Lorraine P.
Berkett1, Renae E. Moran2 , M. Elena Garcia3,
Heather M. Darby1, Robert L. Parsons1, Terence L.
Bradshaw1, Sarah L. Kingsley-Richards1, and Morgan
C. Griffith1 1University
of Vermont, 2University of Maine, 3University of
Arkansas
. .
Funding
Sources:
-USDA Organic Agriculture Research and Extension Initiative
-University of Vermont
-University of Arkansas Division of Agriculture Cooperative Extension
Service
-University of Maine Cooperative Extension
-NIFA Integrated Pest Management (IPM) Program
-Vermont Tree Fruit Growers' Association
IMPORTANT:
It is the grower's responsibility to ensure that any crop production practice
or material used in the orchard is acceptable in their particular state’s
organic certification program. Some materials deemed organically acceptable
on the National List may not be acceptable in some states. Contact your
federally accredited certifying agency
to know what is acceptable and to ensure compliance with regulations in
your state.
NOTE:Where trade names or commercial products are used for identification,
no discrimination is intended and no endorsement is implied. Always read
the label before using any pesticide.
The label is the legal document for the product use. Disregard any information
in this guide if it is in conflict with the label.
Orchard Planning
There are many things
to consider and plan before starting an orchard business. A critical first
step is to find a market for selling your fruit, particularly if you are
starting a new business. It can take as many as several years to build up
enough of a customer base to support a new business where none existed before.
The appropriateness of your site for fruit trees is another criterion that
can make or break an orchard business. Midwinter low temperatures, the existence
of frost pockets, frequency of hail, and soil drainage will impact the ability
to farm with perennial crops. Consider the need for irrigation and access
to a water supply. Availability of reliable labor has been an obstacle in
recent years for large and small operations. A large investment in equipment,
in addition to the cost of trees and a trellis if it is a high density planting,
is necessary to start an orchard. However, orcharding can be a very rewarding
enterprise.
Site
Selection
Before planting a new orchard, select a site with a microclimate and soil
qualities that will benefit fruit trees. Selecting a good site will prevent
long-term problems that cannot be corrected with cultural practices.
Fruit trees are "full sun" plants that need exposure to sunlight
for much of the day. Small orchards that are surrounded by tall trees
will have low yields due to insufficient light.
Select a site that has good air flow. Sloping land that is not
bordered by dense tree stands will encourage air movement and keep cold
air from settling in the orchard. Sites with poor air flow are prone to
damaging cold temperatures in the winter and and frosts in the spring.
Good soil drainage is essential since fruit trees will not tolerate
wet soils. Poorly drained soils will need a drainage system installed
before trees can be planted. The orchard should have a minimum soil depth
of two to three feet. Where soil depth is less than ideal, tree root systems
cannot adequately support the trees, which may consequently fall over
with strong winds.
Variety
Selection
Many varieties (i.e., cultivars) exist with
a range in disease susceptibility, ripening dates and other qualities
that impact farming. When selecting varieties, you should consider both
the willingness of consumers to purchase them and traits that impact cultural
practices such as disease resistance and biennial bearing. Ripening dates
are important for pick-your-own operations, where a selection of several
varieties that ripen over a period of several weeks are needed for consistent
marketing.
Apple scab is the most economically significant disease of apples in the
northeast United States, and its management on susceptible varieties
in organic systems requires multiple applications of mineral fungicides
that can exhibit phytotoxicity to the trees in the orchard, potentially
reducing tree growth, harvestable yield, and fruit quality. By selecting
varieties that have been bred to have genetic
resistance to apple scab, many of the drawbacks of the use of these materials,
as well as from infection by the disease, can be avoided. Examples of
scab resistant cultivars (SRC) include: Liberty, Crimson Crisp, Crimson
Topaz, Freedom, William's Pride, Winecrisp, and Florina Querina. Other
commercially important varieties such as Honeycrisp have partial resistance
to scab and may require fewer fungicide applications for sufficient scab
prevention. No one variety has resistance to all the diseases that occur
in New England.
