Apple, Crabapple, Pear

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Apple, Crabapple, Pear

Author:	OMAFRA Staff
Creation Date:	25 July 2005
Last Reviewed:	20 December 2005

The Gardener's Handbook > Chapter 6: Fruit > Apple, Crabapple, Pear

Apple, Crabapple
Pear
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Apple, Crabapple

Ornamental fruiting crabapples are attacked by the same insects and diseases as apples. See also Chapter 7 - Ornamental Plants.

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Codling Moths

The adult codling moth is greyish brown with lacy lines on forewings and fringed hindwings. The larva is 2.5 cm long, pink, with a brown head. Eggs are laid on the fruit and the larvae enter and grow inside. Dark sawdust-like material is evident at the entry hole and infested fruit often drops before maturity.

Treatment

Cultural control: Regularly gather and destroy dropped fruit by throwing it in the garbage can or burying it at least 60 cm deep. This will reduce the insect population next summer.

Chemical control: As eggs are laid from mid-June until mid-August, spray at about 12-day intervals during that period. Sprays for codling moth and apple maggot are similar in timing and material, and you can therefore use one of the recommended insecticides for both insects. Observe the product's no-spray interval before harvest. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Black Rot and Frog-eye Leaf Spot

Black rot on fruit and frog-eye leaf spot on leaves are fungal diseases. They often occur on unsprayed trees in late summer just before fruit maturity. Small, tan-centred spots with darker borders - frog eyes - appear on the leaves. On fruit, small, purple or red spots turn dark brown as they expand; older, larger spots may also have rings of black specks.

Affected fruit will rot completely in storage. The fungus survives in fruit on and under the trees, as well as in cankers and dead twigs.

Treatment

Cultural control: Destroy mummified fruit and prune out infected branches.

Chemical control: The spray program for apple scab will control this disease. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Fire Blight

Fire blight, caused by bacteria, is most serious on pears and occasionally affects apples.

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Scab

Scab is the most common and serious disease of apples throughout Ontario. Occasionally, it will also affect pears, especially "Flemish Beauty". Olive-green spots appear on leaves; with time, they turn dark brown and black. On fruit, dark, irregular spots appear; if spotting is severe, the skin cracks and the fruit is deformed. Leaves may drop and the crop in the following year may be reduced. The fungus which causes the scab overwinters on dead leaves on the ground. Spores are discharged into the air by spring rain and infect young apple leaves and fruit.

Treatment

Cultural control: Gather and eliminate fallen leaves in autumn. Unfortunately, if there are neglected apple trees in the immediate area, this will not be effective. Once the scab fungus becomes established on a tree, each rain causes new infections.

Chemical control: Prevent infection by covering leaves and blossoms with fungicide spray. In spring, repeated spraying is required to protect the rapidly developing new growth. First spray should be applied when tips of the leaves appear. Repeat as indicated on the product label until mid-June. If no scab is visible, fungicide applications can be discontinued. If scab is visible, continue fungicide applications until mid-August. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Tentiform Leafminers

Tentiform leafminer larvae leave speckled blotches of tented, hollowed out leaf tissue. Adults are tiny (3-4 mm long) moths with brown and white markings. There are three generations per year. The first begins in spring when eggs are laid on the underside of new leaves at the tight cluster stage to pink stage of blossom development (see Flowering Stages on Fruit). Larvae feed between leaf surfaces for 4 to 5 weeks where they create mines or tunnels. They pupate in the mines and then emerge to complete one generation. Low to moderate levels of leafminers (1-7 mines per leaf) do not require control. High levels of infestation, however, will cause the fruit to be undersized and will lead to premature fruit drop.

Treatment

Cultural control: Damage by the leafminer is more severe when trees have been stressed. The best prevention, therefore, is to maintain the health of your trees.

Chemical control: If leafmining has been severe, the first generation to appear the following season must be controlled to prevent late season population growth and indirect injury to the fruit crop. The trunk, large branches and leaves must be thoroughly sprayed. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Apple Maggots or Railroad Worms

Apple maggots, or railroad worms, are a problem in most areas of Ontario. The 6 mm long adult fly is black with yellow legs and yellow markings on its abdomen. It lays its eggs on the fruit from late June until mid-August. The small white maggots that emerge create extensive tunnels, causing the surface to be bumpy and the fruit to drop. When full-grown, the maggots move from the overripe fruit into the soil where they overwinter. If unsprayed apple trees are in the neighbourhood, this insect is very difficult to control.

