The take home message from the National Soybean Rust Symposium that opened Tuesday in Nashville is this: the sentinel plot system is a keeper, the modeling programs are a good start. Both worked in 2005 and both will be tweaked and improved for 2006.
What also worked is the chemical menu that companies quickly ramped into the system, a vast majority of which were granted Section 18 labels for soybean so growers could arm themselves against the virulent disease.
The greatest strength of the sentinel program, which included specially planted sentinel plots of both kudzu and soybean as well as naturally occurring fields of kudzu and commercial planted soybean fields, is that Extension was able to tell growers when rust was in the area.
And when it was not.
"We were able to say 'We don't have any soybean rust in this state,'" University of Wisconsin Extension pathologist Craig Grau says in the opening session of the symposium in Nashville, Tenn.
To put it simply, University of Kentucky Extension pathologist Don Hershman says, "It worked."
"I hope the growers have a high degree of confidence that what we did did make a difference," Hershman says.
The national numbers for 2005 lined up this way: 140 first detections of rust in 130 counties. Of those, Hershman reported, 106 were in soybean, including 31 in sentinel plots. More that 75% of the finds were in fields at R5 or later. The disease always was found in the lower canopy and low-level detections were identified in the lab rather than the field.
"The experience in the South is you've really got to look at these leaves under a microscope," Hershman says. For 2006, then, Extension will look at using fewer sentinel plots and more closely and regularly examining samples from all fields in the laboratory.
"I think in the future we will see fewer plots, but they should be monitored more intensely," Hershman says.
More than one symposium presenter pointed out that when soybean rust is found the grower can win the battle. The key is timeliness of the first application â€“ and using the right chemical.
"If you miss the application window, you're going to be playing catch-up the rest of the season," says James Bloomberg, of Bayer CropScience.