Research: New steam method kills fungus that causes sudden oak death

Courtesy of the USDA

Steam cleaning might just be what the doctor ordered for sick oak trees.

Researchers at Dominican University in California have found a way to use steam sterilization to fight Phytophthora ramorum – a highly virulent pathogen that causes sudden oak death, according to the San Francisco Chronicle.

P. ramorum kills oak trees and has almost completely knocked them out in areas of California such as Big Sur, Jack London and China Camp state parks.

So how do you steam clean a tree? Pretty much the same way steam has been used to sterilize greenhouse soil in the past – steam is pumped through a hose beneath a tarp that covers the infected soil. After about a half hour of pumping 122°F steam through the area, P. ramorum is eliminated, according to the Chronicle.

There still is more work to be done, but researchers from Dominican, the California Department of Food and Agriculture, the U.S. Department of Agriculture (USDA) and Oregon State University are working toward a commercial application of the technique.

P. ramorum has been killing oaks and tan oaks on the coasts of California since the early 1990’s, with other types of plants subsequently being found to be susceptible to the pathogen. More than 1 million trees have died from P. ramorum infection, according to the USDA.

The cause of sudden oak death was unknown until 2001, when scientists identified the water mold P. ramorum as the cause. The same fungus also causes ramorum leaf blight and ramorum dieback. It first was found in Germany and the Netherlands in 1993, according to the USDA.

Infected plants, windblown rain and contaminated soil all can spread the fungus.

Officials have implemented outreach programs along with regulations to stop the spread of P. ramorum, including inspections of nurseries.

To read the full story from the San Francisco chronicle, click here.

For a list of Neogen’s Phytophthora testing products, click here.



Phytophthora ramorum: Stopping the spread – USDA APHIS

Phytophthora ramorum/sudden oak death –USDA APHIS

Phytophthora ramorum program: Past, present and future direction (Powerpoint) – USDA APHIS

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