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FRUIT
NOTES

PREPARED BY
DEPARTMENT OF PLANT AND SOIL SCIENCES

COOPERATIVE EXTENSION SERVICE,
UNIVERSITY OF MASSACHUSETTS, UNITED
STATES DEPARTMENT OF AGRICULTURE AND
COUNTY EXTENSION SERVICES COOPERATING.

EDITORS
W. J. LORD AND W. J. BRAMLAGE

Vol. 42 (No. 1)
JANUARY-FEBRUARY 1977

TABLE OF CONTENTS

Interregional Cooperative Research in Fruit Tree Viruses
and Aspects of Control Measures: Present and Future

When Should an Existing Orchard be Replaced

Cleaning the Weed Sprayer

A Substance that Deters Egglaying by Apple Maggot Flies

Supplement - Establishment and Management of Compact
Apple Trees (Part II) (6 pages)

INTERREGIONAL COOPERATIVE RESEARCH IN FRUIT TREE VIRUSES AND
ASPECTS OF CONTROL MEASURES: PRESENT AND FUTURE^

R.C. McCrum
Department of Botany and Plant Pathology
University of Maine

A few commercial nurseries conduct virus indexing programs in
regard to their propagating stocks and also maintain nuclear stock
blocks. Individual State Experiment Stations as well have for
several years cooperated in certification programs with commercial
nurseries in regard to Prunus tree fruit nursery plants. There is,
however, at the present no general U.S. recognized certification
or regulatory program for distribution of virus-indexed or virus-
free apple nursery stocks. In this respect, the U.S. orchardist
is not as fortunate as his European counterpart in receiving reli-
able virus-free materials. The European distribution of virus-free
material, handled through regulated programs, involving both re-
search and inspection agencies, results in great volumes of clean
budwood from the initial source which is built up and released to
the industry by the cooperating nurseries. Part of the problem in
the U.S. in not duplicating this accomplishment is the reluctance
of the American growers to set up a uniform, regulated approach for
handling virus- indexed trees. Also, because of our numerous and
separate fruit growing areas, there tends to be a larger diversity
in apple cultivars due to the different climatical aspects, grow-
ing seasons, temperature limiting factors, other pressing disease
pathogens, soil types, processing requirements and changing con-
sumer demands, each one a critical factor to specific area growers.
In addition to this, there is a rapid development of patented selec-
tions being offered to the trade.

In spite of these handicaps, there has been considerable prog-
ress in obtaining and using virus-clean apple trees and we must
realize that it is only 5 years since the first introduction and
distribution of the IR-2 program's virus-free apple stocks began.
We are just beginning to realize that our research findings and
dissemination of this knowledge, which has led to increased quar-
antine interest in regard to the import of pome fruit tree mater-
ial, signifies that the U.S. itself must also establish certifi-
cation criteria and procedures in order to export it's own nurs-
ery material to meet the expanding world competition.

There is little or no control on the shipping of virus-infec-
ted apple budwood or treesthroughout the United States. This has
in the past led to a high incidence and spread of latent viruses,
particularly in cases where new cultivars have been desired quickly,
in large amounts, and have been put on older, sometimes infected
stock trees for a fast buildup of material. Exchange of nursery
stocks among regions and nursery suppliers, without detailed inform-
ation as to original source and disease status, also helps to in-
crease the problem.

Part I appeared in Nov. -Dec, 1976 issue of Fruit Notes

With few exceptions, you pay your money and take your chances
in regard to infection with viruses when you purcliase tree stocks.
Progress is being made when nurseries start from original clean
source materials, but it will take several years until large numbers
are built up, particularly with patented varieties. In addition,
grower reluctance to pay premiums for certified virus-free trees
delays the cleanup of U.S. material. This is due to the extra time
and effort it takes to certify and maintain a virus-free program
by the fruit tree industry.

Until the purchaser demands and is willing to pay for trees
certified and indexed as to trueness to name and~Freedom from virus,
he has only the reputation of the seller and nursery to fall back
on.

Problems with stock-scion incompatibilities like the presently
looming brown-line-decline syndrome with some East Mailing types
are suspected to be pathogenic in nature and may be the result of
a combination of viral or mycoplasmal pathogens.

The relationship of stock-scion in regard to known clean
materials is particularly important. It is not good to use virus-
clean materials in one of the components while the virus content
of the other is unknown. One may contain a latent or "hidden"
virus that may damage the other clean component. This was well
pointed out in the decline of Virginia Crab resulting in stem-pit-
ting of the latter hardy stock material. Both parts of a two part
tree must receive a clean bill of health to receive potential bene-
fits of either of the components. In addition, as pointed out by
van Oosten, the use of virus-free bud sources is only one of the
ingredients of a healthy industry. Equally important is the care-
ful attention shown to non-viral aspects of tree selections. Fac-
tors such as fruit finish, trueness to name, stability of the germ-
plasm and a history of the susceptibility of the selection to known
apple virus infections are other important and desirable facts.
Given this information, the grower has a better guarantee of what
the potential of his purchased trees will be in his future orchards.
In today's competitive markets, with increasing production costs,
all factors that can be ascertained should be made available to
the orchardist especially in regard to purchasing his basic ingred-
ient, his trees.

Tests at the Maine Station have demonstrated that considerable
differences in regard to fruit finishing characteristics occur in
selections of Golden Delicious even though they are free from virus
infection. Some virus-free selections produce badly russeted fruit
year after year compared to others which develop good fruit finish
when growing side by side in the same orchard and receiving identi-
cal production practices. (Table 1)

3 -

Table 1,

Non-viral fruit russet in selected clones of Golden
Delicious, in lbs per bushel.

Clone C

Clone H

Russeted

Clean

Russeted

Tree

Heavy

Light

Heavy

Light

Clean

3.5

7.9

3.4*

2.4

4.9

28.5

8.0

21.0

7.6

2.3

17.3

16.5

22.6

11.4

1.9

8.7

27.7

15.5

11.7

1.5

6.2

17.0

12.5

23.7

11.3

2.2

13.9

20.5

13.5

21.6

2.3

7.4

24.8

18.1

14.6

1.0

12.2

23.9

7.2

3.5

.0*

5.9

17.2

9.8

10.7

15.6

10.7

2.6

13.2

20.2

2.4

17.8

18.9

2.7

13.7

13.2

*Less than a bushel

Both clones could be marketed as virus-free Golden Delicious.
It goes without saying that good "seed" produces better crops than
poor "seed." A successful potato farmer insists on knowing the
disease rating and potential of his propagative seed and knows
what the odds are of planting poor seed. It is paradoxical that
apple trees are bought and planted for future envisioned high-
yielding crops often without knowing their possible inherent faults
or capabilities or virus content simply because there is no "pedi-
gree" or labeling system to prevent this from occurring. Somehow
a standard system has to be developed to insure that superior germ
plasm is protected from viral reinfection as well as to insure that
the grower receives specific information certifying that the prod-
uct he receives is the quality product the nursery originally
started with.

Progress has recently been made in reducing certain yellows
diseases of fruit trees originally thought to be viral in nature
but now known to be caused by mycoplasmal pathogens (ultramicro-
scopic bodies contained in phloem cells and transmitted by leaf-
hoppers). There are also similar sized rickettsial and bacterial
type pathogens transmitted by leaf hoppers that affect woody plants.
Fruit trees infected with these pathogens respond to antibiotic in-
jections and disease symptoms are frequently arrested. Such con-
trols are only stop-gap measures as they do not entirely eliminate
infections and must be repeated. With viral infections there are
not even stop-gap chemicals and a tree once infected in the orch-
ard or infected when planted stays infected for the life of the
tree. It is true that the possibility of reinfection with a virus
may occur with insects as in other plants; however, to date, this
has not been shown to happen with the apple virus entities. We,
still do not know what relationship the so-called latent and seem-
ingly inocuous apple viruses have to other plants and should
not continue to spread these around in infected budwood sources.

Tools to handle virus-free superior propagative material are
available. UTiat is needed is an industry-wide cooperative program
establishing checks and controls backed up by regulation and in-
spection measures to insure quality of product from the originator
to the purchaser with proper certification and identification of
tree material. It should be handled by industry so as to keep it
flexible and receptive to changes as they are needed, particularly
with the patented scion and new stock selections, since these must
be controlled by the patent holder. We have the expertise and the
knowhow, all we need is the initiation of a system.

In conclusion, as one old career orchardist was heard to say,
"It takes a lot of Saturday nights without a paycheck before a
newly planted orchard starts to show a profit." The first and most
important aspect of this orcharding business is what you put into
that hole in the ground as the basic investment to live with, grow
with and build upon.

***************

WHEN SHOULD AN EXISTING ORCHARD BE REPLACED

Robert L. Cristensen
Department of Food and Resource Economics

One of the questions confronting an apple producer is that
of the optimal replacement period. Should the old orchard (or
some portion with trees of the same age) be torn out and replaced
now or at some time in the future? This question has become in-
creasingly important because of the trend to compact trees and
higher density plantings.

A difficulty, of course, relates to the fact that a new
planting takes several years to attain production and thus a di-
rect comparison of net income from the old orchard as compared to
the new orchard is not possible. Perrin and Proctor (1Q74) have
outlined a procedure to be used in making such a decision which
takes into account net income flows over the life of the orchard. ^

R.K. Perrin and E.A. Proctor, "The Economics of Replacing Apple
Trees - A Guide for Producer Decision Making", Economics Informa-
tion Report No. 36, Department of Economics, North Carolina State
University at Raleigh, February, 1974.

- 5 -

Th
per yea
the net
value o
ard to
net inc
come £o
ized" n
cipated
orchard

e technique
r over the

present va
btained in
obtain an "
ome from st
r the next
et income f
net income
should be

involves three
life of the new
lue of the orcha
step one is amor
annualized" net
ep two is compar
year from the ex
rom the proposed

for the next ye
replaced.

steps

orcj^a

rd.^

tized

incom

ed wi

istin

new
ar fr

First, annual net returns
rd are discounted to obtain
Second, the net present
over the life of the orch-
e. Third, the "annualized"
th the anticipated net in-
g orchard. If the "annual-
orchard exceeds the anti-
om the old orchard, the old

A simple example may be helpful. The following table presents
the life cycle cash flow for Red Delicious apples sold on the fresh
market.

Table 1

Age of
Orchard

Life Cycle
creases at

Cash Flow Per Acre (With Projected Price In-
2.9 Cents Per Bushel Per Year)

Net Cash
Income

Age of
Orchard

Net Cash
Income

Age of
Orchard

Net Cash
Income

$ -651

$1,277

$1,477

-174

1,360

1,490

-175

1,433

1,469

-62

1,446

1,451

205

1,459

1,432

515

1,462

1,413

847

1,465

1,394

1,033

1,467

1,350

1,113

1,469

1,310

1,194

1,471

1,269

The present value formula with uneven income streams is as
follows:

PV = ^1 + ^2

TT^TT

(1 + i)

(Ui)

where R^^ to R = the atinual net returns in each year
i^ = the appropriate interest rate

Calculating the present value of a future return is the reverse
of compounding interest. If we compound 95 cents at 5-1/4 per-
cent simple interest, we have one dollar at the end of the year.
Therefore, the present value of one dollar received one year from
now, given a 5-1/4 percent interest rate is 95 cents.

"^The following costs are not considered since they are irrelevant
to the replacement decision: all fixed costs for equipment and
buildings and land charges.

- 6

Inserting the numbers from Table 1 into the formula yields the
following (the full series is not presented for reasons of brevity) :

PV =

(-651) + (-174) + (-175) + (-62) +
(I+.IO) ,, . ...2^,. .^.3... ,„.4

(205) + (515)

(1+.10)''(1+.10)"(1+.10)'^(1 + .10)^(1+.10)^

+ _(1,269^

(I+.IO)
= $6,364

For the above table, the present value of the cash flow over
30 years with an assumed rate of 10 percent is $6,364.00.

The annualized value formula is as follows:

A + PV X

1 -

(1 + i)

where :

PV = present value
i = the interest rate

Using the present value computed above and an interest rate of
10 percent, the formula becomes

A = $6,364

= $640

.10

1 -

(I+.IO)

Thus, if the interest rate used is 10 percent the above formu-
la yields an annualized net income of $640.00. If the existing
orchard yields a return net of cash expenses less than this amount,

it should be replaced.

