UCCE in the County of San Luis Obispo

Why are you seeing Oak Mortality?

Blue Oak

 

Blue Oak Mortality

Among the 14 species of oak trees that occur on the central coast, especially blue oaks, have experienced high mortality the past decade. Much of the mortality can be attributed to the intense drought of 2010 to 2013, believed by some to have been the most severe drought in 500 years.

Newsletter Article on Blue Oak Mortality

 

Research Article on Oak Mortality

2b. Das-et-al.-2019_BO-mortality-drought-_Madrono (PDF 608KB)

How Do Blue Oaks Survive Droughts?

 

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During unusually dry years, blue oak trees often drop their leaves several months early during July and August. These trees are not dead, but have evolved this strategy of “Water-deficit leaf drop” to conserve water. Typically, the trees will leaf out normally the following spring.