By Vicky Boyd
University of Florida researchers admit they still don’t know much about a new tomato disorder that first appeared in the state in 2006.
But they say they do know what tomato purple leaf disorder isn’t.
“The only thing we’ve really ruled out definitely is it’s nothing associated with chemical application, and it’s totally independent of nutrition,” says Gary Vallad, an assistant professor of plant pathology based at the Gulf Coast Research and Education Center in Balm, Fla. “And as far as we can tell, there’s no environmental cause—it’s definitely not ozone.”
Regardless of the cause and possible vectors that transmit it, Vallad recommends that consultants and growers keep their eyes peeled for the problem. If they suspect they see it, they should report it to their county Extension agent or contact him at email@example.com or (813)634-0000.
Charlie Mellinger, a principle in the Jupiter, Fla.-based Glades Crop Care, says he and his team of consultants are doing just that in the Homestead and Immokalee areas, where they scout fields.
“We haven’t seen it in the Homestead area this season,” says Mellinger, a plant pathologist. “We’ve seen a few plants here and there in the past but not nearly the size of the problem that seems to have occurred in the Palmetto and Ruskin areas, where it was originally identified.
“We’re keeping our eyes open for anything new and potentially problematic.
That’s why we need to stay alert—just in case it turns out to be yield grabbing, we don’t want to be surprised.”
Bob Gilbertson, a University of California, Davis, professor of plant pathology, says Western pest control advisers should take a similar approach.
So far, the disorder appears confined to Florida. But Gilbertson says PCAs should be on the lookout for it as well as a new ilarvirus first reported during the 2008 season. The ilarvirus was found in scattered fields from Fresno County, Calif., north to Colusa County.
“If they’re going in to monitor fields for tomato yellow leaf curl virus, this is something they should add to the things they’re looking for,” Gilbertson says of tomato purple leaf disorder. “It’s certainly a reason to minimize the movement of transplants, particularly from places like Florida into California. The jury’s still out on how damaging it is, but it’s clearly something you don’t want to see show up here.”
Purple leaf symptoms
Tomato purple leaf disorder first appeared during the 2006 season in Hillsborough and Manatee counties. It has since spread to Suwannee County and the Miami-Dade area.