Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00000297
11/12/99
CARYA DISEASE PROBLEMS
Hickory anthracnose or leaf spot is caused by the fungus
Gnomonia caryae. In wet years the disease causes
severe defoliation. The symptoms are large reddish brown
spots on the upper leaf surface but brown on the lower
surface. The spots may not have distinct marginal
markings. The disease overwinters on fallen diseased
leaves so dispose of infected leaves in the fall.
A large number of fungi cause leaf spots on hickory.
Severe infections can cause defoliation. Many of the
fungi overwinter on diseased leaves, dispose of infected
leaves when they fall.
Witches broom can follow a leaf spot disease caused by
Microstroma juglandis. Symptoms are yellow blotches on
the upper sides of the leaves but white on the
undersides. Severe infections may cause defoliation and
when the fungus invades the stem a witches broom forms.
Leaves on the stems of the witches broom are yellowish,
small, and fall prematurely. Prune out witches brooms
when they form.
Powdery mildew causes a white powdery growth on the
leaves. If the disease occurs late in the season, no
chemical control will be needed.
Try to prevent cankers by keeping trees healthy through
watering during dry weather and regular fertilization.
Avoid wounding the trees unnecessarily and prune out weak
or dead branches.
Verticillium wilt kills individual branches or sometimes
entire sections of the tree. Foliage on affected branches
wilts and later turns brown. Keep trees healthy and prune
out small infected branches.
Related information.
Pesticide Recommendations
Anthracnose
Powdery Mildew
Verticillium Wilt
Cankers
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This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
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