Most larger scale onion growers in the region are already familiar with Dr. Brian Nault's insecticide sequence recommendations for onion thrips management. However, more products have been registered in New York in the last few years that provide alternative options for conventional thrips management (specifically Exirel and Minecto Pro). It's worth keeping in mind that Dr. Nault's recommendations are based on two primary principles:

• Scouting and only spraying at threshold: The days of calendar sprays are long gone. Given the cost of some of the newer chemistries used for thrips management, growers must scout fields and confirm that thrips populations have reached a level of at least an average of 1 thrips per leaf before spraying. Spraying before thresholds are reached not only weakens the resistance management strategy (see point 2), but also cuts into grower profits by unnecessarily increasing the number of insecticide applications each year.

• Resistance management: Onion thrips produce multiple generations each year. They also develop resistance to insecticides more readily than other pests that reproduce more slowly.  One of the goals of the recommended insecticide sequence is to avoid exposing multiple generations per year to the same insecticide. By avoiding the exposure of multiple thrips generations to the same active ingredients in the same year, growers can help preserve the useful life of insecticides that are effective at managing thrips.

The chart that follows outlines several different insecticide sequences developed by Dr. Nault for growers to follow depending upon the severity of thrips pressure in the field. It should be noted that, as indicated below, Minecto Pro is a pre-mix of the same active ingredients found in Agri-Mek and Exirel, so it should NOT be used in sequence with those products. Addtionally, almost all of the insecticides listed in the chart should be used with a non-ionic penetrating surfactant, such as Dyne-Amic or LI700. Only Warrior and Lannate are compatible with spreader-sticker type adjuvants. Since Bravo Weatherstik is formulated with a sticker, it should NOT be mixed with Movento, Minecto Pro, Radiant, Exirel, or Agri-Mek.

This article was published in the June 7th 2018, ENYCHP Vegetable News.  Click here to view the full newsletter.