Crop Scene Investigation - 49 Solved: Why was Richard's field infected with septoria?

Tuesday, March 4, 2014

It took a while, but we finally received a few correct answers to this puzzle.

Richard's poor tillage job after harvesting his 2010 wheat crop allowed septoria leaf spot to gain a foothold in the farmer's first field and eventually infect his 2013 wheat crop.

Agronomist Paul Sullivan explains that Richard's corn-soy-wheat rotation should have ended the disease cycle and eliminated septoria, but a couple of things conspired against him.

"Poor tillage in that field was the biggest problem. The cultivator they used could not handle all the straw and green weeds in the field after harvest. It just moved the residue around and piled it up. In these situations, you need to eliminate the weeds and spread the residue evenly across the field."

Sullivan explains that the piles of trash and weeds across the first field managed to survive to some degree because the field was minimum-tilled for a corn crop in 2011 and planted to no-till soybeans in 2012.

Weather conditions also contributed to Richard's trouble. "The field was really dry in 2011 and 2012. This slowed the breakdown of the organic matter that had been piled up in areas of the field," explains Sullivan.  And when the weather turned wet after planting in spring 2013, the conditions were just right for the lingering disease to attack the wheat crop.

Sullivan says Richard's story is a perfect example of why good tillage practices and spreading crop residues evenly across fields are so important.

Congratulations to Jorg Eichelberger, Owen Sound, for his correct answer. BF