Unfortunately, although this decision criteria. has the appear-
ance of a "rule of thumb" it has many difficulties. Obviously,
the technique requires a large amount of data. Some standardized
yield pattern over time must be assumed and prices
large number of years in the future.

estimated for a
The potential errors in the

Rules of thumb are difficult to attain except in rather simple
decision situations. They almost always assume a number of fac-
tors to remain constant and, as a consequence, often are in error,

- 7 -

future are, however, damped considerably by the discounting techni-
que itself. That is, the effect on the present value of an error
of 50 percent in net income in the 27th year will be relatively
small.

A reasonable manager will also consider the fact that the net
return in a given year from an existing orchard can be highly vari-
able due to the random effects of weather on yield as well as price.
Therefore, the blind application of the $640 criterion might well
be wrong.

In summary: A theoretical decision model does exist for re-
placement of orchards. The orchardist may use the procedure as a
technique to obtain more information concerning such a decision.
This knowledge together with other considerations form the total
bank of information the manager uses in exercising his judgment in
the decision.

***************

CLEANING THE WEED SPRAYER

Cleaning the weed spray between sprayings will preserve the
equipment, help insure uniform spray coverage, and prevent the
chance mixing of incompatible chemicals, or applying traces of the
wrong chemical. Below are suggestions for cleaning weed sprayers
that appeared in Special Circular 81 entitled "Weed Control Sprayers
Calibration and Maintenance" and published by The Penn. State Univ.
Extension Service, University Park, Pennsylvania.

"After each day's use, thoroughly flush with water, both in-
side and out to prevent accumulation of chemicals.

"Choose your cleaning area with great care. It is important
to discharge the cleaning water where it will not contaminate water
supplies, streams, crops, or injure other plants, and where puddles
will not be accessible to children, livestock, pets or wildlife.

"When you change chemicals, or finish spraying for the season,
clean the sprayer thoroughly both inside and out.

"The following steps are suggested for thorough cleaning:

1. Hose down the inside of the tank completely, filling it
half full of water. Then flush out the cleaning water through the
nozzles by operating the sprayer.

2. Repeat the procedure in step 1.

3. Remove nozzle tips and screens. Clean them in kerosene or
detergent solution, using a soft brush. Do not use a knife, wire,
or other hard material to clean nozzle tips. The finely-machined
surfaces of the tips can be easily damaged, causing distortion of
the spray pattern and an increased rate of application.

4. Fill the tank about half full of water and add about 1
pound of detergent for every 50 gallons of water.

5. Operate the pump to circulate the detergent solution through
the sprayer for about 1/2 hour, then flush it out through the boom.

If you have used 2,4-D or an organophosphorous insecticide, be-
fore doing step 6, follow these additional procedures:

a. Replace the screens and nozzle tips.

b. Fill the tank about half full of water and add 1 pint of
ammonia for every 25 gallons of water.

c. Operate the pump to circulate the ammonia solution through
the sprayer for about 5 minutes, and discharge a small
amount through the boom and nozzles.

d. Keep remaining solution in the sprayer overnight.

e. In the morning, flush out all the ammonia solution through
the nozzles by operating the sprayer.

6. Fill the tank about half full of clean water while hosing
down both the inside and outside, then flush out through the boom.

"When finished with the sprayer for the season, remove and store
the nozzle tips, strainers and screens in light oil. Store the
sprayer in a clean, dry shed. If the pump cannot be drained com-
pletely, store where it cannot freeze."

***************

A SUBSTANCE THAT DETERS EGGLAYING BY APPLE MAGGOT FLIES

Ronald J. Prokopy
Department of Entomology

In the preceding 2 issues of Fruit Notes, I have discussed
how apple maggot flies locate food, mates, and egglaying sites and
how this information can be put to practical use in developing traps
for monitoring and (in small orchards) possibly even controlling
maggot fly populations. In this article, I will discuss a unique
sort of behavior engaged in by the apple maggot and its close rela-
tives just after egglaying. The fly-originating chemicals associated
with this behavior offer promise as a new means of controlling the
apple maggot without insecticides in large orchards.

- 9 -

Egglaying by apple maggot females is accomplished when the fe-
male arrives on a susceptible fruit, raises up on its legs, bores
with its ovipositor through the skin of the fruit into the flesh,
and deposits a single egg. The ovipositor is a needle-like protru-
sion from the posterior of the abdomen through which the egg is
passed into the fruit. Following egg deposition, the female with-
draws its ovipositor from the fruit, and then proceeds to circle
around the fruit for about 30 seconds, dragging its fully-extended
ovipositor on the fruit surface behind itself. After this, the fe-
male cleans its ovipositor for a few seconds and then flies off the
fruit.

About 5 years ago, I became very curious as to why the females
engaged in this rather elaborate behavior of ovipositor-dragging.
Actually, my observations of maggot fly oviposition in nature re-
vealed that only about half the cases in which females were seen
attempting to bore into a fruit culminated in ovipositor dragging
while the other half did not. When I examined the fruit, I found
that among females which did drag their ovipositors after attempt-
ing boring, 901 had in fact deposited an egg. On the other hand,
among females which did not drag their ovipositor after attempted
boring, only 2% had deposited an egg. Thus, there was a clear pos-
itive relation between egglaying and dragging the ovipositor after-
ward. This suggested that the act of ovipositor dragging might be
a mechanism for marking the fruit with some sort of substance to
signify the presence of an egg.

I investigated this possibility in a Wisconsin sour cherry
orchard heavily infested by apple maggot flies, which attack sour
cherries in that state. I held a sour cherry by a thin wire at-
tached to the stem, brought the cherry to within a few inches of a
female on a cherry tree, and waited for the female to fly onto the
cherry. Two types of cherries were offered: (1) a clean cherry
never visited or infested by an apple maggot, and (2) a cherry in
which another apple maggot female had just laid an egg and dragged
her ovipositor. It turned out that 621 of the females that landed
on the first type of cherry attempted egglaying, while 01 arriving
on the second type attempted egglaying. Clearly, there was some
sort of deterrent to repeated egglaying associated with the second
type of cherry.

The question now arose as to whether this egglaying deterrent
originated from the eggs, the flies, or the fruit. To answer this
question, I offered the females 4 types of cherries: (1) a cherry
in which a female had laid an egg but was not allowed to drag her
ovipositor afterward, (2) a cherry with a pin prick, and the exuding
fruit juice spread over the fruit surface afterward, (3) a cherry
never visited by any flies, and (4) a cherry in which no egg was
laid, but on which a female (transferred there from another cherry)
had dragged her ovipositor. The results showed that 60-651 of fe-
males that arrived on each of the first 3 types of cherries attemp-
ted egglaying compared with 0% that arrived on the fourth type.

- 10 -

This was strong evidence that some sort of substance (which we will
call a fruit marking pheromone) , secreted from the ovipositor of a
female during ovipositor dragging, was preventing; other females
from attempting to lay an egg.

Of what advantage is it to the flies to deposit such a marking
pheromone? Examination of hundreds of fruits by myself and other
investigators has shown that usually only 1 maggot larva per fruit
can survive to maturity if the fruit is small, 5/8 inch or less in
diameter. Hawthorne fruit, the original native host of the apple
maggot, and sour cherries do not usually exceed this size. There
simply isn't enough food or space in such fruits for more than one
larva to develop. By depositing fruit marking pheromone following
egglaying, a female is in essence saying to other females arriving
afterwards, "Don't bother to lay an egg here. If you do, you'll
be wasting your energy and your egg. There's only room for 1 larva
here, and the larva from my egg already has a head start and would
outcompete the larva from any egg you might lay. You're better off
if you leave this fruit and look for a different one that isn't
marked with pheromone and therefore doesn't already contain an egg."
Apples, which the apple maggot began to infest about 110 years ago,
are of course much bigger than hawthorne fruit or cherries and can
support as many as 15-20 larvae to maturity. Therefore, 15-20 fe-
males can lay eggs in and deposit marking pheromone on apples be-
fore the pheromone begins to become a deterrent to further egglay-
ing.

During the past 4 years, I (alone, or in conjunction with Drs.
Volker Moericke of Bonn, West Germany and Harvey Reissig of Geneva,
New York) have continued to explore various properties of this fruit
marking pheromone. We have found that if pheromone-marked fruit is
kept under dry conditions at normal summer temperatures, the phero-
mone is remarkably stable and is nearly as effective in preventing
egglaying 2 weeks after its deposition as hours after. Surpris-
ingly, the pheromone has proven to be water-soluble, and can be
partially washed away by rainfall. This is not necessarily a dis-
advantage to us, however. For example, we have been able to swish
marked fruit in a container of water, spray the pheromone-water
solution onto clean fruit in laboratory cages, and to a substantial
degree prevent maggot fly egglaying in this fruit. If combined
with an effective spreader-sticking agent, this pheromone should
be able to survive considerable rainfall and remain effective under
a variety of outdoor weather conditions.

Recently, we have found this same sort of pheromone to exist
in all 6 of the close relatives of the apple maggot that we have
examined. These include the blueberry maggot, black cherry fruit
fly, eastern cherry fruit fly, and western cherry fruit fly. Drs.
Byron Katsoyannos and Ernest Boiler of Wadenswill, Switzerland have
also recently found it to occur in the European cherry fruit fly,
the worst pest of cherries in Switzerland. This past year, these
workers collected marking pheromone deposited after about 1 million

- 11 -

cherry fly egg layings in fruit in laboratory cages. They s\\fished.
this fruit in water, and sprayed 10 cherry trees in nature with 2
applications of the pheromone-water solution. The results were ex-
tremely encouraging: only 61 of the pheromone-sprayed cherries had
any cherry maggot eggs or larvae, compared with 100% maggot infesta-
tions of adjacent unsprayed cherries.

In the past 2 months, Reggie Webster and I have discovered that
the fruit marking pheromone of the apple maggot acts net only as
an egglaying deterrent to maggot flies but acts also as a chemical
signal to Opius lectus , a parasite of the maggot eggs. The phero-
mone arrests the parasite females, and elicits a strong degree of
searching behavior for maggot eggs. Parasites encountering fruits
sprayed with marking pheromone are therefore likely to remain in
the area of the pheromone-sprayed tree for a longer time and effec-
tively search out any maggot eggs that might be in the fruit.

The task facing us now is the chemical identification and syn-
thesis of the marking pheromone. This will require the expertise
and equipment of an accomplished pheromone chemist, which are few
in number. We hope in the near future to interest one of them in
tackling this challenging pheromone. If some day the pheromone can
in fact be obtained at reasonable cost, then the pheromone, com-
bined with an effective spreader-sticker, could be sprayed onto our
apple trees to prevent maggot fly egglaying. The deterred females,
which we know move about frequently, might then be captured out by
baited yellow rectangles and/or baited red spheres hung in specific
trap trees. Native or released Opius lectus female parasites would
be retained in the area by the presence of the pheromone. Thereby,
an integrated approach to apple maggot management, combining deter-
rents, attractants, and parasites, could hopefully be achieved.

Establishment and Management of Compact Apple Trees

William J. Lord and Joseph Costante
University of Massachusetts

Part 2

Rootstocks

Commercial interest in size-control rootstocks developed in
the early 1950's in Massachusetts. Presently, those in most
common use are the clonally propagated Mailing (M.) and
Malling-Merton (MM) rootstocks. The degree of dwarfing
induced by these rootstocks is shown in Table 9. A descrip-
tion of these rootstocks and seedlings follows as well as a
summary in Table 10 of the characteristics of the common
and less commonly planted rootstocks.

Table 9. Apple rootstocks presently used in Massachusetts
and their relative degree of dwarfing.

Apple rootstock

Dwarfing (%)
of seedling trees^

M.9
M.26
M.7

MM 106
MM 111
Seedlings

30-50
45-60
55-75
75-90
80-90
100

-Degree of dwarfing will vary with variety and soil type.

