GENETICS, POPULATION BIOLOGY, AND HOST-PARASITE INTERACTIONS OF CEREAL RUST FUNGI AND THEIR DISEASES
Location: Cereal Disease Laboratory
Title: Wheat rusts in the United States in 2011
Submitted to: Wheat Newsletter
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 2, 2012
Publication Date: N/A
Interpretive Summary: Wheat is attacked by three different rust fungi. Spores of the rust fungi are carried by the prevaling winds in the atmosphere throughout the US every spring and summer and are deposited on wheat crops with rainfall. This report summarizes that spread and occurrence of the three rust diseases: leaf rust on wheat; stem rust on wheat, and stripe on wheat in the US in 2011.
Wheat stem rust (Puccinia graminis tritici) was found in Texas, Louisiana, Oklahoma, Kansas, Nebraska, North Dakota, Minnesota, Arkansas, Missouri, Kentucky, Illinois, Indiana, Wisconsin and Michigan in 2011. Nationally, wheat only incurred a trace loss due to wheat stem rust. Race QFCS was the most common race, and race QCCDC was found in Louisiana. Wheat leaf rust (Puccinia triticina) was found throughout the Great Plains region and eastern and southern states. Extreme drought conditions in the southern and central Great Plains limited leaf rust development and inoculum production for areas further north. Additionally, widespread use of fungicide throughout commercial fields in the eastern states and northern spring wheat area further limited leaf rust development. Losses due to wheat leaf rust were minimal in the U.S. in 2011. Over 90 races of P. triticina were identified in 2011. Many new leaf rust races with combinations of virulence to Lr21, Lr39/41, Lr9, Lr17, and Lr24 were detected. Wheat stripe rust (Puccinia striiformis) was widespread and severe in the Pacific Northwest, Sacramento Valley in California and Montana in 2011. Stripe rust was active very early in the Pacific Northwest, e.g. mid-February in Washington and Oregon. Very little stripe rust was found in Texas and Oklahoma, while it was at low levels in Kansas and Nebraska except for scattered hot spots in some fields. Stripe rust was mostly at low levels and widely scattered in the eastern U.S. Significant wheat yield losses due to stripe rust occurred in the Pacific Northwest, California and Montana.