Apricot Thinning: How And When Should I Thin My Apricot Tree


By: Mary H. Dyer, Credentialed Garden Writer

If you have an apricot tree in your garden, you’re probably asking yourself, “Should I thin my apricot tree?” The answer is yes, and here’s why: apricot trees often set more fruit than the tree can support. Read on to learn more about thinning apricots on trees.

Thinning Apricot Trees

Although it’s great to see a tree laden with juicy apricots, branches can easily break under the excess weight.

Apricot thinning ensures that the remaining fruit receives more sunlight and air circulation, which improves the size and quality of the fruit and benefits the overall health of the entire tree. Crowded fruit places the tree at risk of diseases and insect infestation.

Thinning apricot trees is best done in early spring when the apricots are about ¾ to 1 inch (2-2.5 cm.) in diameter.

How to Thin Apricot Fruit by Hand

Apricot thinning is a simple task: just twist the excess fruit gently from the branch. Avoid pulling or yanking the fruit because rough handling can damage the branch.

Allow 2 to 4 inches (5-10 cm.) between each apricot, which is sufficient space so the fruit won’t rub together at maturity.

Apricot Thinning with a Pole

Apricot trees usually don’t exceed 15 to 25 feet (4.6-7.6 m.) in height, but if your tree is too tall for hand thinning, you can remove the fruit with a bamboo pole. Wrap thick tape or a length of rubber hose around the end of the pole to protect the branches, then remove the apricots by gently rubbing or tapping at the base of the fruit. This technique gets easier with practice.

Tip: Thinning apricot trees is time-consuming and messy, but here’s an easy way to save cleanup time (and your back). Just spread a tarp or plastic sheet on the ground to catch the discarded fruit.

Now that you know more about thinning apricots on trees, you can ensure bigger, healthier fruits come harvest time.

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Growing Apricots: Planting Guide, Care, Problems and Harvest

Ame lives off-the-grid on her beautiful farm in Falmouth, Kentucky. She has been gardening organically for over 30 years and has grown vegetables, fruits, herbs, flowers, and ornamentals. She also participates in Farmers Markets, CSA, and mentors young farmers. Ame is the founder and director of Fox Run Environmental Education Center where she teaches environmental education programs in self-sufficiency, herbal medicine, green building, and wildlife conservation.

Nothing says summer more than biting into a juicy apricot. They’re one of those fruits that never tastes as good when you buy them at the grocery store. But fresh off the tree? Heaven.

They’re also a versatile fruit. You can eat apricots fresh, dried, or preserved. You can put them on meat, desserts, in a salad or even in soup. Ready to learn more?


Care for Apricots

Apricots need water consistently throughout the growing season. Lack of moisture in early summer will result in small fruits later in the season, it can interfere with bud set for next year's crop. You will probably need to water deeply every 10 to 14 days if there is no rain. Where there is plenty of moisture in the winter and spring, you may need to water only three or four times during the summer. Apply a small amount of nitrogen fertilizer each spring.

Many growers in western states train young apricot trees to a vase shape (open center). In harsher climates a modified central leader is a better idea. Fruit develops on spurs of 1-year-old branches the spurs live for 3 or 4 years. Weak branches require thinning or heading to strong lateral branches to encourage new fruiting wood and expose more of the inner parts of the tree to sun and air. Remove fruiting wood that is 6 years old or older. Since apricots bloom very early and many flowers may be killed by frost, wait until after petal fall to prune.

Under good growing conditions trees produce too many fruits. If all the fruits are allowed to stay on the trees, your apricots will be small, and the weight of the fruits could break the branches. Thin out the weakest fruits to the three or four healthiest apricots per cluster. The best time to thin is when fruits measure about 1 inch across. If you have only one or two trees, hand-pick the excess fruits.

Apricot Pests and Diseases

Apricots are relatively free of pests and diseases. However, in areas where humidity tends to be high, brown rot disease can pose serious problems. Aside from the plum curculio, the occasional codling moth, and stray peach tree borer, few insects bother these trees. Protect trees from gophers when planting.

The harvest season for apricots is July in mild climates and August in colder ones, though different varieties can be slightly earlier or later. Expect 3 to 4 bushels of fruit from a full-size tree, 1 to 2 from a dwarf. Pick the fruits after they attain a rich apricot color and give slightly when pressed. The apricot season is short, so try to plan around it. If you leave for a 2-week vacation at the crucial time, you may come back to bushels of spoiled fruit on the ground.


UNH Extension

Plums, cherries and apricots, which along with peaches and nec- tarines are often called “stone” fruits, are flavorful additions to the home orchard if the site is suitable. The first consideration is winter hardiness. European plums, hybrid plums, and sour cherries are quite hardy with some varieties tolerating winter temperatures of -20°F or lower. In more protected sites in the Northern part of the state, these stone fruits offer the best chance of success. Japanese plums, apricots and sweet cherries are less hardy and are best suited to home orchards in extreme southern New Hampshire.

