Production Guide
Description
Settlers introduced apple varieties to the U.S., and eventually, apples spread to areas west of New England with help from traders, missionaries and Native Americans. In the Midwest, Johnny Appleseed, or John Chapman, played a particularly significant role in expanding apple production through the region.
Characteristics of an apple tree and its fruit depend on two tree components — a scion and the rootstock to which the scion is grafted. As the portion that grows above ground, the scion dictates an apple fruit’s flavor and appearance and a tree’s fruiting habit. In contrast, the rootstock, which grows under the ground, determines a tree’s size, bearing age and lifespan. The extent to which an apple tree responds to cold temperatures and pest pressure depends on the scion and the rootstock.
Site Selection
Choosing to produce apples is a multiyear investment. Although apple orchards may maintain productivity for two decades, they may involve a significant initial investment and take several years to become established. As a result, growers should select an appropriate site that enables them to make the most of their upfront investment.
When selecting a site, find an area that provides at least six hours of full sunlight. Morning sun helps to dry leaves and minimize disease risk. Well-suited sites have air drainage, which helps to minimize damage from spring frosts. Areas with good air drainage tend to be elevated relative to the surrounding environment. Sloped areas or rolling acreage are examples. However, avoid planting trees on south-facing slopes. During the early spring, such areas tend to get warmer sooner, and trees may bloom prematurely.
To promote healthy root development, soils should be deep and well-drained. In areas that lack the appropriate drainage, operations may lay tile or create berms and plant trees in the raised areas. Soil pH levels should range from 6.0 to 6.5. If growers plan to raise apple trees in a high-density orchard, then irrigation would be critical. By locating apple orchards near water, operations would have ready access to water to use in irrigating.
Fertility
Before planting, use a soil test to measure baseline soil nutrient levels. While testing soil nutrient levels, also run a nematode test. Address any nematode problems before planting. Otherwise, the nematodes may harm tree roots and ultimately stunt or kill apple trees. Post-planting, orchards should continue to conduct soil tests, or leaf analyses are another effective tool to assess orchard fertilizer needs.
Given preplant soil test results, correct soil fertility imbalances before planting trees. Apple trees require adequate macronutrients: nitrogen, phosphorus and potassium. To maximize tree health and fruit quality, several other nutrients are particularly important: calcium, boron, copper and zinc. For example, adequate calcium is necessary to limit bitter pit and lenticel blotch pit. The two disorders are slightly different but are characterized by browning tissue or skin and surface pitting.
Annually, apple orchards will likely benefit from nitrogen fertilizer applications. Trees tend to exhibit the best response when nitrogen is provided at low rates and frequent applications. Trees shouldn’t annually receive more than 2 pounds of actual nitrogen. Too much nitrogen may lead trees to grow too much too quickly, and rapid growth may make a tree prone to developing fire blight. Fertilizer that’s applied should support young trees — those as old as six years old — in annually producing new growth that measures between a foot and 18 inches. Older trees should grow between 6 inches and 12 inches.
Cultivar Selection
Orchard operators should choose apple cultivars based on an operation’s available agronomic resources, cultivar reliability and cultivar fit with marketplace needs (Kaiser). In Missouri, the high summer humidity may cause russetting, which refers to brown “scurfiness” areas developing on fruit skin, in some apple cultivars. Producers may choose to avoid cultivars prone to developing that condition. Additionally, cultivars that offer resistance to common apple diseases may reduce disease control needs later. Disease-resistant cultivars include Liberty, Enterprise, Jonafree, Redree and Goldrush.
