The expression of Tomato Spotted Wilt Virus comes from a combination of factors.
⋅ BY AMANDA HUBER ⋅
In 2022, losses to Tomato Spotted Wilt Virus were estimated at 7% across the Southeastern production area. It’s as great a loss as has been estimated since 1997.
“For every 1% of TSWV in the field, that’s 20 pounds per acre yield loss,” says Scott Monfort, University of Georgia Extension peanut specialist.
Factors For TSWV Increase
The increase in spotted wilt has researchers looking at the various factors that are part of the reason why.
“It could be that we do not continue to plant the same amount of acreage early in the planting season, before May 1, because we don’t have the varietal resistance to support it,” Monfort says.
Another factor is shortened rotations. Scott Tubbs, UGA systems agronomist, says, “As we shorten rotations, that’s going to exacerbate all kinds of problems. Continuous peanut or even an every-other-year, or 2-year, rotation certainly affects disease pressure.”
Another reason could be attributed to the warmer spring that allowed for earlier thrips pressure. However, just as there is no one cause for the increase in TSWV, it is a combination of factors that can help reduce spotted wilt in the field.
Risk Factors Haven’t Changed
Bob Kemerait, UGA Extension plant pathologist, says, “This was a perfect season to show that if you stepped outside of PeanutRx, as the Peanut Disease Risk Index is known, you are going to see more spotted wilt in the field. It’s not just if you used Thimet, if you changed the planting date or if you planted that one certain variety choice. It’s a lot of different factors.
“A lot of times, if I have a call for spotted wilt trouble in the field, I can look at it and, going through the factors in PeanutRx, I can often pick out the factors that may have contributed to the problem. It is often the same with leaf spot and white mold, which are also part of PeanutRx.”
No Single Solution Coming
UGA Extension entomologist Mark Abney says, “These factors have been identified for a while now, and there’s nothing coming down the pike to take their place. If you want to reduce spotted wilt, these are the practices you can follow.
“Essentially, there’s no ‘one thing’ you can do to reduce spotted wilt.”
Although the level of TSWV is cyclical, researchers say, it has been increasing with 2022 being a year of more significant pressure.
The 2023 Peanut Disease Risk Index included research from the University of Georgia, University of Florida, Auburn University, Mississippi State University and Clemson University.
Changes from the 2022 version can be found in the cultivar/variety section of Peanut Rx. Pay attention to all the factors or at least a combination of factors to reduce the impact of TSWV in the field. PG