Phytophthora agathidicida

Abstract

Morphology Differential oogonium ornamentation, together with the size of the oospore, was first recognised to be a diagnostic characteristic by Beever et al. (2009) in their study of representative isolates of the members of Clade 5. The mean oospore widths for P. cocois and P. heveae were not significantly different from each other nor from the Clade 5 mean, but oospore width of P. agathidicida is significantly larger than all other species and P. castaneae is significantly smaller than all other species (Weir et al., 2015). Oogonium wall ornamentation of P. agathidicida is mildly stipulate. Oospores nearly fill the oogonia with a mean width of 27.7 µm, and ranging between 19.8-35 µm. Antheridia are amphigynous, globose, and some have knots at the base (Fig. 2). P. agathidicida is homothallic.