent PC-injured fruit on perimeter-row trapped frees(row 1) compared with injury
on non-trapped trees of interior rows 3, 5, and 7.

Fruit Notes, Volume 67, Winter, 2002

Conclusions

Circle traps baited with benzaldehyde plus GA,
when positioned so as to completely surround trunks
of perimeter-row apple trees, captured numerically
more PC's than any other trap type and afforded a strong
positive correlation between total amount of trap
captures and total amount of PC injury to perimeter-
row fruit. The year 2001 was the first year we used
Circle traps in this position on a tree (formerly they
were placed on lower limbs near the trunk and provided
a weaker correlation between total captures and total
injury). The strong correlation obtained in 2001
suggests that tree-trunk Circle traps baited with
benzaldehyde plus GA, if distributed along perimeter-
row apple trees, can be an excellent indicator of "hot
spots" requiring special attention for controlling PC
as well as "cool spots" requiring lesser attention.

Unfortunately, no trap type showed even a
moderate positive relationship between the time of
occurrence of PC captures and the time of occurrence
of PC injury to fruit. As depicted in Figure 4, even for
our best trap type (tree-trunk Circle traps baited with
benzaldehyde plus GA), captures fell off dramatically
soon after petal fall, whereas fruit injury rose steadily.
Thus, even for this best trap, the data obtained in 200 1
indicate that low trap captures after petal fall cannot
be relied upon as indicative of the lack of need to spray
against PC.

As revealed by other studies that we conducted in
2001 , there are at least three reasons why all three types
of traps used here may fail to capture representative
numbers of PC's active in canopies of commercial
orchard trees after petal fall. First, organophosphate
insecticide spray droplets falling on traps can be
repellent to PC's for 10 days or more after application.
Such droplets can also be repellent when on tree limbs
and branches, but repellency apparently is substantially
overcome by positive chemical stimuli inherent to
surfaces of limbs and branches. Such positive stimuli
are lacking on surfaces of current traps. Second, at
temperatures greater than about 70°F, especially when
accompanied by sun, PC's tend to fly directly into tree
canopies, thereby bypassing Circle and pyramid traps
associated with tree trunks. Temperatures tend to be

higher than 70°F after petal fall. Third, the release rate
of benzaldehyde from vials placed inside of trap tops
( 1 milligrams per day) is sufficient to attract PC's from
a distance, but may be repellent at close range. As tree
fruit grow and themselves release increasing amounts
of benzaldehyde and other attractants, there may be an
increasing tendency for attractive volatiles from the
fruit to outcompete attractive volatiles placed in traps.
Our attempts to increase the amount of benzaldehyde
used in association with traps, so as to be more
competitive with fruit volatiles, have been accompanied
by a decrease (rather than an increase) in PC captures
owing to repellency. Together, these three shortcomings
may limit the usefulness of Circle, pyramid, and
cylinder traps placed at or within canopies of
commercial-orchard trees for monitoring the extent of
threat by PC's after petal fall.

Both cultivar composition of perimeter-row trees
and border area composition had an influence on extent
of trap captures and fruit injury by PC. As in 2000,
perimeter-row trees of Gala, Jonagold, or Fuji
experienced considerably more PC pressure than
perimeter-row trees of Mcintosh or Empire, even
though there was no difference in frequency of
insecticide applications. Also, as in 2000, trap captures
were greater in blocks bordering woods than in blocks
bordering hedgerows or open field. Finally, PC injury
to fruit on trees that received traps was far greater than
PC injury to fruit on interior trees, suggesting that
attractive odor placed on perimeter-row trees acts to
concentrate PC's there and reduce penetration into the
orchard interior.

Ackno wledgm ents.

We are grateful to the following growers for
participating in this study: Keith Arsenault, Gerry
Beime, Bill Broderick, Dave Chandler, Tom Clark, Don
Green, Tony Lincoln, Joe Sincuk, Mo Tougas, and
Steve Ware. This work was supported by Massachusetts
State Integrated Pest Management Funds, Northeast
Regional Competitive Integrated Pest Management
Funds, Northeast Regional Sustainable Agricultural
Research and Education Funds, and the New England
Tree Fruit Growers Research Committee.

*%1# %i^ %3^ ^f^
^j^ ^j|% ^1^ ^j^

Fruit Notes, Volume 67, Winter, 2002

An Odor-baited "Trap-tree" Approach to
Monitoring Plum Curculio

Ronald Prokopy

Department of Entomology, University of Massachusetts

As described in the preceding article, there are
shortcomings associated with placement of plum
curculio (PC) monitoring traps in commercial orchards
for purposes of determining when a spray is needed to
protect fruit against PC damage. Shortcomings are
particularly evident during the middle and latter part
of the PC season, when trap captures remain low
irrespective of trap type or attractive odor, but damage
increases. One of the principal shortcomings involves
need for baiting traps with an increasing amount of
synthetic attractive fruit odor as the PC season
progresses in order that odor might compete effectively
with the increasing amount of attractive odor emitted
by developing fruit in the tree canopy. When used in
association with traps, increasing amounts of synthetic

fruit odor become repellent at close range.

One possible solution to this dilemma could be to
create a "trap tree" where the tree canopy itself is baited
with a high amount of attractive fruit odor. Rather than
using amounts of PC's captured by traps as a potential
but indirect indicator of level of PC egglaying activity,
one would use amount of freshly injured fruit on the
trap tree as a direct indicator. A few such trap trees per
orchard could provide valuable information on sudden
rises in PC damage and hence on the need to apply a
protective spray. Placement of attractive odor directly
on tree branches would eliminate problems of close-
range repellency associated with placement of odor on
or in traps.

