Dry and hot conditions in June may have contributed to a greater number of herbicide injury incidents in Iowa soybean fields this summer, Iowa State University Extension weed specialist Prashant Jha said last week. 

Studies have shown dicamba is more volatile when temperatures are above 85 degrees, which was the case for many dicamba applications in mid- to late June, Jha said.

“Limited rainfall during this period left dicamba on soil and foliar surfaces for extended periods where it is prone to volatilization during hot and dry periods,” he added.

Joel DeJong, ISU Extension field agronomist in northwest Iowa, said cupped leaves on soybean...