Apple growers have several tree rootstock options available, including dwarf rootstock, semi-dwarf rootstock and standard trees. Each produces trees of a different size. Selecting dwarf rootstock, which require a trellis or post, typically will simplify tree pruning and harvesting. These varieties also tend to produce fruit earlier. With dwarf trees, the support structure helps to prevent broken graft unions. Dwarf cultivars are well-suited for high-density planting, which demands an irrigation system and strong expertise and orchard management skills. Semi-dwarf rootstock doesn’t bear fruit as quickly as dwarf varieties. In an orchard, semi-dwarf trees grow larger and may or may not need support from a trellis or post. Young trees may require staking. For growers with less expertise or availability to manage orchards, semi-dwarf trees may be a viable option. A third choice, standard trees may take longer to bear fruit, but they also have longer lifespans and tend to yield more fruit on average. The table summarizes the differences among dwarf, semi-dwarf and standard apple trees based on their time to bearing age, lifespan and projected yield.
|
Type |
Time between planting and bearing age (years) |
Tree lifespan (years) |
Projected annual yield in bushels per tree |
|
Standard |
5 to 7 |
35 to 45 |
10 to 15 |
|
Semi-dwarf |
5 |
20 to 30 |
6 to 10 |
|
Dwarf |
3 |
15 to 20 |
3 to 6 |
When selecting cultivars, the chilling requirement for particular cultivars is another consideration. Chilling refers to the time required at a specific winter temperature for the tree to perform well and bloom and bud on schedule. When a tree’s chilling requirement and environment’s chilling period match, trees are likely to set blooms and leaves normally. Relative to its environment’s chilling period, a tree with a low chilling requirement may bloom early, which may heighten the freeze risk. A tree with a high chilling requirement relative to the environment’s chilling period may fail to flower and set leaves properly. Eventually, trees raised in areas with a chilling period that’s short relative to tree needs may die due to the stress, which can accumulate over time.
In most cases, orchards should grow at least two apple cultivars that bloom at the same time. This is necessary to ensure that trees pollinate well. If a selected cultivar has nonviable pollen, then at least two cultivars with viable pollen are necessary. If a nearby flowering crabapple tree blooms simultaneously with an apple tree, then the crabapple pollen may be sufficient to pollinate the apple crop. Alternatively, some self-pollinating cultivars are available: Lodi, Liberty, Jonathan, Golden Delicious and Rome. Depending on an operation’s marketing plan, a diversified choice of cultivars may be preferable. If selling directly to consumers, for example, then operations may grow five or six cultivars to provide variety and a season-long harvest.
The U.S. raises hundreds of apple cultivars. According to one estimate, the count is roughly 2,500 cultivars, and nearly 100 are produced commercially. However, just 15 represent most of the cultivars grown domestically. The table lists cultivars that tend to be well-suited for Missouri.
Apple Cultivars for Missouri
|
Cultivar |
Harvest period |
Description |
|
Lodi |
Mid-July |
Medium; yellowish green; soft; sweet-tart; may split and become mealy; good for sauce uses; short storage period |
|
Pristine |
Late July |
Medium-large; yellow with blush; slightly tart; short storage period |
|
Williams’ Pride |
Late July |
Medium-large; red; softens quickly; spicy, well-balanced flavor; may brown and soften in hot weather; short storage period |
|
Redfree |
Early August |
Medium; bright red; well-balanced flavor; good texture; prone to biennial bearing; short storage period |
|
Akane |
Mid-August |
Medium; bright red; similar to Jonathan; can soften in hot weather |
|
Gala |
Mid-August |
Small; yellow to red; good fresh flavor; prone to fire blight; brittle wood; short storage period |
|
Honeycrisp |
Mid-August |
Large; yellow with mottled red; sub-acid; juicy; crisp; good flavor; needs calcium applied |
|
Prima |
Mid-August |
Medium to large; dark red; firm but softens in heat |
|
Jonamac |
Late August |
Medium; dark striped fruit; semi-firm |
|
Ozark Gold |
Late August |