In 200 1 , 1 conducted a preliminary trial of this new

lij

0.
U. LU

6 -I

5 -

4 -

3 -

2 -

■ BAITED TREES
dUNBAITED TREES

WEEKS AFTER PETAL FALL

Figure 1. Amount of fruit injured by plum curculio on baited perimeter-row trap trees
and on unbaited trees midway between trap trees.

Fruit Notes, Volume 67, Winter, 2002

approach to monitoring PC's in a small block of apple
trees in Clarkdale Fruit Farm in Deerfield.

Materials & Methods

The entire study was conducted along a 125-yard
section of perimeter-row apple trees bordered by
woods. The trees were mixed cultivars on M.26
rootstock. On May 2 (mid-pmk), every sixth tree was
baited with two dispensers of grandisoic acid (each
releasing about 1 mg per day) and eight dispensers of
benzaldehyde (each releasing about 10 mg per day).
All dispensers were replaced with fresh ones on May
30.

One week after petal fall and weekly for 4 more
weeks, 20 fruit were examined on each of the five trap
trees and on each of four unbaited trees midway
between trap trees. Fruit were counted as injured if a
PC egglaying scar was evident. The trees received two
applications of insecticide to control PC without use
of fi-uit sampling information in guiding timing of spray.

Results

Figure 1 shows that fruit injury on the baited-trees
averaged about eight times greater than on unbaited
trees for samples taken at weeks 1 and 2 after petal fall
and about five times greater than on unbaited trees for

samples taken at weeks 3, 4, and 5 after petal fall. As
the PC season progressed, some of the injured fi-uit on
both types of trees fell to the ground, but total injury
remained the same or increased owing to appearance
of fresh injury.

Conclusions

The results of this preliminary test are very
encouraging in that baiting perimeter-row trees with
attractive odor acted to concentrate immigrating PC's
on the "trap trees." Further research is necessary to
optimize the composition and amount of attractive odor
before this approach can be recommended for
widespread use in monitoring PC's in commercial
orchards. Conceivably, a few odor-baited "trap trees"
along perimeter rows of an orchard might serve not
only as focal trees for monitoring extent of fresh injury
caused by PC but, if sufficiently attractive, might also
serve to aggregate enough of the immigrating PC
population to permit spraying only trap trees, allowing
other trees to remain unsprayed against PC.

Ackno wledgm ents

Thanks to Tom Clark for cooperating in this
experiment, and Jaime Pifiero for preparing the figure.

*%S^ %i^ %3^ %ju
^j^ ^f% ^g% #j^

Fruit Notes, Volume 67, Winter, 2002

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Fruit Notes, Volume 67, Winter, 2002

Fruit Notes

University of Massachusetts
frOH Department of Plant & Soil Sciences
ilOteS 205 Bowditch Hall

tliyU Amherst, MA 01003

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Table of Contents

Flyspeck Disease Management: Comparison of Flint versus Captan m Every-row versus Perimeter-row Sprays

A. Baj, A. Tuttle, and D. Cooley 1

Thmnmg Mcintosh Apple Trees With Blossom Thinners, With and Without Post-bloom NAA:

A Report to the New England Tree Fruit Growers Research Committee

J. Schupp and D. Greene 9

Evaluation of New Apple Varieties, 1998 Observations:

A Report to the New England Tree Fruit Growers Research Committee

D. Greene 13

Influence of Odor-bait, Cultivar Type, and Adjacent Habitat Composition on Performance of Perimeter Traps

for Controlling Apple Maggot Flies

S. Hoffmann, R. Mittenthal, B. Chandler, G. Lafleur, S. Wright, P. Appleton, M. Becker, 5. Dynok, and R. Prokopy .

.20

Editors:

Wesley R. Autio
William J. Bramlage

Publication Information:

Fruit Notes (ISSN 0427-6906) is pub-
lished each January, April, July, and
October by the University of Massachu-
setts in cooperation with the other New
England state universities.

The costs of subscriptions to Fruit
Notes are $10.00 for United States ad-
dresses and $12.00 for foreign ad-
dresses. Each one-year subscription
begins January 1 and ends December
31. Some back issues are available for $3.00 (United States addresses)
and $3.50 (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

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 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 UMass Extension, Stephen Demski, Director, m furtherance of the acts of May 8 and June 30,
1914. UMass Extension offers equal opportunity in programs and employrtienl.

Flyspeck Disease Management:
Comparison of Flint versus Captan
in Every-row versus Perimeter-row
Sprays

Andrew Baj, Arthur Tuttle, and Dan Cooley
Department of Microbiology, University of Massachusetts

In 2001, we began a 4-year study to evaluate new This study seeks to determine if the strategy of

pesticides (in this case, the environmentally benign spraying only the two perimeter-rows in blocks of apple

fungicide, Flint, for flyspeck disease) for apple pests trees during the summer months is adequate to man-

and a pesticide-reduction strategy (spraying only the age the disease at six orchards in Massachusetts. If

two rows of apple trees on the perimeter of the block), proven efficacious, this strategy could help offset high

Flyspeck (FS) disease, like apple maggot fly and plum costs of new materials and help reduce the pesticide

curculio, survives the winter on or in plant material in load on the environment,
the wooded or hedgerow borders and often infests an

orchard block with a significant disease gradient which Materials & Methods
decreases with distance into the block (Cooley, 1996).

