A University of Georgia Extension plant pathologist is urging Georgia peanut farmers to plant a month earlier next year to keep the threat of tomato spotted wilt virus (TSWV) at bay. In 1997, TSWV caused widespread damage to Georgia’s peanut crops. Peanut yields suffered, and the value of the state’s crop was reduced by more than 10 percent. The virus’ impact continues to be felt in 2014, according to UGA researcher Bob Kemerait, who’s based on the UGA Tifton Campus.
He worries that growers have become “complacent” in the fight against the disease.
“The fact that we’re seeing an increase in spotted wilt does not suggest to me in any way we’re going to go back to that period of time (in the late 1990s). What it does do is point out two factors: the first thing is that the disease, which has been quiet for a number of years, has not gone away. It’s still there. Second, and more importantly, as growers plant more resistant varieties, they’ve become complacent in the production practices important to minimizing the risk, and they could get bit by this in the future,” Kemerait said.
TSWV dates back almost 40 years, when it was discovered in peanuts in Texas. It was later found in Louisiana and Alabama. In the 1990s, the virus was detected as a major problem in Georgia-grown peanuts, vegetables and tobacco.
Through resistant cultivars developed at UGA by peanut breeder Bill Branch, the virus’ impact on peanuts was minimal over the next decade. For the last couple of years, though, TSWV appears to have been more severe in peanut fields, and Kemerait is unsure why.
“In the past couple of years, we’ve seen an increase, certainly not to the level it was in 1995 or 1997, but I’m seeing more and getting more reports from growers of tomato spotted wilt virus. We’re not exactly sure why,” Kemerait said. “It’s something we’re aware of. It’s something we’re cautious about.”
Managing TSWV is not as simple as controlling thrips, the tiny insects that transmit the disease. “Managing the thrips through the use of insecticides is not going to reduce severity of tomato spotted wilt,” Kemerait said.
To reduce the virus’ impact, UGA Extension recommends peanut farmers plant in May next year rather than in mid-April, as earlier planted peanuts are more likely to be infested by thrips. Also, planting peanuts at greater plant densities reduces the incidence of the virus, so increased seeding rates are encouraged.
“As an Extension specialist with the University of Georgia, my message and the message of the county agents is: Don’t forget that spotted wilt is out there. Don’t forget that it can affect your crop, and make sure you continue to take steps to reduce the risk,” Kemerait said.
For more information about TSWV in peanuts, see tomatospottedwiltinfo.org.
By Clint Thompson
University of Georgia, College of Agricultural and Environmental Sciences