Fruit Trees in the Home Garden

Fruit trees in the home backyard or garden can be a rewarding investment, use the following tips to manage diseases and pests in fruit trees.

Cultural management practices

To prevent or discourage development of pest problems:

• Select disease resistant varieties whenever possible.
• Prune trees in dormant season or summer to allow for air circulation and improve sun exposure to minimize fungal and bacteria growth.
• Remove all pruned material and dropped fruit and destroy any insect or disease infested plant matter and fruit to reduce risk of problems the following year.

Identification of Pests and Diseases

Proper identification of disease and insects is important to choose the control necessary to remedy the issue with the fruit tree.  If unsure of the insect or disease present, consult with your local nursery, garden center or omafra agronomist for a more detailed understanding of managing best practices for pest and disease on fruit trees.

Additional info on fruit tree pests and diseases can be found on the omafra website:

http://www.omafra.gov.on.ca/english/crops/publications.html

Common Fruit Tree Pests and Diseases

Some common insects and mites that effect fruit trees:

• Aphids – small, sap sucking insects are found on leaves and shoots, generally on soft, new growth and usually appear in colonies.  Damage to leaves and fruit may occur.  
• Leafrollers and Caterpillars – Small caterpillars can attack most fruit trees and can show damage in different ways.  Some will skeletonize leaves while others will roll leaves from margins to feed.  Damage to both leaves as well as fruit can occur throughout the growing season.
• Scale Insects – Several species of scale insects that attack fruit trees, cause small round or shell shaped scales 2-5mm wide on limbs, twigs and fruit.  They can reduce tree vigor and damage fruit in heavy infestations.
• Mites – Mites are tiny, spider like insects that are barely visible to the naked eye and generally appear in the undersides of leaves.  Many species can negatively affect the health and vigor of fruit trees.
• Leaf hoppers – 2 types of leaf hoppers can cause damage to fruit trees in Ontario. They are sucking insects that are generally found on the underside of leaves and causse the leaves to curl under and stunt new growth.
• Peach Tree Borer – This insect attacks stone fruits (peaches, apricots, cherries).  Trees show damage by gumming at the base of the tree that is caused by the cream-colored larvae that feed on inner bark at or just below the soil line.  Younger trees may be girdled and die, older trees may be weakened enough to other pests and diseases.
• Powdery Mildew – Powdery mildew is a fungal disease that infects leaves, new growth and fruit of most fruit trees.  It appears on the plant as grey-white powdery growth on the surface of plant parts.  Powdery mildew can stunt plant growth and cause russeting of fruit.
• Fire Blight – Fire blight is a damaging disease that infects pear and apple trees.  Leaves rapidly wilt, appear scorched and die.  Orange coloring on the shoot tips occur.  Infected areas can show cankers and ooze bacteria.  Fire blight infection can kill young, establishing trees.
• Scab – Scab is a common fungal disease that can affect apple and pear.  Early infections appear as olive-green spots that become brown to black on leaves.  Fruit lesions are circular, brown to black in color.  On apples, scab overwinters on fallen leaves, on pears, it overwinters on fallen leaves as well as infected twigs.
• Peach Leaf Curl – Leaf curl infections occur in peach and nectarine trees.  Infections can start in late winter or very early spring as soon as buds begin to swell.  The infected buds produce leaves with reddish tine with a crisp texture and curled growth.  A white dusting of the fungus can form on the leaves and cause early drop.  Repeated defoliation weakens trees and can lead to tree death.

To manage aphids – apply dormant oil in the late winter to early spring to kill overwintering aphid eggs.  If aphid populations are above acceptable thresholds (5-6 leaves of terminal growth covered in pest), apply insecticidal soap or summer oil.

To manage leafrollers and caterpillars – Thin fruitlet to singles to reduce fruit damage and increase fruit size.  

To manage leafrollers and caterpillars - Apply a BTK product (Bacillus thuringiensis) to infestations.  Btk is a bacterium that kills only caterpillars and wont effect bees, pets or children.

To manage scale insects – Apply dormant oil spray in late winter or early spring yearly.  Prune out any heavily infested twigs and branches.

To control mites – Apply dormant oil in very early spring (before bud burst).  If damage occurs in the summer, wash mites from leaves with water and apply insecticidal soap or summer oil at label rates.

White apple leafhoppers overwinter as eggs under the bark of trees. Nymphs are pale white and approximately 1.0- 1.5 mm in length. The adults are white, approximately 3 mm in length and hold their wings over their backs when they rest.

The potato leafhopper does not overwinter in Ontario; adults are transported in the spring by wind currents from the south. Nymphs are light green and walk sideways across the leaf. The adults are green with wings that fold like a tent across their back.

To control leafhoppers – Apply dormant oil to fruit trees in the late winter or very early spring, wash off leaves with water and apply insecticidal soap or summer oil at label rates during growing season when damage is observed on new growth.

To control peach tree borers – Remove borers by probing the tunnels with a stiff piece of wire.  Protect trees from re-infestation by installing trunk collars around the base of trees made from plastic sheeting or aluminum, etc., ensuring that the top of the collar is well sealed around the trunk.

Some common diseases that affect fruit trees

To control powdery mildew – Follow cultural control methods by pruning trees to allow for good air circulation.  Remove infected growth during dormant season pruning.  For stone fruits, remove leaves and dropped fruit to reduce disease pressure.  During growing season, apply a fungicide containing Sulphur or a summer oil beginning at pink bud and repeat every 10-14 days as required.  Do not apply Sulphur over 26 deg C.  Do not apply Sulphur on apricots.  Apply lime Sulphur on dormant apple and cherry trees to suppress overwintering of mildew.

To control fire blight – Fire blight is a very infectious disease that can be spread by rainfall, insects, wind and pruning tools.  Whenever fire blight is noticed, remove immediately by pruning 14-30 cm below infection and burn or take cuttings to a landfill.  Disinfect pruning tools after use using Lysol, bleach or rubbing alcohol.  Fire blight attacks rapidly growing new growth of trees, reducing nitrogen inputs to tree can slow growth to reduce risk of infection.  No chemical sprays can cure fire blight once a tree has become infected.  During growing season, low doses of copper can slow growth of fire blight and reduce risk of spreading.

To control scab – Remove fallen leaves and twigs and remove infected twigs to reduce chance of overwintering of disease.  Prune trees for proper light penetration and air circulation.  If required, apply a fungicide such as sulphur, lime-sulphur or a biopesticide containing garlic powder as the active ingredient per label directions.  Applications should be made at bud beak and pink bud in the spring, one week after petal fall and then one week later.

To control peach leaf curl – Prune and remove any dead or infected branches around trees.  Apply a protective spray of lime sulphur before buds break in the spring.  Application of a tribasic copper sulphate after harvest in September will give control in most years.

Pesticides

Homeowners wanting to apply pesticide products on fruit trees in the back yard are limited to products that are classified as DOMESTIC.  These products can be found at online retailers as well as in your local hardware stores.  Pesticides should only be used when necessary and according to proper IPM practices.

When applying any pesticide always check the label and follow label instructions and safety precautions.

A list of approved pesticides in Ontario can be found here:

https://www.ontario.ca/page/using-pesticides-ontario

Pesticide Products for Tree Fruit in the Home Garden

Insecticides/Miticides

Fungicides