The 2001 insect pest management results of the study The experiment took place in blocks of apple trees

were reported in Fruit Notes 66:14-18. at orchards in six Massachusetts towns: Harvard, Ber-

xxxxxxxxxxxxxx xxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxx

xxxxxxxxxxxxx xxxxxxxxx xxxxxxxxxxxxxx xxxxxxx

xxxx xxxxxxxxxxxxxx xxxxxxxxxxxxxx xxxxxxxxxxxxxx

xxxxxxxxxxxxx xxxxx xxxxxxxxxxxxx xxxxxxxxxxxxx

Border area Border area Border area Border area

Flint (2.0 oz./acre) Captan 80 (2.5 Ib./acre) Flint (2.0 oz./acre) Captan 80 (2.5 Ib./acre)

4- + + + -1^ + + + -H -I- -I- 4- -I- -I- -I- + -I- + + + + + + + -I- + + + -I- -I- -I- -I- -I- -t- -I- -I-

+ + + + + + + + + + + + + + + -I- 4--I- -I--I- + + + + + + + + + + + + + + + +

+ + + + + + + -(-+ + + + + + + + + +

-I- + -1- -t- -I- + -t- + + -I- + + -(- + + -I- -1- -H

-I- -I- -I- -I- -I- -I- -I- -I- -I- + + + + + -1- 4- + +

-I- + -I- -I- -I- -I- -(- -I- -I- + + + + + + + + +

-I- -I- -I- + -I- 4- + + -I- + + + + + + + + +

Key: + = sprayed tree, — = unsprayed tree, X = trees, shrubs, and vines

Figure 1 . An example of a perimeter-row spray block with fungicide rates in six Massachusetts apple
orchards, 2001.

Fruit Notes, Volume 67, Spring, 2002

Key: Each block below represents a block of apple trees 7 rows deep by approx. 35 trees wide. Cardinal
directions are noted with a capital letter. Principal border is shown at top of block. Host density ratings
ranged from 1 (none to very few scattered) to 4 (continous deep patches of host plants). Flyspeck (FS)
density ratings range from (none) to 3 (high).

Berlin Site

Harvard Site

W Woods

Host den. 4

FS den. 2

S Woods

N Woods

Host den. 4

Host den. 3.5

FS den. 2

FS den. 1

Hawley Site

E Woods

Host den. 4
FS den. (ns)

S Woods
Host den. 4
FS den. (ns)

Warren Site

W Woods Host den. 3.5
FS den. 1

S Hedgerow Host den. 2

FS den. (ns)

W Hedgerow

Host den. 3
FS den. 1

N. Brookfield Site

N Woods

Host den. 3.5
FS den. 1

W Hedgerow
Host den. 2.5
FS den. 1

Shelburne Site

No Borders within 1 00m

Figure 2. Evaluation of alternate host density and flyspeck (FS) density in border area habitats at
six apple orchards in Massachusetts, 2001 .

Fruit Notes, Volume 67, Spring, 2002

Table 1 . Fungicide application schedule for 6 orchards

in Massachusetts, 2001.

Site

Harvard

23-May

31 -May

18-Jul

08-Aug

Berlin

23-May

31 -May

13-Jun

18-Jul

08-Aug

Warren

25-May

02-Jun

16-Jun

19-Jul

10-Aug

N. Brooktleld

25-May

02-Jun

24-Jun

19-Jul

10-Aug

Shelbume

24-May

01-Jun

18-Jul

09-Aug

Hawley

10-Jun

18-Jul

09-Aug

* Bold-face font indicates full cover spra>

; otherwise

2 row vs.

7 row spray

applied.

lin, Warren, North Brookfield, Shelbume, and Hawley.
Cultivars within the blocks were primarily mid-to-late
season, with planting densities ranging from 100 to
1000 trees per acre. The minimum block size was seven
rows deep by 28 trees long (Figure 1). Rows of trees
were divided into four sections, by colored flagging,
to correspond with the four separate post-petal-fall
pesticide treatments. There were two treatments us-
ing new, environmentally friendly materials (the fun-
gicide, Flint, and the insecticide, Avaunt) and two treat-
ments using conventional materials (the fungicide, cap-
tan, and the insecticide, Guthion). For each of these
treatments, there was a two-row perimeter-spray plot
and a full seven-row spray plot.

During the early season (up through petal-fall) the
growers applied fungicides of their choice. Petal-fall
occurred in mid-May at five of the six sites, with the
exception being Hawley, which reached petal-fall on
May 31. After petal-fall, the sites were sprayed ac-
cording to the experimental protocol with the
University's air-blast sprayer.

In early June, border areas within 100m of the ex-
perimental blocks were surveyed for alternate FS-host
density and density of FS on such hosts. Host density
was estimated on a four-point scale, and FS density
was estimated on a three-point scale after examining
known host plants throughout the border for fifteen
minutes (Figure 2). If any FS was found, a more pre-
cise measure was taken by examining 25 stems on al-

ternate hosts every 1 Om along the border.

Sprays applied by the University (Table 1 ) prior to
June 10 were full cover sprays, meaning all trees re-
ceived fungicide. Captan 80 was applied at 1.75
pounds/acre and Rubigan at 4.0 ounces/acre. At three
sites, scab persisted, so one additional unplanned cover
spray was needed in mid-June. For such applications,
Flint was applied at 2 ounces/acre.