Apples are prone to biennial bearing or alternating yields where bloom
and crop load are heavy in one year, followed by a year with scant bloom
and poor yield. All varieties are biennial to some extent but some exhibit
a more severe tendency. To prevent biennial bearing in most varieties,
thin the fruit soon after bloom. Successful early crop load reductions
are the key to preventing biennial bearing. In organic production, methods
of thinning are limited and may not be sufficiently effective to prevent
biennial bearing, so variety selection should include some varieties that
tend toward annual bearing.
Biennial bearing tendency
in apple varieties
Severely biennial bearing
varieties
Varieties with a strong
tendency for biennial bearing
Varieties with a slight
tendency for biennial bearing
Dayton
Delicious
Cortland
Golden Delicious
Empire
Enterprise
Golden Supreme
Fuji
Freedom
Fortune
Goldrush
Gala
Honeycrisp
Jonagold
Gingergold
Northern Spy
Liberty
Idared
Suncrisp
Macoun
McIntosh
Mutsu
Sunrise
Paulared
William's Pride
Pristine
Wolf River
Small-fruited varieties such
as Gala may not produce fruit of a sufficient size for commercial production
when managed organically unless weeds can be well-managed.
Irrigation will also be beneficial for promoting good fruit size in small-fruited
varieties. Macoun, Pristine, Empire, Suncrisp and Sunrise have small fruit
size.
The issues of winter hardiness and required length
of frost-free growing season need to be considered very seriously.
Low winter temperatures limit which varieties can be grown in northern
regions. Apples are the most winter hardy of the cultivated tree fruits
and can be grown in the most northerly locations, but commercially important
varieties such as Cameo, Gala and Golden Delicious are tender in regions
with colder winters.
Rootstocks
and Dwarf Fruit Trees
Fruit trees are not propagated from seed. Instead, they are propagated by
grafting buds or shoots onto rootstocks, therefore the root system is genetically
different from the above-ground portion of the apple tree. Rootstocks can
be selected for traits such as dwarfism, early bearing, disease resistance,
and winter hardiness. Fruit trees are also grafted in order to get "true-to-type"
varieties. Apple trees grown from seed will not grow into the same variety
from which the seed originated, but will be a new and unique type of apple
that may or may not be good.
Trees are classed into groups according to their size; dwarf, semi-dwarf
and standard. Tree size of fully-grown trees is determined by both the scion
variety and the rootstock. The Northern Spy apple is an example of a very
vigorous variety and Honeycrisp an example of a low vigor variety. Trees
size is also determined by its rootstock. Some rootstocks induce a dwarfing
effect on the tree, whereas, standard rootstocks will produce a full-sized
tree. A particular variety can be grafted to a dwarf, semi-dwarf or standard
rootstock, giving the grower a choice in tree size for most varieties.
Rootstocks also influence how rapidly trees begin to bear fruit, a trait
known as "precocity". In general, apple trees on dwarfing rootstocks begin
to bear two to three years after planting. semi-dwarf trees begin to bear
fruit four to five years after planting. Standard trees can take as much
as seven to ten years to reach an age when they bear fruit.
A dwarf apple tree attains a height of eight to ten feet in most conditions
and can be planted as close as three feet, but more commonly at a spacing
of six feet. Because of their smaller size, dwarf fruit trees require less
labor for pruning and harvesting and make a good choice where labor is not
available. However, they require a permanent stake or trellis for support
because of their brittle roots. The roots easily break causing the tree
to lean when the tree is not staked. There are several dwarfing rootstocks
available for apple:
Malling 9 (M.9) and Budagovsky 9 (Bud.9) are fully dwarfing rootstocks which
allow close tree spacing of three to eight feet, depending on the tree training
system, varietal vigor and soil fertility. Bud.9 has greater winter hardiness
than M.9. There are several different clones of M.9. The Fleuren 56 and
T337 clones produce smaller trees than the EMLA, NIC29 or Pajam clones.
Geneva 41 (G.41) is a new fully dwarfing rootstock with resistance to fireblight
and good winter hardiness.
