With Gray Leaf Spot (GLS) and Northern Corn Leaf Blight (NCLB) reaching economic thresholds in some fields, farmers are faced with the difficult decision whether or not to apply a fungicide.
Justin Petrosino, Agronomist with Stewart Seeds says the decision should be based on economics.
“When we think about economics, we’ve got $3.80 corn and you think about a fungicide application you’re talking about 10 bushel you need to gain from that fungicide application in order to pay for itself,” Petrosino said. “So it’s really tight this year so we really want to get out and scout our corn fields and know which hybrids you’re looking at, know its susceptibility rating for the diseases.”
Petrosino says the first step when scouting is correctly identifying the disease, second is determining how much of the disease is present.
“The economic threshold level, according to OSU, is to have five percent leaf coverage of those lesions, so the lesions need to be taking away five percent of the leaf area on the three leaves below the ear leaf on half the plants in the field,” said the Steward Seeds agronomist.