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Peaches: their care and cultivation

Peaches: their care and cultivation – part 2, includes related articles on a home peach orchard

Brenda Olcott-Reid

THE REWARDS OF A HOME ORCHARD — OR EVEN A SINGLE PEACH TREE — are many. Peaches are delicious in pies and preserves, but they are at their finest, perhaps, when plucked from the tree at the moment of luscious perfection and savored out of hand.

Keeping peach trees in peak form takes planning and effort, however; much can go wrong. Selection of disease-resistant, climate-appropriate peach varieties, a topic covered in the first article in this series, is only the first step toward ensuring bountiful harvests. Proper planting, pruning, fertilizing and a program of pest and disease control are other necessary of caring for peaches.

PLANTING PEACH TREES

Choose a sunny, slightly elevated spot for peach trees, where cold air drains away quickly and frost damage is infrequent. Planting on the north side of a house or other building is often ideal; shade cast by the building in winter delays bloom, but the trees receive full sun in summer.

Peaches need soil with high water-holding capacity yet excellent drainage of excess water. They also need high fertility. Generous additions of grassy or organic matter, accomplished by tilling under the section of lawn where the trees are to be planted, will improve all three.

Before planting test the soil pH and phosphorus and potassium levels. Apply nutrients as needed, and lime or sulfur as needed to bring the top 18 inches of soil within a pH range of 6.0 to 7.5. Surface treatments may be required every few years to keep the pH within this range.

Don’t allow a lawn to grow right up to the trunks of young peach trees; competition from living grass greatly reduces growth. Some tress can be so weakened by the competition that they fail to survive the winter. If you don’t plan to till the ground before planting peaches, kill the grass in a 3-foot circle around each planting site with glyphosate (Roundup) herbicide or a thick mulch.

In most areas, peaches should be planted in early spring, about three or four weeks before the leaf buds start growth. This timing allows roots to become established before the trees’ water demands increase. In Zones 8 to l0, where fall-planted trees are not prone to winter damage, autumn is the preferred planting season. One-year-old trees, 4 to 5 feet tall, are the best size for transplanting. Bare-root trees are the most economical and transplant well.

Planting distances for standard peach trees range from 12 feet to 20 feet. The closer spacing is used on shallow or poor soils, or when you plan to prune rigorously; wider spacing is needed for lightly pruned trees on deep, fertile soils. Semidwarf trees can be planted 8 to 12 feet apart and miniature peach trees 5 or 6 apart.

Keeps weeds controlled, and start training the trees to an open-center system with three main scaffold branches (see “Training Peach Trees to an Open-Center System,” page 40).

WATERING AND FEEDING

During the first growing season, water new peach trees twice a week if there’s been no rain. About six weeks after planting (or, in the case of fall-planted trees, two weeks after the trees begin to leaf out in spring), apply a fertiliser containing about 1.5 ounces actual nitrogen in a wide band one foot from the trunk of each tree. (See “How to Calculate Actual Nitrogen,” above.) If soil tests indicate that you need more phosphorus and potassium, use a complete fertilizer.

Take note of the amount and color of summer growth; it will guide you in determining the amount of fertilizer that will be needed next year. Leaves should be medium green and the terminal shoots on each branch should grow 18 to 24 inches.

Apply fertilizer twice during the second year: first when growth begins in spring, and again in early summer. If growth was in the desired range last year, apply about 2 ounces actual nitrogen each time. Use more nitrogen if terminals grew less than 18 inches and leaves were yellowish; apply less if terminals grew more than 24 inches. Continue tree training and mulching to control weeds. Water deeply once a week, applying six to eight gallons per tree.

From the third season on, cut nitrogen applications to 1 ounce actual nitrogen when growth begins and another l ounce in early summer, at least a month before the fruit ripens. Terminal shoots should grow 15 to 18 inches per season. Once trees are bearing, excess nitrogen can cause poor fruit bud set, delayed fruit maturity and softer fruit more prone to rot. Excess nitrogen in fall can interfere with the tree’s natural process of hardening for winter.

Bearing peach trees need at least an inch of water per week until fruit ripens. If no rain has fallen for two weeks, apply one gallon of water per square foot of rooting area, which extends several feet beyond the tree’s drip line. Don’t water more than that while the peaches are gaining size, or they’ll lack flavor and be more prone to rot. Cut watering in half after harvest, and in half again as the leaves begin to yellow in fall, to encourage hardening for winter. Dormant trees may need occasional watering if the winter is dry. Soaker hoses or drip irrigation systems are the most efficient way to water.

