A mealybug has become a problem in many pastures and hayfields of South Texas. On July 28, I sprayed an insecticide control test near near Nursery, TX with Victoria County Extension Agent, Kara Matheney. Yesterday, we visited the test to assess the control obtained in the treatments.
We applied 5 insecticide treatments and left an untreated treatment. The test had four replications.
Control was measured in two ways. First, we used a phone app to determine if there was differences in grass production. The second method to measure control was to count the number of infested grass clumps in 10 grass clumps per plot.
We found no differences in grass between the plots at 7 and 14 days after application. This may be too soon to tell how the grass responds to insect control.
Plots were inspected at 2 and 14 days after treatment (DAT). No differences were found at 2 days after treatment. The lack of differences could be due to the difficulty of determining if a mealybug is alive or dead or because the insecticide Sivanto Prime can be a slower acting product.
I decided to wait and check the test at 14 days after treatment and the test was reevaluated August 11.
At 14 DAT, The number of infested clumps in the plots treated with Mustang Maxx, Carbaryl, and Lannate were not different from the untreated plots. Sivanto Prime treated plots had significantly fewer infested clumps than the others and the untreated.
Sivanto is not labeled for use in pastures in Texas.
What these results do not tell us is if this level of control gained by the Sivanto application will result in a tangible benefit to the grass or prevent additional losses. We plan to continue to follow this and the other tests we are conducting to learn more about how we should manage mealybugs in pastures.
It is important for us to know where this mealybug is being found. If you find fields with this mealybug, you can contact Stephen Biles (biles-sp@tamu.edu, 361-920-1138).
The map below shows the Texas counties where I have been told the mealybug has been found.
