Cut Soybean Plants And The Culprit

 

 

We have received numerous reports of cutworms being problematic in safflower and sunflower so far in 2017. However, while scouting soybeans last week I noticed numerous areas within the field where soybean plants were lying dead near the row, but with no indication of defoliation. Upon closer inspection, it became evident that the plants had been cut near the soil surface. Reports of cutworms in soybean tend to be rare, but there are documented cases of them occasionally causing problems. The cutworm species that we found near the areas with cut plants was the dingy cutworm (Figure 1).

 

 

The dingy cutworm has been covered previously because of its presence in safflower and sunflower this year. The caterpillars are nocturnal, and can be found by digging 1-2 inches in the soil around cut plants. Dingy cutworms get their name due to their dull brown to gray coloration. These cutworms have a distinct pale gray line that runs down the center of their bodies. The dingy cutworm caterpillars have tubercles or spots present on the sides of each segment of their bodies that are all similar in size to one another (Figure 2).

 

 

 

Cutworms tend to be more of an issue in soybean fields that have been planted under reduced or no-till practices, fair to poorly drained fields, or fields with weed or cover crop presence prior to soybean planting. Cutworms can be scouted by examining fields for cut plants and also by digging in the soil near cut plants to determine population densities.