A second consideration is the risk of spring frost injury to blossoms. These fruits, especially apricots, bloom in very early spring, often a week or more before apple trees bloom. They should be planted on sites that offer freedom from late spring frosts. Generally, these sites are elevated relative to the surrounding landscape which allows cold air to flow away on clear, cold nights.

Purchasing Trees

Purchase trees from a reputable garden dealer or nursery. There are several mail order nurseries as well that offer quality, bare-root trees. Select varieties that are hardy. Most catalogs offer approximate hardiness ratings. Specific variety recommendations are found below.

What about Dwarf Trees?

All fruit trees are grafted. A piece of vegetative wood (usually a bud for the stone fruits) is grafted onto a rootstock (a tree grown for just that use). Most of these rootstocks will produce a tree that is quite large in the case of sweet cherries, these “standard-sized” trees often grow to 30 ft in height.

Dwarf rootstocks for plum, cherry, and apricot trees are not readily available for home garden use. Some nurseries now offer sweet cher- ries on dwarfing rootstocks from the Gisela series. These trees will be smaller and they will fruit earlier in life than full-sized or seeding trees. Since sweet cherry trees can be extremely large, making pest control and pruning difficult, purchasing sweet cherries grafted onto these dwarfing rootstocks is recommended.

Stone Fruit Varieties for NH

Methley, Shiro, Santa Rosaand Ozark Premierare Japanese plums that do well in southern NH. European plums to try include Early Italian, Green Gage, Castleton, and Stanley.In the northernmost regions of the state, the hybrid plums Underwood, Pipestone, and Superiorare good choices.

Sour or pie cherries that have performed well in NH include Montmo- rency, North Star,and Meteor.The latter two are naturally dwarf and work especially well in home orchards.

On warmer sites in the southern part of the state, the sweet cherry vari- eties Black Gold, Sam, Lapins,and Hedelfingenare good choices, as are the apricot varieties Goldrichand Harogem.

Soil and Site

Fruit trees will do reasonably well in a wide range of soil types, although they will not tolerate poorly drained soils with a high water table. Stone fruit trees will do best on a site that offers full sunlight all day and should not be planted in the shade of buildings or large trees.

Proper soil preparation is an important first step. For best results, eradicate perennial weeds, such as quackgrass, before planting. The soil pH should be 6.0-7.0 for plums, cherries and apricots. Soil testing can be done through a number of private and public labs. UNH Cooperative Extension offers soil testing services.

Plant trees in early spring as soon as the soil is dry enough to work (late April through mid-May). If the planting site is not ready when trees ar- rive from the nursery, unwrap the trees and “heel-in” the roots in moist soil in a shady spot. Plant trees before their buds break. Plant plum, apricot, and cherry trees 15 to 20 feet apart in the home orchard.

Planting the Tree

  1. Dig a hole large enough to allow the roots to be spread out completely. This usually requires a hole that is wider than it is deep.
  2. Backfill the planting hole with topsoil. Do not use sod to fill the hole.
  3. If you purchase a “dwarf” tree, plant the tree with the graft union 2 to 3 inches above the soil surface. The graft union is the point where the variety was grafted onto the rootstock.
  4. Firm soil around the roots. Backfill the hole 2/3 full, soak in 2 gallons of water, and finish backfilling. If you leave a depression or water catching basin around the tree, be sure to fill it in by autumn to reduce the danger of ice damage to the lower trunk.
  5. Remove any tags or labels attached to the trees to prevent girdling of the trunks.
  6. Do not add fertilizer to the planting hole. Trees can be fertilized after rain has thoroughly settled the soil around the roots, about 3 weeks after planting. Apply 1/2 pound of 10-10-10 or its equivalent by spreading it lightly in a wide circle 16 to 20 inches from the tree trunk.

Pruning

Plum, apricot, and cherry trees are pruned and trained annually in early spring to develop and maintain tree size and shape. European plums, cherries, and apricots are generally trained to the leader system. In this system, a single trunk (or leader) is maintained. Lateral branches with wide crotch angles are developed. Trees are formed with wide bottoms and narrow tops to insure good light penetration into the tree canopy. Japanese plums are generally pruned in the open center system (similar to peaches), but will also do well pruned to the leader system.

Leader System Pruning

Pruning at Planting - Establishing the Leader


Figure 1. European plum trained to the leader system. Photo: W. Lord

Heavily branched (or “feathered”) one-year-old nursery trees will rarely need pruning at planting except to eliminate oversized branches – branches with a diameter exceeding 1/2 to 1/3 the diameter of the trunk or leader. Remove any vigorous, upright branches that may compete with the leader or trunk for light.

