Milling & Baking News - November 1, 2011 - 18

Education and Research 

Scab occurrence lower in 2011 wheat crop than year ago
EAST LANSING, MICH. — The occurrence of Fusarium head blight, or scab, in the 2011 U.S. wheat crop compared with a year earlier was “low to virtually non-existent” in several states, although a few states incurred “significant disease incidence and crop loss,” the U.S. Wheat and Barley Scab Initiative said in its latest newsletter. The greatest incidence of Fusarium head blight occurred in the Upper Midwest where moisture was ample during much of the growing season, with occurrence in the Central states down significantly after last year’s widespread scab problems, according to state plant pathologists and extension specialists reporting in the U.S. Wheat and Barley Scab Initiative’s fall edition of Fusarium Focus. Upper Midwest hard winter and spring wheat regions — Wet conditions across the Upper Midwest contributed to increased scab occurrence in the 2011 crop compared with a year ago. “Scab was a major problem this year in certain areas of South Dakota,” said Kay Ruden, extension/research associate with South Dakota State University. “With the weather conditions being wet to very wet in the spring and wet during the growing season, it was a perfect set-up for all of these (scab and several other diseases) to get a foothold in the wheat crop and cause havoc.” DON levels ranged from 2 to 20 parts per million (p.p.m.) in winter wheat compared with 2 to 9 p.p.m. in spring wheat. Weather conditions offset heavy fungicide use in some cases. “The biggest story from North Dakota is that the growing season had a very unfavorable environment for small grains,” said Marcia McMullen, extension plant pathologist. “Field severities ranged from less than 1% to over 37%, with the highest levels observed in some winter wheat fields.” In comparison, testing of early harvested spring wheat revealed DON levels generally below 1 p.p.m. But this year’s later-harvested durum crop showed higher DON levels ranging from 3 to 5 p.p.m. in September. Delayed planting and hot weather later in the season contributed to increased scab incidence in spring wheat in Minnesota, where field severities ranged from “a few percentage points to as high as 30%,” although early reports indicated DON
18 / November 1, 2011 Milling & Baking News

levels mostly below 2 p.p.m. The increased disease occurred despite a higher portion of acreage (almost 40%) planted to moderately resistant or better varieties and increased fungicide use. Initial estimates suggest scab “may have caused economic losses not seen since 2005” in Minnesota, said Jochum Wiersma, small grains specialist at the University of Minnesota’s Northwest Research & Outreach Center. The 2011 growing season served as a reminder that Fusarium head blight is “a nemesis that you cannot ignore,” he said. Southwest hard winter wheat region — In contrast to the wet northern Plains, dry to extreme drought conditions resulted in very low to no scab reported in Kansas and Oklahoma in 2011. In Nebraska, scab occurrence ranged from very low to severe, with highest levels in the southwestern part of the state. “Overall, losses due to scab statewide were minimal for the most part,” said Stephen Wegulo, extension plant pathologist at the University of Nebraska. “However, losses in several isolated fields were significant.” Central states and surrounding areas soft winter wheat region — Despite weather conducive to scab development during parts of the growing season, dry weather later in the season resulted in low incidence levels in most of the region, and much lower than in 2010. “Vomitoxin levels are relatively low, being below 5 p.p.m. in the majority of harvested fields, with the odd field having 7 to 9 p.p.m.,” said Pierce Paul, a plant pathologist at The Ohio State University. “These numbers are much lower than last year’s numbers, which reflected the most severe scab and vomitoxin problem Ohio has had in more than 10 years.” In 2010 disease incidence was as high as 60% and DON levels were as high as 18 p.p.m. In Illinois, scab was detected in fields but incidence and severity were low, with fungicide use on about 40% of wheat acreage seen as a controlling factor. Indiana reported some high Fusarium head blight levels in the northeast corner of the state, but overall occurrence was low. In Kentucky about 20% of the wheat had at least moderate

levels of Fusarium head blight, but no serious damage was reported. Wisconsin reported a “benign” scab year in 2011. New York also had low levels of Fusarium head blight overall, with more than 90% of the wheat testing below 1 p.p.m. of DON. Scab occurrence in Michigan was very low, although an occasional load of wheat had DON levels in the 2 to 4 p.p.m. range. Use of fungicides increased significantly, to about 75% for soft white and 50% for soft red wheat, due to higher crop values, according to one county extension director. There are no scab-resistant soft white winter wheat varieties, with one-third of the state’s acreage comprised of soft white wheat. Mid-Atlantic soft winter wheat region — “To my knowledge, Fusarium head blight was a non-issue in Virginia (in 2011),” said Erik Stromberg, extension plant pathologist at Virginia Polytechnic Institute and State University. “This was the best wheat crop in my 30 years in Virginia.” There also were no scab problems indicated in the North Carolina and South Carolina wheat crops, and fungicides were not widely used. In Maryland, despite spring weather favorable to scab development, rejections of wheat at mills and elevators were relatively rare in part because of the availability of low-DON wheat for blending, increased use of fungicides and lower disease severity. In contrast, scab was a serious problem in Pennsylvania, where about half of the state’s 2011 wheat crop had vomitoxin levels above the 2 p.p.m. threshold, with the worst incidence in central and southern parts of the state. One state extension agronomist called it “perhaps as bad as I have ever seen.” Southern soft winter wheat region — Georgia indicated no problem with scab, and in Alabama, issues were confined to three counties in the northwestern part of the state, according to university extension plant pathologists in those states. Overall scab incidence in Mississippi was termed light, with some scab reported in eastern areas. An Arkansas plant pathologist reported no significant scab problems in major wheat growing areas of the state. The U.S. Wheat & Barley Scab Initiative will host the 2011 National Fusarium Head Blight Forum in St. Louis on Dec. 4-6. MBN
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Milling & Baking News - November 1, 2011

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