Lack of kestose (fructosylsucrose) production by race 3 of Phytophthora parasitica var. nicotianae differentiates it from races 0 and 1 [Fungal pathogen, tobacco black shank]

The detection of kestoses provides a biochemical differentiation between race 3 and races 0 and 1 of Phytophthora parasitica var. nicotianae, the causal agent of tobacco black shank. Races 0 and 1 produce kestoses (fructosylsucrose) when grown for 5 da on a medium containing 3% sucrose. Under these conditions, race 3 of this pathogen does not produce kestoses. Phytophthora cactorum, P. cambivora, P. cinnamomi (from avocado), P. citricola, P. citrophthora, and P. parasitica also produce kestoses but P. capsici and P. cinnamomi (from pineapple) do not.