Following identification of tomato noticed wilt virus (TSWV) in Alabama and Georgia in 1986, peanut manufacturing within the Southeast confronted an unprecedented risk.
“TSWV was the worst virus in peanuts in the Western Hemisphere,” says College of Georgia Plant Pathologist Albert Culbreath.
Culbreath, talking by way of Zoom know-how to the 53rd Annual American Peanut Analysis and Training Society (APRES) Convention, held nearly for the second yr in a row July 12-16, provided a timeline for the event, unfold and administration of the possibly devastating virus.
He says the an infection timeline in U.S. peanuts started in South Texas. “It was identified in South Texas peanuts in 1971.”
He says Western flower thrips, a vector for the virus, confirmed up in Georgia in 1980. The virus was detected in Mississippi in 1983 and by 1985 South Texas peanut producers reported 50% losses to TSWV. “Some fields recorded 100% losses,” Culbreath says.
By 1990, Georgia producers have been seeing discipline losses to the virus.
Recipe for an infection
Culbreath says manufacturing regimes offered alternatives for the virus to unfold. He calls manufacturing practices within the late Eighties and into the ‘90s a “recipe for severe epidemic.”
Spots on these peanut leaves are signs of Tomato Noticed Wilt Virus. (Photograph by Albert Culbreath)
That recipe included:
- Close to monoculture with 750,000 acres of principally Florunner, a TSWV prone cultivar;
- Introduction of TSWV;
- Massive host vary for TSWV, together with greater than 700 species of vegetation;
- Western flower thrips have been new to the world however tobacco thrips have been endemic.
“A lot of factors came together. We had a rough road for the next few years,” Culbreath says. “In 1997, we saw 12% crop losses to TSWV.”
He says one other issue was early planting. “Much of the crop went out in early April, some in late March.”
Decrease discipline inhabitants can be an element, he provides, and Georgia peanut farmers had reduce on plant populations. “In the absence of spotted wilt, that was possible,” Culbreath says. “Research had shown that reduced seeding rates, especially when they could be planted evenly, was a way to save on production costs without hurting yield. Spotted wilt flipped that.”
A little bit of denial
He says denial additionally performs a job with any new illness risk. “Some tended to believe ‘it’s just another virus and it’s not likely to be a threat.’”
Culbreath says peanut mottle virus, recognized within the Southeast within the Seventies, by no means materialized as a big risk to peanuts. The same state of affairs occurred with the peanut stripe virus recognized in Georgia in 1982.
TSWV was completely different.
“Thrips have a lot of hosts,” he says, providing ample alternative for the virus to thrive. “Tobacco thrips cause unsightly injury to peanut plants, but typically does little real damage, and Western flower thrips do not reproduce on peanuts. As a virus vector, however, thrips are a clear and present danger.”
He says the tobacco thrips is a reliable vector, a long-time pest on peanuts, tobacco, and cotton in Georgia. It reproduces effectively on peanuts and cotton and is lively a lot of the yr in Georgia.
The Western flower thrips, additionally a “competent vector,” was not identified in Georgia till 1980. Identification might have been “coincidental” with detection of Western flower thrips and TSWV. “It is active any time blooms are present on a wide range of plants in Georgia.”
Peanut manufacturing in Georgia is an extended course of, from April to November. “We have little time when peanuts are not present,” Culbreath says. “When we add weed hosts, we have an even more complicated issue.”
Culbreath says the complicated of things favoring thrips and TSWV demanded a tough have a look at manufacturing practices. It took loads of sweat, he says. “That’s how we got here up with SWEAT—Noticed Wilt Eradication Motion Group. We all know TSWV is not going to be eradicated, however we needed to dream huge.
“We have many people, across all disciplines, tackling the problem. The effort includes pathology, entomology, agronomy, weed science, and breeding efforts.”
Southern Runner, launched in 1986, confirmed some resistance to TSWV in Texas, Culbreath says. “It was never widely accepted.”
Georgia Inexperienced was accepted and have become the dominant cultivar within the Southeast. “Georgia Green has moderate resistance,” Culbreath says.
He says Georgia Inexperienced responded to altered practices equivalent to:
- Mid-Could planting date,
- Elevated plant inhabitants,
- At-plant insecticide (Phorate),
- Twin-row sample,
- Decreased (strip) tillage.
“We use a risk assessment index, too,” Culbreath says. ‘It’s a grower device that helps decide greatest actions in an built-in strategy to managing TSWV.
“We saw a significant decrease in losses after we switched to Georgia Green and use of the Risk Assessment Index. One result was that by 2003 less than 2% of the crop is planted before May 1.”
Breeding efforts have been and shall be vital, Culbreath says. “We knew we needed better varieties, so TSWV became a key in breeding efforts. Breeders see great potential to increase resistance from sources of both cultivated peanut and introgression from wild species.”
Culbreath says concerted efforts by a multi-discipline staff made a distinction in TSWV losses. “An integrated management system has been very successful in reducing or preventing TSWV losses. Inter-disciplinary — university, agency, state and company — inter-everything teamwork has been the key.” he says.
He cautions towards complacency, towards assuming, “The tomato spotted wilt problem has been solved. We can take our bows and rest on our laurels…because Bob Kemerait’s (UGA Extension pathologist) phone is still ringing.”
By the numbers
The numbers again up the warning.
“TSWV has not gone away. In 2019 and 2020, we saw an upswing in crop and dollar losses to spotted wilt. We will need to continue emphasizing an integrated approach to managing spotted wilt to buy time until cultivars with higher levels of resistance become available.”
A Navaho saying is suitable, Culbreath says. “Coyote is always out there watching, and Coyote is always hungry.”
He provides, “We have to assume the same about TSWV.”