Malling 26 (M.26), Geneva 11 (G.11) and Geneva 16 (G.16) are small semi-dwarfing
rootstocks that can be planted at a spacing of six to ten feet apart. G.16
is susceptible to latent viruses which can interfere with its productivity.
G.935 is a new rootstock that produces a tree slightly larger in size than
M.26, and has greater winter hardiness than many other rootstocks.
Malling 7 (M.7) is a semi-dwarfing rootstock that does not require staking,
but lacks winter hardiness, is slow to bear fruit and produces root suckers.
Trees on this rootstock can be planted 12 to 14 feet apart. Geneva 30 (G.30)
has similar tree size as M.7, but greater hardiness, early bearing and fewer
suckers. G.30 requires staking because of high yield at an earlier age.
Pollination Requirements
In order for fruit to develop, flowers must first be pollinated. Some species
of fruit trees require cross pollination by another variety, whereas others
will bear fruit when planted alone or with the same variety. When flowers
have not been properly pollinated, they are shed soon after bloom.
Apples are self-unfruitful meaning pollen of a particular variety will not
pollinate or fertilize flowers of the same variety. Therefore, a different
variety of apple that blooms at the same time should be planted in the orchard.
McIntosh and Liberty bloom early and should be cross pollinated by another
early blooming variety. Honeycrisp is late blooming and is best pollinated
by other late blooming varieties such as Northern Spy or Golden Delicious.
Pollination charts are typically available in fruit tree nursery catalogs.
Apples will also be cross pollinated by crabapples and vice versa. Trees
that serve as a source of pollen for another tree are called "pollinizers".
When selecting pollinizer varieties, it helps to select two varieties that
do not closely resemble each other so that they can easily be kept separate
at harvest. A common planting scheme is to alternate entire rows of different
varieties so that they are close to each other, but less likely to be mixed
at harvest. To facilitate management of apple
scab when using fungicide sprays, varieties interplanted in the same orchard
should posses a similar level of resistance. Select varieties that bloom
or ripen at roughly the same time for scheduling insecticide applications
that occur at critical times such as petal fall and close to harvest.
Some apple varieties have sterile pollen and cannot be used for cross pollination.
These are Baldwin, Creston, Gravenstein, Jonagold, Belle de Boskoop, Mutsu,
Crispin, Rhode Island Greening, Roxbury Russet, Shizuka, Spigold, Stayman,
Bramley's Seedling, Wealthy and Winesap. When growing any of these varieties,
plant at least two other varieties for good cross pollination.
Bees are the most important means by which pollen is transferred from one
tree to another. Large orchards greatly benefit from honey bee hives. One
strong hive per acre is recommended. Small orchards may be adequately pollinated
by wild bees in years with favorable weather. When favorable pollination
weather is of short duration, hives will make a difference because the large
number of bees in hives can rapidly pollinate an entire orchard in optimum
conditions of warm, calm weather.
For more information: Pollination
and Fruit Set of Fruit Crops (Cornell University) Pollination
and Crop Load Management (University of Vermont) Native
Bees in Apple Pollination (Cornell University) Pollination
Handbook (ARS USDA) Organic
Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food
Canada) Cultural
Information: Apples (Penn State)
Back to Top Menu Crop Load Management
Apple trees are capable of bearing more fruit than
is healthy for the tree or commercial viable. Reducing the crop load during
the fruit set stage is done by growers nearly every year to encourage good
fruit size and return bloom. Eliminating some of the fruit is accomplished
by applying a fruit thinner or by hand thinning.
Because thinning reduces the number of fruit on each tree, the remaining
fruit grow to a larger size than if all fruit were kept. The earlier that
thinning occurs in the season, the more it promotes fruit growth and final
fruit size. Thinning also lessens biennial bearing by promoting return bloom.
The presence of a large number of fruit on the tree has an inhibitory effect
on flower formation. Apple flowers are formed in the year prior to their
bloom. By reducing the number of fruit early in the growing season, a greater
number of flowers will be formed for the next year.
Fruit thinning can be done by hand. Hand thinning is not as effective in
promoting return bloom as thinning with chemicals, but is very effective
for increasing fruit size since the smallest fruit can be selectively removed.
