CEREAL RUST BULLETIN Report No. 5 June 11, 1996 Issued by: Cereal Rust Laboratory, Agricultural Research Service, U.S. Dept. of Agriculture University of Minnesota, St. Paul, MN 55108 (612) 625-6299 FAX (612) 649-5054 Internet: markh@puccini.crl.umn.edu CRL web page: http://www.umn.edu/rustlab/ * Wheat stem rust was found in southeastern and central Kansas in early June - first report in the Central Plains this year. * Wheat stem rust overwintered in southern Illinois in at least one site found in the second week of June. * Both stripe rust and leaf rust are severe on susceptible wheat cultivars in central Washington. * Barley stripe rust is firmly established in the Pacific Northwest; an emergency label for the fungicide Folicur has been granted for stripe rust control in barley in that region. The small grain harvest is underway from northern Georgia to central Oklahoma. Much of the hard red winter wheat crop in the central plains is in fair to poor condition. In the northern spring grain-growing area, crop planting and crop emergence remains behind average. Wheat stem rust In early June, small foci of wheat stem rust were found in southeastern and central Kansas fields. The crop is close to maturity (dough stage) and the infection sites are too small to cause any significant losses. In early June, traces of stem rust were found in plots and a field in east central Arkansas. During the second week in June, an overwintering center of stem rust was found in plots of soft red wheat at Carbondale in southern Illinois. Wheat leaf rust In early June, traces of leaf rust were found in plots and fields of susceptible cultivars throughout Kansas (Fig. 1). Most of the rust pustules were concentrated on upper leaves indicating that the rust developed from exogenous spore sources. Since the crop is approaching maturity (dough stage) in much of Kansas and the rust infections are light, there will be minimal losses to leaf rust. During the second week in June, light leaf rust was observed on soft red winter wheat in southern Illinois and western Tennessee. The rust pustules were noted on the upper leaves and the rust developed later than usual because the rust originated from exogenous sources. In early June, leaf rust was light but increasing in wheat plots in eastern Virginia. In early June, in the Pacific Northwest, wheat leaf rust was increasing rapidly. In central Washington, 90% severities were reported on susceptible cultivars. In the Palouse area of Washington leaf rust was light to moderate but since the crop matures later in the Palouse than in central Washington, leaf rust could become severe on susceptible cultivars. No new leaf rust races have been identified since Cereal Rust Bulletin # 3. Wheat stripe rust In the Pacific Northwest wheat stripe rust is continuing to increase and some of the susceptible cultivars are being sprayed to control the rust. Stripe rust is starting to appear on spring wheats but cultivars with adult plant resistance should not be seriously damaged. Club wheat multiline cultivars appear to be holding up well although damage will be severe in unsprayed susceptible club wheats. There have been no new reports of wheat stripe rust being found in the central U.S. wheat growing area this year. Oat stem rust There have been no new reports of oat stem rust since the last bulletin. Oat crown rust During early June, light to moderate numbers of aecial infections were found on buckthorns( alternate host) growing in south central Minnesota and east central North Dakota. Aecial infection are one to two weeks later than normal in this area. Crown rust may still have time to build up on the late planted oat crop. Barley stem rust As of June 10, no barley stem rust has been reported in the U.S. this year. Barley leaf rust This year no barley leaf rust has been found in eastern Virginia which is unusual. Barley leaf rust has overwintered in this area nearly every year. Barley stripe rust In early June, throughout the Pacific Northwest barley stripe rust was severe and severities as high as 100% were recorded in some western Washington winter barley plots. Traces of barley stripe rust were observed on spring barley in western Washington. Growers are planning to spray if necessary and an emergency label to use Folicur on barley in the Pacific Northwest has been granted. Rye rusts There have no new reports of rye rusts since bulletin #3.