M.9. This is a true dwarf rootstock (Table 9) and can be use-
ful for specialized orchard culture by commercial growers.
It is a century old, thus well known. This rootstock has a
brittle root system which means each tree will need to be
supported by a post or by a trellis. It is a very suitable root-
stock for high density plantings. Interest in this rootstock is
increasing for use in "pick-your-own" orchards. On a good
site, with good soil and management, cultivars on M.9 can
be productive.

Virus-tested M.9 rootstocks (free of all known viruses) are
becoming available. Preliminary data from the Netherlands
show that; (a) cultivars on virus-tested M.9 rootstocks grow
more vigorously than those on virus-infected M.9's; (b) virus
tested trees usually produce larger yields than virus-infected
trees; (c) the yield efficiency (poundsof fruit/unit of growth)
of the virus-tested trees is equal to or higher than virus-infect-
ed trees; and (d) fruit quality is also usually better for the
virus-tested trees. The stronger growth of virus-tested trees

could be advantageous on poorer soil but a disadvantage for
high density plantings on strong soils.

Cultivars on M.9 are well suited for trellising or the slender
spindle type of training with a single post parallel to the
trunk for support. Apple varieties differ in vigor on M.9 with
weaker growing types like Idared, Empire, Golden Delicious,
and probably MacSpur easier to train as slender-spindles than
Red Delicious, Mcintosh or Cortland. Slender-spindle trees
will be described elsewhere.

M.26. This is one of the new clones from East Mailing from
a cross of M.I 6 and M.9 and introduced to the U.S.A. about
1 958. Its roots are brittle like the M.9 but trees on this root-
stock have better anchorage. Whether or not trees on M.26
are going to require support is still questionable. At present,
we have found temporary support necessary on windy sites
and when nursery stock quality was poor.

An overgrowth of M.26 forms below the graft union and
burr knots (adventitious roots) form on the stock. It does
not suckei as much as M.7. Trees on M.26 produce earlier
than those of M.7 and it propagates well in stool beds. It is
not resistant to wooly aphids or to collar rot. It is reported
to be very winter hardy. M.26 requires well-drained soil for
optimum performance.

M.26 is gaining popularity in Massachusetts orchards but
many questions about this roostock remain unanswered:
anchorage, soil requirements, whether loss from fireblight
will be a problem, and scion/rootstock effects on growth and
fruiting. Therefore, it is suggested only for trial. We have
observed no serious problems but our experience is limited
to 6 years.

M.26 looks very promising in Michigan. They have lost a
few trees in commercial plantings, but these have been on
low, wet heavy soils. Michigan reports that M.26 will sup-
port a free standing tree. To the contrary, researchers in
western New York are rather "cool" toward M.26 because
of its susceptibility to fireblight and its sensitivity to "wet
feet." It requires a well-drained sandy, loamy soil without
the tendency to drought (Table 8).

M.7 is the best stock we have to give a semi-swarf tree.
Twenty years of commercial experience with M.7 has proven
its reliability under our conditions. Cultivars on this root-
stock come in bearing early and continue to produce good
annual crops. M.7 is not without its faults-it produces suck-
ers from the roots, it tends to lean, particularly when budded
to Red Delicious, and it is susceptible to wooly aphids.

Early

Rootstock

bearir

Seedling

M.13

C-

Robusta 5

MM 104

M.2

M 106

M.7

MM 111

C-

Antonovka

AInarp 2

M.9

A+

M.26

A+

Table 10. Summary of rootstock characteristics
(Letters A-E denote estimate of value: A = excellent; E = poor)

Collar Rot

Tolerance to:

Remarks and

bearing Productivity Anchorage Resistance Wet soil Dryness Low T° Recommendations

Highly vigorous-90 to 100% standard

C-

B-

A-

B+

A+

Medium

vigor range-

'60 to 85% c

)f standard

C-

C+

B-

C-

B +

B+

A+

B+

?
Half -size .

?
and smaller

A+

C-

Use now limited.
Does well on wet soils.
Tolerates heavy soils.

Very susceptible to collarrot.

Never very popular.

Avoid poorly drained soils.

Suckers.

Popular with M.9 interstem.

Inadequately tested in U.S.A.

Inadequately tested in U.SA.

Attractive to mice.

Fire blight susceptibility.

VReported as not being hardy where there are mild periods during winter because it has a very short rest period.

Trees on M.7 need to be budded 8 to 10 inches high in
the nursery so that the trees can be planted deeper in the
orchard. Deeper planting provides better anchorage and
reduces suckering. M.7 produces a tap root, thus trees on
this rootstock should be planted on deep, well-drained soils.
In spite of higher budding, providing temporary basal sup-
port by means of 3-foot long hardwood stakes driven 2 feet
into the ground is advisable for Red Delicious and for all
cultivars on windy sites.

MM 106 has some good characteristics and some believe
these outweigh its weaknesses when budded on semi-
vigorous cultivars (Idared, Empire, or spur-types) and plant-
ed on light loam soils. Trees on this rootstock come into
production early. MM 106 also has a strong well-balanced
root system, therefore, anchorage is not a problem. It is
sucker-free and resistant to wooly aphids.

Our Massachusetts orchards frequently have localized
wet areas and in these areas we lose trees on MM 106.
Furthermore, MM 106 produces large trees with such cul-
tivars as Mcintosh. Loss of trees on MM 106 is commonly
attributed to collar rot but may be more directly related to
winter injury at the crown, soil management, or soil drain-
age. (Trees on MM 106 are slow to mature in the fall and
the trunk tissue near ground level, which is the MM 106
portion of the tree, is late maturing and thus more suscep-
tible to low temperatures in early winter than the other
above-ground portions of the tree.)

MM 111. A good rootstock for sandy loam soils because it is

more drought-tolerant than other size-control rootstocks.
It is more vigorous than MM 106, thus it is of no value to
orchardists desiring to increase tree numbers per acre. Cur-
rently, MM 1 1 1 is being used as the understock for interstem
trees because it produces well anchored trees. It is inter-
mediate in winter hardiness.

Seedling. These formerly constituted the bulk of the root-
stock material used for apple trees. No two seedling root-
stocks are identical in genetic makeup. Trees on seedling
rootstocks are well-anchored and more tolerant to unfavor-
able soil conditions than many M. and MM rootstocks. Trees
on seedling rootstocks are slower to come into production
than those on size-control rootstocks. Seedling rootstocks
will produce trees 25 to 30 feet or more in height without
restrictive pruning. Trees on seedling roots are inefficient
because tree centers are unproductive or produce poor qual-
ity fruit due to inadequate sunlight. Presently, seedlings are
used mainly as the understock for spur-type trees and inter-
stem trees.

Interstem Trees

The interstem tree ordinarily consists of: the understock, the
interstem, and the scion variety (Fig. 2A). Interstem trees
cost more, and they are usually only available by contracting
two years in advance. The scheme most often practiced by
the nurseryman is to bench-graft the interstem (M.9) onto
the chosen rootstock (usually MM 106 or MM 111), plant
this tree in the nursery and bud on to it the scion variety in

August.

Trees consisting of four parts denoted as "C" series inter-
stem dwarf apple trees are available from a nursery in Mis-
souri. These have a seedling root, K-14 winter hardy trunk,
a dwarfing interstem (C-6 or C-52) and the fourth part of
this tree is the desired cultivar (Fig. 2B). The nursery reports
that standard cultivars with C-6 produce trees about half size
of standards on seedling roots. The interstem C-52 produces
trees about two-thirds to three-quarters the size of the cul-
tivar on seedling roots. Combining the spur-type cultivars
with the C-6 and C-52 interstems reportedly produces earlier
bearing, heavier yielding, and smaller trees than if standard
type cultivars are used. Our experience with the "C" series
in Massachusetts is limited.

There is an active interest in interstem trees with M.9
interpiece because of the desire for small trees that do not
require support. Tree size should be intermediate between
that produced by M.9 and M.7 rootstocks. It is suggested
that the M.9 interstem should be at least 6 inches long and
positioned on the stem of the understock at least 12 inches
from the top of the roots to permit deeper planting.

Interstem trees are suggested for trial.

Orchard Design

Tree density defined. Terminology and planting distances
used vary among researchers with compact apple trees. Below
is shown the names we have chosen for this publication, the
tree number in each density, and the rootstock and interstem
combinations that can be utilized in each density.

Rootstock and interstem
combinations that can be
Density Number of trees/A utilized in each density^

Low Less than 1 14

Medium 115 to 249

High 250 or more

Seedling, MM 111, MM 106,
Alnarp2, M.13, C-52/K-14/
seedling, M.7.

MM 106, M.7,C-52/K-14/
seedling, C-6/K-14/seedling,
M.9/seedling, M.9/Alnarp 2,
M.9/MM 111,M.9/MM 106,
M.26.

M.9

Cultivar vigor and soil type are factors influencing tree
spacing.

Tree spacing. We cannot make firm recommendations on
planting distances because our experience is too limited.
Furthermore, the number of variables affecting tree size
are great— orchard site, soil, severity of pruning, nutrition
and tree training among others. However, as a guide we have
suggested in Table 11, planting distances that seem reason-
able minimum spacings for our conditions in Massachusetts.
Similar tree spacings are given for both medium and low
vigor cultivars which reflects our lack of experience with the
spacing requirements of various cultivar-rootstock combina-

Fig. 2. Interstem trees. (A) is a3-piece tree with an MM 106
understock, M.9 interstem, and Mcintosh as the
cultivar. (B) is a 4-piece tree with a seedling under-
stock, K-14 winter-hardy trunk, C-6 dwarfing inter-
stem, and Mcintosh as the cultivar.

tions. However, we have 20 years of commercial experience
with M.7 and strongly believe that without restrictive prun-
ing, 16 ft. X 24 ft. should be considered the minimum spacing
of a permanent planting of vigorous cultivars on this root-
stock and that on some soils 20 ft. x 30 ft. spacing is not
too wide.

We have allotted an 8 ft. alley for orchard travel and har-
vest operations. If you like a 7 ft. alley, decrease the spacings
between the rows by I ft. (for example, a 16 ft. x 24 ft. spac-
ing to 16 ft. x 23 ft.).

It cannot be overemphasized that as planting density
increases, it becomes even more important that soil, cultivar
and rootstock be correctly matched. When deciding on what
density to plant, consider the following factors: (1) the
characteristics of the site and soil— windy, poorly drained
soil, etc.; (2) cultivar being planted— vigorous, spur-type, etc.;
(3) time available for tree training and pruning; and (4) meth-
od of marketing— "pick-yourown," processing, or fresh use.

Low density tree planting. Usually allows for full tree devel-
opment with a minimum of pruning to restrict tree spread.
It requires the least investment per acre while production
costs are below those of orchards on seedling rootstock.
Massachusetts growers should consider low density plant-
ings when the cultivar is a vigorous-growing (Mcintosh and
Delicious) standard-type tree and the rootstock is M.7 or
MM 106 because it is difficult to restrict the size of these
trees. Plantings of these cultivars on these rootstocks spaced
10x18 feet, 15 x 20 feet, or 20 x 20 feet have become so
dense that growers have been forced to remove trees while
the orchards were still relatively young.

Medium density tree planting. Thisdensity will require more
careful attention to training and pruning trees than with low
density planting to prevent tree crowding and maintain fruit
quality. It is essential to maintain conical-shaped trees

(Christmas tree shape). The higher investment per acre in
comparisonto low density plantings (Table 1) should be off-
set by earlier, higher yields. Medium density plantings involve
free standing trees-MM 106, M.7, M.26, and interstem trees.
However, more experience is needed before we can be sure
of the stability of trees on M.26 without support.

The trees are smaller than in the low density planting,
easier and less cos'tly to spray, and a higher percentage of
the leaf area is exposed to sunlight which is essential for
flower bud formation and high fruit quality.

High density tree planting. This type of planting will require
the use of M.9 rootstock with the tree individually staked
or supported by a trellis. Thus cost of establishment is
extremely high (Table 1). Adjustments in orchard size and/or
management procedures will be necessary if sizeable acreage
of high densities is planted by the established grower because
of the careful attention needed in growing the trees and
containing them within their allotted space. Few soils in
Massachusetts are suitable for trees on M.9 without providing
supplemental water.

