Pasture Mealybug in Grain Sorghum

This week I was able to visit a field of grain sorghum in DeWitt County that was infested with pasture mealybugs.  The field was ready for a harvest aid application and the grower's concern was the mealybugs may go to the heads after the application and get everything sticky with honeydew. 

Pasture Mealybugs on Grain Sorghum
Photo by S. Biles

Most of the plants had many mealybugs per leaf, generally toward the base of the leaf on the underside. The grower indicated the mealybugs were all over the 60 acre field. We walked a few hundred feet into the field and found them everywhere we stopped. They didn't get there recently; but were first noticed in early June.

The mealybugs were found on the lower leaves but caused significant damage to those leaves and the upper leaves were not as green as they should be. I suspect the mealybugs likely caused some yield loss. 

While there was sooty mold on the lower leaves, very little honeydew was noticed, and it was not very sticky where the honeydew was found. 

Sooty mold caused by honeydew from pasture mealybugs.
Photo by S. Biles

In this field, I do not think the insects are a threat to causing harvest problems due to honeydew production, so an insecticide application is not necessary. If needed the application of Transform or Sivanto Prime at the sorghum aphid rates should be sufficient to control the mealybugs, but we have not tested insecticide control of pasture mealybugs in grain sorghum. Sorghum aphids were also found in very low numbers.

Pasture Mealybugs on Grain Sorghum
Photo by S. Biles

Pasture Mealybugs on Grain Sorghum
Photo by S. Biles



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