HPIPM:Rust FC

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

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Basidiomycota
Subphylum	Pucciniomycotina
Class	Pucciniomycetes
Order	Pucciniales
Suborder	Uredinineae
Family	Pucciniaceae
Genus	Puccinia

Scientific Name

Puccinia polysora

Common Name

southern corn rust

Identification and Life Cycle

Several rust diseases occur on corn, but only common rust caused by the fungus Puccinia sorghi is found in the High Plains. In North America, windblown urediospores from tropical and subtropical environments are the primary inoculum source. Plants are infected from mid-June to mid-July when moderate temperatures (60-77ºF) and high relative humidity (greater than 95%) coincide. The pathogen overwinters on living hosts.

Plant Response and Damage

Common rust symptoms are small, reddish brown to black, linear streaks or pustules that common occur in bands on leaves. The fungus sporulates on both sides of leaves about 7 days after infection. Defoliation and plant stunting may occur. Yield losses of 3 to 8% per 10% area of the leaf area infected have been reported.

Biological Control

Practical biological control strategies have not been developed for common rust.

Cultural Control

Resistant varieties are available and should be planted. Several races of the fungus exist, so single-gene resistance needs to be matched against the prevailing rust races present. Varieties with general resistance are available that do not completely control disease, but reduce the number and size of lesions.

Chemical Control

Well-timed fungicide applications effectively control common rust, and should be applied before significant secondary inoculum develops. Fungicides are most effective when combined with varieties with general resistance.

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.