Researching Avocado Rootstocks for Resistance to Phytophthora cinnamomi (aka root rot)

Aug 20, 2009

The California Avocado Commission (CAC) funded a multiyear study lead by Greg W. Douhan, a UC Plant Pathology and Microbiology researcher, to control avocado root rot. Control of this destructive pathogen will ultimately be accomplished with resistant rootstocks.

The research team is focusing on crossing already-resistant rootstocks, and has identified several that have greatly improved yields on land infested with Phytophthora cinnamomi. Six plots are being tended this year including one in Santa Paula. They have plans for additional plots for the study. Work is being done at the UC South Coast Research and Extension Center in Irvine and at University of California, Riverside (UCR).

"Seed screening seeds from our breeding blocks will continue…We have also collected new isolates of P. cinnamomi to determine how diverse the population is so that appropriate isolates can be used in the initial screening process. My graduate student is finishing up this summer and will hopefully have most of our advanced lines characterized genetically. I am also submitting a USDA grant to work on the parentage analysis of our advanced lines as well as continue to work on genetically characterizing avocado rootstocks.”

To read the entire study report, please visit