Phytophthora boehmeriae Sawada is a species that has been recorded on only a few hosts (Erwin and Ribeiro 1996) since its first description in leaves of Boehmeria nivea (L.) Gaud-Beau, in Taiwan (1927). It has also been reported in China, Australia, Greece (Erwin and Ribeiro 1996) and South Africa (Roux and Wingfield 1997). In South America, it was reported only in Argentina on citrus (Frezzi 1950), and in Brazil on black wattle (Santos et al. 2006). Erwin and Ribeiro (1996) report some additional trees as hosts: Deodar cedar (Cedrus deodora (G. Don) D. Don), eucalyptus (Eucalyptus pilularis Sm.) and Mexican yellow pine (Pinus patula Schiede ex Schlectendahl et Chamisso). In black wattle (Acacia mearnsii De Wild.), P. boehmeriae has been reported in South Africa (Roux and Wingfield 1997) and Brazil (Santos et al. 2006), thus becoming one of the causal agents of the disease known as gummosis, along with P. nicotianae (Santos et al. 2005), P. frigida (Alves et al. 2016) and P. meadii McRae (Roux and Wingfield 1997). Gummosis is the main disease of black wattle in Brazil (Santos et al., 2005) and South Africa (Roux and Wingfield 1997). It is characterized by necrotic lesions on the trunk, from the collar to the upper portions, with or without gum exudation (Santos and Luz 2007).
Sporangia of P. boehmeriae are ovoid to spherical, papillate and caducous, measuring 35 μm × 30 μm, with a length:width ratio of 1.16:1, mean depth of papillae of 4.83 μm, and exit pore of 4.69 μm. P. boehmeriae is homothallic, forming plerotic oospores with smooth walls and amphigynous antheridia. Cultures produce oospores abundantly. Chlamydospores are terminal or intercalary (Santos et al. 2006).