Researchers at Texas A&M University and Auburn University, along with a host of other universities and agencies throughout the United States, Mexico and Canada, have joined forces to battle soybean rust (SBR), a fungus that can cause massive losses in soybean production.
Soybeans are used for everything from food for humans and animals, to the production of fuel, crayons and lubricants, and according to Thomas Isakeit, a professor in Texas A&M’s Department of Plant Pathology and Microbiology, SBR can cause massive losses in yield and increase the cost of production because of the need to apply fungicides to protect the crop.
“Soybean rust is a fungal disease affecting soybean leaves,” says Isakeit, who is also an extension plant pathologist with both Texas A&M AgriLife Extension and AgriLife Research. “Under rainy conditions, the disease can be extensive, causing leaves to drop before the plants have matured. For many years, the disease was not present in the U.S.”
It was feared that if the disease did come to the states, it would have a devastating effect on production, especially to a few Midwestern states that account for most of the nation’s soybean production, Isakeit explains.
Then in the fall of 2004, “Hurricane Ivan brought spores of the fungus into Louisiana and other Southeastern states, but not Texas,” he says. He suspects, although has not proven, that SBR came to East Texas via Hurricane Rita in 2005.
Whereas Texas has been mildly affected by the fungus this year, with only two counties reporting the presence of SBR, Auburn’s home state of Alabama reported SBR in all 67 counties. “Rust varies from year-to-year,” Isakeit points out. In October 2007, for example, 26 Texas counties reported SBR. “That was a very rainy year for Texas and that summer, every county I went to in the eastern part of the state that had soybeans, had rust. We haven’t seen anything like that since, and lately, because of somewhat dry conditions overall, there’s been little soybean rust in Texas.”
To monitor the location and movement of the disease, a national network was established in early 2005. “I’ve been coordinating the reporting of rust in Texas to this website since then,” says Isakeit. “This involved setting up small soybean ‘sentinel’ plots ― an early-warning system ― throughout the state in conjunction with other Texas A&M AgriLife personnel.
“My plant pathology counterparts in other states, including Ed Sikora at Auburn, had similar monitoring programs and reporting responsibilities. The Gulf Coast states are particularly important in this monitoring, since that’s where the fungus is most likely to survive winters.”
Isakeit says the major benefit of this national reporting “is that we have been saving soybean growers millions of dollars annually ($207 million in 2007), by advising them to not spray fungicides. Because the weather varies from year to year, we don’t always get the disease, or it comes in too late to affect the yield. So fungicides don’t need to be applied all the time.”
Monitoring early-planted soybeans or early-production areas is key, says Isakeit, because if SBR is found in those areas, growers in other areas can be advised whether or not to spray fungicide. “In order to be effective, the fungicides need to be applied before the spores reach the plants,” he explains. “They are spraying a healthy crop to protect it, so we are helping them to make a good economic decision to protect their crop. On the other hand, we have enough information to be able to tell growers they are not at risk, so they save money by not having to spray.”
For more information on SBR risk assessment, click here.