University of Arkansas scientists are launching research to answer the questions raised by the arrival of Asian soybean rust in Arkansas. Division research and Extension scientists have formed a working group to educate producers about how to identify and manage the fungal disease.
“All the data we're using are from South America, said John Rupe, UA plant pathologist. “We have a lot of research to do to understand how it works here.”
Rupe and other plant pathologists will research the use of fungicides and cultural practices for the most effective and affordable means of managing the disease. Pengyin Chen, UA soybean breeder, will screen existing varieties for tolerance and resistance while simultaneously working to develop improved varieties with resistance.
Rupe said rust probably couldn't overwinter in Arkansas because it requires a living host. “That means plants with green leaves,” he said. “It has a wide host range, including kudzu, but all of its hosts are deciduous and lose their leaves during the winter.”
That means soybean rust will have to overwinter in warmer climates and blow in on the wind, he said. Because it arrived by hurricane in 2004, there is no established pattern for how it may spread on seasonal winds.
In anticipation of the disease's return, plant pathologists will be looking at the effectiveness of available fungicides, application methods and cultural practices. “Such things as row spacing have an impact on the effectiveness of fungicides because the spray has to reach the lower canopy,” Rupe said.
Because fungicides have to be applied early, sentinel plots with very early-maturing varieties will be used to detect the spread of soybean rust while there's still time to protect the crops.
“We'll also be studying environmental factors to see what conditions make infection more or less likely,” Rupe said.
Chen has obtained seed samples from the USDA germplasm collection that have four major sources of resistance to soybean rust. He will cross them with Arkansas adapted varieties and accelerate the breeding process by cycling plantings in a greenhouse with field plots in Arkansas and Costa Rica.
“We can get two to three generations a year,” Chen said.