Agronomy

Description

Originally a Chinese crop, peaches belong within the rose family. Like apricots, cherries and plums, peaches have hard seed pits, and they’re termed a stone fruit. Freestone and clingstone types of peaches are available. With freestone peaches, the fruit flesh doesn’t cling to the peach pit like it does in clingstone varieties. Depending on the cultivar, peach trees may produce white or yellow fruit. Some cultivars produce flat fruit that resembles a doughnut in shape.

Site Selection

Because establishing a peach orchard is a long-term investment, site selection ranks as a top — or the top — decision for peach producers. First, consider the preferred orchard size. If an operation intends to only serve local markets, then one acre to five acres may suffice. For commercial production, a 10- to 40-acre operation may be more appropriate.

An ideal peach orchard site will have the necessary air drainage, sunlight, soil drainage, soil type, water access, production history and proximity to markets. Frost can damage a peach crop or cause losses. A site with good elevation and air drainage lessens frost damage risk. At 25 degrees F to 28 degrees F, peach flowers can be compromised. Because cold air sinks, fruit grown in low areas may be more susceptible to frost injury. As a result, hill sites may work well for peach orchards. Sunlight is also important. During 80 percent of a day, peach trees should have access to full sun. Proper sunlight exposure dries a tree’s fruit and leaves to discourage disease.

With respect to soil conditions, peaches perform well in sandy loams to clay loams that drain well and are at least 2 feet to 3 feet deep. To address drainage issues, tile or raised beds may help. As another option to correct poor drainage, build terraces before planting, and plant trees in those terraces. Terraces may boost orchard performance, even when a planting site has high-quality soil. For a potential peach tree planting site, test for soil nutrient levels, which can indicate whether fertility adjustments are necessary, and nematodes, which can cause stunting or kill trees entirely as they harm tree roots. A soil test can also measure soil pH. Peach trees can grow when pH levels to range from 6.0 to 7.5.

Avoid disease and pathogen pressure by choosing a site that hasn’t been an orchard for at least three years or hasn’t recently been cleared. Note that if a site had previously grown post oaks, then pathogens, including oak root rot, may pose a problem. When choosing a site, also avoid areas that previously grew broadleaf field crops, including soybeans and alfalfa. They may have infected the site with a virus that’s harmful to peaches and causes Prunus stem pitting. If carryover viruses are concerning, then for at least one year, let a grass cover crop grow. Then, kill the grass cover in 3- to 5-foot strips. Within those strips, plant peach trees at the appropriate time.

In addition to agronomic-related site selection factors, also consider proximity to market. Operations positioned near a large consumer population may have stronger market opportunities. Other site selection criteria may include proximity to competitors and access to transportation and suppliers.

Fertility

Young peach trees grow best when they receive low fertilizer doses at frequent intervals. To ensure proper fertilization, growers may test the soil or foliage for nutrient needs. On a three- to five-year basis, run a soil test. During the growing season, leaf tissue analysis can identify nutrient imbalances. To test foliage, gather two to three leaves per tree from July 15 to Aug. 15. Choose mature, mid-shoot leaves set on new growth that has had good sunlight.

If soil or foliage tests indicate a nutrient deficiency, then supplementation would be necessary. Micronutrient deficiencies may be resolved through foliar or chelate applications. If macronutrient levels are insufficient, use ground applications to correct those deficiencies. With young, newly planted trees, only apply fertilizer — at one cup of nitrogen — if trees grow 8 inches to 10 inches by May. Note that soil-applied nutrients should reach no closer than 18 inches to tree trunks. During the second and third growing years, apply fertilizers at four intervals as long as trees are growing well.

When trees mature and produce fruit, use 50 pounds to 60 pounds of actual nitrogen as a general rule. Growers often break down total requirements into multiple applications during the year. Apply through broadcast or drip irrigation methods. Phosphorus and potassium fertilizer needs hinge on test results.

Cultivar Selection

Peach planting stock results from identifying a particular cultivar and grafting it to seedling rootstock. When choosing cultivars, identify those with not only agronomic characteristics suitable for the given growing conditions but also those that appeal to market preferences.

The table below lists peach cultivars that are well-suited for Missouri growing conditions. Note that the “season” column indicates whether cultivars tend to mature earlier than, later than or at the same time as Redhaven peaches.