In the Netherlands, where all modern plantings are on
M.9, there is a rule of thumb that states that orchard size
should be governed by the number of skilled pruners on the
farm. An apple orchard of 20 to 25 acres is considered large
in the Netherlands and the grower sells his fruit through an
auction, jumble-packed in wooden crates. To the contrary,
the average Massachusetts grower has 50 or more acres, grades
and packs his fruit into bags, cell count cartons or trays,
and in many instances retails part of the crop. Time is such
a limiting factor that many orchardists are forced to hire

custom pruners to prune their bearing orchards.

Orientation of tree rows. North-south orientation of tree
rows is preferred because it favors maximum exposure of
the leaves and fruit to sunlight. However, frequently the
topography of the land and orchard boundaries dictate the
directions in which the tree rows will extend.

When designing the orchard, allow for service roads and
sufficient space at the ends of rows for equipment maneuver-
ability.

Pollination. Most apple cultivars are self-unfruitful and
require cross-pollination to set a commercial crop. In select-
ing a cross-pollinating cultivar, the following factors should
be considered: (1) Age when it begins to flower, (2) season
of bloom, (3) viability of pollen produced, (4) tendency to
flower annually, (5) cross-incompatibilities, and (6) adapta-
bility and value of the cultivar to the region.

Table 1 2 lists some of the cultivars grown in Massachusetts
according to their season of bloom. These are generally suit-
able cross-pollinizers for each other; several exceptions are
noted. These cultivars do not always bloom in the same rela-
tion one to another each year. During years when the pre-
bloom temperatures are high, all cultivars are apt to bloom
at about the same time; when the pre-bloom temperatures
are low, the bloom is late and 7 or more days may elapse
between the early- and late-blooming cultivars. Bloom peri-
ods of those cultivars listed in the early- and mid-season
groups should overlap sufficiently for suitable cross-pollina-
tion in most seasons; the same would be true for those cul-
tivars in the mid-season and late categories. It would be

Table 11. Suggested minimum planting distances for various apple cultivar/rootstock combinations.^

Rootstock or interstem combination

Tree spacing (ft) and trees/acre (in parentheses) for:

Vigorous Medium vigor and

cultivarsV low-vigor cultivars^

M.9 or M.9A

M.26

M.9/MM 106

M.9/MM 111

M.9/Alnarp2

M.9/seedling

C-6/K-14/seedling

C-52/K-14/seedling

M.7or M.7A

MM 106

MM 111

8x 16
14x22
12 X 20
14x22
15x 23
15x23
15 x 23
16x24
16x24
18x26
20x28

(340)
(141)
(181)
(141)
(126)
(126)
(126)
(113)
(113)
( 93)
( 77)

14 (518)

12x

20(181)

lOx

18(242)

12x

20(181)

13x

21 (159)

13x

21 (159)

13x

21 (159)

14x

22(141)

14 x

22 (141)

16x

24(113)

18x

26 ( 93)

^Increase spacings by 2 feet on heavy soils.

VMclntosh, Delicious, Cortland, Macoun, Puritan, Spartan.

'^Most spur-type Mcintosh, spur-type Delicious, Paulared, Tydeman's Early, and Jerseymac have medium vigor. Golden Delicious,
Idared, Empire, MacSpur, and Rome are cultivars with low vigor.

Table 12. Approximate bloom period of apple cultivars
producing viable pollen for cross-pollination.^

Early

lidseason

Late

Empire

Jerseymac

Julyred

Lodi

Mcintosh

Niagara

Paulared

Puritan

Tydeman

CortlandV Macoun

Delicious'* IVIelrose''

Early Mclntoshy Northern Spy, Red Spy

Golden Delicious Rome, Gallia

I da red

Spartan

Spencer

^ Bud sports or strains of an apple cultivar are not cross
fruitful with each other or the parent cultivar even though
they have viable pollen and functional ovules. Examples:
Delicious strains such as Richared, Starking, Red Prince
and Starkrimson will not pollinate Delicious or each other
and vice versa.

VCortland and Early Mcintosh are cross-incompatible but
are suitable pollinizers for other cultivars.

'^Melrose and Delicious are said to be cross-incompatible.
Both are suitable pollinizers for other cultivars.

The cultivars listed below are triploids; they do not pro-
duce viable pollen and are ineffective in cross-pollination.

Early

Midseason

Late

Gravenstein

Baldwin

Mutsu

Rhode Island Greening

Spigold

unwise to rely on early blooming cultivars to cross-pollinate
a late-blooming cultivar or vice-versa.

One should not rely entirely on strongly biennial culti-
vars such as Early Mcintosh as cross-poliinizers for annual
cultivars such as Cortland, Delicious and Mcintosh. When a
strongly biennial cultivar fails to bloom, there is no suitable
pollen to cross-pollinate the usual annual flowering cultivar.
Hence, the annual cultivar will fail to set a commercial crop
in alternate years and tends to become biennial, also.

In low density plantings, the pollinating cultivar may be
set either in solid rows or interplanted with the main cultivar.
The former is preferred because interplanting with the main
cultivar can create problems in spraying and be an incon-
venience in harvesting. When the pollinator cultivar is set in
solid rows, alternate 1 or 2 rows of the pollinator with 4 rows
of the main cultivar. Where interplanting is used, every third
tree in every third row should be a pollinator cultivar.

Early Mcintosh and Golden Delicious are probably par-
tially self-fruitful and it is advisable to set them in solid rows
with fewer pollinating rows than with other varieties to
reduce the tendency of oversetting and for convenience of

spraying. To the contrary, Cortland, Mcintosh and particu-
larly Delicious require a high proportion of pollinators, par-
ticularly on sites where poor pollinating weather is apt to
occur rather frequently.

It is well documented that foraging bees tend to work up
and down rows rather than across rows. When trees are
planted at low densities and the trees are not crowded in
the row, the bees will move between trees somewhat indepen-
dently of the row. However, medium and high density plant-
ings may eventually have little space between trees in the
row, thus forming virtually a solid hedgerow. As a result,
the distribution of pollenizer pollen across one or more rows
may be seriously limited because of movement of the bees
along the hedgerows instead of between adjacent rows.
Thus, it may be advisable that every fourth tree in every
row be a pollinator cultivar.

Orchardists almost invariably rely on honey bees for pol-
len dispersal, and they usually do this by renting colonies
from beekeepers. We suggest that one, but preferably two
colonies per acre be brought into the orchard at the time of
10% bloom. The hives may be arranged singly or in groups
of 4 in various locations. Grouping is superior because
colonies competing with each other increase bee activity.
Bees can "set a crop" in 2 good flying days (temperature
about 65° F and partial sun). After full bloom, bees should
be removed as soon as possible so that you can continue
your spray program.

Soil Preparation

Frequently, hay fields and pastures with reasonably good
fertility, can be planted to trees without extensive land
preparation. While it is generally true that newly-set fruit
trees do very poorly in a heavy grass sod, it is possible to
obtain growth equal to that obtained under cultivation by
the use of herbicides.

Hay fields, and especially pastures, frequently have low
fertility. Fertility can be increased by applying 500 to 600
pounds of a complete fertilizer such as 10-10-10 and by
application of sufficient high magnesium lime or a high cal-
cium lime. A soil pH of 6.0 to 6.5 is desired for orchards.
Soils which have not had frequent applications of lime will
require 2 or more tons of lime per acre. (It is always advis-
able to have the soil tested to determine its pH and lime
requirements. Information on taking soil samples and where
to send them for analysis can be obtained from your County
Extension Office.)

Paraquat (an herbicide) can be applied in 4 to 6 foot wide
strips along the tree rows the year prior to planting or after
planting to control grasses and broadleaf weeds. Residual
herbicides should not be used for preplanting weed control
because the trees planted in the treated soil may be killed.
When paraquat is used the year of planting, the spray must
not hit the v\/ood of the tree, otherwise injury may occur.
Information on herbicide usage can be obtained from your
County Extension Service.

On newly cleared land and soils which are low in fertility

and are not too stony or likely to erode badly, It is advisable
to build up the soil by seeding and plowing or disking under
cover crops before planting trees. Spring oats, buckwheat,
or millet can be sown as the summer cover crop and spring
oats for the winter cover crop. This is an opportune time to
apply lime because it can be incorporated into the soil during
the disking of the cover crops.

When the trees are planted, a mixture of grass seed and
oats can be sown. During the summer, the oats can be cut
and let lie or be raked around the trees for mulch.

On a fairly level site which is not subjected to serious
erosion, it may be possible to interplant with low growing
crops such as pumpkins, for "pick-your-own" or roadside
stand sales. These crops can be grown for a few years to
help defray the cost of caring for the young trees until they
come into production. The rows of the cultivated crops
should not be planted so close to the tree rows that they
interfere with growth of the young trees. Intercrops in a
young orchard should be considered as a temporary enter-
prise and they should be discontinued just as soon as they
interfere with tree growth and care.

Mapping the Orchard

Once the decisions are made concerning cultivars, rootstocks,
and planting distances, the orchard design should be drawn
to scale on paper. Be sure to map the location of the drainage

system, wet spots, and changes in soil type.

After planting, record any changes in original planting
plan, and record the date of planting, name and address of
nursery supplying the trees, weather conditions at time of
planting, and other information of value.

Staking the Field

A base line (the first row) is laid out on one side of the field
parallel with an adjacent row of trees in an existing orchard,
a fence, or a road. Stakes are placed along this line where
the trees are to be planted. {I/Vhen staking the field be sure
to allow sufficient room along the edges of the orchard for
equipment maneuverability.) Now establish several rows of
stakes at the spacing desired for the alley between trees at
right angles to this row (Fig. 3). Right angles can be deter-
mined with a measuring tape and stakes using the carpenter's
square method in which 9 ft. X 12 ft. x 15 ft. or 12 ft. x 16 ft.
X 20 ft. are the lengths of the sides of the right-angled triangle.
A right triangle can be constructed out of wood strips if
desired. Now that the stakes are in place, the remainder of
the orchard can be staked by "sighting-in" on the stakes
and with the tape measure.

When staking the field only 1 or 2 months prior to plant-
ing, a couple of handfuls of lime can serve as an alternative
to staking each tree location.

Fig. 3. A method of staking the orchard before planting. In this planting, the first row is laid out 30 feet from an existing
fence and the location of the trees in the row staked (12 feet apart in the row). Right angles are determined at both
ends and the middle of the first row with a 12 ft. x 16 ft. x 20 ft. right triangle. By stretching a measuring tape along
the 16 ft. side of the right triangle, the location of the trees can be staked. The rows are 20 feet apart.

Cooperative Extension Service
University of Massachusetts
Amherst, IVIassachusetts
R. S. Whaley
Director
Cooperative Agricultural Extension Work
Acts of May 8 and June 30, 1914

Official Business

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FRUIT
NOTES

PREPARED BY
DEPARTMENT OF PLANT AND SOIL SCIENCES

COOPERATIVE EXTENSION SERVICE,
UNIVERSITY OF MASSACHUSETTS, UNITED
STATES DEPARTMENT OF AGRICULTURE AND
COUNTY EXTENSION SERVICES COOPERATING.

EDITORS
W. J. LORD AND W. J. BRAMLAGE

Vol. 42 (No. 2)
MARCH/ APRIL 1977

TABLE OF CONTENTS

The Use of a Pressure Tester to Measure Firmness of Apples
Apple Trees on M.26

Mite Predator Studies in Massachusetts Apple Orchards in 1976
Pomological Paragraphs

Selecting the best spacing for the variety, rootstock and
soil

Early heavy cropping

THE USE OF A PRESSURE TESTER TO MEASURE
FIRMNESS OF APPLES

William J. Bramlage
Department of Plant and Soil Sciences

Firmness of apples is used worldv\fide as a measure of ripeness
and "condition" of the fruit. The most widely used instrument for
firmness measurement is the Magness-Taylor pressure-tester (devised
in 1925), although the Effegi tester (developed recently in Italy)
has met some acceptance due to its compact size and convenience.
Tests comparing the Magness-Taylor with the Effegi indicate that
readings of the 2 instruments are quite comparable, and I shall as-
sume that what is said in this article about use of a Magness-Taylor
is equally true about use of an Effegi tester.

