New York is a major state in US apple production, and in many ways our soils and climate are perfect for growing this hardy fruit. Even so, apples are difficult to grow successfully in the Northeast because many insect and fungal pests find them as nourishing as people do.
Home gardeners can grow apples with little pruning or pesticide spraying, enjoying their flowers and shade, watching the remarkable diversity of wildlife that feed on their fruit and then harvesting what's left for juice or preserves.
Apple trees will usually bear for half a century or more with minimal care, but they require considerably more attention and management if regular harvests of fruit without major pest damage are desired. This bulletin offers some suggestions for growing apples without excessive hassles and pesticides.
Hundreds of apple varieties are available from nurseries, but some are especially suitable for home gardeners. Disease resistance is a major factor to consider because common store-bought varieties require numerous fungicide sprays to control the "major" apple diseases of scab, powdery mildew, fireblight, and cedar-apple rust.
New and traditional varieties resistant to these diseases include 'Pristine,' 'Redfree,' 'Freedom,' 'Liberty,' 'Priscilla,' 'Jonafree,' 'Golden Russet,' 'Enterprise,' and 'Goldrush'-listed in order of their harvest time, from mid August to early November. These varieties will produce usable fruit without fungicide sprays, although they may be blemished by other "minor" fruit diseases prevalent in the warmer and more humid regions of the Northeast.
Storage ability is another important varietal trait for home gardeners. Apples that ripen in late summer or early fall usually will not keep for more than a month, even in refrigeration. Many of the later varieties that ripen in mid-October to November-traditional varieties like 'Northern Spy,' 'Winter Banana,' and 'Roxbury Russet,' or newer varieties like 'Keepsake,' 'Idared,' 'Enterprise,' and 'Goldrush'-can retain good eating quality for up to five months in a root cellar or refrigerator.
Ideal storage conditions are temperatures slightly above freezing, with 90-95% relative humidity. Most varieties can also be sliced and dried, or canned to provide year-round eating of home-grown fruit. For long-term storage, apples should be picked about a week before they ripen fully-softening, sweetening and developing their full characteristic flavor and aroma-and only fruit without insect or disease damage should be stored.
Soil and Site Requirements
Apples are very adaptable to different soils and climates, and usually don't require fertilizer in home gardens. They can survive almost anywhere except lowland swamps or high mountains, but they will grow and fruit better in sites with moderately well drained loamy soils and a frost-free growing season of at least 135 days.
Trees in open sunny locations will produce larger, better colored and more flavorful fruit, with fewer disease problems. Most soils provide enough water and nutrients for apples if weeds beneath trees are suppressed by mulching, cultivation, or herbicides. Weed control is especially critical during the first 5 years after planting; for mature trees regular mowing is sufficient to keep meadow voles, rabbits, and climbing weeds like poison ivy or Virginia creeper in check.
Several insect pests usually require control even on disease resistant apple trees. A dormant oil plus a copper fungicide like Bordeaux mixture applied at "budbreak" (usually mid-April) will help reduce over-wintering disease and insect pests. Additional insecticide sprays at "pink tip" just before bloom, at "petal fall" after bloom, and then two weeks after petal fall will control the most common and serious fruit damaging pests-plum curculio weevil, codling moth (the proverbial "worm" in your apple), and leaf-roller moths.
Apple maggot is the other major pest problem, and usually lays its eggs in apples from mid July to mid August. In small orchards, apple maggot can be "trapped out" by hanging several red wood or plastic balls in each tree in mid July, and baiting them with a feeding attractant and a sticky substance such as 'Tanglefoot.' Two properly timed insecticide sprays will also control apple maggot.
If you decide to use pesticides on your fruit trees, it's important to choose an insecticide which is least toxic to people, pets, and helpful biocontrol species of birds and insects. Imidan and Carbaryl are often recommended. Proper timing is also essential for effective chemical control.
Local Cooperative Extension offices often have newsletters or electronic bulletin boards providing information about fruit pest life cycles and control timing for each region. Of course you may also want not to use any pesticides and let nature take its course. Without any insect management usually 90 to 98% of apples will be infested or blemished-but some of that blemished fruit is good for sauce or preserves, and even 5% of a typical crop on a big apple tree may be enough for fresh eating and storage.
Apples are genetically self-incompatible, so each variety requires another variety or some wild apple trees or a crab apples nearby to provide pollen. Without a source of compatible pollen and bees to carry it from tree to tree, the fruit will not "set."
Even with good pollination, most of the fruitlets will spontaneously abort and fall during the "June drop." This process is beneficial because much of the fruit that falls is damaged or seedless, and would not develop into an edible apple.
Ideally, every other "spur" (the stubby side shoots that bear fruit) should have an apple by mid June. If there is more than one apple per spur, or if every spur has a fruit, the excess fruit should be hand thinned before the end of June.
Thinning the crop to one apple on every other spur will increase fruit size at harvest and prevent trees from developing an "on and off" biennial bearing pattern with too much crop one year and little or none the next.
Training and Pruning
Apple trees require periodic pruning to remove weak, diseased or heavily shaded branches, but excessive pruning delays the onset of flowering and fruit production in young trees, and causes too much vegetative growth and shade in mature trees.
For young trees it is best to develop a single vertical trunk, and position selected side branches evenly out along and around the main trunk at an angle of 30 - 45 degrees from the horizontal. Branches of young trees can be bent into desired positions and held there with string, trellis wires or spreader bars. Once a new ring of wood is formed (usually by late June) these strings or spreaders can be removed, although you may want to use the same strings and trellis to hold up young branches that are heavily cropped so they don't droop or break under the weight of fruit.
There are many different rootstocks for apple, and they produce a range of mature tree sizes from 8 to 30 feet. Dwarfing rootstocks offer many advantages-smaller trees that bear fruit several years after planting, room for more varieties when space is limiting, easier and more effective pest control with hand-held sprayers, less need for pruning, and larger, better quality fruit.
Dwarfed trees are just as long-lived and cold-tolerant as big trees, but they require more attention to weed control, water and nutrition, and are less tolerant of low-fertility soils, because they divert more resources into fruit than roots, trunk and shoots. It is essential to use a pole or trellis to support trees on dwarfing rootstocks.
Harvest time for apples is determined by variety, weather conditions during the growing season, and intended uses for fruit. Different varieties mature and ripen from early August to mid November.
As they mature, apples increase rapidly in size, green flesh and skin colors change to white or yellow, and the characteristic red or orange blush or stripes develop. Starch breaks down into sugars, fruit become less acidic or tart, seeds turn brown, the flesh softens, and the characteristic aroma of each variety develops.
Warm, sunny days and cool nights promote these maturation processes, while rainy, warm weather delays them. All of these changes are used to determine when apples are ripe or ready for harvest.
For long-term storage, fruit should be picked a week or so before they ripen, while for processing or immediate consumption they should be left to ripen fully until they attain peak flavor and eating quality.
Ian Merwin, Department of Fruit and Vegetable Science, Cornell University, Ithaca, NY, 14853