Practical Guide for Organic Apple Production

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
. .

Horticulture

Organic IPM

Soil Health &
Ground Cover Management

Marketing & Economics

Orchard Equipment

Practical Guide Home

The OrganicA Project

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.

Last updated: 2012

Horticulture
Orchard Planning - Site Selection - Variety Selection - Rootstocks & Dwarf Fruit Trees - Planting and Trellis building - Tree Training - Pollination Requirements - Crop Load Management - Nutrients & Fertilizers for Organic Orchards - Harvest & Storage

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.

For more information:
Establishing an Apple Orchard (eXtension)
OrganicA, A Resource for Organic Apple Information (University of Vermont)
UVM Apple Orchard
Organic Apple Production: A Beginners Guide (ATTRA)
Apples: Organic Production Guide (ATTRA)
An Organic Apple Production System for New York (Cornell University)
A Grower’s Guide to Organic Apples (Cornell University)
Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)
Penn State Tree Fruit Production Guide
UMASS Fruit Advisor
Cornell University Fruit Pages
VermontApples.Org (Vermont Tree Fruit Growers Association)
Planning and Establishing Commercial Orchards in Wisconsin
Integrated Fruit Production Checklist for New York Orchards
Growing Apples for Cold Climates (Idaho)
Home Orchard Guide (Penn State)
New York Fruit Quarterly (Timely Research Reports from Cornell University Fruit Specialists)
Establishing an Orchard (Penn State)

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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.

For more information:
Site Selection and Preparation in Vermont Apple Orchards (University of Vermont)
Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)
A Grower’s Guide to Organic Apples (Cornell University)
Establishing an Orchard (Penn State)

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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.

The growing season of Vermont, New Hampshire and Maine is too short for some apple varieties. Braeburn, GoldRush, Granny Smith, Pink Lady and Rome Beauty do not ripen before the first freeze and lack their characteristic varietal flavor when grown in areas with a short season. Varieties that ripen after Golden Delicious require a long growing season and may not ripen in northern New England.

For more information:

Cultivar and Rootstock selection (University of Vermont)
Scab Resistant Cultivars (Cornell University)
Antique Apples for Modern Orchards (Cornell University)
Making Sense of New Apple Varieties: Trademarks and Clubs (Cornell University)
A Grower’s Guide to Organic Apples (Cornell University)
Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)
Apples: Organic Production Guide (ATTRA)
Cultural Information: Apples (Penn State)

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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.

Malling-Merton 106 (MM.106) and Malling-Merton 111 (MM.111) are semi-dwarfing rootstocks that do not require staking, but require more space than dwarf trees and are slow to bear fruit. They can be planted at a spacing of 18 feet apart for most varieties. MM.106 lacks winter hardiness. The lack of precocity and greater need for pruning makes these rootstocks undesirable for commercial producers.

For more information:

Apple Rootstocks: Understanding and Choosing the Right Rootstock (eXtension)
A Grower’s Guide to Organic Apples (Cornell University)
Cultivar and Rootstock selection (University of Vermont)
Cultural Information: Apples (Penn State)

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Planting and Trellis Building

Preparing to plant a high density orchard


Building a trellis for a high density orchard


Planting a high density orchard


For more information:
Planting and Establishing High Density Apple Orchards
(Cornell University)
A Grower’s Guide to Organic Apples (Cornell University)

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First Year Tree Training in a High Density Orchard

For more information:
Tree Training and Planting Systems (University of Vermont)
A Grower’s Guide to Organic Apples (Cornell University)
Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)
Cultural Information: Apples (Penn State)

Cornell Orchard System Training Factsheets:
Tall Spindle System: Planting, Pruning, and Training
Vertical Axis System: Planting, Pruning, and Training
Slender Pyramid System: Planting, Pruning, and Training
Slender Axis System: Planting, Pruning, and Training

Pruning Basics:
Pruning and Training Apple Trees, (Teryl Roper, University of Wisconsin)
Pruning Mature Apples and Pears, (HYG-1150-93, Ohio State University)
Training and Pruning Apple Trees, (Cornell Cooperation Extension Publication / Info Bulletin #112)
Common Pruning Mistakes, (Caleb Torrice, Cornell Cooperative Extension)
Renovating Old Apple Trees, (James Schupp, University of Maine)
Techniques for Training Young Apple Trees (Jon Clements, University of Massachusetts)

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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)

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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)

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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 collected across 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)

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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)

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For more information:

Abiotic Problems of Apple Trees and Fruit
(eXtension)
Cold Hardiness (University of Vermont)