Hand thinning is also very effective for breaking up clusters of fruit.
When fruit set in clusters, the close contact of individual fruit creates
a favorable habitat for disease and insects. Also hand thinning allows for
insect infested or diseased fruitlets to be removed from the orchard, thus
reducing spread of the damage throughout the season. However, the high cost
of labor must be considered when using hand thinning as a way to manage
crop load. Hand thinning is typically done after the June drop period which
usually occurs late in June to early July in northern New England. A target
of one fruit per blossom cluster on every other cluster born on the tree
is considered a target for a good crop load.
Certain types of compounds, when applied to apple trees, will cause a number
of fruit to drop off and at the same time, allow some of the fruit to remain
on the tree. Advantages of this method are cost savings and the early reduction
in crop load which improves return bloom. There are several types of chemical
thinners registered for this use, but none have been approved for use in
organic orchards in New England. Lime sulfur sprays
applied with oil are known to reduce the crop load, but have not
been registered for this specific purpose.
If used for management of disease or arthropod pests,
lime sulfur applied alone or in combination with oil during the bloom
period reduces the crop load by preventing some of the flowers from being
fully pollinated. Published research has shown effectiveness
at variable application times, but use of these
materials near bloom or fruit set should be sometime after 30% of
the blossoms have opened to ensure sufficient pollination and fertilization.
Lime sulfur and oil can also cause some thinning when applied after bloom,
but the mode of action of post bloom thinners is not clear. Based on research
trials in the Hudson Valley of New York, a 2.5%
solution of lime sulfur with 2% oil applied at the end of bloom and again
four to seven days later caused some thinning
on treated McIntosh and Empire trees, but leaf burn and fruit russetting
were observed. Fish oil, mineral oil and plant-derived oils can be
used if approved for organic production and labeled for
their intended use, and they vary somewhat in cost and effectiveness.
Temperatures above 80 °F after application of oil or lime sulfur can increase
potency and cause fruit skin russetting.
For more information: Pollination
and Crop Load Management (University of Vermont) A
Grower’s Guide to Organic Apples (Cornell University) Crop
Load Management of New High Density Apple Orchards (Cornell University) Evaluation
of Organic Pest Controls and Fruit Thinning on Multiple Apple Cultivars
(Cornell University) Organic
Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food
Canada) Apples:
Organic Production Guide (ATTRA)
Back to Top Menu Nutrients
and Fertilizers for Organic Apple Orchards
The perennial nature of apple trees requires that their nutrient needs be
maintained in a holistic and long-term manner. Apple trees have special
nutrient requirements that take into account both the need for good yield
and fruit quality. Fertilizing to promote lush shoot growth and large fruit
size will be detrimental to the flavor, color and shelf-life of apples.
On the other hand, insufficient fertility can lead to small apples and unproductive
trees.
There are several essential nutrients, each with important functions in
plant growth. Some are used in large quantities, the macronutrients, and
others in very small quantities, the micronutrients (also known as trace
elements). The goal of fertilizing is to maintain the level of each nutrient
within an optimum range. An excess of any nutrient leads to negative effects
on the tree that are difficult to correct. Deficiencies are more common
and can be fixed by applying an appropriate fertilizer.
Many commercial products are available for fertilizing, so check with your
certifying agency to find out which ones are approved for use in organic
orchards. Some products are not appropriate for foliar application to fruit
trees. Before buying any product, make sure it has been previously tested
on apple to determine if it is safe or won't burn fruit and foliage.
Soil and
Leaf Tissue Analysis
To determine the fertilizer needs of an orchard, it is important to consider
both the supply of nutrients in the soil and the demand for nutrients
by the tree. The amount of nutrients available in the soil is measured
by soil testing. Tree demand for nutrients is affected by the ability
of the root system to absorb nutrients and the ability of the tree to
use them. This is measured by leaf tissue analysis. Both tests are used
to indicate the need for fertilizer and are generally required in certified
orchards to document a need for fertilizer.
How to take an orchard soil sample
Soil samples can be collected any time during the growing season, but
it is usually convenient to collect them the same time as leaf samples.
