September 22, 2015 / Modified sep 22, 2015 2:16 p.m.

Testing to Tackle Lettuce Fungus Under Way in Yuma

One grower allows small part of his fields for trial on seeds developed to elude disease.

Yuma lettuce harvest spotlight Field workers harvest lettuce in Yuma, February 2015.
Kate Sheehy, Fronteras Desk

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By Amanda Solliday, Arizona Science Desk

This story was updated to make clearer that the University of Arizona is the lead research group in the study.

Fusarium wilt — a lettuce disease caused by a soil-dwelling fungus — is becoming a more common problem in fields. The disease causes lettuce to droop and turn brown, making it unsuitable for sale.

Typically, when lettuce wilt appears, the grower would then rotate to another crop like broccoli or cauliflower. But one farmer in Yuma dedicated three acres of his troubled field to research led by the University of Arizona.

UA conducted a test of resistant lettuce varieties 13 years ago in a field known to contain the disease. Since then, plant breeders have created new types of lettuce designed to elude fusarium wilt.

fusarium fungus spot The fusarium fungus enters the plant through the roots, causing lettuce to wilt or die.
Photo courtesy of Michael Matheron - University of Arizona

One farmer has dedicated three acres of his fields for the test, and scientists and seed company representatives hope the resistant varieties will appear healthy. The researchers also want to see some sick plants to verify the presence of the disease.

“If the crop is successful, half of this lettuce or more will be dead," said Victor Heintzberger, president of Vanguard Seeds of Salinas, Calif., the spring and summer capital of leafy greens.

Heintzberger traveled from Salinas to test some of the varieties his company is developing, saying that a field trial like this is an opportunity to verify results seen in the lab.

The test has spurred a bit of friendly competition to see who will have the best-looking lettuce.

“I’m expecting to see one bed here totally green all the way through," Heintzberger said. "And that will have a Vanguard Seed flag on it.”

Heintzberger said he hopes the wilt-resistant lettuce from his company will be commercially available as soon as next year.

The Arizona Science Desk is a collaboration of public broadcasting entities in the state, including Arizona Public Media.

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