Soybean rust may make its way farther north in 2007, especially after last year's shift in the geographic distribution of the fungus that causes the disease, says Glen Hartman, a USDA plant pathologist in the University of Illinois Department of Crop Sciences.
The disease caused little damage the past two years, but the fungus that causes soybean rust is overwintering in different regions this year than other winters.
"The current situation is different than it has been during the last two years," Hartman says in a University of Illinois release. "There has been a marked increase in the size and location of the areas where the fungus occurs since moving into the upper Midwest late in the 2006 growing season and where it will potentially overwinter this year. That presents the real possibility that there could be an increased threat to the major growing areas during 2007."
The fungus overwintered only in southern Florida in 2005, and last year it stayed in Florida, Georgia, and Alabama before spreading later in the summer. The spores appeared in large areas of Louisiana in 2006, though, potentially setting up a new scenario.
"Spores from that part of the country have a direct pathway up the Mississippi River Valley into Illinois and other major soybean growing areas in the Midwest," Harman says. "The situation has changed enough that soybean growers will need to be on heightened alert during the early part of the growing season."
Nevertheless, Harman points out, a hard freeze could still curb the risk of a major outbreak.
Hartman says to watch for rust building up in Louisiana, Alabama, and Mississippi early in the growing season. Such a buildup would greatly increase the chance of spores drifting north into the Midwest.
The map covering the entire country is located on the USDA's website at www.sbrusa.net/. Reports from the sentinel plots in Illinois, part of the sentinel network to monitor for the spread of soybean rust, and other useful information on rust can be found at www.soybeanrust.org.