New Blight Alarms California Olive Growers

The pathogen Neofabraea has been observed on both Arbosana and Arbequina trees in the Sacramento Valley, Glenn County and San Joaquin.

Neofabraea (Photo: Olive Oil Commission of California)
Jul. 26, 2016
By Wendy Logan
Neofabraea (Photo: Olive Oil Commission of California)

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The California olive indus­try has been alerted to an alarm­ing new dis­ease that appears to be spread­ing among olive cul­ti­vars com­monly used for oil pro­duc­tion. At a recent board meet­ing of the Olive Oil Commission of California (OOCC), it was reported that the pathogen Neofabraea had been observed on both Arbosana and Arbequina trees.

It’s new to California and it’s alarm­ing, for sure.- Florent Trouillas, U.C. Davis

The dis­ease is akin to bulls eye rot” in apples and pears being grown in the pacific Northwest. The pathogen was pre­vi­ously iden­ti­fied by U.C. Davis researchers in Sonoma County on olive fruits at two com­mer­cial orchards in Sonoma County in 2013, affect­ing the Coratina and Picholine varietals. 

The newly affected region includes the Sacramento Valley and Delta: Glenn County, just north of Sacramento, and San Joaquin County to the south. Symptoms include defo­li­a­tion, twig lesions, and leaf spots, and both humid grow­ing areas and El Nino appear to pro­vide favor­able envi­ron­ments for the disease.

It’s new to California and it’s alarm­ing, for sure,” said Florent Trouillas, a Cooperative Extension spe­cial­ist in plant pathol­ogy at U.C. Davis. It appeared out of nowhere. This is def­i­nitely some­thing the indus­try needs to be pre­pared for.”

Trouillas said the research on Neofabraea, specif­i­cally focus­ing on olive oil olives, was ini­ti­ated this past spring in the San Joaquin area where it hass been recur­rent. It’s quite seri­ous when you find the dis­ease has affected entire rows of trees. And we haven’t yet vis­ited any groves where table olives are grown.”

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The OOCC research com­mit­tee is now into the prob­lem and fund­ing is likely to be sought to inves­ti­gate the rot and its biol­ogy and come up with solid strate­gies that grow­ers can imple­ment to con­trol it. 

Given the dev­as­ta­tion caused by the Xylella fas­tidiosa pathogen that has rav­aged more than a mil­lion olive trees in south­ern Italy over the past two years, the boom­ing California olive oil trade should be on high alert as more is learned about the new blight.


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