Fungicides were applied twice in the summer, with
one spray on July 1 8 or 1 9 and the other on August 8
or 9. The two Flint treatments were applied to trees at
a rate of 2.0 ounces/acre, and Captan 80 was applied
at 2.5 pounds/acre. All sprays were delivered with the
equivalent of 150 gallons per acre.

FS counts began July 15. One hundred fruit were
sampled in rows 1,3, 5, and 7, in each of the four spray
treatments. Four hundred fruit were counted per treat-
ment, and 1600 fruit per block. Distance between rows
ranged from 8m (Shelbume) to 3m (Hawley). The
sample area was comprised of the bottom 6 feet of fruit,
on all sides of the tree. The typical sample was 20
fruit, from five trees, within each row. Also, the first
and last tree of each row, for each treatment, was not
sampled, since such trees could have been affected by
spray drift. Samples occurred weekly or semi weekly
until early September, when they were conducted
weekly. Counts continued until harvest, with the last
count on October 1 .

Fruit Notes, Volume 67, Spring, 2002

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Fruit Notes, Volume 67, Spring, 2002

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20 H

-20 -
-40 -
-60
-80

Perimeter-rows captan treatment

r^=0.10

95% Confidence Interval

— I —
60

Distance to Principal Border (m)

Figure 4. Percentage of apples infected with flyspeck at harvest versus the distance to princi-
pal border (parallel to the block): Harvard, Berlin, Warren, North Brookfield, perimeter-rows
captan treatment, 2001 .

FS was discovered in row 1 at the Harvard site on
July 16, in both the Flint (9%) and captan (13%) pe-
rimeter-rows spray treatments. At the Berlin site, FS
was found initially on August 27, in rows 3, 5, and 7,
of all but the seven-row Flint treatment. FS was first
discovered at the Warren site on August 29, in row 5
of the perimeter-row captan treatment. At the North
Brookfield site, FS was found on August 15, in both
the perimeter-rows Flint and captan treatments. The
Shelbume site first had apples infected with FS on
August 16, in the unsprayed rows of the perimeter-
row spray treatments of Flint and captan. FS was not
found at the Hawley site, despite counts continuing
into early October. It was not surprising, given the
absence of FS on alternate host plants within the sur-
rounding border in June.

When harvest counts (September 6 to 13) from all
treatments and all rows of all sites were compared (Fig-

ure 5, upper graph), Flint treatments had as little or
less FS than captan treatments in rows 1 , 3, and 7. The
perimeter-rows Flint count (6% infected fruit) was
slightly higher than the perimeter-rows captan treat-
ment (5%), but overall, Flint compared favorably to
captan. The lowest average FS incidence was found
in the seven-row Flint treatment. The perimeter-row
captan treatment had the most FS, with 17% of fruit
infected in row one. This high average number was
greatly intluencedby the 100%) incidence in this treat-
ment and row at the Harvard site. When the Harvard
data were omitted (Figure 5, lower graph), FS inci-
dence in this row and treatment was reduced to \%.
Row 5 of the perimeter-row Flint treatment had the
next highest FS incidence, with ?%> of fruit infected.
With Harvard omitted, FS incidence in row 5 of all
treatments was greater or equal to the FS incidence in
rows 3 and 7 of the respective treatment.

Fruit Notes, Volume 67, Spring, 2002

■ 2 Row Flint

• 2 Row captan 80 —A— 7 Row Flint —X— 7 Row captan 80

18%
16% ^

14% -

12% -

■4^

10% -

8% -

6% -

4% -

3 5

Row Position Relative to Border

All 6 Sites 9/6-9/13

-♦- 2 Row Flint

- 2 Row captan 80 —A— 7 Row Flint -^ \3^ %S^
^1^ ^f% ^j% #^

Fruit Notes, Volume 67, Spring, 2002

Thinning IVIclntosli Apple Trees Witli
Blossom Thinners, With and Without
Post-bloom NAA: A Report to the New
England Tree Fruit Growers Research
Committee

James R. Schupp

Hudson Valley Laboratory, Cornell University

Duane W. Greene

Department of Plant and Soil Sciences, University of Massachusetts

The objective of these studies was to test the
efficacy of blossom thinners to replace carbaryl for
obtaining selective thinning of Mchitosh apples.

Evaluation in Maine
Materials & Method

Mature Rogers Mclntosh/M.7 apple trees growing
at Highmoor Farm, Monmouth, ME were selected for
uniform bloom. Treatment plots were surrounded on
all sides by one or more buffer trees, to prevent over-
spray. All thinning treatments were applied with an
airblast sprayer calibrated to apply 135 gallons of
dilute spray per acre, with 70% of the spray delivered
to the top half of the tree canopy. Blossom thinning
treatments were applied May 1 2, 1 998 when 70 to 80%
of the blossoms were open. The weather at the time of
application was sunny, temperatures was 72° F, with a
4 to 6 mph wind from the west. Blossom thinning
treatments were:

1 . Untreated control

2. Ammonium thiosulfate (National Chelating), 5
gallons per acre

3. Wilthin (Entek Corp.), 12 quarts per acre

4. Endothall (Elf Atochem), 2 pints per 100 gallons

5. NAA, 12.5 ppm

For plots that received post-bloom thinner, six
ppm NAA was applied on May 27,1 998 when fruitlet
diameter was 10 mm. The weather at the time of
application was sunny, temperature 64° F, with a 1 to 2
mph west wind. The treatments were arranged as a
split plot design. Blossom thinners were the main plot
treatment, postbloom NAA was the sub-plot
treatment, and there were five replications.