Medium to large; yellow; resistant to russetting; soft fruit; may drop fruit in hot weather |
|
Jonafree |
Early September |
Similar to Jonathan |
|
Jonathan |
Early September |
Medium; red; tart but well-balanced flavor; prone to fire blight and powdery mildew |
|
Liberty |
Early September |
Small or medium; red over green; tart; coarse texture; McIntosh-type; disease-resistant |
|
Empire |
Mid-September |
Medium; red; McIntosh-type; prone to fruit rot; may suffer in Missouri summers |
|
Golden Delicious |
Mid-September |
Large; yellow; tends to russet; sweet and well-balanced flavor; prone to biennial bearing |
|
Jonagold |
Mid-September |
Large; red over yellow; well-balanced flavor; doesn’t pollinate other apples; soft texture |
|
Red Delicious |
Mid-September |
Medium to large; solid red; sweet with little acidity |
|
Suncrisp |
Mid-September |
Medium-large; yellow with orange blush; sub-acid flavor; firm; crisp; prone to russet; requires thinning |
|
Crispin |
Late September |
Large; yellow-green; very juicy; mostly sweet flavor; doesn’t pollinate other apples |
|
Arkansas Black |
Mid-October |
Medium to large; deep purplish color; firm; coarse texture; good flavor; long storage period |
|
Braeburn |
Mid-October |
Large; red; good, well-balanced flavor; very firm; good texture; fire blight; slow to ripen; prone to bitter pit; long storage period |
|
Enterprise |
Mid-October |
Large; bright red; spicy; juicy |
|
Fuji |
Mid-October |
Medium to large; reddish; sweet; crisp; juicy; prone to russetting and bitter pit; slow to ripen |
|
Northern Spy |
Mid-October |
Small to large; greenish yellow with red blush; crisp; firm; juicy; tart; long storage period |
|
York |
Mid-October |
Medium to large; red blush over green-yellow; firm; crisp; juicy; long storage period |
|
Goldrush |
Late October |
Large; yellow; semi-tart; juicy |
|
Granny Smith |
Late October |
Medium to large; green; crisp; tart but well-balanced flavor; slow to ripen; prone to powdery mildew |
To ensure that your operation will have apple rootstock available for planting, order early. In previous years, a rootstock shortage has created challenges. To expedite the time between planting and full production, growers may choose well-branched or feathered trees.
Planting
Apple tree planting typically occurs during the fall or early spring. If planting during spring, then target the planting date between late March and April 15. Fall planting of container trees works well between mid- and late October.
Between receiving your nursery trees and planting them, the tree roots must stay moist. Otherwise, the trees may die. “Heeling in” trees is one strategy for storing them temporarily. That involves placing trees at an angle in a shallow, open trench of soil that’s well-drained but moist. Then, cover the roots with soil to protect them. Trees often do well when they’re heeled in on the north side of buildings.
When planting, space rows evenly. Before planting, staking rows can help to maintain equal spacing. To maximize light interception, north-south rows are preferred. As indicated earlier, tree spacing — and ultimately, orchard density — will vary by cultivar type. For example, trees with dwarfing rootstock work well in high-density plantings.
To prepare for planting, first create planting holes that are roughly 2 feet wider than trees’ root systems, which may be pruned selectively to remove broken roots or trim long roots. For depth, planting holes should allow the tree to grow at the same depth that it had been growing. A tree’s graft union should extend 2 inches higher than the soil surface. Before placing a tree in its planting hole, surround the trunk with hardware cloth that runs 4 inches deep into the soil. The cloth will discourage damage from rabbits, mice or voles. After this preparation, position the tree in the planting hole. Ensure that roots don’t overlap, and then, use soil to fill the hole. When filling a planting hole, use “native soil” that originates from the planting site. Fertilizer or other soil amendments shouldn’t be applied. To complete the planting process, tamp the soil around the tree to firm the disturbed soil and remove air cavities. If air pockets are near roots, then they may cause roots to dry. Watering post-planting will also help to close spaces in the soil. Plus, it adds moisture for trees.
