Thrips are proving to be a reliable early season insect pest for Georgia peanut producers, and researchers are working with the state’s farmers to find effective treatment options.
Some of this research was reviewed during this year’s Georgia Peanut Tour on the Bulloch County farm of Greg Sikes, near Savannah in the southeast portion of the state.
Sikes, who has been farming for about 16 years, has 7,000 acres in production, including 2,200 acres of peanuts, 4,200 acres of cotton, and the remainder being a balance between cotton and peanuts.
In trials on his farm this year, Sikes planted the Georgia-06G variety in single rows with Thimet and in double rows with imidacloprid – a liquid in-furrow treatment versus a granular in-furrow treatment.
“The reason we’re doing that is the easy application of the imidacloprid,” says Sikes. “We’re already going with a liquid in the furrow for an innoculant and a fungicide, and it’s a lot easier to put the material in there with those and take care of everything at one time than it is to try and put out a dry product through a different hopper box.”
Imidacloprid is much safer to handle and easier to use, says Sikes. “This year, the thrips pressure was pretty heavy, and we saw results from both treatments. I don’t know if I can say right now if one was better than the other. Twin-row equipment is much more expensive to run, but we get faster coverage with twin rows and less weed pressure. We also get better peanut hay quality, and we have a lot of peanut farmers in this area who use peanut hay to feed cattle,” he says.
Tiny but formidable foe
Thrips are tiny insects, so tiny that you probably wouldn’t know it if they were lighting on you, says Mark Abney, University of Georgia Extension entomologist. But growers shouldn’t underestimate their impact on peanuts. Thrips move in huge migrations in the spring, and they go to the peanut plant just as it is coming out of the ground.
There are two problems that thrips can cause, says Abney. One is tomato spotted wilt virus, which could have devastated the peanut industry if not for resistant varieties.
“Thrips is the only way in which that virus is spread. Even though thrips are in the field and transmit the disease, resistant varieties can still make a good yield,” he says.
But thrips do more than just transmit the virus, notes Abney. “When they suck on the plant juices, they stunt the plant, and you’ll end up with very small plants. They do that in the first four weeks of the plant’s life, when you’re trying to get the plants up and make a crop, and that could have an impact later in the season.”
For many years, he says, growers used Temik to control thrips in peanuts. While it was very effective, it also had the highest mammalian toxicity of any pesticide used in agriculture.
“So we’re forced to come up with some new technologies for controlling thrips. We’ve got some other granular products like Thimet that also are very effective. But growers don’t necessarily love handling granular products, so we’re looking at other options.”
One of these options, says Abney, is to use a liquid product in-furrow like imidacloprid
“This is a neonicotinoid insecticide. This class of insecticide has received a lot of press lately, and most of it hasn’t been good. It has low mammalian toxicity, but there’s some concern about its effect on honey bees. But potentially, it’s a very good way for growers to control thrips. It’s up-front in the furrow, and then we don’t have to worry about it anymore. We’re also looking at seed treatments for thrips control. These could help the grower to increase efficiency. But we’re not at 100-percent effectiveness with those technologies. We still have to come back and make foliar sprays.”
Abney says 2014 was an active year for insects in Georgia peanuts. Much like 2013, thrips pressure was seen early. Then, he says, growers went straight from that to some caterpillar problems that were higher than normal this year.
Two insect pests that have been really problematic for growers this year have been lesser cornstalk borer and two spotted spider mites. “Those are probably the two most important pests we have had in Georgia. They are not a pest every year but when they are it can be really problematic,” Abney says.
“We have spent a lot of money and heartache trying to control those two pests.” Both pests are very difficult to control especially in non-irrigated fields with the hot and dry conditions we have seen in 2014, he adds.