Small Grains Disease and Pest Update 07/21/25 (and preparing for harvest)

It isn't hard to find Fusarium Head Blight (FHB) or Bacterial Leaf Streak (BLS) across much of Minnesota. 

BLS is appearing relatively late in the grainfill period, and yield losses caused by the disease will be relatively small.  

The same cannot be said for FHB, as the conditions continue to favor disease development. The best time to assess how many early infections occurred is probably this week.  These early infections result in the characteristic tumbstone kernels. These tombstone kernels can be easily removed during combining, and it is the simplest and cheapest way to reduce the amount of deoxynivalenol  (DON) in the harvested grain. Unfortunately, it's too early yet to see if the current stretch of favorable conditions will result in many late-season infections. Late-season infections are more difficult to deal with as the infected kernels have a near-normal appearance and weight but contain enough deoxynivalenol  (DON) to result in discounts or rejections at the point of sale.  

Finally, armyworms are at treatable levels along the eastern beach ridge of the Red River Valley. The threshold to treat army worms is 4 to 5 larvae per square foot, any time before harvest.  Be cognisant of the preharvest interval (PHI) for your insecticide of choice, as many products labeled for use against armyworms have a PHI of 14 days or more.