The Online Gardener's Handbook 2010
Chapter 5: Fruit
Apricot, Peach, Nectarine, Plum and Prune

Table of Contents

  1. Introduction
  2. Apricot
  3. Nectarine
  4. Peach
  5. Plum and Prune
  6. Learn More

Introduction

In this chapter, a description of various pests of tender fruit will be provided along with suggested management options. These management options will not include the use of pesticides. Some biopesticides and certain reduced risk pesticides are still available to the homeowner for controlling weeds and pests in lawns and gardens. For more information, refer to Chapter 2 of this handbook and the Ministry of the Environment's website. For suggestions on managing specific weeds and pests, consult local horticulturalists, Master Gardeners or your local garden supply centre.

NOTE FOR TREE OWNERS: There is an exception under the ban that allows you to hire a licensed exterminator authorized to use commercial pesticides to maintain the health of your tree. This exception applies only to pests that threaten the tree's health. For example, the exception cannot be applied to a pest that impacts the quality of the fruit but will not kill the tree itself. To obtain this exception, licensed exterminators are required to obtain a written opinion from a professional tree care specialist that a pesticide is necessary to maintain tree health. For more information, contact the Ministry of the Environment.

Note that many fruit trees can tolerate some damage, particularly to the foliage, without suffering lasting impacts. Pest descriptions below include suggestions for cultural controls however in many situations these may not be necessary.

Apricot

Cytospora Cankers

Cystospora is a fungal infection occurring on the trunk and lower branches that usually enters through wounds in the tree. Twigs develop brownish-black areas around winter-killed buds or scarred areas on the bark. By early summer, a gummy substance appears, and later the bark separates from the wood. The cankers grow larger every year, and are most conspicuous on the main trunk or scaffold branches.

Management Options

As cytospora enters through wounds in the tree, your best defence is to control for peach tree borers (see below) and to avoid bark injury, long pruning stubs, winter injury, or brown rot injury to twigs. Prune trees in spring, not fall, and remove any dead wood before the end of June. Do not prune in cool, wet weather. Do not apply fertilizer after June. Healthy trees growing on well-drained, deep, sandy soil are less likely to get cankers.

Peach Tree Borers

Peach tree borers attack peach, nectarine, apricot and sometimes plum and cherry trees. For more information, see Peach.

Bacterial Spot

Bacterial spot causes small, round, tan spots to appear on leaves which later turn purplish and angular. Small, sunken, round spots also appear on the fruit and later the fruit cracks. Extended periods of wet weather encourage the spread and development of the bacteria.

Management Options

Remove all fruit at harvest and remove infected leaves regularly. When planting, avoid shaded areas with poor air circulation. Keep trees well pruned to promote air circulation and promote rapid drying of foliage and fruit. Plant resistant varieties, if available.

Brown Rot

Brown rot is a fungus that attacks various parts of the tree. Blossoms that become infected shrivel, twigs are killed, and fruit becomes covered with grey-brown mould and rots rapidly. Infected fruit may drop or hang on the tree throughout the winter, and mould can develop on the fruit even after harvesting.

Management Options

Throw all mouldy fruit in the garbage or bury it to reduce infection next summer. Cut dried fruit (mummies) out of trees when pruning and dispose of it in the same manner early in the fall. Remove all remaining fruit from trees at the end of the season. Keep trees well pruned to promote air circulation and promote rapid drying of foliage and fruit.

Nectarine

Cytospora Canker

Cystospora is a fungal infection occurring on the trunk and lower branches that usually enters through wounds in the tree. For more information, see Apricot.

Leaf Curl

Leaf curl is a fungal disease that affects peaches and nectarines. Symptoms are noticeable in spring as reddish areas on leaves, which thicken and blister, causing leaves to curl. Eventually, leaves turn yellow and drop. Twigs and shoots may also be affected, with twigs becoming distorted and reddish areas appearing on the fruit surface. The tree is weakened if disease occurs several years in succession.