Fruit set was evaluated by limb counts and by
cluster counts. All the flower clusters on one or two
limbs per tree were counted at pink. The limb
circumference was measured, and limb cross-sectional
area (LCA) was calculated. The number of fruit on
each limb was counted, and fruit set was calculated as
the number of fruit per 100 clusters and as the number
of fruit per LCA. Fruit counts were done shortly after
petal fall and again in July to evaluate both initial and
final set. Twenty-five fiower clusters on each tree
were tagged, and the number of fiowers on each cluster
was recorded. The number of fruit on each cluster was
counted and fruit set was calculated as the ratio of fruit
to flowers for each cluster.

Yield per tree was determined in a single picking

The Maine portion of this study was conducted at the University of Maine Highmoor Farm, during the time that Dr
Schupp was with the University of Maine.

Fruit Notes, Volume 67, Spring, 2002

at harvest. Fruit size distribution was categorized
using a FMC Weight Sizer (PMC Corp. Lakeland, FL).
The weight sizer was adjusted to divide the fruit into
four diameter size categories: 57-63 mm, 64-69 mm,
70-75 mm, and greater than 75 mm. Twenty fruits of
the 70-75 mm category were selected from each tree
for fruit quality analysis. Red fruit color and russet
were estimated visually. Fruit firmness was measured
on the EPT-1 firmness tester (Lake City Technical
Products, Inc. Kelowna, BC, Canada), with two
opposing punctures per fruit. The soluble solids of the
fruit were determined using an Atago PR-101 digital
refractometer (Misco Products Divn., Cleveland, OH).
Seed number was counted.

set, especially on control trees, however, the rankings
of the treatments remained essentially unchanged.
There were no treatment interactions on fruit set, yield
or fruit characteristics between blossom thinners and
post-bloom NAA in this study. Wilthin, endothall and
NAA applied at bloom reduced yield (Table 1).
PostbloomNAA had no effect on yield. There were no
significant effects of thinners on fruit size distribution
(data not presented). There were no treatment etfects
on fruit red color, fruit firmness, soluble solids
concentration, or seed number (data not presented).
Fruit from trees treated with Wilthin had higher
incidence of russet than fruit irom NAA- or endothall-
treated frees (Table 1 ).

Results

Discussion

Fruit set was reduced by all blossom thinners,
while post-bloom NAA had no effect on fruit set
(Table 1). Final fruit set was much less than the initial

Environmental conditions during bloom and for
the following month were characterized by warm
temperatures and high sunlight, making favorable

Table 1 . Effect of ammonium

thiosulfate (ATS), Wilthia endotliall, and NAA used

as blossom thinners and NAA used as a

postbloomthumer on fhut set and fhut size of Rogers

Mcintosh'.

Maine.

Initial set

Final set

Fmit/cnr

Fmit/100

Fruit/cm"

Fnut/100

Russet

Yield/

limb cross-

blossom

limb cross-

blossom

Skin surface

tree

Treatment

sectional area

clusters

sectional area

clusters

(%)

(kg)

Blossom thinners

Control

17 a

143 a

3.4 a

31a

15 ab

67 a

ATS 5 gal/acre

91b

2.5 ab

28 ab

13 ab

60 ab

Wilthin 12 qt/acre

43 c

1.5 b

17c

28 a

50 c

Endothall 2 pt/acre

93 b

1.4 b

16c

40 d

NAA12.5ppm

105 b

2.0 b

24 b

10b

55 be

Postbloom NAA

None

2.1

NAA 6 ppm

2.2

Significance

Blossom thinner (BT)

***

Postbloom thinner (PBT)

BTxPBT

Fruit Notes, Volume 67, Spring, 2002

conditions for initial fruit set. All the blossom thinners
were effective in reducing the initial fruit set and
number of fruit per flower cluster during this period. A
prolonged period of heavy cloud cover from June 1 3 to
June 17, 1998 resulted in heavy June drop for all the
trees in this study. This episode of fruit drop
commenced on June 23, and was more severe than the
fruit drop caused by blossom thinners. Much of the
potential effect of chemical thinners on yield and fruit
characteristics at harvest was obscured by this natural
fruit drop.

The most effective blossom thinner, Wilthin,
caused severe phytotoxicity and fruit russet. Future
studies should address this concern by evaluating the
effect of lower rates of Wilthin. These data indicate

that blossom thinners show some promise. More study
is needed to select the best chemicals and to optimize
their use.

Evaluation in Massacliusetts

Materials & Methods

A block of mature Marshall Mclntosh/M.26 apple
trees growing at the University of Massachusetts
Horticultural Research Center, Belchertown, MA
were selected. Treatment trees were selected so that a
buffer tree was located on each side of a treatment tree
to prevent spray drift. Prior to bloom 2 limbs per tree,
1 to 15 cm in diameter, were selected and tagged. At

Table 2. Effects of Ammonium thiosulfate (ATS), Wilthin,

endothall and NAA used as

blossom thinner alone or combined with a

postbloom NAA

application.

