Crop Updates / News and Information
| 03/05/05 | Soybean Rust Overwinters in Florida
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| Submitted by: Denise Wright
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| Soy Rust Confirmed in Florida 03/01 17:22 By Mike McGinnis DTN Staff Reporter DES MOINES (DTN) - A lab test by Florida state agriculture officials confirmed Tuesday afternoon Asian soybean rust lesions were indeed on a kudzu plant found near Tampa Bay. This rust detection is the first confirmed case in the U.S. in 2005 Denise Fiber, a spokesperson for the Florida State Agriculture Department, said a visual test of the rust sample found Feb. 23 had proven positive and now a lab test showed the same result. The soybean rust infected leaf was found on a kudzu plant in Pasco County, Fla. This becomes the southern-most location of the disease in Florida. “This just confirms what we already knew,” Fiber said. “We are completing a comprehensive soybean rust survey program that will help us track any movement of spores throughout the state of Florida. We are doing all that we can to identify any new outbreaks of soybean rust and communicating with the industry and the rest of the stakeholder groups nationwide.” The devastating soybean disease was first discovered in the U.S. last November in Louisiana. The rust spores quickly spread to nine states in the south in a matter of weeks. Florida now has found soybean rust in 18 counties. On Tuesday, the University of Florida’s Institute of Food and Agricultural Sciences Department used a Polymerase Chain Reaction (PCR) lab test that is a mandatory test on rust suspected samples that come from counties without positive finds. A PCR is a molecular test that looks for the exact DNA sequencing for a particular organism. Under an agreement between the USDA and state ag officials, if a state has previous detections of rust, all samples that follow will be confirmed by its own state lab. But for states that find their first detection of rust, those samples need to be sent into the USDA lab for confirmation. Because Florida had positive cases of rust last November, the recent suspected leaf sample was confirmed by its state lab officials. Timur Momol, a plant pathologist at the University of Florida, told DTN because kudzu plants are very widespread in the southern U.S. this positive find of soybean rust is troubling. There are thousands of acres of the plant kudzu found as far north as southern Illinois, he said. Kudzu plants in the Midwest are dead now, he said, but could become hosts during the spring. “This positive rust find is not good news. Because from there it will move to other areas with kudzu," Momol said. "In Florida, kudzu is everywhere. As it gets warmer, the rust will probably just keep spreading northward. We need to track this county by county heading north. This information of how fast it spreads would be extremely useful for growers in the Midwest." Momol said this could be the starting point for the epidemic of the spread of rust in the U.S. “The rust spores on the kudzu will be enough to keep its population going higher and going northward,” he said. Though plant experts have found rust spores to survive the winter, Momol said, the overwintering host could be kudzu or still be unknown. “The rust spores were found alive on a green kudzu plant but maybe they come from another host legume plant that stayed alive during the winter and then jumped onto kudzu. This is what we really don’t know yet,” he said. Meanwhile, a mild Florida winter may have helped rust spores survive because of few hard freezes, Momol said. Kudzu in the panhandle of Florida won't turn green until mid-March, so chances are slim rust will be found there. “In the next few weeks, one of my colleagues plans to plant sentinel plots for soybeans and other beans trying to get spores to land on them if they are in our area,” he said. "This would help detect the infection earlier than commercial planting of soybeans.” Momol said because the national plant diagnostic network, a USDA effort to fund land-grant universities and first-detectors training, was formed in 2002 to help crop experts identify exotic pathogens this should help the U.S. with enhanced early detection of the disease. Mike McGinnis can be contacted at michael.mcginnis@dtn.com. (TD) Copyright 2005 DTN. All rights reserved.
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