Crop Scene Investigation 61 Solved: What took a bite out of Stan's Soybeans?

Friday, April 8, 2016

by BERNARD TOBIN

Stan initially thought a disease had infected his soybeans, but they were actually being eaten by stink bugs.

When Syngenta agronomist Shawn Brenneman arrived at Stan's 50-acre field just outside Hamilton, he quickly concluded that Stan's disease diagnosis was actually a pest problem. For Brenneman, it was obvious that insect feeding had occurred and the delayed maturity is consistent with the work of stink bugs. "If a stink bug comes in early enough, it can actually affect the physiology of the plant and delay maturity," he explains. "When they insert their mouthpiece, they are injecting enzymes which can cause a delayed maturity reaction in the plant."

The stink bugs were likely very active in the field during the dry August conditions. Brenneman recalls that Stan did not scout the field during this time. He also notes that the field is situated close to Hamilton, which has an established stink bug population.

"They overwinter in people's houses. That's why we couldn't find them when we searched the trash in Stan's field in September. They were probably there in June, July and August."

Based on yields in the area, Brenneman estimates that stink bug damage reduced Stan's yield by about 20 per cent. "That's because some seeds didn't form while others were diseased and shrivelled up. That entry point also allowed other diseases to come in and the number of healthy seeds were reduced."

Congratulations to Robert G. Ivison, Tilbury, ON, for his correct answer.

Thanks to all of you who submitted answers this season. We really appreciate all the comments and personal stories you shared along with your answers. CSI will return in the fall. BF