Fruit set

Postbloom

Fruit/cm"

Fruit/

Fruit

NAA

limb cross-

100 blossom

weight

Treatment

(6 ppm)

sectional area

clusters

(g)

Control

6.9 a

66 a

146 e

NAA

5.9 a

55 a

158d

ATS 6 gal/acre

1.9b

23 b

175 abc

ATS 6 gal/acre

2.6 b

22 b

184 a

Wilthin 12qt/acre

2.6 b

28 b

170 be

Wilthin 12 qt/acre

2.2 b

21b

182 ab

Endothall2pt/100gal

3.1b

25 b

164 cd

Endothall2pt/100gal

3.3 b

37 b

158d

NAA 12 ppm

6.1 a

62 a

171 be

NAA 12 ppm

5.7 a

61 a

177 ab

Significance

Blossom thinner (BT)

***

NAA

BT X NAA

Within columns, means not followed by th

e same letter are significantly different at odds

of 19 to 1.

Fruit Notes, Volume 67, Spring, 2002

the pink stage of flower development all blossom
clusters were counted on the two tagged limbs.
Blossom cluster density was calculated using LCA.
Trees were replicated based upon blossom cluster
density. All thmnmg treatments were applied with an
airblast sprayer calibrated to apply 125 gallons of
dilute spray per acre. Blossom thinner treatments were
applied May 4, 1998. Full bloom occurred about 0.5
day before application. Weather at the time of
application was partly sunny and warm with
temperature reaching 70°F soon after application.
Blossom thinning treatments were:

ATS, Wilthin, and endothall thinned significantly and
comparably (Table 2). NAA did not thin when applied
as a bloom thinner. NAA at 6 ppm did not thin when
applied alone at the traditional postbloom timing or
when applied following any of the blossom thinner
treatments. All blossom thinning treatments increased
fruit size. NAA, when applied as a bloom thinner,
increased fruit size even though it did not significantly
reduce crop load. Likewise, the postbloom 6 ppm
application of NAA alone increased fruit size although
crop load was not significantly reduced. There were
no blossom thinner X NAA interactions.

1 . Untreated control

2. Ammonium thiosulfate (National Chelating) 6
gallons/acre

3. Wilthin (Entek Corp.), 12 quarts per acre

4. Endothall (Elf Atochem), 2 pints per 100 gallons

5. NAA 12 ppm

For plots that received post -bloom thinner, 6 ppm
NAA was applied on May 18, 1998 when fruit size
averaged 9.0 mm. Weather at the time of application
was sunny, warm and breezy with temperature at 76 to
78°F at application time and a high temperature of 80°
F was reached later in the day. Treatments were
arranged as a split plot design. Blossom thinners were
the main plot treatment, postbloom NAA was the sub-
plot treatment, and there were seven replications.

Fruit set was evaluated by first counting all
persisting fruit on the tagged limbs at the end of June
drop in July. The fruit set was calculated by dividing
the number of fruit by the LCA. At the normal harvest
time on September 10, 40 fruit from each tree were
harvested randomly from around the periphery of the
tree. The harvested fruit were then taken to the lab
where total weight was taken and the average fruit size
calculated. Observation of the harvested fruit
indicated that there appeared to be no russet attributed
to treatment.

Results

Soon after application phytotoxic effects were
observed on the flower petals and leaves of all
blossom-thinned trees except those receiving NAA.

Discussion

ATS, Wilthin, and endothall were used in previous
years on apples at rates of 1 %, 6 qts/acre and 1 .5 pints/
100 gallons, respectively, with disappointing results.
Little phytotoxicity was noted and minimal thinning
recorded. Higher rates were used this year in an
attempt to locate a rate where some thinning would be
achieved. Cool, damp, rainy weather immediately
preceded the application of blossom thinners in
Massachusetts. We speculate that the large amount of
phytotoxicity was attributed to greater penetration of
the thinner into the leaves because of the cool, cloudy,
and rainy weather the week before application rather
than due to an excessively high amounts of thinner.
While we have noted for years that absorption
following a cool wet penod can be increased, this may
be even more important when the thinner of choice,
thins by burning.

It IS also interesting to note that fruit size was
increased significantly even though crop load was not
reduced significantly. Crop load may have been
reduced enough to increase fruit size. It is also
interesting to note that early thinning at bloom time
may actually increase fruit size more than by thinning
later. Note fruit size on trees treated with post bloom
NAA as compared with NAA used as a blossom
thinner.

These data suggest that blossom thinning is a
viable and eftective way to reduce crop load. More
study is necessary to select the best chemical and
concentration to achieve appropriate thinning.

^f^ ^I^ %S^ %S^ %1^

#1^ ^{^ #1^ ^{^ ^{^

Fruit Notes, Volume 67, Spring, 2002

Evaluation of New Apple Varieties, 1998
Observations: A Report to the New
England Tree Fruit Growers Research
Committee

Duane W. Greene

Department of Plant and Soil Sciences, University of Massachusetts

During the growing season I evaluated about 1 25
named varieties and numbered selections. Below are
my observations on the performance of many of these
in 1998.

Arlet

I continue to be on the fence with this apple. It has
good, but not outstanding flavor. It does not suffer
from biennial bearing, and fruit size is good. It russets
here, up to 25% of the surface, it drops and it does
become greasy. A drop control compound is
appropriate with Arlet. I am cooperating with Sarah
Weis on storage of Arlet this year to get a better
assessment of its postharvest life.

