COLUMBUS – Continued rains at flowering could put wheat at risk for head scab in most of northern Ohio.
According to Ohio State University plant pathologist Pat Lipps, the only way infection levels could moderate is if temperatures remain relatively cool, with daytime highs below 60 degrees.
Wheat is vulnerable to scab infections if it rains at flowering, or Feeke’s Growth Stage 10.51, because airborne spores need moisture to germinate and infect wheat, Lipps said.
Wet weather is also critical before flowering, as the spore-producing Fusarium fungi thrive in saturated crop residues that were left on field surfaces over the winter.
Other areas safe.
In other areas of Ohio, wheat flowered between Interstate 70 and U.S. 30 throughout the week of May 20, putting the crop at moderate risk depending on weather conditions. Southern Ohio fields faced the least risk because dry weather limited spore development before the crop flowered during the week of May 13.
Northeast Ohio was considered to be at low risk due to low moisture levels.
What to look for.
Farmers should assess damage by scouting 10 days after flowering, which is when symptoms appear. Infected wheat will have dead or bleached-out florets scattered throughout a field.
Generally not all the florets will show symptoms while the rest of the head will be green.
By harvest, seeds in infected heads will be shriveled and have a white to pinkish color.
Bad year in 1996.
Ohio’s last head scab epidemic in 1996 caused a 30 percent yield reduction in soft red winter wheat. The 1996 wheat loss was estimated at $107 million, compared to a more limited 1995 outbreak that caused $68 million in losses.
High levels of scabby kernels in harvested wheat may indicate high levels of vomitoxin, which is undesirable for baking quality. In addition, vomitoxin can cause health problems in livestock.
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