Hydrangea, Oakleaf
Symptom Cause  
Leaves curled and discolored; honeydew evident on undersides of leaves, sometimes sooty mold forms
Aphids
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Buds and flowers spotted; deteriorate
Botrytis
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Leaves turn yellow
Chlorosis
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Leaves webbed together, are dark-green and become gnarled.
Leaf-tier moth larvae
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Leaves stippled, yellowing or bronze; dry out and drop may be webbing visible; sometimes galls form on leaves
Mite
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Knotted growths on stems; roots
Nematodes
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Leaves covered with white powder
Powdery Mildew
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Leaves skeletonized; flowers damaged
Rose Chafers
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Leaves spotted with powdery brown pustules
Rust (on plants)
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Leaves yellow, drop; bumps on leaves and stems; sticky material on leaves
Scale Insects
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Black powdery sooty mold fungus forms on honeydew
Sooty Mold
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