WATER MANAGEMENT – ‘Rust Watch’ Improves Disease Management

Because soybean rust is difficult to see, everyone involved with rust is doing a
better job of scouting for soybean diseases.

By Carroll Smith

May2012ssAfter the mild winter that the Southern states experienced, soybean rust is on everyone’s radar this year. So far, patches of rust on kudzu have been confirmed in Louisiana, Alabama and Florida.

LSU AgCenter pathologist Clayton Hollier said his associate, Patricia Bollich, found rust on kudzu near New Iberia.

“Patricia found several pustules of rust on kudzu in multiple locations at this site and is continuing to monitor it,” Hollier says. “In follow up visits, she has found that each of these locations within the site has spread.”

The Louisiana pathologist notes that even with the mild winter and plenty of moisture, rust is still a big question mark for 2012 for area farmers until we get a little further into the season.

The Southeast weighs in

In Alabama, Ed Sikora, Extension plant pathologist with Auburn University, confirmed that rust has been found in Bay Minette in Baldwin County.

“In addition to the relatively warm winter, we’ve had a mild spring with consistent rainfall and avoided any significant freeze events that would have killed back the kudzu completely,” Sikora says. “So, with the disease present and favorable weather conditions, soybean rust is ahead of where it was at this time in 2011. At this point, rust has the potential to move into soybeans, but is not yet considered an imminent threat. However, we will keep our eyes on it.”

According to University of Georgia Extension plant pathologist Bob Kemerait, there is no rust in Georgia yet that he knows of. He does say, “I will be surprised if we don’t have some moving out of Florida fairly quickly. Rust has been confirmed in kudzu in Quincy just across the Georgia line, and the weather system that brought in cool temperatures during April creates favorable conditions for the movement of rust.

“I tell our growers that the risk of rust is elevated this year over last year because of the very warm winter, which allows rust to survive in areas when it normally wouldn’t have,” Kemerait adds. “We don’t think it is in Georgia yet, but it is close.”

Although most of the scouting has been on kudzu at this point, all of the Southern states have planted or are planting sentinel plots that will be monitored for soybean rust as the season progresses.

Better decision-making

If a silver lining can be found in the threat of a disease, it would be that farmers and consultants are doing a better job of disease management since rust moved into the United States, Hollier notes.

“In general, farmers, consultants, county agents, university personnel and everybody involved with rust is doing a better job of scouting for soybean diseases,” he says. “Because rust is so hard to see, now they are looking at every spot that they weren’t looking at before. Over time, we have seen an increase in our overall state average soybean yield. You can’t attribute this trend completely to disease management, but I think you can attribute some of it to more vigilant scouting for disease and better decisions regarding fungicide applications.

“Everyone is paying more attention to the environment, what the weather is predicted to do and the presence of other fungal diseases besides rust when making their fungicide application decisions,” Hollier says. “In 2012, we’ll probably handle rust the way we’ve always handled it. Scout, then deal with it when we find it.”

Auburn’s Sikora also reminds everyone to visit the Soybean Rust ipmPIPE Web site frequently during the season for updates.

“This Web site (www.sbrusa.net) is the best source for information about soybean rust in the United States and whether it is spreading from the areas where it has now been identified,” he says. “Pathologists are keeping a close eye on the confirmed patches and sending updates to this Web site whenever they see anything change.”

So, for now, the “rust watch” remains in place as farmers continue to get their crops planted and up and growing. And, as Kemerait notes, “If it is as hot and dry as it was last year, soybean rust will be the least of our soybean farmers’ worries.”

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