The content of 'What's wrong with my plant? Apple tree leaves and branches' was prepared by The University of Minnesota Extension and has been revised and republished by FreshFruitPortal.com.

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Holes in leaves or parts of leaves missing

Eastern Tent Caterpillar

Malacosoma americanum

• Larvae feed on leaves, sometimes defoliating trees
• They make a web or “tent” in the fork of the branches
• Larvae are hairy with blue, black, and orange markings, and a white stripe down the back, almost 2 inches when fully grown

More information on Eastern Tent Caterpillar

Forest Tent Caterpillar

Malacosoma disstria

• Chews entire sections of leaves, often leaving some major veins; defoliation can be severe
• Hairs along sides of body, blue and black with characteristic footprint shaped white markings on top of body, almost 2 inches long when fully grown
• Occurs in May and June

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Cankerworms

Paleacrita vernata and Alsophila pometaria

• Chews smalls holes between veins at first, later chewing leaf tissue except for major veins, and eventually chewing all of leaves except midvein
• Defoliation typically light to moderate, although it can potentially be severe
• Smooth-bodied, light green to brown, 1 1/3 inch long when fully grown; moves in characteristic looping motion
• Occurs late April/early May until June

More information on Cankerworms

Cecropia

Hyalophora cecropia

• Chews entire sections of leaves; defoliation typically is minor
• Light green body with double row of reddish orange knobs on thorax behind head; also series of smaller yellow and blue knobs on abdomen; grows up to 4 inches long
• Becomes a large, attractive moth
• Occurs in August and September

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Discolored, cracked or sunken area of branch

Fire Blight

Erwinia amylovora

• Branch cankers have dark, sunken and cracked bark, sapwood is streaked reddish brown
• Young shoots bend over forming a 'shepherd's crook'
• Infected leaves wilt, turn gray then dark brown
• Infected blossoms first turn gray, then black
• Infected leaves and blossoms remain attached to the tree, often even in winter
• Infected fruit are shriveled and discolored
• Drops of sticky honey-colored liquid can be seen on infected plant parts in warm wet weather

More information on Fire Blight

Black Rot
Botryosphaeria obtusa

• Branch cankers can be sunken, reddish brown or rough looking or cracked bark; cankers may remain small or enlarge to become several feet long
• Leaves on girdled branches wilt, die and turn brown
• Round leaf spots with a purple border and tan center
• Large brown spots with brown rings form on fruit
• Fruit is rotted but remains firm
• Fruit may become mummified and remain on tree
• Common on stressed trees and trees infected with fire blight

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Sunscald

• Vertical Cracks appear primarily on the south and southwest side of branch or trunk
• Occurs during winter, often noticed early spring

More information on Sunscald

Source: University of Minnesota Extension