Protect peach trunks and larger scaffold limbs from winter sun scald by wrapping them in white plastic tree guards, or painting them with white interior or exterior latex paint thinned with an equal part of water. The paint reflects light to keep the bark from heating up so much during sunny winter days, and so prevents the bark cracking that would occur when temperatures plummet at night.

FRUIT DROP AND THINNING

Peaches bloom lavishly, producing 10 times as many flowers as they need to set a full crop. The abundance of blooms ensures that even if a frost kills 90 percent of the blossoms, you’ll have plenty of peaches. If frosts don’t reduce the crop, far too many fruits will set. In those years, you’ll have to “thin” the fruits by removing some while still small. Thinning enables the remaining fruits to grow bigger and sweeter, reduces split pits and prevents the tree’s branches from breaking under the weight of an excessive crop.

Soon after natural fruit drop begins, gently shake the limbs to knock off loose fruits that will fall anyway. Then remove scrawny, misshapen or poorly developed fruits that flick off easily with your finger. Next, twist off all diseased or insect-damaged fruits, dropping them into a bucket for disposal. Look closely for the crescent-shaped egg-laying scars of the plum curculio, about 1/8 inch long.

Thin the remaining peaches to about 6 to 8 inches apart, letting the biggest fruits remain. Don’t leave fruits any closer than 4 inches apart or they may touch when ripe. Fruit rots thrive in the humid niches created by too-close fruits and spread rapidly across fruits that touch.

Some years you’ll need to thin heavily, removing up to 75 percent of the young fruits. In other years the trees will need only light thinning in spots. When you’re done thinning, rake up and dispose of all the dropped and thinned fruits to help prevent pest problems.

PEACH PEST MANAGEMENT

Most peach diseases can be prevented without sprays. To avoid problems, choose disease-resistant and cold-hardy varieties and rootstocks, purchase virus-free trees, plant them in a good location, thin excess fruits and prune out any diseased or dead branches. Although these cultural practices usually preclude peach diseases, the many pests of peaches often call for some pesticide spraying.

In milder, humid areas where bacterial canker can be a problem, apply a single spray of Bordeaux mixture or copper fungicide on the trunk and limbs when leaves drop in autumn. This fall spray will also help control shothole — a problem on the West Coast — and peach leaf curl, a widespread disease that weakens and can defoliate trees. For best control of shothole or leaf curl, spray again just before the buds begin to swell in spring.

Superior oil can be combined with the Bordeaux or copper spray to smother aphid eggs, mite eggs and San Jose scale if these are a problem. Apply oil only when the temperature is over 50 degrees. On the West Coast, where peach twig borers chew cavities in the scaffold limb crotches of peach trees, add diazinon to the copper/oil or Bordeaux/oil spray just before buds swell.

Peach tree borers can seriously damage trees and provide a foothold for perennial canker, which kills trees. These white worms tunnel beneath the bark on the trunk, at or below the soil surface. Prevent them by spraying the lower 12 inches of the trunk, and the ground around the trunk, with Thiodan or Lorsban insecticide in late May or early June, as advised by your local extension agent. If borers have already entered peach trunks, apply para-dichlorobenzene moth crystals around trunks in early fall.

In arid areas west of the Rockies, Oriental fruit moth is the only troublesome fruit-attacking pest. It may require two or three sprays of ryania or phosmet (Imidan), but can be at least partially controlled by beneficial parasitic wasps. Determine the best times to release parasites or spray insecticides by monitoring Oriental fruit moth populations with pheromone traps, or ask the local extension service to let you know when peak moth flights occur.

East of the Rockies, two sprays are essential soon after bloom: when all the petals have fallen, and again 10 to 12 days later. Combine in the sprayer wettable sulfur or another fungicide to control brown rot and peach scab on the fruit, and phosmet (Imidan) to control plum curculio and Oriental fruit moth, two worms that tunnel into the fruit. Spray a third time with the same materials, in mid-June to mid-July, as advised by your extension agent. Check the peaches for brown rot twice a week as they gain size, and spray with wettable sulfur alone if you see any rot on uninjured fruit. If wet weather prevails, sulfur may be applied every 10 to 12 days, up to 10 days before harvest.

HARVESTING

Pick peaches when they just start to soften and twist off easily. Each variety will ripen all its fruit within a week to 10 days. After you’ve harvested for a few days, birds will probably start pecking the fruit, so you may have to pick some stillfirm fruits and let them soften on the kitchen counter.

Peaches should be eaten or processed at their peak of freshness. They can be stored in the refrigerator for a few days, but they lose some of their flavor that way. Peaches may be dried, canned, frozen, or made into preserves. Left in buckets, they spoil quickly.

