- Cool-Season Grass
- Cool-Season Vegetable Crops
- Dry Beans
- Field Corn
- Invasive Pests
Western Flower Thrips
Western flower thrips (Frankliniella occidentalis) is the most common thrips species on cotton in the San Joaquin Valley. This species is becoming more common and widespread across the Cotton Belt and is recognized as a difficult species to control, compared with tobacco thrips and other species occurring in the South. In California, in most years foliar treatments are not needed for thrips. An acephate seed treatment is commonly used to provide ~3 weeks of thrips control. After this period, the combination of vigorous cotton varieties and favorable temperatures allows the plants to outgrow the thrips damage. In some years and locations, a foliar application may be needed to lessen the chances of thrips damage to seedling terminals, which cannot be compensated for by the plants. The plant damage from western flower thrips is similar to that in other states by feeding on leaves and buds and distorting cotton seedling leaves. Only in situations where a prolonged thrips infestation is destroying seedling terminals is treatment generally justified in the SJV.
Field research was conducted at the Shafter Research Station in 2014. Research was done to evaluate the activity against early-season thrips of 1.) registered foliar products, 2.) experimental foliar insecticide treatments, 3.) organic treatments, and 4.) Orthene-treated seed. Field research was conducted on Phytogen 725RF planted on April 22, 2014. The treatments were evaluated in plots four rows wide by 20 ft. long with four blocks in a randomized complete block design. The Orthene seed treatment was applied at planting. The foliar treatments were applied with a backpack CO2 sprayer on May 8, 2014 at 30 GPA. Ten cotton seedlings were sampled from each plot on each of the four “weekly” sample dates starting with the first true leaf stage. Seedlings were inspected in the laboratory and thrips were recovered using a dissecting microscope or with a washing technique; numbers of thrips (immatures and adults) were tabulated. In addition, the heights of five seedlings, wet and dry weights of the above-ground plant and the roots were obtained per plot on four dates (once per week). Thrips damage was rated on 6 June as follows:0=no injury, 1=10% injured leaves, no bud injury, 2=25% injured leaves, no bud injury, 3=75% injured leaves, 0-25% bud injury, 4=90% injured leaves, >25% buds injured, 5=dead plants.
Click here for more details and the results from this 2014 study.