New materials and an old technique for thrips control

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Thrips may be a greater problem this spring than in previous years because of changes in the market and high energy costs. Many new plant introductions are cutting propagated, and whenever we move live plant material around, the chances for a few “hitch hikers” getting into your greenhouse goes up. To save energy growers are cutting back on their own plug production and importing plugs and liners from specialists; another opportunity for thrips to become established. Heating houses a week or so before filling them is an excellent way to starve out any thrips that hatch from pupae in the soil, however this isn’t practical because of high fuel costs.

The key to reducing thrips problems is monitoring incoming plant material before it is placed into your houses and the ranges throughout the crop. Every box of plant material should be opened in a “quarantine” greenhouse or the headhouse and a yellow, sticky card placed into the box for a few hours. Any adult thrips in the new plants will show up on the card. Keep the card among the plants as they are placed in your holding area just in case thrips hatch from pupae in the medium. Yellow, sticky cards should also be throughout your greenhouse not only to monitor for thrips but also whiteflies and other pests.

The new insecticides TriStar, Safari and Aria are labeled for thrips control. TriStar and Safari have the same Mode of Action [MOA] (number 4 in Dr. Cloyd’s Mode of Action chart – see following article) as Marathon and should not be used in a rotation with Marathon, Celero or Flagship to prevent resistance developing. TriStar, Safari Marathon, Celero and Flagship all are about equally effective for thrips control. Aria is a selective feeding blocker in the same MOA group (number 10) as Endeavor. Each pesticide in your rotation should have a different MOA to slow resistance. Other materials that can be used in a thrips control rotation include: Conserve (MOA 5), Avid (MOA 6), Orthene (MOA 1), Azatin (MOA 14), Decathlon (MOA 3), Mesurol (MOA 1) and Pedestal (MOA 8).

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