Western Flower Thrips (WFTs - Frankliniella occidentalis) are often a problem year after year in greenhouse production. They are tough to manage during all crop growing stages, but even more so when crops are flowering. They can be very difficult to control, particularly in flowers and buds due to their preference for tight, dark places. WFTs prefer feeding on pollen, young foliage, flowers and buds. Feeding can cause curled, distorted, puckered and chlorotic foliage. Typically, irregular white spots form, and the leaf surface may appear silvery or have a stippled appearance. New growth and flowers typically are deformed and discolored with feeding scars. WFTs also have the ability to transmit viruses such as impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV).

To reduce the chance of high populations of WFTs resulting in crop injury, start control measures early and use an integrated approach. Listed below are basic thrips control strategies:

§  Inspect new shipments of plants and remove or treat plants that contain thrips.

§  Start with a clean growing area. Old plant material and “pet” plants are a perfect place for thrips to hide out between crops. Remove stock plants and leftover plants from the growing area. These can serve as not only as hosts for thrips but also as reservoirs for viruses spread by thrips. Be sure to control weeds in and around the perimeter of the greenhouse.

§  Screening (opening size < 200 microns) on doors and vents can help prevent thrips from moving into the greenhouse from outside crops or weeds.

§  Inspect crops regularly for the presence of thrips and physical damage caused by their feeding. Use sticky cards to monitor populations early in the crop cycle, before flowers or buds are present. Include Thripline^™ ams pheromone lure from Bioline^™ pest control products with your sticky cards to increase thrips movement, which will provide an earlier and more accurate population assessment.

§  Proper use of chemical controls:

o    Begin spray rotations when populations are low and before flowers or buds are present.

o    First apply products that are effective on adults and immature stages such as Avid^® miticide/insecticide, and then rotate to an insect growth regulator following an appropriate rotational program such as Scimitar^® GC insecticide and Flagship^® 25WG insecticide on foliar-feeding thrips.

o    <