David Owens, Extension Entomologist, owensd@udel.edu
Congratulations to Chris Cawley for accurately identifying the nondescript yellow and red and brown spots on the soybean leaf as belonging to Septoria Brown Spot.
Septoria Brown Spot on soybean.
According to Dr. Alyssa Koehler, “This is a disease that we see pretty consistently every year. This fungus survives in debris and is favored by warm, humid conditions. Even though incidence can be high, yield loss is not typically observed. It usually stays lower in the canopy with limited impact to yield in most years. If it moves rapidly though the canopy to the top leaves and causes premature defoliation, around 5% yield loss may be associated.”