Treating for soybean rust a field-by-field decision

In the midst of these ideal late-summer growing conditions, an Alabama Extension soybean agronomist says fungicide sprays may be warranted for beans that have reached the reproductive stage, but haven’t yet reached the R6 level, when seeds touch the pods.

Right now, thanks to ample rainfall throughout much of the state, late-planted soybeans have posted solid growth and offer great yield potential, says Dennis Delaney, an Alabama Cooperative Extension System agronomist.

Delaney shared this advice with growers during the annual East Central Alabama Crops Tour, held Wednesday, Aug. 22, with various stopovers throughout east and central Alabama.

But there is a flipside to this. As Delaney stresses, what’s good for soybeans is also good for some major soybean diseases, not to mention, a few soybean pests.

Researchers throughout the country enjoy what amounts to a bird’s eye view of this issue. They have developed what amounts to an agronomic canary in a coal mine — a series of what they call sentinel plots of soybeans that help them monitor for signs of one of the most virulent weather-related disease, soybean rust. 

The plots, planted at various times throughout the growing season, are designed to give Delaney and other soybean experts a clear picture of the diseases spread throughout the state.

“We want to get that continuous blooming — continuous green material that we can watch and sample as the rust moves north.”

As Delaney relates, soybean rusts follows a pattern: it overwinters on kudzu in the Gulf Coast — Baldwin and Mobile counties — and moves north, following the rain and maturing soybeans.