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College of Food, Agricultural, and Environmental Sciences


Recent Rains Slowing Wheat Harvest

July 15, 2003

WOOSTER, Ohio — Excessive wet weather is delaying wheat harvest in Ohio and increasing the likelihood of shattering, low test weights and the occurrence of vomitoxin in the grain. Vomitoxin, also known as DON, is a toxic chemical produced by the fungus that causes head scab. Pat Lipps, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center, said that wheat in northern Ohio is ready to be harvested but the fields may still be too wet to get into. In southern Ohio, about 70 percent to 80 percent of the wheat has been harvested, but reports are trickling in that vomitoxin is present in the grain, taking a bite out of producers’ profits. “So far we have reports of grain in southern Ohio having anywhere from zero to six parts per million of vomitoxin,” said Lipps, a professor with OARDC’s Department of Plant Pathology. “Grain with up to two parts per million of vomitoxin is not being docked by buyers at this point in time. Grain with three parts per million is being docked 15 cents a bushel, at four parts per million, you are looking at a 30 percent dock, and anything over five parts per million is not being accepted. Grain producers will have to store it for a while and see if they find some other market for the poorer-quality grain.” According to the Ohio Agricultural Statistics Service, only 11 percent of the state’s wheat has been harvested, compared to 82 percent this same time last year. A week’s worth of heavy rains and flooding have created a variety of problems for growers right at harvest time. In addition to continued growth of the head scab fungus and vomitoxin production in the grain, the wet conditions have also favored a condition called “puffing.” Puffing results from the continuous wetting and drying of the grain, and each time the grain swells from moisture and then shrinks due to drying, the grain becomes smaller than normal. The impact is low test weights, said Lipps. “The lowest test weight we’ve heard of so far is 50 pounds, where normally it should be 58 to 60 pounds per bushel,” he said. The small amount of soft white wheat grown in Ohio is suffering from “sprouting,” a condition where the grain germinates while still in the heads, which makes the grain useless for food products. “White wheat does not have a dormancy period before the grain germinates or the period is very short. If it goes to the ripe stage, dries to a certain moisture level and gets re-wetted, the grain will germinate in the heads,” said Lipps. “Red wheat has not had that problem because the grain has a dormancy period of about three weeks before it germinates.” Despite the problems experienced in southern Ohio, agronomists are optimistic that Ohio will still pull off an average wheat harvest. Wheat in northwest Ohio — the state’s major wheat-production area — has not yet been harvested. The grain is either still too wet to harvest or the fields are too wet to bring in equipment. “We are waiting to see how the majority of the wheat will turn out. Northern Ohio has not received the intensity or duration of rainfall that southern Ohio has received so we are somewhat optimistic that we are going to see some reasonable wheat,” said Lipps. “Test weights will not be as high as expected, but hopefully the vomitoxin levels will be low. We need a few days of drying time to get the crop down to 15 percent or 16 percent moisture, and a few more sunny days to get the fields dry enough to get the combines in.” For growers who have yet to harvest their wheat, Lipps recommends they adjust their combines to blow out lightweight kernels; get into their fields as soon as possible to harvest; and prepare themselves for vomitoxin testing or grain docking if they know their wheat has been infected by head scab.

Candace Pollock
Pat Lipps