Concrete drainage ditch on a slope above an avocado grove to divert runoff water and soil contaminated with the Phytophthora root rot pathogen, <I>Phytophthora cinnamomi.</I>.
Concrete drainage ditch on a slope above an avocado grove to divert runoff water and soil contaminated with the Phytophthora root rot pathogen, Phytophthora cinnamomi..
Credit: David Rosen