Wheat harvest promising despite disease

WOOSTER, Ohio – Wheat harvest is progressing rapidly across Ohio with decent yields and high test weights, despite the early-season problems with Fusarium head scab.

Ahead of 2003. According to the Ohio Agricultural Statistics Service, 34 percent of the wheat has been harvested, 30 percent more than last year during this time.

Harvest in the southern portion of the state is nearing completion, with harvest in central Ohio just beginning and fields in northern counties waiting in the wings.

Counties are reporting lower yields compared to last year – 15 percent to 20 percent lower in some cases, due to disease problems from head scab and Stagonospora glume blotch.

Looking good. Despite the variable disease problems, Pat Lipps, an Ohio State University Extension plant pathologist, said he is very pleased with the way the wheat crop is turning out.

“The prognosis at the end of May and at the beginning of June with all the rain we got during the flowering period was not good,” said Lipps, with the Ohio Agricultural Research and Development Center.

“We thought scab would be more severe than it turned out to be. Our test weights tell us the disease must have been confined to certain kernels on the heads and other kernels were not affected. So our test weights and yields are reasonable.”

Average yields. Lipps expects the state average bushel-per-acre yield to run in the low 60s. Last year, the average was 66 bushels per acre. Currently, most growers are bringing in 60 to 70 bushels per acre.

Some diseased fields are only faring in the 50-bushel-per-acre range, while other fields are generating 80 or 90 bushels per acre.

“The most interesting aspect of these reports is the considerable variability in yield among fields across a location,” said Lipps. “Variety, planting date, planting depth and drainage had a profound impact on yield as did variety resistance to disease.”

Test weights. Where wheat may be slightly falling short in yields, it’s making up for it in test weights. Lipps said most areas are reporting 58-pound test weights. This is a slight improvement over last year’s average.

“A good test weight for Ohio is 59 to 60 pounds,” said Lipps. “We think that the reasonable test weights are from growers doing a better job in getting in the fields earlier and cleaning out the smallest seed with combines using higher flow rates to blow out a lot of the shriveled kernels.

“Blowing out kernels means you are losing some of your yield, but saving them is not going to add that much to yield because the seeds are diseased and small.”

Grain quality. Of course, with good test weights comes better grain quality, and Lipps said the quality might be better than expected this season.

“We are getting reports of some areas having problems with vomitoxin (the toxin produced by the fungus causing head scab) in the grain, but for the most part grain quality has been acceptable,” said Lipps. “I think the grain quality will be better this year than last year in most areas of the state.”

Lipps does encourage growers to harvest their wheat as soon as possible. Recent localized rains have prevented some harvesting, which could help fuel further growth of the head scab fungus that already exists in heads of infected plants.

Harvest ASAP. “If it continues to rain, that means the grain continues to get wet, and whenever the moisture gets high enough the fungus can grow and continue to shrivel grain and produce vomitoxin,” said Lipps.

“We try to encourage growers to get out there and harvest as quickly as possible. Once wheat is harvested, dry it down to 13.5 percent to 14 percent moisture. The fungus will no longer grow at that level and no more accumulation of vomitoxin in the grain will occur.”

Lipps said the average field in Ohio has about 13 percent of the heads affected by scab; that translates into about 2 percent to 3 percent scab severity. This is based on a survey conducted in 116 fields throughout 19 counties.

Controlling head scab is difficult but a big factor is choosing a wheat variety with some level of resistance.

Looking ahead. Lipps said growers are already evaluating varieties for next season’s crop and the Ohio Wheat Performance Test, which should be released in about a month, will also aid growers in choosing the best varieties that not only resist head scab but provide high yields and adequate test weights.