Root & Crown Rot
fungus Phytophthora species causes one of the most common
disease problems in the landscape for rhododendron and azalea. This fungus is a
"water mold," and thrives in poorly drained or wet conditions. A
wilted plant is usually the first sign of trouble. Rhododendron leaves will
curl inward and droop. Drought can cause similar symptoms. Roots of affected
plants appear soggy or blackened, and the outer portion of the root easily
pulls away from the inner portion.Crownrot causes the lower portions of the
stem to have a brown discoloration of the wood near the soil line.
of disease is important, because chemical controls are ineffective once
symptoms appear in the landscape. Begin by purchasing disease-free plants from
a reputable nursery. Avoid plants that lack normal green color, appear wilted
in the morning, or have dark, discolored roots. Select resistant varieties for
azaleas and rhododendrons in a well-drained and well-aerated soil. Heavier clay
soils should be amended with organic matter before planting. Avoid planting in
areas where water can collect around plant roots.