Whenever a branch does need to be pruned, it is important to cut out the entire branch. If you prune offending branches by simply cutting a portion off the end, you will not solve the structural problem the branch is causing. Rather, the branch will re-grow in a vigorous and upright manner, creating unwanted shading of other wood and delayed fruiting. Remove the branch by cutting at the outside edge of the branch collar that forms where the branch is attached (Fig. 2).

While well-branched trees are the ideal, you often have to settle for trees that have only a few or perhaps no branches. If the few branches that exist are uniformly distributed around the tree, then no pruning is required.

If the tree is one-sided, the best course of action may be to remove all branches and start over. This is often the case when a tree comes with only one or two branches. After removing these branches, cut the leader off at a height of 33 - 36 inches above the ground to encourage development of wide-angled branches.


Fig 2. The branch collar is evident (and marked with an arrow) on this young plum tree. Photo: B. Sideman

Leader System - Pruning in Later Years

The basic pruning rules do not change as the tree ages, although the size of some pruning cuts might. For leader-trained trees, continue to eliminate vigorous, upright branches that might compete with the leader and eliminate any oversized branches that develop.

Some branches that didn’t seem too vigorous in years 1 and 2 may become problems, growing at a much faster rate than other parts of the tree. These excessively large branches will need to be removed by cutting them out completely. Some shade problems may develop as growing branches crowd each other. Again, rather than cutting back all branches, selectively eliminate 1-2 whole branches to eliminate shading.

It is essential for the health of the tree that branches larger than 1/3 the diameter of the trunk where they are attached be removed over the first few years of a tree’s life.

Open Center System Pruning

Pruning at Planting - Establishing the Open Center System

If using the open center system for Japanese plums, head the trunk back to 24 to 30 inches at planting. Limbs arising below the heading-back cut should be cut in half to promote the development of strong, wide-angled scaffolds and thinned to leave only the best 3 or 4. Remove any limbs growing 15 inches or less from the ground.

Open Center System - Pruning Young, Non-Bearing Trees

In spring the year after planting, select 2 to 3 well-developed, wide-angled scaffold limbs and remove other branches entirely.

From the second to the fourth years, remove any branches that grow straight up through or toward the center of the tree. Prune lightly to eliminate overlapping and dam- aged limbs.

Open Center System - Pruning Bearing Trees

Maintain tree height at 9 to 10 feet by heading back scaffold branches to an outward growing lateral. Re- move weak or diseased branches as well as those that grow up, through or across the center of the tree or downward. Thin out remaining vigorous branches to prevent crowding.


Figure 3. Schematic diagram of a young open-center tree before pruning (left), with pruning cuts shown (yellow lines), and after pruning (right). Note that very low limbs are removed, and four well-developed wide-angled scaffold limbs were kept.

Fertilizing

Manage stone fruit trees to ensure production of 6 to 12 inches of new growth each season. For most home orchards, an application of 1/2 pound of a complete garden fertilizer (such as 10-10-10) to non-bearing trees and 1 pound to mature bearing trees is sufficient. Adjust rates in response to tree vigor. If trees are growing too vigorously, do not fertilize. If trees are not growing well, double the fertilizer rate. Fertilizer should be applied in May by spreading it uniformly on the surface of the ground under the tree from the drip line in to within 16 inches from the trunk.

Pollination and Fruit Set

Sour cherries are generally self-fruitful and a single tree will do well. Most European plums and apricots are self-fruitful however, cross pollination often results in larger, more dependable crops. For that reason, 2 or more varieties of each are generally recommended.

Sweet cherries and Japanese and hybrid plums generally require cross-pollination to set crops. Not all combinations work well and specific pollination needs of varieties are usually included in nursery catalog descriptions. The sweet cherry varieties Black Goldand Lapinsare self-fruitful.


Figure 4. Japanese plum trained to the open center system. Photo: W. Lord

Thinning

Plums benefit from fruit thinning. Fruit size will be greater and disease risk reduced due to better drying of fruits after rains and heavy dew. Hand-thin plums in mid-June by reducing clusters of set fruit to single fruits.

Managing Pests and Diseases

Cherries are especially attractive to birds. It is not uncommon for the entire cherry crop to be destroyed by birds. Netting offers the best protection but application and removal can be difficult as trees grow. Flash tape, scare eye balloons and other visual deterrents offer limited control. More information about bird management is available in the publication Bird Damage Prevention for Northern New England Fruit Growers.


Figure 12. This simple temporary support for bird netting is erected over these sour cherry trees just before fruit ripens, and is removed just after harvest.