Each standard-size peach tree can produce three to five bushels of fruit per year during its prime, usually from its fourth to twelfth years, though frosts will reduce that yield in some seasons. A semidwarf tree should yield two to four bushels per year, and a genetic full-dwarf peach about one bushel per year. And although peaches are short-lived trees, it’s easy enough to raise replacements that will soon take over in providing that wonderful taste of summer.

RELATED ARTICLE: How to Calculate Actual Nitrogen

Fertilizers are labeled with a series of three numbers, such as 12-12-12 or 10-6-8. The numbers indicate the percentage of total nitrogen, available phosphoric acid and soluble potash, in that order.

Fertilizer recommendations are often given in terms of “actual nitrogen.” No fertilizer is pure nitrogen, so you’ll need to make a quick calculation to determine just how much of any fertilizer product to use.

First, grab a calculator. Start with the amount of actual nitrogen needed; multiply by 100; then divide by the percentage of total nitrogen (as shown on the package). The result is the quantity of the product that contains the needed amount of actual nitrogen.

For example, you need to apply 1.5 ounces of actual nitrogen per tree. You plan to use a complete plant food that is labeled 30-12-11. To calculate: 1.5 oz. x 100 [divided by] 30 = 5 oz. per tree.

Another example: You need to apply 2 ounces of actual nitrogen per tree. You want half the nitrogen, or 1 ounce, in the form of urea (45-0-0) and the other half from blood meal (12-0-0). To calculate: 1 oz. x 100 [divided by] 45 = 2.2 oz. urea per tree; 1 oz. x 100 [divided by] 12 = 8.3 oz. blood meal per tree.

RELATED ARTICLE: Training Peach Trees to an Open-Center System

An important objective of pruning fruit trees is to create a sturdy framework of limbs that won’t collapse under the weight of a heavy crop. For peach trees, an open-center system of three or four wide-spreading branches is often recommended. Here’s how to train your trees:

YEAR ONE

Early spring: Peach trees usually arrive from the nursery with branches. Remove weak branches, those that arise from the trunk at a narrow angle (shown at A in the diagram) and those closer than 18 inches to the ground (B). Keep any strong branches arising at a wide angle, and cut them back by about one-third to an outwardgrowing bud (C). Cut the main upright central leader back to about 30 inches tall (D) to stimulate growth of additional branches.

Early summer: The most vigorous shoots, arising from the top two or three buds, will have narrow crotch angles, so cut these shoots back to stubs with just three to five leaves. This procedure, called stubbing back, will encourage growth of wide-angled shoots below. If you already have three or four good branches arising between 18 and 28 inches off the ground and spaced about equally around the trunk, choose these for scaffold limbs, and cut other branches back to stubs. If you don’t have enough good branches, the stubbingback pruning should encourage growth of some, while retaining enough leaves on the tree.

YEAR TWO

Early Spring: Choose three or four scaffold branches if this wasn’t done last summer. (Note: Only two of the scaffold branches are visible in the side-view illustrations. The top-view drawing shows an ideal configuration of three evenly spaced scaffold limbs.) If one scaffold has grown much more than the others, cut some off to bring it into balance with the others (E). The only other pruning needed on the scaffolds is to remove dead, diseased or damaged branches, and those arising within 6 inches of the trunk (F). Completely remove any growth on the trunk below the scaffold branches. Cut back the branches in the tree’s center, above the scaffolds, to short stubs (G). A small cluster of shoots will develop from these stubs and keep the scaffold branches growing outward.

Early summer: Cut back the shoots arising from the stubby growth above the scaffolds to three to five leaves.

YEAR THREE

Early spring: The tree should now have a well-formed vase shape. Completely remove the stubby growth above the scaffolds (H). Again prune to balance the scaffold branches if needed, and remove any dead, diseased or damaged branches. The tree should have some flower buds this year, so prune as little as possible to retain the most fruit.

YEAR FOUR AND ON

Early Spring Continue to prune out dead, diseased or damaged branches each year. Remove upright branches or cut them back to outward-growing branches. As the tree grows and spreads, cut back older branches to encourage the growth of new fruiting wood closer to the trunk. Thin out crowded branches, but wait until after bloom to do this, adjusting the amount of fruiting wood you remove to the amount of fruit set.

Early summer: Pinch or cut back the tips of all new shoots, removing about an inch of growth, to keep the tree in bounds and channel energy into fruit bud formation instead of excess leaf growth. As the tree gets dense, remove some new shoots entirely to keep it open.

Brenda Olcott-Reid, Ph.D., is horticulture coordinator at Coffeyville (Kansas) Community College and raises many fruit trees at her home in Chetopa, Kansas.

COPYRIGHT 1996 KC Publishers, Inc.

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