Lilac (Syringa)
Symptom Cause  
Leaves wrinkled or curled; discolored, stunted, tend to fall off
Aphids
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Early spring, brown spots with yellow around brown
Blight (bacterial)
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Leaves turn yellow.
Chlorosis
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Brown spots; discolored; holes on leaves
Fungal Diseases
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Many holes in trunk and branches; small limbs girdled sawdust at holes
Lilac Borers
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Tip of leaves brown, internal larvae trails visible.
Lilac Leaf Miners
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Leaves yellow, drop; bumps on leaves and stems; sometimes sticky leaves
Lilac Scale
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Leaves covered with white powder
Powdery Mildew
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Leaves turn yellow
Soil Is Too Alkaine
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Black powdery sooty mold fungus forms on honeydew;
Sooty Mold
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Shrub is stunted
Too Close to Black Walnut Tree
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Yellowing of foliage, gradual defoliation
Verticillium Wilt
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Holes chewed from outside to middle of leaves
Weevils
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Shoots branch from lateral buds
Witches' Broom (fungus)
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