Stone fruits commonly experience several insect and disease pests in New Hampshire. These include brown rot and plum curculio on fruits and black knot on branches. Basic information on how to manage these pests is available in the publication Home Fruit Spray Schedule.


Problems and Solutions to Growing Apricots

While growing apricots is relatively problem-free, you might encounter a few pests and diseases.

Sucking Insects

Aphids, mealybugs and scale insects are common pests on apricot trees. They all chew or suck on the sap in the leaves. Damage signs are yellowing and dropping leaves.

You may also see a sticky substance on leaves or you may notice ants going up your trees because they’re attracted to this sticky material, which is called “honeydew. ”

This group of sucking insects can be controlled by applications of insecticidal soap. For more severe cases, horticultural oil and neem oil work well. Remember to spray under the leaves where the bugs may be hiding.

Plum Curculio

Plum curculio is a beetle that goes after plums, peaches, and apricots. The adult insect is brownish-gray, about 1/4-inch long, with a hard-shell. They’re easy to recognize because they have a long nose and four bumps on their back.

You can spot a plum curculio infestation because the bug makes a crescent-shaped hole in fruit. It then lays its eggs inside the apricot. The larva hatch and tunnel around inside the fruit.

The fruit may drop prematurely.

To prevent them clean up all dropped fruit immediately so they don’t get in the soil. Use neem oil to control infestations.

Borers

Borers are insects that burrow into the branches and trunk of the tree. They can be difficult to treat because they hide where you can’t see them. To see if you have an infestation, look near the base of trees for globs of sap and brown frass.

To treat borers, cut out the infected limbs in the winter and destroy them by burning. This interrupts the life cycle of the borers. You can also use a small knife and dig out any borers.

Place a cone at the base of trees in the spring before the insects become active. Good maintenance is key to preventing borers because they focus on trees that are stressed or injured.

Tent Caterpillar

You’ve probably seen the nets that these adults moths make to lay their eggs. They look like large nets wrapped around the branches of trees. Hairy, grayish-brown caterpillars with cream-colored stripes hatch out of these nests and begin to consume leaves.

The goodness is that they are easy to spot and dispose of by using a rake to remove the web. Burn to destroy the caterpillars.

Fruit Drop

This is a big issue with apricots – maybe more so than any other fruit tree. Fruit drop can be the result of several different factors. Your tree may be overloaded with fruit or have apricot scab.

Apricot scab is a disease that leaves the fruits covered in small, olive-green spots. The spots grow into larger green blotches. They may crack open and fall from the tree. This is superficial damage and fruits can be peeled and used.

Prevention includes good sanitation. Pick up all fruits that fall to the ground, clean up branches, and add compost in the spring to support good health. Neem oil can destroy the fungus when applied in the fall after harvesting and again in early spring when buds set.

Pit Burn

Apricots may develop pit burn. This causes the centers to become soft and is caused by excessively high temperatures.

When temperatures reach more than 100°F the fruits are susceptible to developing pit burn. Drought conditions also add stress to the tree and may make them more susceptible.

To prevent pit burn, give your apricots trees consistent moisture during a drought to help cool the tree. Consider placing a drip irrigation or soaker hose at the drip line around your apricot trees.

Bacterial Canker

Canker is a bacterial disease caused by the Pseudomonas syringae bacterium. It is spread by rain and overhead watering. A cool, wet spring is the ideal environment for this disease to catch hold.

The disease is easy to spot and looks like gummy cankers and water-soaked that appear on the growing limbs and trunk of apricots. Leaves develop brown spots and fruit develops dark, sunken, areas that smell bad.

Plant disease-resistant varieties and prune out affected branches if you get the disease.


Cutting, or pruning, an apricot tree requires specific tools. Pruning shears are used to cut small limbs with a diameter under 3/4 inch. Use lopping shears on branches with a diameter larger than 3/4 inch but smaller than 2 inches. A pruning saw takes care of any branches larger than 2 inches in diameter. Pruning tools work best when kept clean, rust-free and sharp. Before each use and after removing diseased limbs, dip the tools' cutting blades in a 9-to-1 mixture of water and bleach. Cleaning the blades with that water-bleach solution prevents the spread of diseases.

An apricot tree usually receives early training to an open center system that allows sunlight to reach all parts of the tree. Once it is established to that system as a young tree, the apricot requires yearly maintenance to maintain its size and shape. Heading cuts shorten branches while thinning cuts remove entire limbs. Make each heading cut at a 45-degree angle about 1/4 inch above a bud.

Another part of pruning an apricot tree is thinning its fruits, which provides consistency in fruit production from year to year. Remove fruits that look damaged or oddly shaped. Ideally, the fruits are spaced about 4 to 6 inches apart, with excess fruits removed when they reach 1 inch in diameter.


Watch the video: How to Thin Peaches


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