Asian soybean rust finally appeared in the U.S. last season but had little impact after years of warnings about its potential catastrophic effects on soybean yields. That doesn’t mean the researchers were wrong and no-tillers can ignore the threat.

Marty Wiglesworth, a plant pathologist working as technical brand manager of fungicides for Syngenta Crop Protection, concedes, “We started last year thinking the sky was going to fall, but now most of you realize that there is hope for us against this disease.” But, he cautions, “Don’t look at 2005 as a normal year for soybean rust.”

During 2002, the first year of infection in Brazil, rust did not have a huge impact. “The second year, there was a little more effect, and by the third year it really had a catastrophic impact upon the growing business. Each year since then, there has been a significant impact,” Wiglesworth says.

Don’t Hesitate

In just 4 weeks, he says, “An untreated field with lush, green soybean foliage with just a little bit of yellowing that a grower wouldn’t really notice, turns to sticks.”

Rust traveling to the U.S. starts out as very small wind-borne spores that can travel hundreds or thousands of miles in the air before landing on a soybean leaf, or on a kudzu leaf, which acts as a substitute host in the South, Wiglesworth says.

After 4 to 9 days, an observer might be able to see a very small, dust-like particle on the leaf. But Wiglesworth warns that even…