With its worldwide and longstanding use, and the importance
of its measurements, one may assume that the Magness-Taylor is used
in a standard way and that readings by different users are closely
comparable. Not so! There is no standard technique and readings
are often grossly variable among users of the instrument. In 1
test in Geneva, New York, it was found that professional users of
a Magness-Taylor varied as much as 3 to 4 lbs in the readings they
obtained on the same lots of apples! Following an informal discus-
sion at a meeting in December, 1975, where it was evident that use
of pressure testers differed widely, 10 Northeastern post-harvest
horticulturists-^ agreed to 'gather data on factors that can influ-
ence pressure test determinations, in hopes of standardizing a tech-
nique. The results of this collaborative effort, coordinated by
Dr. G.D. Blanpied of Cornell University, are summarized here.

The Magness-Taylor pressure tester : The instrument itself may
be a cause of erroneous readings. First , there are 2 sizes of plun-
ger "heads" that might be used. For apples, the larger one, with a
diameter of 7/16 inch, is always used; the smaller, 5/16 inch head
is for use on pears, which are much harder than apples until nearly
ripe. A second problem is that the instrument may not be calibrated.
Calibration is relatively simple and should be checked regularly.
To calibrate, place the plunger on an accurate scale and press down
slowly until the scale registers a weight that occurs on the pres-
sure tester scale. Check this weight against the recorded reading
on the pressure tester. Several different points on the scale should
be tested in this manner. If the readings on the scale and on the
tester do not correspond, the readings on apples you obtain with
the tester should be adjusted accordingly, or better, the spring in
the pressure tester should be replaced or the instrument sent to the
factory for re-calibration, if necessary. A rusty spring should
always be replaced.

Collaborators were: G.D. Blanpied, Cornell Univ.; D.H. Dewey, Mich. State Univ.;
R.E. Hardenburg and A.Watada, USDA, Beltsville, Md. ; M. Ingle, W.Va. Univ.;
R. LaBelle d, L. Massey, Geneva, N.Y. ; G. Mattus, V.P.I and S.U., Blacksburg,Va. ;
W. Stiles, Univ. of Me. and W.J. Bramlage.

- 2 -

Choosing a sample for testing : The user should consciously and care-
fully choose the fruits that will be tested, knowing the factors that
may influence the readings.

A. If you are testing in the orchard, it is likely that fruit
from the outside of the tree will test firmer than those
toward the inside of the tree.

B. Fruit size is a very important factor. In general, the
larger the fruit, the softer it will be. Sometimes a 1/4
inch difference in diameter can make a 1 or 2 lb differ-
ence in the pressure test! Following years of careful
record-keeping. Dr. George Mattus suggests that you not
vary more than 1/4 inch in diameter among the fruit you J
test. Obviously, some kind of sizing device is therefore '
necessary in choosing a sample. Further, you should test

a size that is representative of the majority of the crop,
and specify the size you are testing. You cannot accurately
compare firmness of lots of fruit if you sample 3-inch fruit
in one lot and 2-1/4 inch fruit in the other.

C. The temperature of the fruit can have a small but sometimes
significant influence on pressure tests. Firmness tends

to be slightly less when apples are warm than when they
are cold. This is not nearly as important a point as is
the size of the fruit, but for maximum accuracy, the user
should be consistent about testing either warm fruits or
cold fruits.

D. A very important but controversial question is: How many
fruits should you test, and how many times should you test
each fruit? Obviously, 1 fruit is not sufficient, and the
more fruits you test, the more accurate will be the aver-
age pressure reading. But, between these 2 indisputable
points there is little agreement. Many people test only
once per fruit, but many others test twice -- once on each
of the opposite sides (usually blush and green sides).
Some people may even test as many as 4 points on an apple.
(Is 1 apple tested on 2 opposite sides equal to 2 apples
tested on 1 side? Probably not.) How many different fruits
should you test? Most people agree that 10 fruits from a
given lot is probably minimal for accuracy, but may prefer
20 to 25 fruits to reduce error. If only 10 are tested,
they should probably each be tested on 2 opposite sides.

I personally prefer testing 20 apples once on a designated
(green or blush) side. The significant point here is, how-
ever, that a large enough sample must be tested to overcome
the variation within the population of fruits being samp-
led. If large variation exists, a large sample size is
required.

Making the test : Having calibrated the pressure tester and care -
fully chosen a~sample, how should you test the fruits? First, you
shouldrecognize that the fruit is not of uniform firmness. Gener-
ally, the blush side is firmer than the green side. This differ-
ence may be as much as 1 lb of pressure. Therefore, either consis-
tently test the blush side, knowing it is firmer, or the green side,
knowing it is softer, or else test both the blush and the green sides
and average the readings.

Since the skin badly distorts a pressure test on an apple, it
must be removed from the area to be tested. The depth of the cut
removing this skin influences the reading: the deeper the cut, the
higher the reading. Dr. Robert Hardenburg suggests use of a potato
peeler (stainless steel to avoid rusting) for quick, shallow, con-
sistent cuts. These cuts should be made at a point half way between
the stem and calyx ends of the fruit. Never test a bruised area.

For testing, the fruit should be placed on a hard surface (e.g.,
table top) rather than being hand-held. The plunger should be in-
serted to the line inscribed on the plunger . Testing only to the
"yield point" of the fruit tissue (i.e. , when it "gives") produces
an erroneously low reading, and going beyond the line gives a high
reading. However, the most critical feature of testing is the speed
of applying the force . The faster you apply the pressure, the higher
will be the reading. The proper speed is about 2 seconds, and to
regulate your speed it is suggested that you say to yourself, "1001,
1002, as you insert the plunger into the fruit. This may sound
childish, but it is extremely critical as can be seen simply by ap-
plying force at different speeds during calibration. The user needs
to frequently check himself during testing to make sure he is test-
ing at the proper speed. Applying pressure too fast is probably the
greatest source of false readings by users of the pressure tester .

Having tested the fruit, how do you read the scale? Some read
it to the nearest whole lb., others to the nearest 1/2 lb., and some
may even read to the nearest 1/10 lb. It seems clear that reading
to the nearest 1/2 lb. is sufficient, and if your sample size is
reasonably large, the nearest 1 lb. is satisfactory. Again m.y prefer-
ence is to the nearest 1/2 lb.

With an accurate instrument, careful sampling, and precise
testing, you should obtain a quite accurate firmness measurement
of the fruits. But this accurate measurement still may not truly
represent the "condition" of the apple. Some sources of error are
the following.

A. Nitrogen (N) level of the fruit: Increasing the N level in
apples may reduce firmness of apples more than it affects
postharvest "condition" of them if the apples were at the
threshold of N-deficiency before treatment. Thus, you may
misjudge "condition" by comparing lots of widely varying
N levels.

B. Watercore: The more watercore in a fruit, the firmer it
may pressure test, even though increasing watercore indi-
cates increasing fruit maturity. Pressure tests may indi-
cate very little about "condition" of watercored apples.

C. Water loss: If apples are losing water rapidly, they may
"soften" due to loss of turgor, i.e., wilting. This soften-
does not represent what is usually regarded as "loss of con-
dition."

There are probably other complicating factors, also, but these
examples illustrate the importance of observing the fruit you are
testing, recognizing symptoms of complicating conditions, and being
careful about how you interpret the results of pressure tests.

With the importance of firmness in the acceptability of apples,
and the ease of using pressure testers, these instruments seem cer-
tain to remain as key determinants of apple quality in the foresee-
able future. Yet, it is shocking to see how erratically these de-
vices are used. At present, a term, like "10-lb Mcintosh" may actu-
ally mean little to anyone but the person who tested the fruit; these
same apples may test 12 lbs. to another person, and 8 lbs to still
a third person. Yet, Mcintosh apples truly testing 12 lbs. of pres-
sure have grossly different potential than ones truly testing 8 lbs.
If we are going to use firmness as a meaningful guide to apple qual-
ity, we all need to re-examine our testing procedures, and do our
utmost to standardize them so that our determinations can become
more comparable and our interpretation can be more accurate. Here
is a problem that can be overcome with good judgement and little or
no expense.

***************

APPLE TREES ON M.26

William J. Lord
Department of Plant and Soil Sciences

Observations this past year show that the vigor of non-bear-
ing trees on M.26 is variable. ( Assuming that all the trees are
on M.26.) Trees of the same variety , within a block, may be ex-
tremely variable in some orchards with some weak and/or difficult
to train. This may mean that trees of M.26 react more to unfavor-
able growing conditions than those on more vigorous size-control
rootstocks .

Roger Young, Kearneysville, West Virginia, reported at the
19th Conference of the International Dwarf Fruit Tree Association
on March, 1976, that leaning in a test orchard of the trunk or leader
(central leader not being upright) of trees on M.26 was a problem

5 -

especially with 'Stayman', ' Rome ' , ' Winesap ' , and 'Jonathan' culti-
vars. Non-bearing 'Red Prince Delicious' planted at our Research
Center in 1971 or 1972 have developed leaning. The leaning appears
to be caused by something other than poor anchorage . In other orch-
ards, poor anchorage appears to be a problem. Trees that were pro-
vided either no support or a short stake for support at planting,
now require an 8-foot stake for support in some instances. This
was not due to early, heavy cropping. Whether or not the stakes can
be temporary or needed permanently is not known.

We need a free-standing tree smaller than that produced by M.7.
But I'm beginning to wonder if M.26 is the answer for some orchards.
Approximately 8% of the trees in Massachusetts on size-control root-
stocks are on M.26. Thus, in several years we can better evaluate

M.26.

***************

MITE PREDATOR STUDIES IN
MASSACHUSETTS APPLE ORCHARDS IN 1976

Robert G. Hislop and Ronald J. Prokopy
Department of Entomology

In several 1976 issues of Fruit Notes , we described certain
techniques developed by researchers in other apple growing regions
of North America to reduce spraying for apple insects and mites
without sacrificing fruit quality or quantity. These accomplish-
ments were made possible by careful monitoring of insect popula-
tions in the orchard, and selection of orchard sprays to which mite
predators were resistant. In this issue of Fruit Notes , we will
describe work we have been doing this past year toward a similar
goal of reduced spraying for mites in Massachusetts apple orchards.

Our study is long term and its objectives twofold: (1) to
determine which species of mite predators occur naturally on wild
or unsprayed abandoned apple trees, and (2) to determine if any of
these predators occur or thrive in commercial orchards. This should
provide some indication as to which types of spray programs are con-
ducive to the buildup of these beneficial predators in our orchards.

We knew at the beginning of our study that Amblyseius fallacis ,
a predatory mite known to play a key role in the suppression of red
and two spotted spider mites in some commercial apple orchards in
the midwest and southeast, also occurs in some northeastern states.
Several of its habits are well known, such as remaining in the
ground cover until July, when it moves up into the tree canopy to
feed on plant feeding mites. Here it is exposed to the constant
onslaught of cover sprays directed against principal insect pests.

- 6 -

Because of this exposure, A. fallacis eventually developed resis-
tance to certain organophosphorous Tiisecticides . Portions of our
orchard survey, described below, were undertaken in hopes of dis-
covering this particular predator in Massachusetts orchards.

Last spring, we began intensive tri-weekly sampling of mite pop-
ulations from March through October in the orchard at the Belcher-
town Research Center, and in 6 commercial and 3 abandoned orchards
in 3 different locations across the state. In the Belchertown orch-
ard, each of the materials Zolone*, Guthion*, Imidan*, and Sevin*
were regularly applied by airblast sprayer to each of 3 groups of
trees, with 3 groups left unsprayed for comparison. Among the com-
mercial orchards, 3 used one type of spray program, while the other
3 used a different program. In each orchard, samples were taken of
the ground cover under the trees, bark, and leaves of 3 'Red Delici-
ous' and 3 'Mcintosh' trees. The ground cover and bark were sam-
pled to determine if mite predators, especially A. fallacis , existed
in these habitats at different times of the season.

Bark and ground cover samples were placed in funnels under
heat lamps which forced mites out of the samples into jars of pre-
servative placed at the bottom. Leaf samples were brushed in a
mite brushing machine, the mites landing on glass discs on which
they could be readily observed. All mites were counted, including
red and two-spotted spider mites, tiny apple rust mites, and preda-
tory mites and insects.