Peach Cultivars for Missouri

* Maturity compared with Redhaven peaches, which in central Missouri tend to ripen during the second week of July

When selecting peach cultivars, agronomic considerations include disease resistance, maturity, sensitivity to micronutrient imbalances and nematode resistance. Additionally, the winter chilling requirement is another factor to consider. Winter chilling refers to the time that a cultivar should be exposed to temperatures at 45 degrees F or cooler. It affects when a tree leaves dormancy and how well it performs during springtime blooming and growing. Planting a cultivar with a low chilling requirement may cause trees to exit dormancy too early and face springtime frost-related damage. On the other hand, choosing trees with a chilling requirement that’s too high may lead to delayed dormancy break and lost peach fruit. If a planting site includes areas with different cold injury risk, then consider choosing cultivars with different chilling requirements and strategically planting cultivars where they fit best with the environment. Note that hardier cultivars are necessary for orchards in northern and central Missouri.

With respect to consumer preferences, freestone peaches with good flavor and little fuzz tend to be popular. Additionally, consumers tend to prefer large peaches that have good shape and color, are well-matured and show no insect or disease damage. If processing markets are available, then they typically demand clingstone fruit.

Depending on the cultivar, peach trees may yield mature fruit at different times. Diversifying cultivars can extend the harvest as fruit from different cultivars ripens at different times.

Planting

In Missouri, operations should target planting peach trees at some point between late March and April 15. After receiving a shipment of young trees, inspect the plantings for vigor, disease or insect damage and other injuries. Before planting, “heel in” trees by digging a trench in the soil. Trenches do well on a building’s north side. Position tree roots within the trench. The trees should lean south at a 4 degree angle. To protect the roots, cover them with moist soil, firm the soil to keep air from reaching the roots, and apply water if needed. At no point should peach tree roots dry out. They also shouldn’t be allowed to freeze.

At planting, dig holes large enough for all roots to fit. For more specifics, a tree should be planted as deep as it was planted at the nursery. In terms of width, plan for the hole to be roughly 2 feet wider than the tree’s root system. Prune roots if they’re diseased or damaged. Broken roots may also be removed by cleanly cutting them, which facilitates quick healing. If roots are longer than 12 inches to 18 inches, then growers can trim them to the 12- to 18-inch length. Sides of the planting hole should be loosened to enable roots to grow through those sides.

When designing an orchard’s layout, attempt to create evenly spaced rows. Specific row spacing may vary by production preferences and practices. Orchards that use cultivation or no irrigation may benefit from allocating more space between rows. With the extra space, peach trees would face less competition for soil moisture and avoid damage from mechanical operations.

After placing tree roots into a hole, fill the hole with soil, tamp to remove air pockets, and water. Then, trim the tree to just its trunk and a 24- to 36-inch height. For one-year-old trees, cut lateral branches from the trunk. Older trees can have lateral branches removed to stubs. Surround the truck with a protective grow tube, or wrap it with aluminum foil. If using foil, then following the first growing season, all foil should be removed.

Cultural Management

Peach trees require proper pruning and training for them to live a long life and produce well. Post-planting, pruning and training begin soon after springtime growth emerges. At that time, remove all shoots but the strongest four or five. The shoots selected to remain should be spaced evenly and located on the main stem’s top 6 inches. At least one remaining shoot should extend into prevailing winds. Ultimately, train peaches to have an open center, which leads to the tree structure resembling a martini glass. With an open center, peach trees benefit from good sunlight and air movement.

In the dormant period between the first and second growing seasons, peach trees should be pruned to have just three or four permanent scaffold limbs and a trunk. Beginning in the second dormant season, prune trees to have the open center. When pruning, ensure that you leave some one-year-old wood. On peach trees, only limbs that are one year old will bear fruit. Tree pruning should encourage a canopy that supports the present year’s crop and optimizes the orchard’s next year of production. Pruning should also prevent trees from growing taller than 7 feet to 8 feet. Taller trees would make harvesting fruit by hand more difficult.

When peach trees mature, pruning occurs during dormancy and summer. With winter pruning, typically 40 percent of the tree is removed. For summer pruning, wait until harvest concludes. Pruning that follows can minimize shading. When pruning, focus on removing branches that have died or developed disease, suckers that grow from the roots and water sprouts that emerge from the tree’s center.

Peach trees also require fruit thinning. To realize a full crop, a tree only needs to retain 10 percent of its flowers. After thinning peaches, those that remain can grow into larger, high-quality fruit, and trees can also continue to grow. A tree that produces too much fruit may also yield peaches that lack good color and flavor. Plus, limbs may break if pressured by heavy fruit. After frost risk passes, Missouri growers should thin fruit; so target thinning in May. Rather than remove fruit, some growers may choose to thin peaches during flowering. When thinning, leave fruit to set at eight-inch increments. Creating more space between fruit generally indicates that the remaining fruit will grow larger. During drought-like conditions, thinning fruit more liberally may help trees to cope with the dry weather.

To support pollination, peach orchards often add hives for honey bees. Insecticide applications should avoid harming pollinators, including the honey bees.

