HPIPM:Damping Off, Seedling Blight Sorghum

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Basidiomycota
Subphylum	Agaricomycotina
Class	Agaricomycetes
Order	Cantharellales
Family	Ceratobasidiaceae
Genus	Rhizoctonia

Scientific Name

Rhizoctonia solani

Scientific Name Synonyms

Moniliopsis aderholdii

Corticium solani

Rhizoctonia napaeae

Thanatephorus cucumeris

Common Name

Rhizoctonia damping-off, blight and rot

Author: Howard F. Schwartz, David H. Gent, and William M. Brown, Jr

Identification and Life Cycle

Many pathogens can cause damping-off of sorghum seedlings in the High Plains region, including Pythium spp., Fusarium spp., Phoma spp., Aspergillus spp., and Rhizoctonia spp. Pythium spp. appear to be the most important. Damping-off is associated with cool, wet soils. Damping-off pathogens are common soil inhabitants and can survive in soil and crop residues as dormant oospores or sclerotia, pathogenically on alternate hosts and weeds, and saphrophytically on crop residues.

Plant Response and Damage

Damping-off can occur before or after sorghum emergence. Pre-emergence damping-off results in a brown, gelatinous rotting within the seed coat. Radicles and cotyledons may become brown and soft after germination, but fail to emerge. Red, brown, or black lesions may also form along roots and at the root tip, halting root developing. Water-soaked, greasy lesions may also form on stem and roots after emergence when infected with Pythium spp., causing plants to collapse and wither.

Biological Control

No biological control strategies have been developed for sorghum damping-off and seedling blights.

Cultural Control

Plant high quality seed in well-prepared, warm soils that encourage rapid emergence. Damaged, weathered, or moldy seed germinate poorly and are more prone to damping-off and seedling blights. Avoid compaction, poor drainage, herbicide injury, and other factors that delay seedling emergence and dispose plants to disease. Varieties differ in their vigor and tolerance to damping-off and seedling blights. Hybrids tend to be most tolerant to damping-off and seedling blights and should be planted where available.

Chemical Control

Treat seed with broad-spectrum systemic and contact fungicides.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.