Separate samples should be collected for each orchard
block, which is defined as a unit typically of ten acres or less that
has uniform groundcover management, soil texture
and fertility, and fertilizer applications.
The soil should be a composite or mixture of 15 separate samplings
randomly collectedacross
each block. Using a sampling tube, augur or spade, take the soil
from within the tree row and to a depth of 8 inches. Place the composite
sample in a container and mix thoroughly. Label the sample with the name
of the orchard and block and prepare the sample
according to the instructions of the lab doing the analysis.
The best time to collect leaves for tissue analysis is 60 to 70 days after
full bloom or usually the end of July. Samples collected at other times
will give a falsely high or low reading of some nutrients. Take a random
sample from throughout the orchard. Select trees in good health and typical
of the orchard in tree size, age, crop load and vigor. Do not take leaves
from sick trees. Avoid yellow leaves on Honeycrisp. Collect 50 to 100
leaves from shoots that are approximately one to two feet in length. Pick
leaves that are midway down the shoot. Avoid leaves from shaded parts
of the canopy or that are yellowing from stress. Prepare leaves according
to the instruction of the lab doing the analysis.
Nutrients
Used by Fruit Trees
Photosynthesis and general tree growth depend on an adequate supply of
nitrogen. Too much nitrogen leads to excessive leaf growth, but
also to large-sized fruit that have poor flavor and color. Nitrogen deficiency
stunts growth and reduces fruit size. Nitrogen should be supplied in enough
quantity to maintain vigor, but limited in quantity to ensure that fruit
quality is not impaired. Nitrogen deficiency is common where weeds are
not controlled.
Apple trees use as much as 100 lbs. per acre of nitrogen each year, but
the actual amount varies from orchard to orchard. Dwarf fruit trees require
less nitrogen than semi-dwarf and standard-sized trees. Most soils supply
from 30 to 80 lbs. per acre each year. The need for additional nitrogen
generally ranges from none to as much as 40 lbs. per acre. Leaf tests
are the most accurate method of measuring the nitrogen status of an orchard.
When leaf tests indicate low nitrogen, an increase in nitrogen fertilizer
is justified.
Nitrogen-containing fertilizers include but are not limited to compost,
blood meal and fish products. The amount needed to correct a deficiency
is still largely guess work since not much research has been done using
organic sources and because of the slow-release nature of many organic
fertilizers. Fertilizers vary in nitrogen content, cost, and ease of application.
Manures and manure-based composts are not readily spreadable, require
large volumes, and can be expensive to
transport and apply. However, they contain other essential nutrients making
them useful in organic production.
Manures vary in age or stage of decomposition. Raw manure generally has
a higher degree of available nitrogen than composted manure, but may not
be allowed in organically certified orchards. Because of the potential
for harmful bacteria that may contaminate the crop,
the National Organic Program regulations do not allow manure applications
within 90 days of harvest. However, given food safety
concerns with the introduction of raw manures into orchards, their
use cannot be recommended. Manure composted
according to NOP guidelines does not have the microbial hazard
and is less likely to burn roots, but has less nitrogen.
General tree growth, fruit flavor and color depend on potassium.
Soil potassium can be quickly depleted by vigorous trees and in seasons
with a heavy crop. Apple trees use approximately 120 to 180 lbs. per acre
of potassium annually. Much of the potassium is permanently removed in
the fruit and is not recycled back to the soil, so there is a gradual
depletion that should be supplemented when soil tests indicate a need.
The soil supply is highly variable from orchard to orchard and should
be measured periodically with a soil test in combination with a leaf test
to determine the need for potassium.
Adding potassium fertilizers without magnesium could create an imbalance
leading to magnesium deficiency. A fertilizer that contains both elements,
such as potassium-magnesium-sulfate (langbeinite)can be selected to prevent
an imbalance. Composted manure incorporated before planting trees can
raise the level of potassium and magnesium in the soil. One ton of most
composts can supply 10 to 20 lbs. of potassium. Where magnesium occurs
in abundant supply, potassium chloride (muriate of
potash) is a more economical choice.
