Western Flower Thrips

Western flower thrips are out in full force. If you have sensitive crops it is important not to let your thrips population get out of hand.

Growers were provided a brief relief from western flower thrips when Conserve SC was labeled for ornamental crops. Unfortunately, there are cases being reported of western flower thrips not responding to Conserve label rate applications.

This developing tolerance may be a result of some growers not following the label instructions. The Conserve SC label states “no more than three consecutive applications should be used, nor should there be continuous use for more than 30 days. Consider rotating to a different active ingredient with a different mode of action or use no treatment for the next generation" and "Regardless of the crop or pest being treated (excluding leafminers, spider mites and/or diamondback moths), do not apply Conserve SC more than 10 times in a 12-month period inside a greenhouse or a structure that can be altered to be closed or open”.

Due to the intense nearly year-round thrips pressure some growers face, they are exceeding the three consecutive applications and the 10 total applications per year. One common mistake growers make is applying Conserve repeatedly for thrips and then again for caterpillars, mites, or leafminers. This causes them to exceed the number of total applications that can be made in a year. It is critical to follow the label instructions to reduce the development of resistance in western flower thrips to Conserve.

The recent labeling of Pylon for western flower thrips control provides greenhouse growers (not labeled for outdoor use) a highly effective rotation partner to use with Conserve. As with Conserve it is important to follow the resistance management component of the Pylon label to lengthen the period of efficacy of this product for thrips management.

There are a number of other insecticides that can be used in rotation for thrips management. These include, but are not limited to, Avid, Azain XL, BotaniGard, Enstar II, Pedestal, Mesurol and Orthene.

I am currently working on a project to monitor the tolerance level of western flower thrips to Conserve in East Texas. I will report more on this when the project is completed.