We also sampled the leaves of 20 other commercial orchards
from which we had obtained the spray history. This sampling was
conducted only once--at the peak of the mite season in August.

Our results to date reveal arboreal mite predators to be widely
distributed in Massachusetts apple orchards. However, Stethorus
punctum , the black lady beetle important in Pennsylvania apple orch-
ards , and Typhlodromus pyri , the predatory mite important in Western
New York, were not found in our survey. The situation in abandoned
orchards was quite different from commercial ones. In commercial
orchards, fewer kinds of mite predators were found, the predominant
species being A. fallacis . This predator was seldom encountered in
abandoned orchards'!! Red and two-spotted mites were virtually ab-
sent in abandoned orchards, which is not surprising in view of the
high predator populations found there. Growth of these populations
was likely aided by high abundance of one of their food sources,
the apple rust mite.

In many commercial orchards where the spray program included
repeated applications of Zolone* and/or Benlate*-glyodin combination
arboreal mite predators were scarce or totally absent. It appears
that one or all 3 of these materials may have been toxic or repel-
lent to the predators. In such orchards, the two-spotted spider miti

*Trade name

was the principal mite pest and miticides were applied repeatedly
(2-4 applications) for its control. Two-spotted populations first
appeared in early June, increasing thereafter until miticides were
applied in July and August.

In comr.ercial orchards where the above materials were not used,
arboreal mite predators, particularly A. fallacis , were present in
numbers sufficient to exert some suppressive effect on the spider
mites. In most such orchards, the predominant mite pest was the
European red mite. In 2 of the intensively studied orchards, pop-
ulations of red mite peaked in late June in one orchard and late
July in the other. In each case, only one miticide application
was needed. A. fallacis (which appears to be only slightly suscep-
tible to the principal miticides used in all sample orchards: Plic-
tran* and Omite*) first appeared in the trees in July and increased
thereafter in apparent response to increasing European red mite pop-
ulations. The miticides undoubtedly eliminated part of A. fallacis '
food source but apple rust mites were present in sufficient numbers
to provide alternate food. In the third orchard studied intensively,
spider mites never reached numbers high enough to cause damage and
no miticide was needed.

None of the arboreal mite predators, including A. fallacis ,
appeared in the bark samples, suggesting wind dispersal as the pri-
mary means of their getting into the tree. The ground cover samples
are still being analyzed. When completed, this analysis should
tell us more about the early season habits of these mite predators.

We are encouraged by the wide distribution of certain arboreal
mite predators such as A. fallacis in Massachusetts apple orchards.
However, results to date tend to confirm our suspicion that these
important predators either cannot survive or are repelled in orch-
ards sprayed with certain insecticides and/or fungicides. This is
of immediate economic importance to the grower, and may have serious
long-term consequences as well. For example, if spider mites ever
become resistant to all available miticides (which is a possibility),
orchardists using these materials will almost certainly have little
protection against spider mite buildup. In orchards where the build-
up of mite predators is not discouraged, it is likely that miticide
usage can be reduced in most cases.

During the next two years, we will be continuing our field and
laboratory studies so that we may more fully comprehend the poten-
tail of natural enemies, particularly mite predators, in the suppres-
sion of red and two-spotted spider mites in our commercial orchards.

***************

POMOLOGICAL PARAGRAPHS

S electinR the best spacing for the variety, rootstock and soil .
We can try, but I believe that one cannot accurately select the
best spacing for the variety, rootstock, and soil under our condi-
tions. To do this, one may have to use several rootstocks in the
same row because of the variable nature of our soils. Even then,
it would be guess work. Personally, if I make an error, I prefer
that the spacing be too wide rather than too close. I believethat
the average Massachusetts apple grower who stores and grades his
own fruit hasn't the time nor money to fight trees too closely
spaced for their natural vigor.

ft**************

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

***************

All pesticides listed in this publication are registered and cleared
for suggested uses according to Federal registrations and State Laws
and regulations in effect on the date of this publication.

When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.

NOTICE: THE USER OF THIS INF0R>1ATI0N ASSUMES ALL RISKS FOR PERSONAL
INJURY OR PROPERTY DAMAGE.

WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS
AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN
ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE-
STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER
AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS.

Establishment and Management of Compact Apple Trees

William J. Lord and Joseph Costante
University of Massachusetts

Parts

Purchasing Trees

Quality trees are the foundation of a successful orchard;
anything less is a gannble. Thus, the following points are
worthy of nnention.

1. Plan ahead (a year or two is best), thereby making
it possible to plant the trees you want when you
want them.

2. Tree quality rather than price should be the major
consideration. One-year-old trees, 4 to 6 feet in
height and at least 5/8 inches in diameter usually
grow faster than lower grades.

3. Insist on 1-year-old branched trees or whips budded
14 to 16 inches above the bottom of the rootstock.
Trees budded lower than this may have to be staked.

4. We suggest purchasing from nurseries that dig their
trees in the fall and store them.

5. Don't accept second best even if it means waiting a
year or more for quality trees on the desired root-
stocks and/or of the desired cultivar. The time waiting
usually can be well spent on site preparation.

6. When ordering interstem trees be sure to specify a 6
to 7 inch dwarfing stem piece grafted on a 7 to 10
inch long understock. Degree of dwarfing varies with
interstem length— the longer the interstem, the great-
er the dwarfing.

Care of Trees on Arrival From the Nursery

Check the trees to determine if tree count and cultivar/root-
stock and size agrees with order and to determine if injury
to the trees might have occurred in handling and shipping.
Do this where it is cool and the roots will not dry out.

If planting conditions are not suitable, open the bundles
of trees and store them in a cool, well-ventiled area and be
sure the roots are kept moist, or heal them in a shady area,
or cover the roots with wet soil, peat or sawdust in an open
shed. DO NOT store trees with apples or where they have
been stored. It is possible that residual ethylene in the stor-
age atmosphere might break dormancy of the trees and when
planted they may fail to grow properly or even die. Pear trees
are especially sensitive to injury.

All photographs in this and subsequent parts bv Louis J. Musante.

Time of Planting

Fall planting of apple trees is not recommended for Massa-
chusetts because there is too much risk of winter injury to
the trees. The trees should be planted in the spring as soon
as the frost is out of the ground and the soil easily worked.
Most years, planting can commence in late April, thus the
target for receiving trees from the nursery should be April 1 5.
Late planting is a frequent cause of unsatisfactory tree
growth.

Planting

The soil should be in a good workable condition at planting.
Do not plant in a wet "soggy" soil. The hole for the tree
should be large enough to take in the entire root system. It
is important to dig the holes the right depth because if dug
too deep the tree may settle after planting and the graft
union will be below ground. To the contrary, the hole should
be deep and wide enough so that the roots will rest on the
bottom without having to "pin-them-down" with soil.
Plant the trees in good loam soil. When the hole is hand-dug,
place the top soil on one side and the subsoil on the other
side. This will enable you to place the top soil around the
roots when setting the tree. Putting 2 to 3 pounds of high
calcium lime on the soil scheduled to be returned to the
planting hole may improve the calcium level of the trees for
2 or 3 years. Haul in some rich soil if the soil is not good.
A half bushel of good soil with 2 to 3 pounds of high cal-
cium lime mixed with it will help the trees off to a good
start.

Planting holes are most frequently dug with tractor
mounted augers. A 9-inch auger is suitable for trees on M.9
rootstock. However, a 12-inch auger is needed when the post
for supporting the tree is going to be placed in the planting
hole. A 2-foot auger orbackhoe is best on a poorly prepared
soil and for trees on rootstocks other than M.9.

Soaking the tree roots in water for 12 to 18 hours prior
to planting is a good practice. During planting, keep the roots
moist by covering them with wet burlap or canvas or keep
them in water to prevent drying. At planting, the broken
roots should be removed and the trees set in the holes so
that the largest roots, and if possible, the heaviest branched
side is toward the prevailing wind. Plant the tree with a slight
slant in the same direction. When planting on dwarfing root-

stock, the graft union after tree settling should be 2 inches
above ground line. Allow an additional 2 inches at planting
for tree settling.

After planting, the soil should be thoroughly tamped
around the roots so they will be in contact with wet soil. It
is not necessary to water trees unless it is extremely dry prior
to and after planting.

Opinions differ concerning the planting depth of 3-piece
interstem trees. Some suggest that these trees should be
planted with the lower graft union 2 inches above ground.
Other individuals suggest deeper planting with the top of
the interstem 2 inches above the ground. We have tried both
methods and have observed that when the rootstock portion
is less than 7 inches in length, shallow rooting can be expected
when the trees are planted with the lower graft union 2 inches
above the ground. The trees may be less vigorous than those
planted deeper (the top of the interstem 2 inches above the
ground) and frequently require support.

Four-piece trees can be planted 12 inches or more in depth
because the trees of this type may average 20 inches in length
between the scion union and the top of the roots. However,
the trees should not be planted too deeply to prevent scion
rooting.

Placement of sand or gravel around the tree base after
planting will help stabilize the tree. It also helps to keep the
area dry and thus reduces the danger of collar rot. Do not re-
move soil from around the trunk, place the gravel or sand on
top of the soil. (The trees will not scion root in these materi-
als.) When the wind causes the trunk to sway, the gravel will
trickle down and around the trunk, thus helping to stabilize
the tree. Also, this will prevent the formation of an open

area around the trunk where water will collect and contribute
to crown disorders.

Supporting Trees

Tree support is now accepted as a standard procedure in
apple growing. The need for tree support is dependent on
rootstock, cultivar, soil type, and site. For example, all trees
on M.9 need support. Delicious on IV1.7 need support whereas
Mcintosh on this rootstock is generally well-anchored on
deep, well-drained soils. On windy sites, it may be advan-
tageous to provide at least temporary support for all trees
on M.26 and M.7 rootstocks. Support methods mclude:
(a) temporary basal support which is practiced so that the
tree can establish a strong lateral root system; (b) permanent
support by posts; and (c) permanent support by a trellis.

Temporary support. This can be provided with a 3-foot long
hardwood stake driven 2 feet into the ground next to the
trunk at planting time. Plastic ties, nylon ties or wire can be
used to fasten the tree to the post. When wire is used, the
wire around the tree should be covered by a section of inner
tube, a section of plastic hose, or cloth to prevent tree injury.
Temporary support may be necessary for the first 5 or 6
growing seasons.

Permanent post. Pentachlorophenol-treated (penta-treated)
or creosote-treated posts are used for trees on l\/l.9 root-
stocks. These should be allowed to weather for a year
before use because of possible injury to the trees by the
creosote or penta. The posts should be 8 to 8/4 feet in
length, at least 2 to 2y2 inches in diameter at the base, and
set V/2 to 2 feet in the ground (Fig. 4). Soon after planting,

Fig. 4. A planting of trees on M.9 rootstocks after 3 growing seasons. The trees are individually supported by an 8-foot post
set 2 feet in the ground.

Fig. 5. In this orchard, the end posts are stabilized with a
wire extending from the posts to an anchor bolt.

Fig. 6. End post of trellis using monofilament. A hole was
bored in the end post for the insertion of the "feed
through" device for the monofilament. The "feed
through" device secures the monofilament and
eliminates the need of stapling the monofilament.

plastic or nylon ties should be looped in a figure 8 around
the tree and post at about 2-foot height to provide tree
support. In older plantings, 3 to 5 of these ties are used
per post for tree support and to keep the leaders vertical.

Trellis. Training apple trees to a trellis is quite similar to train-
ing grape vines to the Kniffin system. The trees are supported
on trellises of 8 to 9-foot long preservative-treated posts set
2 to 272 feet in the ground and perhaps spaced 24 feet apart
in the row. The end posts are stabilized with a wire extending
from about the height of the top wire of the trellis to an
anchor bolt (Fig. 5) or to a "dead-man" buried 3V2 to 4 feet
deep and 4 to 5 feet from the post. No. 9 galvanized wires
or plastic wires stapled to the posts or passed through the
interior of the posts complete the trellis (Fig. 6). The bottom
wire generally is 2 feet above the ground, while the others
are spaced 12 to 18 inches apart above it depending upon
the height of the posts (Fig. 7).