Treatment

Cultural control: Hang sticky red balls or yellow traps, available at garden centres, in the tree to trap the adults and prevent egg laying. Gather the fruit as it drops and throw it in the garbage can or bury it at least 60 cm deep to reduce maggot flies and damaged fruit the following summer. Encourage your neighbours to do the same. Destroy wild and unsprayed apple, prune and hawthorn trees in the vicinity if possible.

Chemical control: Spray leaves and fruit to kill flies before egg laying. Repeat as indicated on the product label from late June until mid-August, but observe the no-spray interval as stated on the product label. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Powdery Mildew

Powdery mildew is sometimes a problem on the young shoots of apple trees. The most susceptible varieties are Cortland, Ida Red and Jonathan. It causes distorted, rolled leaves with white velvety fungus growth on the upper surface. Severely infected shoots are dwarfed.

Treatment

Cultural control: Prune out infected terminal shoots. Improve air circulation around the tree.

Chemical control: Spray when first noticed and repeat as indicated on the product label until the symptoms disappear. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Rosy Apple Aphids

Rosy apple aphids overwinter as eggs at the base of buds. The eggs hatch as the buds unfold and immature larvae begin to feed on leaf and flower bud clusters, resulting in rolled leaves and clusters of misshapen apples. Several generations occur each year.

Treatment

Cultural control: Syrphids, ladybugs and lacewings are good natural predators of aphids and often will keep populations below damaging levels.

Chemical control: If this pest was a problem during the previous year, spray just before blossoms open but not during bloom. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Aphids

Aphids are soft bodied greenish to brown, pear-shaped insects 5 mm in size. They are a common problem on apple and sweet cherry and less so on sour cherry. They attack the growing end of twigs throughout the summer, sucking sap and causing leaves to curl, pucker and turn yellow. Fruit is affected when infestation is severe. A sooty deposit is found on the apple fruit. Control is very difficult once this insect becomes established and leaves are curled.

Treatment

Cultural control: Syrphids, ladybugs and lacewings are good natural predators of aphids and often will keep populations below damaging levels.

Chemical control: Spray apple trees when aphids are abundant and repeat as necessary. If aphids infested sweet cherry the previous year, spray when leaf buds break. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Pear

Codling Moths

Codling moths lay eggs in the pear fruit, and the larvae enter and grow inside.

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Black Rot and Frog-eye Leaf Spot

These diseases are caused by a fungus, and often occur on unsprayed trees in late summer just before the fruit matures.

Fire Blight

Fire blight, caused by bacteria, is most serious on pears and occasionally affects apples. Blossoms are usually first to be infected and turn black and shrivel. The disease spreads to spurs and leaves, and young twigs turn black later in the summer. Sunken reddish-brown bark lesions that ooze an orange-brown liquid may appear on larger branches. Warm weather and high humidity or rain favour the spread of this disease. If blossoms are infected, bees and other pollinators spread the bacteria to blooms on healthy shoots or trees.

Treatment

Cultural control: Remove and destroy twigs 25 cm below the affected part. If pruning shears are used, dip blades in a solution of 1 part chlorine bleach to 4 parts water after each cut. Avoid heavy application of nitrogen fertilizer. Abandoned pear trees and rosaceous ornamental plants will harbour this disease.

Chemical control: None are known at this time.

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Scab

Scab is the most common and serious disease of apples throughout Ontario, but it can also affect pears, especially the variety Flemish Beauty.

Pear Leaf Blister Mites

Pear leaf blister mites cause blisters and dark, dead spots on the leaves of pear. If severe, the tree may be weakened.

Treatment

Cultural control: None

Chemical control: Spray before leaf buds break if this insect caused severe damage to leaves in the previous year. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Pear Psylla

The most obvious symptom of pear psylla is the honeydew that surrounds the insect on the leaf. Later, the honeydew turns black and sooty. Hot weather before and during the blossom period favours heavy infestations. If severe, leaves turn pale with dead areas, fruit is dwarfed and trees are weakened. The honeydew may also be found in late summer, as there are several generations.

The adults are reddish-brown, emerging in early spring to lay eggs on twigs. Both the adults and larvae feed by sucking the sap.

Treatment

Cultural Control: None

Chemical control: Spray when honeydew is noticed and repeat at 12 days intervals. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Pear Slugs

Pear slugs are the larvae of sawflies and are not true slugs. The slime-covered larva is 1 cm long, dark green at first and later orange. It feeds on leaves of pear, cherry and plum, creating large ragged holes or leaving only a framework of veins. Telltale slime trails are also present.

Treatment

Cultural control: Dust larvae with talc or dry, fine soil to dry them out.

Chemical control: Any insecticide used during the summer against other fruit insects also controls pear slugs. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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