Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001239
11/12/99
RHODODENDRON DISEASE PROBLEMS
Gray blight infection follows an injury, such as winter
injury. A spot, which is at first white with a dark brown
margin, forms on the leaf. Protect plants from winter
injury.
Dieback is also called Botryosphaeria canker. The leaves
are attacked near the tips or at the margins; then spots
form on the entire leaf. Leaf stalks and twigs are
eventually infected. Prune off infected parts.
Leaves infected with Phytophthora dieback turn brown,
roll, then drop off. The stem shrivels and a canker
forms, eventually girdling the stem. Prune out diseased
branch tips.
Powdery mildews of different genera form a white coating
on the leaves.
Leaf spots may be caused by any number of fungi.
Related information.
Pesticide Recommendations
Phytophthora on Rhododendron
Powdery Mildew
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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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