Asian soybean rust was discovered in a University of Delaware sentinel plot in late October, but after review, it turned out to actually be in Maryland. Either way, it’s the first time rust has been found in either state.
The sentinel plot, which was determined to be just over the state border in Worcester County, MD, was a late-planted Group VII soybean deliberately chosen to provide green susceptible plant material late into the season. A sample was collected on Oct, 23 and incubated until Oct. 28. Experts determined that there was one soybean rust pustule on one leaf out of the 100-leaf sample.
“The primary significance of this find is to illustrate that soybeans in the Mid-Atlantic region can become infected with soybean rust given the right combination of events,” said a report by Extension experts. “However, this particular discovery has no direct implications for soybeans in our region. It happened at the very end of the growing season, and in fact frost had already damaged the upper most foliage of this extremely late soybean sentinel plot. There is no remaining green foliage in this sentinel plot and all commercial fields are in various stages of harvest. Furthermore, soybean rust is not seed-borne and has no overwintering mechanism other than survival on live host tissue, so the organism cannot establish itself in our region. Any infections that may occur in subsequent years will depend on reintroduction of spores from long distance.
“The key message to take from this find is that soybean rust can blow into our region and under the right combination of temperature, moisture, and plant susceptibility could cause infection in our soybean crop. It will take a combination of unusual events to provide those favorable conditions earlier in a growing season to be a significant threat. Nevertheless, we must keep vigilant to protect this significant component of our agricultural economy,” the report continued.
(Source: Maryland Cooperative Extension)