Hydrangea, Smooth
Symptom Cause  
Leaves curled and discolored; honeydew on undersides of leaves, sooty mold
Aphids
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Failure to bloom
Frost Damage
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Failure to bloom
Improper Pruning
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Some leaves turn pale green to yellow; new leaves yellow; plant stunted
Iron Deficiency
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Leaves webbed together, are dark-green and become gnarled.
Leaf-tier moth larvae
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Leaves stippled, yellow, dirty; webbing on interior stems of plant
Mite
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Leaf covered with white powder
Powdery Mildew
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Leaves skeletonized; flowers damaged
Rose Chafers
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Leaves spotted with powdery orange-brown pustules
Rust (on plants)
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Leaves yellow, drop; bumps on leaves and stems; sometimes sticky leaves
Scale Insects
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Black powdery sooty mold fungus forms on honeydew;
Sooty Mold
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Outside leaves yellowish, brown; leaves drop
Sunburn
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Outside leaves yellowish, brown; leaves drop.
Sunscald
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