Below are a few words from Mark Abney, UGA Peanut Entomologist, about managing thrips in peanut.
As usual, thrips management will be the first insect issue peanut growers face in 2018. These tiny pests will be present in virtually every peanut field in the state, but the severity of infestations will vary from field to field based on several factors. An online tool that predicts the intensity of thrips pressure is available from NC State University https://climate.ncsu.edu/cottonTIP , and weekly thrips trapping data from Georgia are also available online from April to June https://site.extension.uga.edu/peanutent/ . While not perfect, these tools can help growers make informed decisions about best management tactics for thrips.
Most growers in 2018 will use either phorate (Thimet) or imidacloprid (Admire Pro or others) in furrow with the seed. Both of these treatments kill thrips, and each has its own set of plusses and minuses. Thimet is the only insecticide available that has been proven to reduce the risk of Tomato Spotted Wilt (TSW) in peanut. This disease is transmitted by thrips, and fields planted prior to 10 May are at increased risk of infection. Aldicarb (Ag Logic 15G) will go out on some peanut acres in 2018. This product has looked very good from the standpoint of reducing thrips injury in UGA small plot trials, but growers should be reminded that aldicarb will not reduce the risk of TSW.
CruiserMaxx Peanut is still available in 2018, but use will be limited. This seed treatment is very convenient for growers, but a foliar application of acephate (Orthene) is needed to prevent thrips injury if insect pressure is moderate to high. Growers who use CruiserMaxx Peanut or choose not to apply any in-furrow insecticide to peanuts planted prior to mid-May should plan on making an acephate application within the first 20 days of planting. There continues to be a small percentage of growers who do not use any at-plant insecticide for thrips management. I do not recommend omitting an at-plant treatment on any fields planted prior to 10 May. The thrips prediction model and population monitoring websites mentioned previously can help growers make adjustments to their thrips management tactics as the planting season progresses.
No insecticide will provide 100% control 100% of the time. You will likely get calls from growers who used an at-plant insecticide and have what they consider to be unacceptable levels of damage. If the field was treated with Thimet, look for signs of “Thimet burn”. There has been more than one case where a grower thought Thimet was applied only to find out later that a mistake was made. Mistakes with imidacloprid or aldicarb will not be as easy to diagnose. When trying to determine the cause for severe thrips injury consider when the peanuts were planted, the uniformity of injury (is there a pattern that indicates clogged nozzles or blocked tubes), activity in surrounding fields (mass migrations of thrips from maturing wheat fields can overwhelm insecticides) and the formulation and rate of the product used. Keep in mind that sometimes there is no good answer…stuff happens.
The good news is that peanut can and routinely does compensate for early season thrips injury. You can be pretty confident when you tell a producer that if growing conditions are favorable, he or she can still make very good yield in spite of thrips injury.