Water Management

As mentioned previously, orchard design can dictate whether irrigation is necessary. If irrigating, then the water being used should be salt-free and clean. An area that lacks clean, salt-free water may not work well as a peach orchard site.

Trees spaced more closely are more likely to require more irrigation. Assuming that orchards use drip irrigation, a peach tree’s water requirements in the first two years may range from 7 gallons to 56 gallons per week, depending on the month and weather conditions. As trees mature, the weekly water requirement tends to average about an inch. Mature trees particularly require adequate moisture in the six weeks before peach harvest, and irrigation generally isn’t as necessary until that time.

Weed Control

Weed pressure can have a detrimental effect on peach orchards as weeds can aggressively compete with young trees for water and nutrients. Young trees are especially vulnerable to weed competition. For best results, peach orchards have mowed, native sod lanes between tree rows, which are maintained in weed-free strips. The sod prevents weed pressure. By the time an orchard reaches maturity, the weed-free strip should have increased from the roughly 3- to 5-foot strip created at planting to a 10- to 12-foot strip maintained at maturity.

In an orchard, operators can manage weeds using mechanical or chemical methods. Although mechanical control avoids chemical exposure, repeated cultivation is necessary. Note that mechanical operations should disturb the top three inches of soil at maximum. Deeper cultivation can harm roots. Chemically controlling weeds tends to be more popular because chemical applications are reliable, effective, economical and required less frequently. If spraying chemicals, then avoid glyphosate in first-year trees, except if spraying aluminum foil-wrapped trees. Older trees have more resilience to chemical applications.

Insects and Diseases

Several diseases can create problems for peach trees or fruit. Those include brown rot, bacterial leaf spot, peach leaf curl, peach scab, phytophthora, cercospora, powdery mildew and rust. In Missouri, bacterial leaf spot is particularly troublesome. The disease can cause trees to lose their leaves, yield less fruit and produce fruit with quality issues. Bacterial leaf spot doesn’t respond well to sprays meant to control it, so growers should consider cultivars that offer some resistance.

In terms of insect pressure, oriental fruit moth, plum curculio, spotted wing drosophila and borers can cause damage. Fruit may be susceptible to damage from tarnished plant bugs and stink bugs. To monitor pest levels, trapping can help to determine whether pests exist and whether they’re present at levels high enough to cause damage.

Like when growing other fruit crops, insect damage can limit yields and stress trees. Peaches are susceptible to pests other than just insects, however. Mice and other rodents can harm the trees themselves. Birds may pose a threat to maturing fruit. If birds begin to target peaches, then netting trees or installing scare devices may help to limit the damage.

Harvest and Storage

Because peaches require hand harvesting, the harvest season is labor-intensive. During a growing season, peach trees may require three to five harvesting passes. The staggered harvest is necessary because fruit doesn’t mature evenly. Peaches that set within the lower interior portion of the tree ripen more slowly.

At harvest, peach fruit should be firm-ripe. Plus, in terms of coloring, peaches ready for harvest will have a yellow background and a red blush. Note that access to peach markets is important, especially when the fruit is harvested at maturity. If selling to wholesalers, then earlier harvesting may enable the fruit to ship better.

After picking peaches, harvesters may place the fruit in half-bushel baskets, drop-bottom picking bags, wooden boxes or plastic containers. Handling should attempt to preserve fruit quality. Bruised or damaged fruit may spoil more easily. If growers pick and haul fruit in the same container, then that can limit bruising.

After harvest, peaches should be refrigerated at 31 degrees F to 32 degrees F. Humidity should range from 90 percent to 95 percent. In those conditions, fruit will store for roughly two weeks to four weeks. Peaches that undergo hydrocooling shortly after harvest can effectively have field heat removed. This primes the fruit for extended time in storage or transportation.

Sources

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Kaiser, Cheryl, Matt Ernst and John Strang. 2014. Peaches. University of Kentucky. Lexington, KY 40506.

Kamas, Jim, Larry Stein and Monte Nesbitt. 2010. Peaches. Texas A&M System AgriLife Extension. College Station, TX 77845.

Marini, Richard P. and Gregory Peck. 2014. Growing Peaches & Nectarines in Virginia. Virginia Cooperative Extension. Blacksburg, VA 24061.

Roper, Teryl R., Daniel L. Mahr and Patricia S. McManus. Growing Apricots, Cherries, Peaches, & Plums in Wisconsin. University of Wisconsin-Extension, Cooperative Extension. Madison, WI 53706.

Stafne, Eric Thomas. 2016. Growing Peaches in Mississippi. Mississippi State University Extension. Mississippi State University, MS 39762.

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