Looking to minimize the effects of tomato spotted wilt virus (TSWV), peanut farmers in the Virginia-Carolina region might want to use a combination of practices to reduce their risk to the virus.
Before heading to the field with peanut seed this spring, consider the variety, plant population, at-plant insecticide application, row pattern and tillage you use to lessen the risk to the virus.
While noting that TSWV cannot be prevented, specialists in the region are recommending the same systems approach as developed in Georgia in the mid-1990s. The virus is vectored by thrips.
The system uses individual practices to reduce the cumulative risk to serious problems with the virus.
“One point needs to be made up front,” says Rick Brandenburg, North Carolina State University Extension entomologist. “We cannot prevent tomato spotted wilt virus in peanuts. All we can do is use several approaches to minimize its impact.”
The virus had already got the attention of researchers before it increased dramatically late in the season in North Carolina and Virginia. Researchers stepped up their efforts to find ways to manage the virus.
By evaluating the practices recommended in Georgia, researchers in North Carolina hope peanut farmers will be better able to manage the virus in the coming year.
Asked to describe the recommendations at grower meetings over the winter, Brandenburg and David Jordan, North Carolina State University Extension peanut specialist, used the word “cautious.”
Variety plays the largest role in reducing the risk of TSWV, Brandenburg says.
NC-V 11 has more resistance to the virus than NC-9. Recent studies show Gregory and VA-98R to have reasonable resistance to TSWV.
Under light TSWV pressure, Perry, the new release from North Carolina State, demonstrates resistance to the virus; however, under heavy pressure, the new variety has a high incidence of TSWV.
Because of a later-than-usual infestation of thrips in 2001, V-C planting date studies didn't give researchers much confidence. In Georgia's TSWV Risk Index, early-planted peanuts, as well as later-planted peanuts, showed more risk to serious TSWV infestation. The V-C narrow window of opportunity makes the planting date less of a factor. Experts are, however, recommending avoiding early planting.
In studies, seeding rate and row spacing had a positive effect on reducing the risk of TSWV, Brandenburg says. Twin rows offer an advantage over single rows.
As has been documented before, reduced-tillage peanuts have less incidence of the virus. A reduction in tillage equates to a reduction in thrips, Brandenburg says.
In-furrow or at-plant insecticide use of Thimet showed less incidence of the virus when compared with Temik, Brandenburg notes. “Our studies show that trend, but we need more studies before we can make a recommendation.” Follow-up insecticide treatments didn't reduce the virus, however.