Management Options

Remove and destroy infected leaves as they appear in the spring. Plant tolerant varieties, if available.

Oriental Fruit Moths

See Insects and Diseases Affecting Many Fruit Crops.

Peach Tree Borers

Peach tree borers attack peach, nectarine, apricot and sometimes plum and cherry trees. For more information, see Peach.

Bacterial Spot

Bacterial spot causes small, round, tan spots to appear on leaves which later turn purplish and angular. For more information, see Apricot.

Brown Rot

Brown rot is a fungus that attacks various parts of the tree For more information, see Apricot.

Peach

Cytospora Cankers

Cystospora is a fungal infection occurring on the trunk and lower branches that usually enters through wounds in the tree. For more information, see Apricot.

Leaf Curl

Leaf curl causes leaves to curl and reddish blisters to appear. For more information, see Nectarine.

Oriental Fruit Moths

See Insects and Diseases Affecting Many Fruit Crops.

Peach Tree Borers

Peach tree borers attack peach, nectarine, apricot and sometimes plum and cherry trees. The adult or their larvae are seldom seen, but brown frass and gum appear on the trunk from the scaffold branches down to exposed roots, due to larval feeding. Gum may also appear at wounds and on winter-injured bark, which are entry places for the borers. Young trees may be killed. Older trees are able to survive light infestations for a few years but may also weaken and die unless borers are controlled.

Adults are wasp-like moths that lay eggs around the base of the trunk in late summer and early fall. Caterpillars, 2.5-3.0 cm long with brownish heads, hatch and burrow into the wood.

Management Options

Wrap strong paper - not tarpaper - around the trunk of young, transplanted trees up to the lowest branch, and leave in place for at least two years after planting. Any pruning or accidental wounds should be scraped clean. If the tree is infested, remove gum and poke flexible wire into the holes to kill borers. Sterilize the hole with a solution of 1 part bleach in 4 parts water and seal with putty. Do this in the spring and fall.

Bacterial Spot

Bacterial spot causes small, round, tan spots to appear on leaves which later turn purplish and angular. For more information, see Apricot.

Brown Rot

Brown rot is a fungus that attacks various parts of the tree. For more information, see Apricot.

Plum and Prune

Apple Maggots or Railroad Worms

Italian and Stanley plums are susceptible to apple maggots, whereas other plum varieties are not. For more information, see Apples.

Tentiform Leafminers

Adult tentiform leafminers are tiny (3-4 mm long), brown and white moths. The larvae damage the leaves, creating speckled blotches of hollowed out, tented tissue. For more information, see Apples.

Pear Slugs

Pear slugs are the larvae of sawflies and are not true slugs. For more information, see Pears.

Peach Tree Borers

Peach tree borers sometimes attack plum trees. For more information, see Peach.

Bacterial Spot

Bacterial spot causes small, round, tan spots to appear on leaves which later turn purplish and angular. For more information, see Apricot.

Brown Rot

Brown rot is a fungus that attacks various parts of the tree. For more information, see Apricot.

Black Knot

Black knot is a fungal disease of plum and sometimes cherry. Early symptoms appear as greenish swelling that expand over a period of 1-2 years to become hard, woody black swellings up to 10 cm long on branches and small twigs. These eventually girdle and kill the branches.

Management Options

Remove and burn all infected branches. This should be done in late winter, before any new growth begins. Do not leave pruned knots in the garden, as this will serve as a source of new infections. Knots on bigger limbs can be cut out - make the cut at least 10 cm below the knot as the fungus colonizes the inner bark beyond the visible swelling. It is important to prune every year, as early infections are not easy to see. Destroy nearby wild or neglected plum and cherry trees. Japanese plums are more resistant to this disease than European varieties. Mature black knots may be naturally colonized by a parasitic fungus, making them appear creamy-yellow to pink in colour. Black knots colonized by this beneficial fungus do not produce spores.

Learn More

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 25 July 2005
Last Reviewed: 28 June 2010