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Rhododendron
Disease
Armillaria root rot
Botrytis shoot blight
Gray blight
Leaf spot
Lime-induced chlorosis
Marginal leaf necrosis
Physiological leaf spot
Phytophthora blight
Phytophthora root rot
Powdery mildew
Ramorum leaf and shoot blight (Sudden oak death)
Rust
Salt injury
Sunburn
Tissue proliferation
Insect
Aphids
Azalea bark scale
Caterpillars
Lecanium scale
Rhododendron lace bug
Rhododendron whitefly
Root weevils
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Caption: Rhododendron rust
Photo by: R.S. Byther
Rhododendron : Rust
(revision date: 4/23/2014)
Use Integrated Pest Management (IPM) for successful plant problem management.
Biology
Yellowish spots on the upper leaf surface and dark brown or purple spot on the lower leaf surface can indicate the presence of a rust infection. Later, the underside develops blisters which break open to reveal characteristic yellow to orange or reddish spores. Rusts can also affect azaleas. The disease overwinters on the host plant.
Management Options
Non-Chemical Management
Prune and destroy infected leaves.
Clean up and destroy any diseased leaves that have fallen to the ground.
Select non-chemical management options as your first choice!
Chemical Management
IMPORTANT:
Visit Home and Garden Fact Sheets for more information on using pesticides
None recommended
Images
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Caption: Rhododendron rust
Photo by: R.S. Byther