Phosphorus is important for flower bud development and general tree
growth. Fruit trees in the Northeast rarely respond to phosphorus fertilization
once they are planted since phosphorous does not readily move into soil.
The most effective method to increase soil phosphorus is to incorporate
it into the soil prior to planting. A preplant soil test can determine
how much is needed since soils will vary considerably and some soils may
not need any additional phosphorus. With good soil preparation before
planting, fruit trees will rarely develop phosphorus deficiency. On the
other hand, too much phosphorous creates zinc and copper deficiency. Some
organic fertilizers are high in phosphorous and should be used only where
a need for phosphorus occurs.
Calcium is important for general growth and for improving the storage
life of fruit. A deficiency can lead to premature fruit breakdown and
other disorders such as bitter pit. Where weed control is inadequate,
apple trees will be prone to calcium deficiency. Deficiency does not always
indicate low soil supply, but could indicate low soil pH or persistent
drought. Maintaining soil pH above 6.0 is important for maintaining the
availability of calcium in the soil. Calcium deficiency can also be caused
by an excess of potassium.
Apple fruit are poor at absorbing calcium which makes them prone to low
calcium disorders. To prevent a deficiency, some calcium fertilizers can
be applied directly to foliage. Apples that will be placed in long-term
storage and varieties prone to bitter pit should receive at least two
applications of foliar calcium fertilizer.
Magnesium is important for good bud development and normal fruit ripening.
Magnesium deficiency occurs when potassium in the soil is high in relation
to magnesium. A magnesium-containing fertilizer such as potassium-magnesium-sulfate
(langbeinite) can be incorporated prior to planting or spread over the
soil after planting. One or two foliar applications of magnesium sulfate
(Epsom salts) at petal fall and again two weeks later will correct magnesium
deficiency for one season. Products vary in magnesium content, and not
all are safe to apply to foliage. If soil pH is low, selecting lime that
contains magnesium will also correct low magnesium.
Boron is important for root growth, fruit set, normal fruit shape
and size. A severe deficiency will cause small, lopsided apples or apples
with internal corky tissue. Boron can be incorporated before planting,
ground applied after planting, and applied in a foliar spray. Ground application
of a boron fertilizer is recommended once every three years when a leaf
test indicates below optimum levels. One pound per acre of actual boron
in a ground application can be applied as a correction. A Solubor™
product containing 17.5% actual boron can be applied at a rate of 6 lbs.
to get one pound of actual boron, but can only be used where a deficiency
has been documented with a leaf test. Foliar applications with Solubor™
before and in the month after bloom will correct deficiency on a short
term basis. Foliar applications of boron close to harvest time will interfere
with normal fruit ripening.
Manganese and zinc deficiency are common and can be prevented
by good soil preparation before planting and supplemental foliar micronutrient
applications after planting. Severe deficiency interferes with bud development
and leaf growth. To correct a deficiency, some products of chelated micronutrient
can be applied directly to trees during the growing season and will supply
enough zinc and manganese to maintain levels for one season. Foliar applications
can cause fruit russetting and should only be applied according to the
labeled instructions. Copper and iron are trace elements
that are infrequently deficient. Early season copper sprays to prevent
disease provide enough copper to prevent deficiency in most cases.
For more information: Mineral
Nutrition of Fruit Trees (University of Vermont) Orchard
Nutrition Management (Cornell University) A
Grower’s Guide to Organic Apples (Cornell University) Nutritional
Effects on Fruit Quality for Apple Trees (Cornell University) Organic
Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food
Canada)
Back to Top Menu
Harvest and Storage Growers need to anticipate how
much yield will occur in order to have sufficient harvest supplies and needed
labor. Most conventional orchards in northern New England produce 400 to
800 bushels of apples per acre. Organic orchards may
yield less than half of conventionally-managed
orchards, so a yield 200 to 400 bushels
can be expected with good management and growing conditions. Orchard age
determines potential yield with older orchards producing less than trees
that are 10 to 25-years-old. As trees within an orchard die or become stunted
from various stresses, the orchard loses part of its
production capacity. Yield will also vary substantially from year to year
because of weather variations and the natural tendency of apples to alternate
or bear biennially.
