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United States Department of Agriculture

Agricultural Research Service

Research Project: Production Management Research For Horticultural Crops in the Gulf South

Location: Southern Horticultural Research

Title: Rhizoctonia damping off and root rot in: compendium of azalea and rhododendron diseases

Authors
item Copes, Warren
item Benson, Michael -

Submitted to: American Phytopathological Society Press
Publication Type: Book / Chapter
Publication Acceptance Date: June 28, 2012
Publication Date: N/A

Interpretive Summary: Rhizoctonia damping-off and root rot are sporadic disease problems that occasionally cause substantial crop loss in plant nurseries of many ornamental plants, including azaleas. Control should include a combination of sanitation, cultural, and chemical practices. Cultural controls include regulating irrigation frequency and not adding high levels of nitrogen. Fungicides from five chemical classes and a few biocontrol products are available for controlling root rot development. The information will be directly useful to extension specialists and crop advisors, as well as ornamental plant production managers.

Technical Abstract: Rhizoctonia solani has been reported to cause damping-off and root rot of rhododendrons and azaleas. Damping-off often includes groups of dying and dead seedlings. Decline of rooted plants in containers results from both root rot and stem necrosis below or above the soil line. Root rot is usually noticed due to the yellowing of leaves, often lower leaves, but also by reduced plant growth. Root rot of both seedlings and larger plants is evident as a complete necrosis of roots and as necrotic lesions on roots. Control should include a combination of sanitation, cultural, and chemical practices. Cultural controls include regulating irrigation frequency to avoid extended saturation of the media and high humidity conditions and not adding high levels of nitrogen. Fungicides from five chemical classes are available for applying a drench treatment to control disease symptom development. Commercial products of biocontrol agents have been shown to reduce Rhizoctonia root rot development.

Last Modified: 4/16/2014
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