Care of Trees the First Year

Heading the newly planted tree. It is difficult to find agree-
ment on this very important phase of tree training. No. 1
trees of non-spur types (standard types) frequently are head-
ed at 30 to 36 inches or not at all if planted early. Spur-type
trees which don't branch as readily as standard types are
generally headed at 28 to 30 inches. Heading spur-type trees
rather severely should promote branch development which
might otherwise be inadequate in number. (The lower the
tree is headed, the greater the number and length of the
branches.) Regardless of heading height, both spur and stan-
dard types (non-spur) may still fail to produce a sufficient
number of branches the first year in the orchard. As long as
leaf size and color are good, the trees should develop good
lateral branching the second season.

When newly planted trees are not headed severely enough,
they usually develop branches that are too high. The next
pruning season, the trees may have to be headed again to
induce branching between the height of 20 to 30 inches above
ground level (the desired height of the lower permanent
branches). Thus a year is lost.

Pruning in the planting season. As a xu\e, all desirable branch-
es on the free afp/anf/nff should be left unpruned. An excep-
tion to the rule would be when a tree has one large branch.
This should be removed because it may cause one-sided
branch development on the tree by inhibiting the growth of

Fig. 7. Tree being trained on a trellis. In this orchard, the
posts are set 22 feet apart. The bottom wire is 2 feet
from the ground with 2 wires above spaced 22 to 24
inches apart. The depression at the base of the trees
should be filled in with soil, sand, or gravel to prevent
accumulation of water.

]

Fig. 8. Mcintosh on M.26 after one growing season. This
tree had one strong branch at planting that should
have been removed. It now competes with the leader
of the tree. It should be removed and the leader
headed at 28 to 30 inches to stimulate branch devel-
opment. Fig. 9 shows the same tree after pruning.

other branches or it may compete with the leader (Figs. 8
and 9).

Pest control. An essential for optimum growth in compact
orchards is adequate pest control. Too often, young plantings
are sprayed inadequately because of the practice of applying
what is left in the tank after spraying bearing orchards. This
is an unwise practice considering the high cost of establishing
orchards and the need of early returns on the investment.
Growers with substantial acreage of young plantings may
find smaller and less expensive spray equipment than com-
monly used in older trees a good investment.

The most common pest problems in young apple orchards
in Massachusetts are scab, sucking and chewing insects, and
tree borers. Generally, for the first 3 years, 7 to 10 sprays
annually are required to control these pests. The entire tree
should be sprayed including the trunk. It is well to remember
this when selecting mouse guards because some types inhibit
good spray coverage as well as sunlight and air movement.

Young plantings can be sprayed on an alternate row

Fig. 9. The same tree as in Fig. 8 after pruning.

basis (spraying every second or third row and then reversing
the order of travel the next spray). The first growing season
of the planting, the dosage rate per 100 gallons can be 25%
of that recommended for bearing trees. The dosage rate
should be increased annually and by the fourth growing
season, a full dosage rate and spray schedule is recommended.
For information concerning pest control, contact your
County Extension Office. Pest control charts are revised
annually.

Fertilization. Lime but not fertilizer or manures can be put
in the planting hole with the roots. Lime can be added by
throwing 2 to 3 pounds of high calcium (Ca) lime on the soil
destined to be returned to the planting hole. A nitrogen (N)
fertilizer, a complete fertilizer, or one containing N, potas-
sium (K2O) and minor elements, should be applied after a
rain has firmed the soil around the roots of the newly planted
tree. Fertilize at the rate of 1/4 to 1/3 pound of ammonium
nitrate (33% N) or its equivalent by spreading lightly in a
wide circle around the tree (8 to 12 inches from the tree
trunk). Calcium nitrate is gradually replacing ammonium
nitrate as the common source of nitrogenous fertilizer be-
cause of low Ca levels in Massachusetts apple orchards.

Chemical weed control. Paraquat can be applied anytime
during the growing season under newly planted trees and
dichlobenil is safely applied in the late fall or early winter
at the end of the growing season. Apply paraquat at the rate
of 1 quart plus spreader per acre in mid-May and again in
mid-July taking necessary precaution against hitting the tree
with the direct spray or spray drift. Drift can be a major
problem when applying herbicide sprays. To reduce this
problem, you can use a foaming agent (adjuvant) with the
spray, avoid spraying when the wind is greater than 5 miles
per hour, avoid high pressures, and use nozzles that produce
coarse sprays with a minimum of fine droplets. A flooding
flat nozzle is particularly good for drift control and is de-
signed to operate at 15 to 20 psi.

Dichlobenil (Casoron*) should be applied at the rate of
100 to 150 pounds of 4% granular per acre. Its use is de-
scribed elsewhere in this publication.

Guards for mouse protection. Encirclement of tree bases
with hardware cloth guards to prevent mouse injury has been
a standard practice for many years. Hardware cloth must
have 3 or 4 wires to the inch to be mouse-proof. The guards
should be 6 inches in diameter and 18 inches in height. They
should be set in the ground on top of the tree's root crown.
Hardware cloth is expensive and has to be cut to the desired
dimensions.

Plastic-lined mouse guards can be purchased precut from
a local distributor. They are cut to form a circle 3 inches in
diameter and 18 inches in height or a 6 inch circle with 10
inch height.

Plastic mouse guards have become popular the last several
years because they are more economical than hardware cloth
or plastic-lined mouse guards. However, they shelter insects
and should be examined annually for constriction of trunk
growth.

Pruning

At this point, it is well to recognize the fact that pruning
procedures cannot be fully and accurately described. Fur-
thermore, no two trees, which appear similar at planting
time, grow alike even when subjected to similar pruning and
training procedures. Cultivars differ in growth characteristics
and their response to pruning. Lastly, rootstocks, soil and
growing conditions influence tree vigor and pruning and
training requirements of trees. At best, all we can do is dis-
cuss the basic principles for training and pruning and you
will have to learn the finer details by experience.

We suggest training and pruning trees to obtain and main-
tain a conical shape (Christmas tree shape) because this
form allows better penetration of sunlight into the trees
and light distribution along the sides of trees. A conical tree
shape is only possible with a central leader tree and only
possible by removing and/or shortening the strong branches
in the upper part of the tree and retaining the shorter, weaker
branches. Presently, many trees in our orchards have large
branches in the upper third of the trees which inhibit light

penetration into the lower section of the trees.

In the past, the main objective of pruning an apple tree
was to produce a large percentage of Extra Fancy apples at
lower costs. This is still the prime objective but many growers
are now attempting to obtain the benefits of early, heavy
production by closer spacings of compact trees. As a result,
the problem has arisen of trying to contain the trees within
their allotted spacings especially when thecultivar-rootstock-
soil has not been properly matched.

Training and pruning of trees becomes increasingly impor-
tant as planting density increases. Growers lacking time to
do detailed pruning and training, as being suggested for medi-
um and high density plantings, would do well to establish
only low density plantings. Such a planting system is rela-
tively easy to manage and not so sensitive to variations in
soil conditions, errors in pruning, and other management

procedures as are medium and high density plantings

Season to prune. Commercial growers commence pruning
some types of fruit trees in January, but home orchardists,
because of limited tree numbers, can wait until the arrival
of milder weather. Pruning may be done through the blos-
soming period but late March or April is preferred. Water
sprouts on apple trees should be removed in mid-summer
and dead or diseased branches can be removed whenever
they are present.

Pruning systems. It appears logical to suggest the following
pruning systems, based on orchard density, for Massachusetts
orchards.

1. Low density orchards: minimal containment of tree
spread and height.

2. Low density orchards: containment of tree height.

3. Medium density orchards: containment of tree spread
and height.

4. High density orchards: staked ortrellised.

Pruning low-density orchards with minimal containment of
tree spread and height This system involves pruning tech-
niques used in the past and described in countless pruning
bulletins. The tree has a central leader and pruning involves:
(1) the selection of desirable scaffold limbs; (2) the removal
of undesirable limbs to eliminate whorls of branches and
thus permitting only one branch to develop at a given level
as shown in Fig. 10A; (3) maintaining the dominance of the
leader by suppressing or removal of competing leaders;
(4) restricting too rapid development of certain scaffold
limbs by heading-back to an outward growing horizontal
shoot or branch; and (5) on bearing trees, the elimination

^Growers may be able to increase production per man hour
and per acre without the problems encountered with vigor-
ous cultivars on semi-dwarf rootstocks at close spacings if
M.26 and interstem trees prove reliable under our con-
ditions.

of those tree parts which tend to bear fruit of poor size and
color.

Limb positioning (described elsewhere in this publication)
is a very important practice on cultivars, such as Red Deli-
cious, which possess the inherent tendency to develop narrow
crotches.

The "novice" fruitgrower should purchase (fee 25 cents)
Leaflet No. 290 entitled "Pruning Fruit Trees in the Home
Orchard" from the Bulletin Center, Stockbridge Hall, Univer-
sity of Massachusetts, Amherst. This leaflet contains illustra-
tions, photographs, and discussions which will increase the
reader's understanding of basic pruning techniques.

Pruning low density orchards with containment of tree
height. Many growers would like to restrict tree height to
about 12 feet even in low density orchards. The central
leader and branch development on the central leader in the
upper portion of the tree requires considerable attention
in order to accomplish this goal. The following training and
pruning procedures for restriction of tree height \s suggested
for trial. These procedures involve the development of
branches in layers on the central leader and heading the cen-
tral leader annually (Fig. 1 0B) fe(/f/?of /7ea(y/>7g the past sea-
son's growth on scaffold limbs as shown in this figure. Tree
height can also be restricted by using pruning procedures
described under the previous heading and by annual heading
of the central leader as described below.

Fig. 10A. Two year old tree being pruned by standard prun-
ing procedures. The lowest limb should be 18 to
20 inches from the ground, all others spaced 4 to
8 inches apart vertically on the trunk and each
one about 90° around the trunk from the one
below it.

Fig. 108. Two year old tree being pruned as suggested by
the USDA. It has 2 layers of limbs. The leader
will be headed annually [heavy marks ( — ) indi-
cate heading cuts] . The one year old wood on the
branches is headed annually until branches on
which this wood is borne start to fruit.

First dormant season.

1. Select central leader and remove branches competing
with it (Figs 11 and 12). (This could have been done
in June of the first growing season.) See Fig. 13.

2. Head the central leader by removing % to V2 of its past

season's growth (Fig. 12).
p

a. When heading leader of a weak tree or one with

no lateral branching, be aware that the first level
of branches should be developed within the verti-
cal spacing of approximately 1 8 to 30 inches from
ground level.

b. If the leader and lateral branch development is
poor, head it regardless, developing both the first
and possibly some of the second level of branches
the following year.

3. Select lateral branches (3 to 5 if possible), well-spaced
vertically around the trunk for the first level of perma-
nent branches at the base of the leader. (These branches
could have been positioned with spring-type clothes-
pins during the first growing season.) Fig. 14 shows the
use of clothespins to position branches.

a. If only one branch has developed or the branches
are too high or low, remove them and start over.

b. If branches have developed on only one side, do
the same.

4. Branches lower than 18 to 20 inches from the ground
should be removed.

Second dormant season.

1. A well-grown tree will have branches on 2 and 3 year
old wood. However, most trees will not make sufficient
growth to make possible the selection of a second level
of branches 20 to 24 inches above the lower level of
branches at the base of the central leader.

2. Remove all shoots competing with the previous sum
mer's extension growth of the central leader. (This
could have been done in June of the previous growing
season. Also, it may have been possible to retain some
of these competing shoots if they had been positioned
with spring-type clothespins during the previous grow
ing season.)

3. Head the central leader by removing Va to V2 of its past
season's growth depending on tree vigor and the pres-
ence or absence of lateral branches on the previous
summer's extension growth of the central leader.

4. Remove all branches along the central leader for a dis-
tance of 20 to 24 inches between the uppermost branch
of the first layer of permanent branches and the top
of the leader. (This could have been done during the

"Heading— usually refers to cuts made into current season's
shoots or 1 -year-old shoots. Only part of this wood is re-
moved, leaving part of the same age wood on the tree.