Autumn Gold

This is my first year with this cultivar and I had j ust
a couple of fruit. I believe that I harvested it too late,
October 19. It is a medium to large apple with some
russet and is not too attractive. The ones I tasted were
neither crisp nor juicy but I believe that they were
overmature. There were longitudinal cracks in the
pedicel end, throwing up a red flag. Flavor was of
bananas, fruity and very pleasant. It had a good sugar
to acid ratio. I rated the flavor very high, even with the
faults.

AA 62 (Stellar)

I continue to favor this attractive lemon yellow
apple. It is extremely attractive and has a large L/D
ratio (over 1 .05) even here. It has no russet but it is

exfremely susceptible to apple scab. Flesh is crisp,
juicy, fruity, and very good. One thing that I did note
this year is that at harvest it had an ethanol (aldehyde)
taste that detracted from the flavor. It did have some
moldy core this year. I have noted this in other apples
in the past including HoneyCrisp. I will continue to
look at this one.

AA122

This is the first year of evaluation of this oblate
deep yellow apple. It has white inconspicuous
lenticels and yellow flesh. The flavor was OK, being
slightly sweet with a bitter after taste. It was rated in
the middle of the pack. If it does not have outstanding
flavor or crispness, the evaluation time of this apple
will be short.

Braeburn

It IS a somewhat unlikely candidate to be grown in
New England because of late maturity. It blooms
profusely and set can be excessive if not thinned very
well. I have used three applications of 6 ppm NAA
with or without carbaryl on Braeburn with success.
Fruit size is good and color is acceptable. It is not very
good at harvest but after a period of cold storage it does
taste very good. It has good postharvest life. I do
recommend planting this apple in New England.

Cameo***

I consider this to be one of the best new cultivars.
It ripens in mid-October here. It has good L/D ratio

Fruit Notes, Volume 67, Spring, 2002

and quite good if not quite different color. It is a highly
striped apple with about 80% of the surface a dark
reddish brown color. It is a very grower-friendly tree.
This tastes like a very good Delicious but the taste is
very mild. While I never hope that is will be sold as
Delicious, I think that it will appeal to people who
actually do have taste for it but are attached to the
unfortunate versions of Delicious available today. I
am high on this apple and think that it will sell here in
the East. It does have biennial bearing tendencies.

COOP 25 (Scarlet O 'Hara)

This IS a medium sized brownish red apple that I
have liked for two years. It can be picked, and actually
tastes very similar when harvested over a 4-week
period from late September to late October. It is one
of the crispest and best storing apples I evaluate. It
stores better than Fuji or Braebum but not quite as well
as HoneyCrisp. It has a mild, fruity, vanilla flavor with
a good sugar to acid ratio. I would plant this even if it
were not a scab resistant apple. Anyone who is looking
for a versatile scab resistant apple should be looking at
this. It is very susceptible to fire blight so areas where
this is a problem should proceed very carefully.

were sent to me by Stark from the Delbard Nursery in
France that fruited for the first time this year. It has an
80% dark maroon surface and looks like a Delicious.
Harvest date was on August 24, just about with Ginger
Gold. It has a distinctive sweet perfumy flavor. It is
quite crisp and veryjuicy but the skin in tough. I rated
it quite high and noted that it was a very good apple.

Delgorov

This is an extremely attractive bright orange-red
apple that is about 80% red striped. It is medium small,
fairly crisp, juicy, but the flesh seems somewhat dry. I
noted that it was a fairly good apple with a good sugar
to acid ratio. Harvest is 2 weeks before Gala.

Deljoron

The color of this apple is almost 100% dark
burgundy red. It in many ways reminds me of an
Empire in appearance and taste. The flesh is white
with a tinge of green. The skin is smooth somewhat
tough, with many tan lenticels. It ripens about with
Delicious. I was favorably enough impressed with it at
harvest to note that I should continue to look at it.

COOP 37

Delorina

I have looked at this cultivar for three years now. It
is very similar to GoldRush in appearance and time of
ripening. It is somewhat attractive with a 20 to 30%
orange cheek. It has a strong vanilla taste, veryjuicy,
and medium in size. I rate it good but not exceptional,
although my tasting notes include the comment 'look
at again'.

Creston

This was a difficult year for apples that are not
highly colored because of the heat. Creston suffered,
and consequently it was not very attractive. However,
compared with other apples evaluated it was one of the
crispest and juiciest. It was also rated very high in
flavor, and overall as being very desirable. It was also
large. We should continue to evaluate this apple.

Dalrouval

This is one of the several selections of apples that

A small dark cherry red apple ripening with and
looking somewhat like Delicious. It has yellow flesh
with yellow flecks, slightly sweet, moderate acidity,
and IS somewhat crisp and juicy. Flavor is tangy and
slightly fruity. I rated it fairly high.

Delshel

This is a an extremely dark red, medium to small
apple that is

Gala-like in appearance. It has scarf skin and reminds
me to a very large extent of Buckeye Gala. It has
prominent tan lenticels and a pleasant fruity taste. It
ripens about two weeks before Gala. I rated this quite
high.

Enterprise

The quality of this apple improved immensely this
year. It was near the bottom of the list last year. While
not on the top, it did move up quite a bit. What is the

Fruit Notes, Volume 67, Spring, 2002

difference? We had a very hot summer and I beUeve
that was the difference. It was extremely attractive,
medium size, sweet, crisp, juicy, and shghtly fruity.
Last year I described its flesh as tough, dry, and
sawdust-like. The bottom Ime here is that it is meant to
be grown in warmer climates. In warm years it will be
very good.

