Submitted to: Wheat Newsletter
Publication Type: Other
Publication Acceptance Date: 2/29/2000
Publication Date: N/A
Technical Abstract: Occurrence of leaf rust and stem rust was lighter than normal in southern Texas and the Southeast in 1999, but significant losses (3.4%) to leaf rust occurred in Kansas. Both leaf rust and stem rust were more severe than normal in winter and spring wheat in the northern Great Plains. Losses to leaf rust in the northern Plains ranged from 2 to 4%. Stem rust race RCRS was the most common race in the southern and central Great Plains replacin TPMK, which had been the most common race for many years up to 1998. Race QCCJ was the most common race of stem rust found in the northern Great Plains followed by race RCRS. Leaf rust races MBRQ and MCRQ were most common in the Southeast, and MCDL was most common in the southern and Central Great Plains. Leaf rust races MBDL and THBL were most common in the northern Plains. Increases in virulence to Lr17 in the central Plains and to Lr2a in the northern Plains partly accounted for the increased losses to leaf rust in these regions. Stripe rust was severe in California, causing 7% yield loss in 1999, but damage was relatively light in the Pacific Northwest due to effective adult plant resistance. Stripe rust was found early in the Great Plains before stripe rust was found elsewhere in the U.S. Hot weather limited stripe rust development in the Great Plains after its initial appearance, so no losses occurred there.