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Santa Maria Sun / News

The following article was posted on August 7th, 2013, in the Santa Maria Sun - Volume 14, Issue 22 [ Submit a Story ]
The following articles were printed from Santa Maria Sun [] - Volume 14, Issue 22

Local strawberry growers battle a crop disease linked to last year's whitefly infestation


Local strawberry fields that were infested with whiteflies (pictured) in June 2012 are now showing symptoms of pallidosis, a viral disease that can lead to crop dieback.

Stunted plant growth, discolored leaves, and brittle roots: the symptoms of pallidosis, a disease currently affecting strawberry fields in Guadalupe and other parts of the Santa Maria Valley.

“It’s a little bit of a perfect storm that has happened and it’s really hurting some of the growers,” said Laura Gregory, grower communications specialist with the California Strawberry Commission.

According to information from the University of California Cooperative Extension, strawberry fields in the Santa Maria Valley and other areas that suffered from heavy whitefly infestations in June 2012 have developed symptoms of pallidosis-related decline.

“We saw white flies in huge numbers [in 2012],” said Hillary Thomas, production research manager with the California Strawberry Commission. “And those numbers continued into the fall.”

Thomas said scientists with the California Strawberry Commission worked with experts from other agricultural organizations, such as the U.S. Department of Agriculture, to delineate the boundaries of the infected fields and to develop a winter management plan to deal with the flies.

“We started to see fields go down in May,” Thomas said, adding that when scientists see whole fields get infected, they usually expect the problem to be the result of a soil-borne disease.

However, scientists suspected the recent decline could be caused by a virus because of the fields’ proximity to the whitefly infestation. They started processing field samples for the partner viruses associated with pallidosis-related decline and came up with positive matches.

Pallidosis is caused by a complex of several viruses, which can be transmitted by whiteflies, aphids, pollen, fungus, and other unknown sources. The disease occurs only when one of the whitefly-transmitted viruses is present in the plant along with one of the other viruses.

The leaves of infected plants dry out, and the plant eventually dies. The severity of the infection can range from mild symptoms in some fields to total crop dieback. While some crops might not show progressive symptoms, the virus is systemic and remains in the infected plants.

There are no chemicals to treat the disease, but it can be mitigated by not planting near infected fields or using healthy transplants to prevent the introduction of additional viruses. Pesticides can be used on the insects that transmit the virus.

The California Strawberry Commission’s Thomas said scientists are still working on the area-wide management plan to prevent infestation of this coming fall’s strawberry transplants; they are currently holding area-wide action plan meetings.

It’s uncertain how much money growers have lost as a result of the infestation and corresponding disease.

For more information, call the commission at 1-831-724-1301 or visit the UC Cooperative Extension’s website at


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