The University of Missouri (MU) soybean breeder plans to crossbreed new varieties this summer, based on what he learned during an 18-day trip to Vietnam.

"We may have material, at least based on initial screening, that looks pretty good," Shannon said after seeing his 50 top varieties growing in rust-infected soybean fields in Southeast Asia.

Shannon, stationed at the MU Delta Center in Portageville, and David Sleper, soybean breeder in Columbia, Mo., sent soybean seeds to be planted in Vietnam last February. After their trip to Vietnam in May, they came home optimistic about the possibility of finding rust-resistant genes in MU varieties.

"It's all very preliminary," Shannon said. "We'll learn more during the season."

Compared to susceptible Vietnamese varieties, the Missouri beans "looked pretty decent," Shannon said. That leads him to hope that his soybeans already have resistance, or at least tolerance, to the fungus.

Shannon is not waiting for confirmation. He is already planning crosses, examining the pedigrees of the varieties that looked the best in Vietnam. "We'll go back to the parent lines and start making crosses," Shannon said.

Soybean varieties grown in the United States came from seed originally brought from the Far East. It is likely that some varieties have been carrying rust resistance all these years, but they have never needed the rust resistance until now.

Asian soybean rust devastated yields in South America after the fungal disease was first found there four years ago.

The first cases of Asian rust were found in the southern United States last fall, after a passing hurricane touched a corner of South America on its way north.

Just before of the first killing frost in 2004, two cases of Asian soybean rust were found in the Bootheel. The spores of the fungus cannot survive in freezing zones, but the disease was found overwintering on kudzu in Florida.

MU researchers reacted quickly, Shannon said. "Rust was found in November, and we had our varieties planted in Vietnam by February."

Shannon gives full credit for the quick response to Henry Nguyen, a native of Vietnam and head of the National Center for Soybean Biotechnology on the MU campus in Columbia. "Henry knew the scientists at the research centers there," Shannon said. "I don't know of any other state that has that kind of connection."

Nguyen had already received soybean seed from Vietnam for his work in mapping soybean genes. At that time, rust resistance was not a great concern in the United States.

The recent visit opened the door to receiving more seed from resistant Vietnamese varieties. "They've had rust for a long time," Shannon said. "They live with rust, just like we've been living with soybean cyst nematodes. There, rust is everywhere."

If rust resistance is already in varieties adapted to Missouri, rapid progress can be made, Shannon said. "If we have to use resistance from Vietnamese varieties not adapted to our conditions, it will take a little longer.

"Varieties that yield well will be the first consideration in any breeding program," Shannon said. "If they don't yield, our growers won't plant them."

Seed from new crosses made this summer will be sent to Vietnam for testing in rust-infected fields. "If we don't have rust in our plots, we're not going to introduce rust just to test our crosses," Shannon said. "Our farmers wouldn't stand for that."