STARKVILLE, Miss. (DTN) -- A limited, stewarded introduction of a new Bt cotton trait that targets thrips and tarnished plant bugs will occur this year as the product awaits approval from some export markets.
Tim Dabbert, Bayer cotton traits and agronomic systems manager, said ThryvOn cotton has received full approval from regulators to be planted in the United States. However, some countries haven't given the product stacked with Bollgard 3 with XtendFlex Technology the OK yet.
Dabbert is hopeful for a full commercial launch in 2023. This year, though, he expects plantings to be similar to 2021 at 4,600 acres as part of a stewardship program with select growers. Limiting acres keeps production manageable to ensure ThryvOn cotton is only used domestically and out of export channels. It also gives the company more data on the cotton trait's effectiveness.
"It's an exciting new product we're working to get on the market as soon as we can," Dabbert told farmers and ag industry officials last month at the Mississippi State University (MSU) Row Crop Short Course in Starkville, Mississippi.
Based on ThryvOn studies by researchers at MSU and the University of Arkansas, the Bt trait does a good job mitigating damage and yield loss from the insects it is engineered to control. Data suggests the number of foliar applications to combat the pests may also be reduced. Recent research findings on ThryvOn, including thrips and tarnished plant bug efficacy and management, were released at the row-crop short course.
The cotton Bt trait, MON 88702, expresses the protein mCry51a2. It targets tarnished plant bugs, western tarnished plant bugs, tobacco thrips and western flower thrips. All the pests are costly to cotton growers. Multiple foliar insecticide treatments -- on average, each treatment costs about $20 per acre, according to researchers at the conference -- are often needed to provide effective control of the pests. An MSU study estimated thrips and plant bugs cost cotton growers a combined $242 million in 2018 in control and yield losses.
While ThryvOn works well, Dabbert said it's not 100% effective. Farmers still must scout fields and spray insecticides when needed.
"It's very important for people to know how it works," he continued, referring to its efficacy and that crop scouting and other pest control measures will likely be needed.
Dabbert declined to provide a price estimate for ThryvOn cottonseed when it's fully launched but noted it will be competitive with other traited seed.
Here's ThryvOn research highlights from the MSU conference.
THRIPS RESEACH: Whitney Crow, MSU row-crop entomologist, said thrips are responsible for $6.5 million of economic loss in cotton in Mississippi. Two years of research at two locations in the state on the efficacy of ThryvOn on mitigating plant injury from thrips indicates cotton with the Bt trait sustains less damage than cotton without the trait.
Thrips attack and feed on leaves, leaf buds and very small squares. The pests can stunt plant growth, reduce yields and even cause plants to die.
MSU rates cotton injury caused by thrips in research plots on a scale of zero to five. Zero is no damage to plants, three is unacceptable damage to plants and five is plant death.
MSU research indicates ThryvOn cotton at the two-leaf stage with an insecticide seed treatment had an average injury rating in research plots of about 0.6, and the trait only was about 0.8. Non-ThryvOn cotton with an insecticide seed treatment and without a seed treatment had an average injury rating of about 1.2 and 2.8, respectively.
At the 3.5 leaf stage, the thrips injury rating in research plots for ThryvOn cotton (with and without a seed treatment), were both between 0.5 and 1. Non-ThryvOn cotton with a seed treatment had an injury rating of about 1.2. The injury rating for cotton with no trait and no seed treatment was about 3.3.
"We know from this research that there are fewer thrips associated with ThryvOn technology ... and minimal damage. But they are still present," Crow said. "So, you need to keep that in mind as we move forward. They will still be present with this technology."
At this time, Crow said, the Bt trait can effectively control thrips.
"Going forward, Mississippi State does not recommend making any foliar applications on ThryvOn (for thrips)," she said. "Hopefully, it will eliminate the need for foliar applications."
PLANT BUG RESEARCH: Ben Thrash, University of Arkansas Extension row-crop entomologist, said research indicates ThryvOn technology reduces plant bug damage compared to cotton without the trait. Thus, square retention is better, which can lead to better yields.
Recent studies near Marianna, Arkansas, showed season total square retention for ThryvOn cotton averaged just over 80%, while non-ThryvOn cotton averaged a little more than 60%. At plots near Tillar, Arkansas, the retention gap narrowed quite a bit with ThryvOn still on top with about 82% compared to about 78% for non-ThryvOn.
"I think that really tells the story about ThryvOn," Thrash said. "Looking at our unsprayed fields for ThryvOn versus non-ThryvOn, we had about a 1,000-pound-per-acre yield benefit for ThryvOn."
The Bt trait helps control plant bug nymphs but not adults, although some researchers speculate adults will avoid ThryvOn cotton. Spraying to control adult plant bugs in ThryvOn cotton when economic thresholds warrant will be needed, but research indicates less applications are likely compared to cotton without the trait.
In a recent study that examined spray application frequency for plant bugs versus profit on ThryvOn and non-ThryvOn cotton, Thrash said two insecticide applications were profitable for ThryvOn, and spray applications three through seven were not. In non-ThryvOn cotton, profit potential incrementally increased from the first spay application to the fifth before profit potential started to decline.
"For the ThryvOn cotton, we really weren't seeing a yield benefit for the cost of application after the second shot," Thrash said, noting profit potential was as good or better with less spray applications on ThryvOn cotton compared to non-ThryvOn.
MSU Extension Entomologist Angus Catchot added, "You're going to save a spray or two, and sometimes more (with ThryvOn), depending on the plant bug pressure and where you are located."
OBSERVATIONS OF INTEREST
-- If fewer insecticide applications are needed for ThryvOn cotton, Thrash anticipates less resistance to insecticides in the future. Tarnished plant bugs, for example, have shown resistance to the insecticide acephate.
-- Thrash said some insecticides may become more effective when used on ThryvOn cotton.
-- ThryvOn cotton yielded higher than non-ThryvOn cotton in most studies, researchers report.
-- Catchot said ThryvOn cotton will give producers more time to spray for plant bugs when needed, which could result in more timely applications. "It'll allow a little more slop in the system with no penalty for yield. I think that is really important," Catchot continued.
PLANT BUGS AND COTTON 101:
Cotton is susceptible to tarnished plant bug injury during the early squaring period. Tarnished plant bugs use their piercing-sucking mouthparts to feed on squares, flowers and young bolls. Small squares and bolls that have been injured will often shed from the plant, leading to reduced yield potential or delayed crop maturity. Learn more at www.cottoninc.com/cotton-production/ag-research/entomology/plant-bugs/.
THRIPS AND COTTON 101:
Thrips are slender, straw-colored insects about 1/15 inch long, with piercing-sucking mouthparts. Adults are winged and capable of drifting long distances in the wind. They attack leaves, leaf buds, and very small squares, causing a silvering of the lower leaf surface, deformed or blackened leaves, and loss of the plant terminal. Read more at https://cottonbugs.tamu.edu/….
Read a DTN story about the USDA deregulation of ThryvOn cotton at www.dtnpf.com/agriculture/web/ag/crops/article/2021/01/20/usda-deregulates-new-bt-cotton-trait.
Learn more about ThryvOn cotton at https://traits.bayer.com/….
Matthew Wilde can be reached at firstname.lastname@example.org
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