ThryvOn technology shows promise for controlling thrips and plant bugs, according to research from the University of Arkansas System Division of Agriculture.
Gus Lorenz, Distinguished Professor and Extension Entomologist for the University of Arkansas System Division of Agriculture, discussed cotton insect management, during the Arkansas online Cotton Production Meeting.
Tobacco thrips have confirmed resistance to thiamethoxam (Cruiser), and there is testing for acephate resistance as well.
"We know there is a problem with acephate resistance, and it's something we're going to have to deal with," Lorenz said. "Acephate is one of the products we use a lot when we have to make foliar applications for thrips because it's cheap and it's effective, but we may be quickly getting to the point where it's not going to work for us anymore. This is something we need to keep in mind as we're going into 2021.
"The exciting thing I want to talk about is the difference we're seeing with this new ThryvOn technology. ThryvOn is another gene like Bollgard 2 and Bollgard 3. It's a gene that gives protection to the cotton plant for thrips and plant bugs."
Plots from a 2020 trial show little to no thrips on cotton with the ThryvOn technology despite having no insecticide seed treatment.
"The technology will have some limited release this year, so some will have the opportunity to try out this technology," he said. "So far, we like what we're seeing with thrips control."
In two large block trials (20 acres) in Tillar and Marianna, Ark., they compared ThryvOn cotton with conventional cotton, which showed a substantial reduction in thrips numbers compared to conventional cotton.
"Sometimes, when we make a transition to new technology, going from a small plot to a large plot, there may be differences in the level of control we see," Lorenz said. "In this situation, particularly for thrips, we saw a good amount of control in our large plots in Tillar and Marianna, like what we have seen in our small plot trials.
"Another plus with this technology is the control for other insect pests. It not only provides good enough control where we won’t have to make foliar applications, which saves money, but it also helps avoid secondary problems like spider mites and aphids."
Tarnished plant bugs
In trials, ThryvOn technology also helped to control plant bugs.
"When you look at the data from 2019 for plant bugs, we compared conventional cotton to the Lygus Transgenic cotton," Lorenz said. "We had an unsprayed check at a threshold treatment of three per five-row feet, and a 2X threshold of six plant bugs per 5-row feet.
"The test indicated with the Lygus Transgenic that you don't have to spray weekly with this technology to get a good level of control for good yields."
Over the past several years, when comparing ThryvOn to conventional cotton, there is a trend for a yield increase with this technology over the conventional cotton, regardless of the spray regime.
"In 2020, we looked at a large block trial to see how the trends we had already seen with the technology were holding up," he said. "Generally speaking, there were considerably fewer plant bugs in the cotton with the ThryvOn trait versus the cotton with no trait."
Last year, they averaged three applications on the cotton with the trait and four applications on the cotton with no trait.
"The cotton with the trait had fewer plant bugs, regardless of spray application," Lorenz said. "In most cases, the trait alone is providing a level of control season long, which is what we like about this technology.
"There is a good yield response with the trait compared to the no trait. I hope a lot of producers get the opportunity to evaluate this technology in 2021. We feel like it provides a good level of control while saving about one to two spray applications a year, depending on how severe the plant bugs are.
"Overall, when we look at our square retention data, the traited cotton is holding squares better. Regardless of how many plant bugs are out there when we look at the square retention, it is good."
Another plus to this technology is it provides growers some cushion between plant bug applications.
"If it rains and you can’t get in the field to spray, you have a little cushion to make an application later when you can get in the field," Lorenz said. "If you're a few days late on conventional cotton when you have bad plant bugs, it is going to cost you. With this technology, it is going to give you a little more time. Another plus to this technology is it appears there is no yield lost associated with adopting the technology as we’ve seen happen in the past."