Asian soybean rust has now been confirmed in Alabama and Georgia, putting the dreaded disease in at least five Mid-South and Southeast states. Samples from Florida, Louisiana and Mississippi have previously tested positive for the fungus.
Alabama Agriculture Commissioner Ron Sparks said state crop specialists had pulled a suspicious soybean sample from a field in Mobile County that tested positive for the rust last Friday.
Three days earlier, a county Extension agent in extreme southwest Georgia found the disease in some soybeans nearing harvest. It was only the first of many suspicious samples pulled in the state.
“When we first reported these samples, a USDA survey team official came down to work with our agronomists,” says Bob Kemerait, Georgia Extension plant pathologist. “He was taken across the soybean production area around the coastal plain – from the southwest corner of the state towards the Savannah River.”
While it hasn’t been confirmed through the USDA yet, “Our diagnostician suspects, based on samples brought in, that we’ve got this rust in a wide swath across the coastal plain,” says Kemerait. “In fact, in most places it was looked for, it was found.”
The rust hasn’t been confirmed on Georgia kudzu yet. However, a sample from Seminole County looks “very likely” to be infected.
“The initial discovery was on some leaves that were almost completely dried down,” says Kemerait. “The agent, though, was very attentive and was able to pick through the leaves and find it. Later, the disease appears to have been found on some volunteer soybeans. We’re waiting for confirmation on that. Also, there are some suspicious double-cropped beans following sweet corn. Those beans aren’t as dried down as those planted earlier. We’re finding signs of the rust in those as well.”
Calling it an “incredible coincidence,” on Nov. 9, Kemerait was part of a training session on Asian rust for county Extension agents. The next day, “We were having another round of meetings over breakfast, and I got a call saying rust had been found in Louisiana. I’d said during training the day before, ‘We expect it will show up next year.’ Well, it was a little earlier than that.”
The big question Kemerait is being asked: How is Asian soybean rust being found in so many different scenarios and areas in the state so late in the year?
“The first thing, based on the where it, is we believe it came in on a hurricane. Second, we had numerous hurricanes and storms pounding us in a short time period. That kept us out of the field. When growers were able to get back in the field – and soybeans are a fairly minor crop for Georgia – it was time for picking peanuts and harvesting cotton.
“Third, soybean rust symptoms late in the year are almost exactly what growers were expecting to see from a healthy crop – drying down and defoliation. Had it been earlier, there would have been red flags and we’d have been more concerned.”
The biggest concern for Georgia, says Kemerait, is the portion of the state’s 250,000 soybean acres grown on marginal land. “In the absence of a resistant variety, will the bottom line allow beans to be grown? The profit margin is already tight on those fields.”