Within an orchard, strategically plant cultivars in environments well-suited to their needs. As an example, if a cultivar is prone to blooming early, then planting it in an area with proper air drainage, such as high on a hillside, may minimize the frost damage risk.
Cultural Management
After planting, orchards must begin pruning and training their trees, and these are practices that should continue at least annually. These practices ensure that the tree has adequate exposure to light, which affects tree vigor, disease incidence and fruit quality.
Often, apple trees are trained to have a central leader structure, which leads to apple trees looking similar to Christmas trees or narrow pyramids. As a general rule, a central leader structure will have scaffold limbs, which are side branches, extending at 50- to 60-degree angles. Producers may use weights affixed using clothespins to encourage branches to form the desired angle. To achieve the appropriate angle, producers may also try placing spacers between branches or tying branches.
Growers start pruning apple trees in the first growing season. At that time, prune trees to four scaffold limbs. Roughly 26 inches to 30 inches should be between the ground and the lowest scaffold branches, and the scaffold branches should be positioned at consistent increments around a tree trunk. If four scaffold branches don’t exist, then producers can prune the tree to a 30-inch height and cut any existing scaffold branches.
In later years, pruning should help the tree maintain its central leader form and ensure that other branches don’t compete with the central leader. The pruning should allow the tree to grow multiple groups — three or four — of scaffold branches that are within 24 inches to 30 inches of the neighboring scaffold branch group. Pruning during tree dormancy can also remove suckers, branches growing down, broken branches, branches that touch, branches that lack enough light exposure and branches that don’t grow at the correct angle . During pruning, operators should also discard branches damaged by diseases or insects. When the tree reaches the desirable height, producers may prune the central leader annually.
Orchard operators generally target pruning to times when trees are dormant. Later, summer pruning may follow to enable light to reach into tree interiors. Fruit coloration benefits from good light exposure. Avoid pruning branches that are one-year-old growth; it may trigger trees to produce too much vegetation. Cuts made during pruning should be near the trunk, but the collar should be preserved. If trees weren’t pruned properly for several years, then slowly work with the tree to create the desired central leader structure. During a given growing season, apple trees should at most have just one-third of their limbs cut.
With respect to pollination, proper cultivar selection can support apple orchards being pollinated well, as mentioned earlier. However, apple orchards also rely on honey bees during the pollination period. Producers should allocate one hive per acre.
Apple thinning is necessary after fruit sets. Very young trees — those planted within the prior two years — should have all fruit removed. Removing the fruit enables the tree to become well-established. In more mature trees, thinning apple fruit enables the remaining apples to grow into large fruit that’s accepted by buyers, and it supports the next year’s blooming. Thinning can also discourage disease and insect damage. Plus, limbs bearing fruit that hasn’t been thinned may break due to the weight To thin apple fruit, growers may choose chemical methods or engage hand labor.
As a general rule, target early June for thinning fruit. At thinning time, the fruit diameter should be roughly 3/8 inch to 5/8 inch. When thinning, create at least a 6-inch spacing between apples, and in each fruit cluster, choose to keep just one apple. Thinning fruit may require removing at least 75 percent of a tree’s apples.
Water Management
Apple trees benefit from a regular supply of moisture. In an average week, apple trees demand an inch of water. If irrigating, then avoid water directly touching a tree’s crown. Water exposure exacerbates the risk of soil-borne pathogens harming trees.
Weed Control
Weed competition has the potential to hinder orchard establishment. It may limit the moisture and nutrients that apple trees have available to them. Plus, weeds may serve as cover for harmful pests. Weeds, including dandelions, that bear blooms may attract pollinators and limit pollinator visits — and consequently, pollination — to the apple trees.
