Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00000467
11/12/99
CRATAEGUS INSECT PROBLEMS
Aphid infestations are not always obvious. Sometimes the
insects are not seen but the distorted growth, honeydew
on the leaves, and sooty mold growing on the honeydew are
obvious.
Borers attacks may be prevented if the trees are kept in
good vigor with regular fertilization.
Leaf miners symptoms are brown blotches on the leaves.
Use pesticides when the leaves are just fully expanded or
when the blisters first appear.
Lace bugs can be a serious, though occasional, problem.
The insect feeding on the undersides of the leaves causes
chlorotic flecks on the upper leaf surfaces. The lower
sides of the leaves are covered with brown sticky flecks.
The pear slug skeletonizes hawthorn leaves and these
sawfly larvae have a slimy appearance. A few insects can
be washed off with a garden hose.
Tent caterpillar nests can be pruned out while still
small. Do not burn nests while the nests are in the tree.
The injury from the fire may exceed that caused by the
insects.
Overwintering scales may be controlled with dormant
sprays. To time crawler sprays, identify the specific
scale insect.
Spider mites are so small they can cause much foliage
discoloration before being detected.
Related information.
Pesticide Recommendations
Aphids on Ornamentals
Lace Bugs
Spider Mites
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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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