By August, growers should be ready with the labor needed to harvest the
apples and storage bins or boxes to hold the fruit. For Pick-Your-Own, finding
labor is not as critical, but thought should be given to advertising or
some notification that apples are ready for picking. A means of transporting
fruit from the orchard to the packing house or farmstand may require the
purchase of a forklift, flatbed wagon or truck. Other harvest supplies that
may be needed include orchard ladders and picking buckets. Orchard ladders,
designed for outdoor use, should be used instead of other types to ensure
the safety of pickers. In split farms that contain both
certified organic and non-certified plantings, careful segregation of the
crops including separate storage containers and areas must be followed and
approved by your organic certifier.
The harvest of apples can begin as early as August and extend to the end
of October, depending on varieties and geographic location within New England.
Most varieties are harvested between Labor Day and Columbus Day. Actual
harvest date of a particular variety varies from year to year depending
on bloom date and other orchard conditions such as crop load.
Average First Harvest for Common Apple Varieties
Mid to Late August
Early September
Mid September
Late September
Early October
Mid to Late October
Early Mac
Gingergold
McIntosh*
Macoun
Liberty
Golden Delicious
Paulared
Zestar!
Honeycrisp
Cortland*
Jonagold
Northern Spy
SnowSweet
*Cortland and McIntosh can
be harvested as early as the beginning of September, depending on preference.
When apples cannot be harvested
by their anticipated ripening date, a "stop-drop" can be applied to prevent
fruit drop. Only one material is OMRI-approved for organic orchards, ReTainŽ.
For more information on using ReTainŽ as a harvest aid, consult an extension
specialist or crop consultant.
The optimum date for a variety depends on how and when it will be marketed.
With a Pick-Your-Own operation, harvest date is less critical since fruit
will not be stored for any length of time. However, fruit can ripen and
drop off the tree if weather or other conditions interfere with customer
traffic. Fruit quality is important for retail and wholesale marketing
and is largely affected by harvest date and storage conditions. Consumers
expect crisp and tasty apples. For apples sold soon after harvest, this
is not difficult to accomplish. Where apples will be stored one to several
months prior to their sale, harvest timing is critical for good keeping
quality. Harvest prior to full ripeness will prevent excessive loss of
firmness and development of breakdown. However, apples harvested too early
will not ripen properly and will develop problems in storage. Cold storage
at an optimum temperature for the variety will also keep apples in good
condition.
The optimum harvest time for long term storage is based on maturity indices
such as starch breakdown, ground color, texture and seed color. Apples
contain starch in the flesh which breaks down into sugars as they ripen.
Starch breakdown begins in the core and progresses to the outer cortex
near the skin creating a pattern that can be visualized when an apple
is cut in half and stained with an iodine solution. The iodine stains
the starch a dark purple and indicates the degree of starch breakdown
and indirectly the stage of ripeness. Another indicator of fruit ripeness
is the ground color or green portion of the skin as it changes from dark
to light green and then to yellow as the fruit ripens. This can be used
to time harvest, but may require some experience with the particular variety.
Seed color changes from white to brown as apples ripen, but this can be
imprecise as an indicator of fruit maturity. Flavor and texture are useful
indicators when apples will be marketed soon after harvest, but may take
some experience when growing a new variety.
When fruit are stored, they must be kept distinctly
separate from non-certified crops. For maintaining the best quality,
storage at a temperature near 32 °F is optimum for most varieties. Chill-damage
sensitive varieties such as Honeycrisp or Empire should be stored
at a temperature of 37 to 38 °F, but storage life will be shortened. Bitter
pit is also more likely with organic production and warmer storage temperatures.
For apples stored longer than four months, controlled atmospheres may
be needed to maintain crispness. More information on controlled atmosphere
storage can be obtained from your extension specialist.
For more information: Harvest
and Postharvest Considerations (University of Vermont) A
Grower’s Guide to Organic Apples (Cornell University) Harvest and
Postharvest Handling (Penn State)
