Thrips Cocktail for the Last Two Years
of the 20^th Century

In 1997, I wrote an Ohio Florists' Association Hotline called Thrips "Cocktail", outlining a pesticide rotation program for controlling western flower thrips on greenhouse ornamentals. As we enter the last two years of the 20thCentury, it seems appropriate to take another look at this rotation and make modifications where necessary.

I. The rotation suggested in 1997, along with some comments, is listed below:

A. Apply a tank mix of Avid (8 oz/100 gallons) + Azatin (10 to 16 oz/100 gallons). Reapply after five to seven days. Note that Avid is not registered for control of western flower thrips (or any other thrips, for that matter), but greenhouse ornamental plants are listed. In most states it is legal to use a pesticide against a non-labeled pest, as long as the site (plant in this case) is on the label. The manufacturer (Novartis) has discouraged the use of this product for controlling pests that are not on the label, as a part of their pesticide resistance management program. However in this case the horses are already out of the barn (way out). Adding horticultural oil (e.g. Sunspray) at 0.5 - 1% by volume will increase the activity of Avid. In this case, it is not necessary to use Azatin in the mix.

B. Five to seven days after the applications in (A), apply a tank mix of Thiodan 50WP
(1 lb=1 bag/100 gallons) + a Pyrethroid (e.g. Decathlon, Talstar, Tame - at suggested label rates). Reapply after five to seven days. Note that thrips are not on the Thiodan label, but greenhouse ornamental plants are listed. As in the case of Avid, it is legal in most states to use Thiodan to control non-labeled pests on labeled crops.

C. Five to seven days after the applications in (B), apply Mesurol 75WP (8 to 16 oz/acre). Reapply after five to seven days.

D. After five to seven days, repeat the cycle, beginning at step one.

II. The above rotation has been effective for most growers. Different chemical families are applied each time. The products are still on the market as this is written. However, there are other older and newer products that should be considered as additions or substitutions to the rotation. Here are some other suggestions. Others may have their own favorites.

A. Conserve SC (6 oz/100 gallons). Repeat after five to seven days. Conserve is a new product for the greenhouse market, and has been very effective against western flower thrips.

B. Beauveria bassiana (BotaniGard or Naturalis-O (label rates). Make at least three applications, five to seven days apart. Use when thrips numbers are low. A tank mix with Azatin may be more effective.

C. Fenoxycarb (Precision 25 WP, 2-4 oz/100 gallons, or Preclude Total Release Aerosol, rate depending on can size). Repeat after seven days.

D. Dycarb 76WP (12-20 oz/100 gallons). Reapply after seven days.

E. Carzol 92SP (8 oz/100 gallons). Reapply after five to seven days. Carzol is registered only in Ohio, Indiana, Utah, North Carolina and South Carolina.