DSU students study ways to prevent disease in alfalfa

Dr. Andrew Sathoff, an assistant professor at Dakota State University (DSU) in Madison, S.D. is passionate about alfalfa. For about four years, he has led DSU undergraduate students in researching what’s in the soil and better ways to treat microbes that cause diseases such as seed and root rot in alfalfa.

A Minnesota native, Sathoff earned a doctoral degree in plant pathology at the University of Minnesota in 2019 and studied under Dr. Deborah Samac, who he said was “probably the top alfalfa pathologist in the world.” He said Samac is also a United States Department of Agriculture research coordinator in St. Paul and instilled in him an interest in alfalfa.

“I trained with her for five years,” Sathoff said. “I was more interested in teaching, but I had my summers free for research. After I moved to South Dakota I just wanted to see all the different diseases that were in the ground. It’s been a long time since there’s been an active alfalfa pathologist in the state.”

Sathoff said South Dakota plants the second most acres of alfalfa in the U.S. and he saw the fact that there wasn’t many people researching the crop as an opportunity to develop projects to do with his biology students. He said they’ve done most of their research during the summers.

In the summer of 2020, they found Aphanomyces in the soil, which causes root rot.

“That was kind of a big deal,” Sathoff said. “It’s probably the most important alfalfa disease in the U.S. and we confirmed it’s presence in South Dakota and we advised growers how to plant resistant varieties of alfalfa and how to use fungicides and all of that great stuff to combat the disease.”

As they were doing the Aphanomyces work, they also found Pythium and Fusarium in the soil, which cause seed rot. Sathoff said they advised Mustang Seeds, which helped fund the research, to double coat alfalfa seeds with the fungicides Apron XL and Stamina to protect the plants.

“When they’re applied in combination on the alfalfa seed they do a nice job to prevent rot,” Sathoff said.

This past year, he and his students worked with biocontrols that can be used by organic growers who don’t use fungicides. He described a biocontrol as a microbe that attacks another microbe, or “biological based control of diseases.” He and his students researched what commercial biocontrols would work against the Aphanomyces and Pythium isolates.

“We were super surprised that these biocontrols did a great job at controlling these diseases,” Sathoff said.

They presented their findings at conferences around the country including Plant Health 2022 in Pittsburgh and the World Alfalfa Congress in San Diego. Sathoff said his students were the youngest presenters at those particular conferences. His students have also authored articles on the findings.

Sathoff said their research has been supported by the National Science Foundation’s Established Program to Stimulate Competitive Research.

“My responsibility is to train researchers,” Sathoff said. “I have money to hire these students, to train them over the summer, and I can pay them a bit. It’s kind of to build research infrastructure in the state, to train the next group of researchers.”

Sathoff said the research done so far has been making an impact and alfalfa growers in South Dakota have been applying some of the findings.

“The growers around here seem to be really backing this research-based evidence and making some real changes, planting more resistant varieties of alfalfa to Aphanomyces or using that double seed coating with two different fungicides,” he said. “It’s fun to see growers make some of these research-based changes.”

Looking to the future, Sathoff said he wants to explore yellow flowering alfalfa, which is more winter hardy. He said not much has been done to evaluate the plant for disease resistance and he wants to see if it’s resistant to regional diseases like crown rot and if the plant could be incorporated into commercial lines.

Sathoff is also interested in diagnosing diseases based on soil samples, which is something his mentor, Samac, is working on.

For those interested in learning more about alfalfa and other forage crops, Sathoff said DSU is hosting a Winter Forage Meeting organized by the Midwest Forage Association on Feb. 28. He said the research done by he and his students won’t be on the agenda, but many other topics will be. People are encouraged to register for the event and those who register before Feb. 21 will receive a $10 discount. Those interested can register at www.midwestforage.org/SDmeeting.php.