Posts Tagged: verticillium wilt

Pest threats 'overblown'

It's been nearly 20 years since olive, walnut and pistachio farmers first declared war on cotton, but the Glenn County Board of Supervisors declared Tuesday that fear of verticillium dahliae levels might be a a bit overblown, said an article by Susan Meeker in the Colusa County Sun-Herald.

The board agreed to revisit the 2008 regulation that prevents cotton growers from planting in the same field three years in a row if the level of verticillium wilt is detected in 3 percent or more of the crop.

Doug Munier, farm advisor for University of California Cooperative Extension, said verticillium dahliae exists in native valley soils and is spread by movement.

"Verticillium was a minor problem with cotton was first planted in the mid-1990s and it is still a minor problem after 17 years of production," he said.

New bee threat more media hype than reality
Wayne Anderson, The Washington Times

Government officials, leading bee experts and average beekeepers around the country say the strange discovery of a deadly bee parasite fly that makes honeybees act "zombie-like" is not seen nationwide — but only in a recently published San Francisco State University study. And some even question the veracity of the discovery itself.

The parasite fly is a long-time resident of California and a known nemesis to other bugs besides honeybees, the article said.

“They’ve been known to infest or parasitize bumblebees for some time all over the country,” said Eric Mussen, California State bee specialist and professor at the University of California, Davis. “It’s not new. We’re aware of it. I don’t believe it’s a terribly important thing to honeybees as a whole.”

Scientists perplexed by verticillium wilt in lettuce

UC scientists in the Salinas Valley are trying to figure out why certain varieties of lettuce became susceptible in the 1990s to the fungus that causes verticillium wilt and how the fungus is getting into the soil.

"This is one of the more important diseases facing growers in the county," the Salinas Californian quoted UC Cooperative Extension farm advisor Steve Koike. "It has a significant impact and is increasing each year."

Strawberry crops have long suffered from the disease, but lettuce was immune. Strawberry fields are often fumigated to kill fungi, other soil-borne pests and weed seeds, however, the value of the lettuce crop doesn't justify fumigation and methyl bromide, the primary fumigant, is being phased out.

Lettuce farmers must look for other ways to manage fungus-contaminated fields, Koike told reporter Melissae Fellet. Growers can plant crops immune to the fungus, such as broccoli, cauliflower or celery, or they can plant fungus-resistant lettuce varieties.

The scientists, initially mystified about the source of the fungus, recently discovered that spinach seeds from Denmark, Holland, New Zealand and Washington state have been carrying the fungus into Salinas Valley fields, where it persists in the soil for years.

USDA awarded the researchers a $1.5 million grant to investigate how the fungus is transferred from the seeds to lettuce. UC Davis plant pathologist Krishna Subbarao, who is headquartered at the USDA research station in Salinas, is the principal investigator.

Lettuce with verticillium wilt.

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