Ideally, apple trees would have 18 inches to 3 feet between the trunk and growing ground vegetation. To minimize weed pressure near apple trunks, growers often use weed barriers. They may choose from organic and inorganic options. For operations that choose organic mulch as a weed barrier, they should apply the mulch at roughly a 6-inch depth. Over time, organic mulches will break down, and reapplication may be necessary. Despite their likelihood of degrading over time, organic mulches have several benefits in addition to weed control. For example, they help to keep moisture in the soil and soil temperatures relatively steady. They also contribute to the growing area’s soil structure.
For other weed management approaches, growers may choose from chemical or mechanical weed control strategies. Note, however, that mechanical control has the potential to damage tree roots, and it may trigger erosion. That said, if using mechanical cultivation, then it should be shallow. To chemically control weeds, producers may apply glyphosate. In young trees, protect the tree from chemical damage by using aluminum foil or plastic wrap to cover the trunk.
Insects and Diseases
Several insects and diseases can target apple orchards. In terms of insects, those known to cause harm to apple trees include the San Jose scale, codling moth, oriental fruit moth, plum curculio, stink bug, aphid and leafhoppers. Others include apple maggot, tarnished plant bugs, flat-headed apple tree borers, mites, leaf rollers and leaf miners. Timing spray applications to 10- to 14-day intervals during the growing season may be necessary to keep pests from harming apple fruit. Although insect control is important to protect orchard and fruit health, adopt practices that minimize insecticide harm to pollinators. This is particularly important as apple trees bloom.
Although deer and voles aren’t insects, they’re pests that can damage apple orchards. Deer may rub trees. Browsing is another concern with deer. Too much deer-related damage to trees, especially young ones, could result in losing the damaged trees. To deter deer from entering an orchard, consider installing an electric fence, or permitting hunting can help with control. Voles, which can feed on apple tree roots and trunks, pose a risk during the winter.
Diseases capable of harming apple orchards include apple scab, cedar apple rust, fire blight, sooty blotch, flyspeck and fruit rot. If the infection is severe, then fire blight can cause whole trees to die. Other pathogens known to affect apple trees are powdery mildew, bitter rot, collar rot, black rot and cotton root rot.
Manage diseases by selecting from several practices. For example, to reduce apple scab incidence, growers may identify scab-resistant cultivars. Other disease management techniques include removing infected branches during pruning; administering agricultural antibiotics as trees flower; and curtailing nitrogen supplementation, which leads to less vigorous vegetative growth.
Harvest and Storage
To know when apples are ready for harvest, growers watch for clues such as color, starch and sugar content and firmness. Desired ripeness at harvest depends on whether the apples will be sold locally or shipped to markets. If storing apples, then pick them when they’re mature but haven’t fully ripened. In Missouri, the state’s apple trees tend to produce marketable fruit between July and October.
Orchards most often use hand labor during apple harvest. Pickers should do all they can to minimize fruit bruising and other damage. Not only are damaged apples less appealing to buyers, but they’re also less likely to store well. During harvest, one tip involves picking fruit by holding it in the palm, twisting it somewhat and giving it a slight tug. This method is preferable to pulling the fruit using only fingertips. Soon after harvest, apples that will be stored benefit from having field heat removed.
The extent of an apple crop’s potential storage life depends on the cultivar and the storage method. As a general rule, apples that mature later in the growing season generally can be stored for longer periods. Typically, optimal storage conditions are those that provide a temperature between 30 degrees F and 40 degrees F; specific temperature needs depend on the cultivar. The relative humidity in storage should range from 90 percent to 95 percent.
Storing apples enables operations to extend the marketing season. With traditional cold storage at 30 degrees F to 36 degrees F, apples may keep until March. This storage method often uses water to add humidity and maintain fruit moisture levels. Controlled-atmosphere storage is another option. It provides a refrigerated environment that removes oxygen and adds carbon dioxide. Operations may use a controlled-atmosphere facility to store and market apples through July. As another strategy to lengthen apple storage life, some growers may use SmartFresh, a plant-growth regulator that curtails ethylene production and, consequently, slows the ripening process.
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