If you have been walking or riding through peanut fields in Georgia over the past week you have almost certainly noticed fields with thrips injury, or as some of my colleagues say, “thrippy peanuts”. Thrips injury varies in severity from minor feeding scars on fully expanded leaflets to severely deformed or dead terminal buds. Peanuts planted the last week of April through the second week of May are experiencing the most pressure, and drought stress is making things worse in non-irrigated fields.
A lot of calls in recent days have focused on whether or not a foliar insecticide application is needed in these thrippy fields. There is no easy or definitive answer in most cases. In my experience, thrips injury typically peaks around 30 days after planting. After that, thrips numbers tend to decline, peanut growth increases rapidly, and we forget about thrips for another year. Most of the time I do not think an insecticide application at 4 weeks after planting will pay for itself; however, if peanut terminals are being severely injured, immature thrips are still present, and the plants are experiencing drought and/or herbicide stress, treatment might be warranted. A good rain and favorable temperatures is the best treatment for this situation.
While thrips injury has dominated the conversation for the last week, we will soon face a related but far more serious issue. Tomato spotted wilt virus (TSWV) is transmitted by thrips, and symptoms will be showing up in peanut fields in the coming weeks. Fields that were planted after May 10 and that were treated with phorate (Thimet) will be at reduced risk compared to early planted fields with either a different or no at-plant insecticide. It is important to remember that foliar insecticide sprays will not reduce the risk of TSWV in peanut. The following link is to a short video about thrips and TSWV that might be of use as you check peanut fields over the next couple weeks. https://www.youtube.com/watch?v=M2-KPcmLNEs
For more information about thrips management in peanut, contact your local University of Georgia county Extension Agent.
