Crops - Crop Scene Investigation 8 Solved: What was the trouble with Troy's stunted corn?

Friday, February 29, 2008

What was the trouble with Troy's stunted corn? - Solved

by DEB CAMPBELL

Spray contamination was the source of trouble in Troy's corn. The University of Guelph lab report confirmed the presence of glyphosate in the injured plants. It also confirmed that there was no glyphosate in the healthy plants.

The source of contamination is more difficult to identify. It may have been the result of an improperly cleaned sprayer. Even a small amount of glyphosate residue can contaminate the next spray load and cause considerable damage to the subsequent crop. That's why triple rinsing with a cleaner and checking all potential points of contamination in your sprayer is essential. The contamination could have also been the result of human error - the sprayer operator may have unintentionally added glyphosate to the tank.

In Troy's case, 80 per cent of his two fields of corn were affected and they weren't going to recover. Plants were yellow and stunted with dead tissue on the new leaf. This description is a diagnostic feature of low-dose glyphosate injury. It's important to note that disease, root rot, and insect feeding can also share these symptoms. Other crop protection products can cause the same type of injury as well. All of this adds up to a tricky conclusion.

Fortunately, new diagnostic tools are available to take away the guesswork.

However, once glyphosate injury occurs, there is no fix. The only way to proceed is to start over. Troy's fields were replanted with an early developing hybrid. Unfortunately, Troy lost precious time in an already short growing season.

What about the 20 per cent of the crop that was unaffected? We determined that the uninjured plants were not out of the ground at the time of herbicide application. They emerged safely after application and had grown past the stage of the injured plants. Troy had also noted a difference in the intensity of damage between the two hybrids. Hybrid sensitivity was a factor here.

Don't hesitate to call your seed representative if something seems amiss after planting. The sooner you act, the sooner we can help evaluate what is wrong and get you on your way to a viable crop. BF

Congratulations to Blair Scott, Teeswater, for his correct answer.

Deb Campbell, CCA, is a Field Agronomist for NK Brand, Syngenta Seeds. She is based near Dundalk.