As part of an early detection system for Asian soybean rust, “spores of interest” have been found in west Tennessee. A slide collected on July 5 in a Jackson-area spore trap held two suspicious spores, a potential precursor to soybean rust.
“That means the spores landed on the (petroleum jelly-smeared) slide between collection dates - June 27 to July 5,” said Angela Thompson, Tennessee Extension soybean specialist on Monday. “Since it’s such a small number of spores, a definite confirmation can’t be made, just a visual affirmation that the spores look like soybean rust.”
In the same time period, 10 spores were found in a trap near Bowling Green, Ky., said Thompson.
“We’ve got 10 spore traps in Tennessee – one in Jackson at the experiment station where the spores were found. We, like most other states in the area, send the spore trap slides to plant pathologist John Rupe at the University of Arkansas in Fayetteville. He checks the slides for spores that look like Asian soybean rust.
“The main thing is we haven’t found any presence or sign of disease on soybeans. And that includes the sentinel plot the soybean trap was located in the center of.”
For the next several weeks, Thompson said extra samples will be collected from the Jackson sentinel plot. “Those will have tests run to check for rust. We’ll also be stepping up spore trap slides collections – now, at least twice a week. That’s not only due to the spore find, but to make sure we’re on top of anything the big storm from the Gulf brought our way.”
Tennessee’s growing conditions have been very similar to other dry states in the Mid-South. Many areas have had very little rain resulting in short soybeans.
“It doesn’t excite producers at all to think about having to spray a fungicide on some of the little beans. Overall, the dry conditions weren’t conducive to the disease’s development. Even if we did have two soybean rust spores, I don’t believe the conditions a week or two ago would have promoted the disease.”
However, with recent rains, that may change. “Today, temperatures are in the 70s and it’s humid. Everything has gotten a good soaking. So conditions are better for rust. But I don’t know if we’ve got a big enough spore load in our area to cause problems. At this point, there’s no reason to be extremely worried. We’ll continue watching this closely.”