Cereal Rust Bulletin Report No. 3 May 2, 2001 Issued by: Cereal Disease Laboratory U.S. Department of Agriculture Agricultural Research Service University of Minnesota 1551 Lindig St, St. Paul, MN 55108-6052 (612) 625-6299 FAX (651) 649-5054 markh@cdl.umn.edu For the latest cereal rust news from the field, subscribe to the cereal-rust-survey mail list. To subscribe, send an email message with the word subscribe in the message body (not subject line) to: cereal-rust-survey-request@coafes.umn.edu Reports from this mail list as well as all Cereal Rust Bulletins are maintained on the CDL website (http://www.cdl.umn.edu/). ------------------------------------------------------------------ * Wheat leaf rust is very light throughout the southern U.S. * Wheat stripe rust development has slowed in the southern U.S. * Oat stem rust has been found in southern Alabama. * Barley stripe rust is starting to increase in the Pacific Northwest. ------------------------------------------------------------------ Winter wheat development is behind normal because of the cold winter and cool springtime temperatures throughout much of the southern wheat-growing area of the United States. In the central Great Plains, the crop is in good shape and behind normal maturity. Throughout the spring grain-growing area, the cold temperatures and scattered precipitation have delayed field work and planting progress is 1-2 weeks behind normal. Wheat stem rust. As of April 30, no wheat stem rust has been reported in the U.S. Wheat leaf rust. In late April, only light amounts of wheat leaf rust were found in many locations throughout southern U.S. fields and plots. The most severe rust was found on susceptible lines and cultivars in southern Texas nurseries. By late April, leaf rust was light in plots in southern and central Georgia and Alabama, central Louisiana and central Texas. In plots at Tallassee in central Alabama a 40% severity was reported on 20% of the plants of the cultivar Jackson and in few of the other entries only 1-2% severities were observed. This is lightest leaf rust that has been observed at this date in the southern soft red winter wheat area in many years. Late planting of the crop in the fall, colder than normal winter in January and February and dry conditions in April have contributed to the slow rust development in the southern U.S. The southern wheat growing area will provide reduced amounts of leaf rust inoculum for the northern wheat growing area. Wheat stripe rust. In Texas by mid-April, wheat stripe rust had slowed with the onset of hot dry weather. In central Texas rust was severe in a few fields. In north central Texas, stripe rust was severe on highly susceptible lines but undetectable in fields. In northeast Texas, the Rolling Plains or High Plains of Texas, stripe rust was not detected in either fields or nurseries. The hot dry weather in April slowed stripe rust development in Louisiana wheat fields. By late April, only light amounts of stripe rust were found in central Louisiana wheat plots at the one-half berry stage and none had been reported in fields. In late April, the only report of stripe rust in Arkansas was in an infection center 2 feet in diameter in the east central part of the state. Last year stripe rust was severe by this date throughout the state of Arkansas. In late April, centers of stripe rust were found in the Plains nursery in southern Georgia. The southern soft red winter wheat growing area will provide minimal stripe rust inoculum for the northern wheat growing area. By mid-April, wheat stripe rust had reached 70-100% severities in plots of susceptible entries in the Davis, California nursery. The cool moist conditions were ideal for rust development. In late April, winter wheat was in the late jointing stage in western Washington and early jointing stage in eastern Washington, which is slightly later than normal. As usual, stripe rust was severe in the cereal disease nurseries at Mt. Vernon in the Skagit Valley in northwestern Washington. Severities of 40 to 60% were reported on susceptible wheat entries while in commercial fields traces of rust were observed. In late April, in a few eastern Washington fields, traces of stripe rust were found. Oat stem rust. In late April, in a field of the cultivar Chapman near Fairhope in southern Alabama, scattered centers of oat stem rust with 60% severities were found. The overwintering centers were 2 meters in diameter. Rust development was slow in these centers because of the cool temperatures in March, while the April weather was warmer but moisture was the limiting factor. In late April, oat stem rust was severe in nursery plots in Baton Rouge, Louisiana and the crop was near maturity. The dry weather in much of the southeast U.S. has slowed oat stem rust development. Oat crown rust. By mid-April, traces of oat crown rust were found in nurseries in Dallas, Pilot Point, and Prosper in north-central Texas. By late April, crown rust was severe in Baton Rouge, Louisiana plots. In late April, 20% severities at the early milk maturity stage were observed in southern Alabama oat nursery plots. Buckthorn. Buds on buckthorn, the alternate host for oat crown rust, are just beginning to break in the buckthorn nursery at St. Paul, Minnesota. This is later than normal for most years. Barley stem rust. As of April 30, no barley stem rust has been reported in the U.S. Barley leaf rust. In early April, barley leaf rust was severe in plots at Uvalde in southern Texas. Stripe rust on barley. In mid-April, 20% severities were reported on susceptible barley entries in the Mt. Vernon nursery in the Skagit Valley in northwestern Washington. Rye rusts. In late April, traces of rye leaf rust were observed in a field in southern Georgia.