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College of Food, Agricultural, and Environmental Sciences


Frost Damage May Contribute to Low Wheat Yields

July 3, 2002

WOOSTER, Ohio - Frost damage on Ohio wheat that occurred earlier in the growing season is becoming more evident now that harvest has begun.

Pat Lipps, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center, said frost damage to the crop is more widespread than originally suspected and may become a contributing factor of low yield potential in some areas.

"I assumed yields would be down from last year because of the poor weather conditions we've had this growing season, not just from the freezing temperatures. I expected lower tiller numbers per square foot and smaller heads, but not what they (Extension agents) are reporting, obviously," said Lipps.

Wheat harvest began in southern Ohio two weeks ago and continued into central Ohio late last week. Lipps said yield reports in southern counties, such as Ross, have not been optimistic.

"Freezing injury in Ross County is probably more than what we expected. Yields are running between 10 and 60 bushels per acre," said Lipps. "Ross is a good wheat-producing county, so growers should be averaging higher than the 60s." Frost damage to wheat is not easy to diagnose because it rarely produces noticeable symptoms. "Frost injury symptoms are somewhat cryptic in that unless you go into the fields and look at the heads, you can't tell if they are filled or not," said Lipps.

When temperatures fall below 30 degrees for several hours during a time when the wheat is developing heads, the cold temperatures cause sterility and the result is little or no kernel development.

"What you have are heads which may be entirely blank with no kernels at all, or just a few kernels developed with the rest of the florets empty," said Lipps. "Frost damage doesn't really change the coloration of the heads, so you can't really see it." Earlier this year, in mid-May, Ohio experienced several nights of cold weather where temperatures dropped to freezing or below. Lipps said that frost damage to wheat occurred in counties as far north as Allen and Crawford.

"Those two counties had some heads beginning to emerge during that cold period. Anything farther north probably was not in head and may have escaped any frost injury," he said. He estimates it'll be another two weeks before it can be determined how extensive the frost injury is.

"When weather conditions are off and disease levels are low, the wheat still does well, but not quite as well as some exceptional years. And when you have extraordinary situations like frost injury, that's going to take even a little bit more off the yield potential," said Lipps. "This is the first time I've seen frost injury to this extent in the state of Ohio and I've been here since 1979. I think the yields will be respectable, but not a bin buster this year."

Candace Pollock
Pat Lipps