Early season, severe thrips damage can open the door to reduced yields for peanuts and increase the risk for tomato spotted wilt virus. Peanut growers must protect peanut plants against thrips when necessary, and here’s a discussion on the most-popular ways they do it.
“No matter what thrips management tactic is chosen, scouting is still a good idea. Nothing provides 100 percent control 100 percent of the time. The only way to know if a problem is developing is to monitor fields regularly,” said Mark Abney, University of Georgia Extension peanut entomologist.
Abney says there are several ways peanut farmers go about managing thrips, but he talks about the four most-common ways peanuts farmers have gone after the tiny insects in recent years.
1) Phorate (Thimet 20G) in furrow: Decades of data show Thimet does a good job of reducing thrips injury, plus it can also reduce the incidence of tomato spotted wilt virus. Thimet is an organophosphate. As with all pesticides, growers need to read and follow label instructions carefully, Abney said. Thimet does cause some phytotoxicity, commonly called “Thimet burn,” on peanuts, but the injury isn’t associated with yield lose. Growers concerned about TSWV know the risk of infection is highest in peanuts planted before May 10. “Using Thimet on early planted peanuts will provide some reduction in risk,” he said.
2) Thiamethoxam (CruiserMaxx Peanut) seed treatment: Thiamethoxam is the active ingredient in CruiserMaxx Peanut seed treatment. Moderate to severe thrips feeding injury has been seen on thiamethoxam-treated peanut when thrips pressure is high. Abney does not currently recommend an automatic foliar insecticide application for thrips on CruiserMaxx Peanut, but he does highly recommend soon after seedling emergence that growers regularly scout fields for adult and immature thrips Reproducing thips in a field can signal the need for a foliar insecticide application. Thiamethoxam does not reduce the risk of tomato spotted wilt in peanut.
3) Imidacloprid (Admire Pro, Velum Total and various generics) liquid in-furrow: Imidacloprid applied as a liquid in the furrow at planting has given good control of thrips in trials at University of Georgia and other Southeastern universities in recent years, he says. Imidacloprid has been shown to be compatible with most liquid inoculants and fungicides but not all combinations of products have been tested. Like thiamethoxam, imidacloprid will not reduce the risk of tomato spotted wilt in peanut.
Abney asks that growers pay close attention to the formulation of the product they plan to use. Rates vary by formulation.
“Applying a 2F product at a 4F product rate will result in significantly less active ingredient than the label recommendation. Velum Total contains both imidacloprid and an active ingredient targeting nematodes,” he said. “Growers who want to use imidacloprid for thrips but who do not have a nematode problem do not need to invest in the additional AI, but should choose a stand-alone imidacloprid product.”
Farmers should also be aware of resistance issues with the neonicotinoid class of insecticide. “Populations of tobacco thrips with reduced susceptibility to neonicotinoids have been documented. But not much has changed with imidacloprid in my mind. There were some fields last season, both research and commercial, where efficacy against thrips seemed to slip compared to what we have seen in the past, but overall, I do not think there were many problems. We will continue to monitor the efficacy of the neonics in 2017,” he said.
4) Acephate (Orthene) foliar spray: Orthene will still kill thrips, and Georgia peanut farmers use it pretty steady when at-plant insecticides “run out of steam … The problem associated with leaving off an at-plant application in favor of a foliar spray alone is timing,” he said, noting, again, scouting is key to know when to pull the trigger with this thrips approach.
“Given the hectic schedule of most growers in the spring and the potential for unfavorable weather,” he said, “being able to cover large acreage with a foliar application is a gamble most growers should avoid.”
The peanut market is not facing an oversupply and the market situation now is pretty tight as peanut farmers begin to make final planting decisions for the 2017 season. Peanut contracts are not great but decent, with offers going for $450 to $475 per ton or a bit better on partial production. But other commodity prices will continue to be down in 2017. With that, farmers of all stripes might look for creative ways to cut costs.
“We need to be sure not to cut labeled rates in an effort to save money. Reduced rates will likely lead to reduced efficacy and can ultimately cost more in supplemental treatments or lost productivity,” he said.