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Reporting on science, technology and innovation in Arizona and the Southwest through a collaboration from Arizona NPR member stations. This project is funded in part by the Corporation for Public Broadcasting.Additional stories from the Arizona Science Desk are posted at our collaborating station, KJZZ:

Farmers and Researchers Convene To Halt Lettuce Wilting Disease

Amanda Solliday - KAWC

More than 150 lettuce growers and researchers are gathering this week in Yuma to discuss a soil-borne fungal disease that damages lettuce crops in the United States and abroad.

The international conference is hosted by the University of Arizona’s Yuma Center of Excellence for Desert Agriculture.

Mike Matheron is a plant pathologist and professor at the University of Arizona. Matheron is leading a field test to see which varieties of lettuce withstand the disease.

“You see this plant obviously is much smaller than, just barely hanging on compared to its neighbors here,” Matheron said. “So this is a prime example of plant infected with fusarium wilt fungus.”

The fungus can travel on dust particles and seeds, or migrate on shared equipment.

“From a disease development perspective, it is coming along well,” Matheron said. “We should get some good data from this.”

The disease he’s talking about, fusarium wilt, is particularly troublesome for lettuce growers.

No one knows exactly how much total economic damage the disease causes, but American farmers see wilt more and more each year since it was first discovered in California in 1990 and Arizona in 2001.

At the meeting, researchers and growers said right now, each possible tactic – such as breeding new varieties, as well as rotating crops, delayed planting, sterilizing the soil with heat – offers only a partial defense or is not economically feasible. Chemical treatments are ineffective.

As the manager of JV Farms, Arizona lettuce grower Matt McGuire called himself a “fusarium survivor.” One of the UA breeding trials is located in his infected field.

“We haven’t found anything to be effective or effective 100 percent of the time,” McGuire said.

Nov. 13, the final day of the conference, will focus on identifying future projects most likely to curb the disease.