Pathogenic specialization in Phytophthora vignae

Abstract

Pathogenic changes in Phytophthora vignae detected in the field in southern Queensland are documented.

Evidence presented demonstrates that at least four distinct pathogenic races of P. vignae exist. At least three resistant genes are available in a collection of c. 500 cowpea strains and cultivars examined.

The danger of needlessly exposing resistant cultivars to infection is discussed.

It is concluded that field or generalized resistance should be explored more fully.