Fig. 11. Jerseymac on MM 106 after one growing season.
Tine tree developed wide-angled lateral branches.
It is necessary to select one of the 3 upright branch-
es as the central leader and head the central leader.
Fig. 12 shows the same tree after pruning.

previous growing season.)

5. A few trees will have lateral branches on the previous
summer's extension growth of the central leader. On
these trees, it will be possible to select laterals for the
second layer of branches. Select 3 or 4 lateral branches
for this second layer allowing several inches vertical
spacing between branches. Remove excess branches.

6. Continue the selection of the first level of scaffold
branches at the base of the leader. Three to five
branches are needed. These should be well-spaced
vertically around the trunk and the lowest limb 18
to 20 inches from the ground.

7. Position the branches at the first level to an angle of
45° with wire or wood spreaders described elsewhere
in this publication. Those that developed the previous

Fig. 12. The same tree as in Fig. 1 1 after pruning.

growing season could have been positioned at that
time with spring-type clothespins.

8. Remove upright shoots (watersprouts) that may have
developed on the branches at the first level, branches
growing towards the center of the tree, downward, or
competing with the selected, permanent scaffold
branches.

9. Heading of branches may be required on some cultivars
to stiffen them and on spur-types to force lateral
branching.

Third dormant season

1 . A well-grown tree now has 2 distinct layers of branches
(the first at the base of the central leader and the sec-
ond 20 to 24 inches above the first layer) and possibly
the beginning of a third layer on the previous season's
extension growth of the central leader.

2. The previous summer's extension growth of the central
leader is pruned and competing shoots removed as de-

'■■ s

Fig. 13. A hormone is synthesized in the growing points of
the branches in the upper parts of the tree and
translocated downward. (The greater the amount
of hormone, the wider the branch angles.) There-
fore, crotch angles are relatively narrow in the
branches highest on the trunk where little or no
hormone reaches them from growing point above,
and they are progressively wider toward the base
of the tree as shown in this figure. Furthermore,
the smaller the supply of hormone, the greater the
growth. This is why the greatest growth was made
by the uppermost branches of the tree shown In
this figure.

scribed for the second dormant season.

3. Select 3 or 4 lateral branches, if they are present, on
the previous season's extension growth of the central
leader for the third level of branches. These should be
18 to 20 inches above the second level of branches.

4. Continue the selection of the second level of scaffold
branches (20 to 24 inches above the first level). Three
or four are needed and should be well-spaced vertically
(3 to 4 inch spacing) and the branches not directly

Fig. 14. Spring-type clothespins used on lateral shoots the
first growing season to position branches. The
clothespins could have been removed after 2 or 3
weeks. Note the plastic-lined mouse guard. The
gap at the bottom of the guard makes it ineffective
for mouse protection.

above one another.

5. Position the branches at the second level to an angle
of 45°.

6. Prune the scaffold branches in the first layer at the
base of the leader as described for the second dormant
season.

Fourth dormant season.

1 . At this time, scaffold branches should be well distrib-
uted along the central leader in layers. There should
be 3 distinct layers on well-grown trees and the start
of a fourth layer, depending on how well the tree has
grown.

2. The one-year-old and two-year-old sections of the

MOW TO GET THE HIGH DENSiTT TREE Off TO A GOOD STA«T
MEAVr MASKS SHOW WHERE PRUNING CUTS SHOULD BE MADE

1 •y*ar-old ttoot
Head tide thoolt

4-vear old lection Spreod brorich-
et, remove forlred termlnoll to o
lingle iheet and head that ihool
Head tide thoott

S-yeor-old lectlon and older If
tree hat filled alloned ipare,
head back where neceiiar> into
7 year-old wood to on unheaded
lide ihool Avoid heading cute
into 1 -year-old ihooti until the
tree It fruiting well

Fig. 15. A diagram of the "constructive training" program suggested by Dr. D.R. Heinicke in USQfK Agriculture Handbook
No. 458 entitled "High Density Apple Orchards-Planning, Training and Pruning." (Reproduced with permission of
the author.)

central leader should be pruned as in the third dormant
season— heading the extension growth, removal of
competing lateral shoots, selection of branches for
the third level, and positioning of branches in the third
level.

3. The framework of the 2 lower levels of branches has
been established. Remove only water sprouts and
those branches which are growing toward the center
of the tree, or are competing with permanent scaffold
branches. Excessive pruning invigorates growth and
delays formation of fruit buds.

Care beyond the fourth year.

1. Prune to maintain the conical shape with short, weak
branches in top of the tree.

2. Head the central leader annually. If it gets too vigor-
ous, cutting into 2-year-old or older wood may be
necessary. The central leader above the cropping area
should not carry too many branches.

3. Try to develop new branches in the tree instead of
attempting to invigorate old wood.

a. Water sprouts that are growing in the direction
of a vacant area can be kept to fill that section
with bearing wood or as replacements for older
bearing branches. Positioning of these water
sprouts would be beneficial in many instances.

b. An occasional new shoot, growing at an angle
from a branch, can be retained to provide new
bearing wood for the future.

4. Cut all dead and diseased wood, all branches that have
a tendency to grow inward toward the tree's center,

and all water sprouts that are growing straight up,
whether in the center of the tree or from the upper
surface of side branches.

5. Drooping shaded wood that has become weak and
unproductive should be removed.

6. Where two branches are growing so close together
that one shades the other, the less desirable branch
should be removed.

7. All suckers at the base of the tree should be removed.

Pruning medium density orchards. A training and pruning
system for medium density orchards is described in Agricul-
ture Handbook No. 458 published by the USD A. ^ We have
no experience with this system in Massachusetts but since
there is grower interest in it we have attempted to describe
it below. The training and pruning procedures suggested in
Agriculture Handbook No. 458 (See Fig. 15) may be most
suitable for spur-type trees which branch less readily than
standard types.

Planting time.

1 . Head trees at about 28 to 30 inches.

^Agriculture Handbook No. 458 published in 1975 by the
USDA and entitled "High Density Apple Orchards-Plan-
ning, Training and Pruning." You can purchase this publi-
cation for 65 cents a copy from the Superintendent of
Documents, U.S. Government Printing Office, Washington,
D.C.

Fig. 16. Mac Spur on IV1.26 after 1 growing season. Since
only one branch developed at a low level (less than
18 inches from ground), it should be removed and
the tree headed again at 30 inches.

First growing season.

1 . When shoots average 3 to 6 inches in length:

a. Select central leader plus 3 to 5 potential branches
and remove all other shoots.

b. Remove shoot growth lower than 18 inches from
ground.

First dormant season.

1. Tree is now composed of new terminal shoot growth
(one-year-old section of tree) and the original whip
with lateral shoots (two-year-old section of tree).

2. Select the central leader and remove all competing
shoots.

3. Head the central leader by removing !4 to Vs of its
past season's growth. Head it to induce branching
that will be 18 to 24 inches above the branches at the
base of the leader.

Fig. 17. Same tree as in Fig. 16 after pruning. For those
with "courage" trunk renewal is a method of get-
ting weak trees to grow properly. This involves
cutting back the tree to a few buds to develop a
new trunk.

a. If leader development is poor, head it regardless
so that a strong leader will develop which can be
headed at an adequate height the following year.

4. Select 3 to 5 lateral branches, well-spaced vertically
around the trunk for the first level of permanent
branches at the base of the leader on the two-year-old
section of the tree.

a. If only one branch has developed or the branches
are too high or low, remove them and start over
(Figs. 16 and 17).

b. If branches have developed on only one side of
the tree, do the same.

5. Head each branch by removing % of the past season's
growth. This will keep the branches vegetative, stiff-
ened and encourage development of lateral side shoots
(Fig. 18).

Fig. 18. Heading cuts as advocated by the USDA induces lateral branching as illustrated in (A). Branches of this type have
greater fruiting potential than the unheaded branch shown in (B). Heading cuts to induce lateral branching may not
be essential on non-spur type trees. (Redrawn with the permission of Don R. Heinicke.)

Second growing season.

1. When current season's growth is 3 to 6 inches long,
remove those shoots competing with the terminal
branch extension and the central leader.

Second dormant season.

1. Tree now composed of 1, 2 and 3-year-old sections
with one or two levels of branches (Fig. 10B).

2. The 1 and 2-year-old sections are pruned the same as
the first dormant season. This consists of removing
shoots competing with extension growth of the leader
and selecting 3 to 5 lateral shoots to form the second
level of branches on the central leader. The second
level should be 18 to 24 inches above the first level at
the base of the leader. Head the leader and lateral
shoots (branches) by removing '/= and % of their past
season's growth, respectively.

3. In the 3-year-old section:

a. Position branches to open areas and spread to a
45° angle before pruning.

b. Thin excess shoot growth and maintain 3 to 5
lateral branches in the lower or first level.

c. Prune the lateral branches as if each were a central
leader tree.

1. Single out terminal shoot and remove compet-
ing shoots.

2. Head terminal shoot by removing Va of its cur-
rent season's growth.

3. Thin^'-' vigorous shoots growing upright on
the branch.

4. Head side shoots of the branch by removing '^
or less of the current season's growth. This
won't be necessary with some cultivars.

Third growing season.

1. Remove shoots the same as in the second growing
season. In addition, remove all vigorous upright shoots
developing on lateral branches.

nird dormant season.

1. The tree now is composed of 1,2, 3, and 4-year-old
sections with 2 or 3 levels of branches.

2. The 1, 2, and 3-year-old sections are handled as
described before. Be sure to allow adequate space
between limbs developing one above the other.

3. Some of the headed shoots on the 3-year-old section
will have lateral shoots develop below the point of

^ ^Thinning refers to the removal of branches in a portion
of the tree or throughout the tree to reduce competition
between limbs and permit greater light and spray pene-
tration.

heading. If too many develop, remove some (thinning
cuts), keeping those more horizontally positioned.

4. Do as little pruning as possible in the 3-year-old section
of the tree. Tfie leader Is the only terminal requiring
heading each year

5. In the 4-year-old section, reduce the number of head-
ing cuts:

a. Remove all shoots competing with terminal
growth.

b. With regard to shoots developing on the branches:
remove over-vigorous ones, head lightly some with
moderate vigor, and leave the rest of moderate
and weak vigor shoots unheaded.

c. Where side shoots were headed the year before,
cut (thin) into 2-year-old wood to a weak side
shoot or a bud, removing the vigorous terminal
growth.

6. Fruiting should be confined to the 4-year-old section.

Fourth growing season.

1 . Remove fruit from central leader and ends of branches
to maintain tree form (may be necessary in third sea-
son for some cultivars). Follow procedures practiced
in the third growing season.

Fourth dormant season.

1. Tree is now composed of 1, 2, 3, 4, and B-year-old
sections with two to four levels of branches depending
upon how well the tree has grown.

2. Encourage fruiting rather than growth, so, do as little
pruning as possible.

3. If possible, avoid heading into 1-year-old wood in
sections where fruiting is to be encouraged.

4. In 5-year-old section:

a. If tree has filled allotted space, head back where
necessary into 2-Year-old wood to an unheaded
side branch.

b. Avoid heading cuts into 1 -year-old wood until
the tree is fruiting well.

Care beyond the fourth year.

1 . Keep a vegetative terminal shoot on the central
leader. It may be necessary to cut back into the older
wood to renew the terminal shoot.

2. Make mainly thinning cuts by removing an entire
branch or cutting back into older wood to a side
shoot (1 -year-old wood) or branch.

3. Follow procedures 4 to 9 as outlined in section
entitled "care beyond the fourth year" for low den-
sity orchard with containment of tree height.

4. Cultivars, such as Cortland and Golden Delicious
with flexible wood, often need to be headed back to

a more horizontally growing branch near the trunk.
Branches of Cortland tend to droop and this cultivar
has a tendency to lose its dominant central leader.
Thus, particular attention must be given to keeping
the leader dominant. Mcintosh and Jerseymac should
present no serious problem if well trained during the
first 4 years. Cultivars, like Delicious, Early Mcintosh,
and Macoun, need limb positioning because they are
inclined to develop strong upright limbs.

Pruning high density orchards with trees stai


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