Fiorina

I hear very little about this apple, but it is very
good, especially for a disease resistant apple. It is very
attractive and its skin is glossy like a HoneyCrisp. It is
somewhat crisp, very juicy, with a good mild buttery
flavor. Fruit size is medium. I rated it very high.

Fortune

Although red color development was delayed, it
did come along. It was not very firm or crisp this year
and acidity was rather high. Although it was not at the
top of the list flavor, overall I rate it as an above
average apple. The iiTegular shape is a problem as is
its mammoth size. I have serious reservations about
whether this will make it with all of the good
competition.

Fuknishiki

This is the first year I evaluated this apple and it
may be my last. It is not attractive with 70% pinkish
red color. It has scarf skin and the flesh is greenish
yellow. The skin is extremely tough, and the flesh is a
nondescript, chalky and astringent flavor. It is not very
good.

Fukutami

A small bright cherry red apple. While the
cosmetics are good, the taste is not. Although it is
somewhat sweet, the flavor is masked by extremely
high acidity even when it has watercore. It is not good
enough.

Gala Supreme

A year ago I was quite impressed with Gala
Supreme. I am out of favor with this apple now for
several reasons. It has no better than "good"

appearance. It can be quite tart at harvest even though
sugars are quite high. The flesh is grainy and the taste
is nothing spectacular. It has a chalky aftertaste that I
attribute to high tannins. It has problems in storage in
that it loses firmness rapidly.

Ginger Gold

The luster of this apple was not tarnished this year.
It remains a very crisp, juicy, mild tasting apple that
has a great deal of customer appeal. It is often
harvested too early, when it is still too green. Even at
this stage it is good, certainly better than most. It does
not hold up well in storage so only those that can be
sold at harvest should be planted. It holds up well on
the tree. If one follows starch ratings, it loses starch
very slowly. It may go from 2 to 5 ( on a scale of 8 )
over a 2.5 week period, whereas others lose starch
much faster. This is definitely a winner in New
England.

Golden Supreme

This is a very high quality apple, both in looks and
in quality, but its faults may kill it. It is not precocious,
and it IS quite biennial. It ripens irregularly and
extensive preharvest drop is possible. Under ideal
conditions it is an absolutely beautiful apple. I still like
this one a lot and I am not willing to give up on it. It
does store quite well.

GoldRush

We had a hot summer and consequently this did
much better than it has in the past. Normally it is small,
russeted, with high acidity. Acidity does mellow in
storage, but not enough. This year it did do better, but
it will never be a good apple for us unless global
wanning pushes the mid- Atlantic region weather up to
New England. I do not recommend it for this area.

Hampshire

For New England or for cooler areas, I believe that
Hampshire has a place. It is medium size plus, quite
uniform in size, and attractive. It has a very mild taste
at harvest. The apple mellows after 4 to 6 weeks in
storage giving it a very tender yet pleasing taste and
texture. It holds up well in CA storage. I recommend

Fruit Notes, Volume 67, Spring, 2002

planting Hampshire, at least on a limited basis until we
get more out there to evaluate.

Hardy Cumberland

This is a very attractive nearly 100% blush dark
red apple. It has somewhat of an irregular shape.
Flavor is good but mild, not sweet, crisp, or juicy. I
evaluated it over a 3-week period from the end of
September to October 19, with similar results. I will
continue to look at this, since I have not formed an
opinion yet, other than it is good.

HotteyCrisp

The popularity of this apple is amazing but it has
so many things going for it that it deserves it. It is the
crispest and best storing apple that I have ever worked
with. Fuji is not even in the same category, but neither
are any other apples currently under test. Its faults or
problem are surfacing including leaf hopper suscepti-
bility???, poor growth, lack of color, off tastes to
mention a few. However, this apple has staying power
and it will be a dominant player at least in the East for
many years to come. We must work through the
apparent problems. I could mention many things here
but I believe that this apple has so much potential that
a whole article should be devoted to it. I am on my
third planting of HoneyCrisp, with no intention of
slowing down.

Hiianguan

This IS not an attractive or visually appealing
apple. It has 70% brownish red color that is somewhat
striped and mottled. It is quite crisp and very juicy.
The juice is extremely thick, unlike most other apples.
It has an extremely strong vanilla taste, to the point of
being objectionable. It is no better than medium size.
The poor appearance, the size problem and the very
strong flavor lead me to conclude that this is an apple
that will not make it.

Huashiiai

Huashuai is in the middle of the pack on too many
characteristics. It lacks too many distinguishing
features to have a bright future. It is very Delicious-

like in appearance and taste. It lacks character/flavor.
It IS not crisp enough or juicy enough to overcome
other deficiencies. It is similar to Cameo in some
respects, but Cameo will win because it is larger, has
better color, is more attractive, and I believe it tastes
better.

Hudson '5 Golden Gem

I have fruited this wonderful apple for several
years but have not reported on it because it is different,
a fringe apple. It is a completely russeted apple that
ripens in Golden Delicious time. The size is medium
to large, and the shape somewhat oblate to conic. The
taste IS pear-like, but lacking the grit. Everyone that
tastes this apple just loves it. It is somewhat sweet but
with enough acid and tannins to give it character. The
appearance is so different that it attracts attention. We
are planting two


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