Phytophthora species associated with crown and root rot of apple in Chile

Phytophthora cactorum, P. cryptogea, P. gonapodyides, and P. megasperma wer e isolated from necrotic root and crown tissues or the rhizospheres of appl e trees exhibiting typical symptoms of Phytophthora root and crown rot in t he Central Valley of Chile. Representative isolates of all four species wer e pathogenic on a variety of apple rootstocks and scions in trials conducte d on excised shoots and 1-year-old MM.106 rootstock grown for 4 months in i nfested potting medium. P. cactorum was the most frequently isolated specie s and the most virulent in pot tests, although a significant Phytophthora s p.-apple genotype interaction was observed. This is the first report of any species other than P. cactorum causing root and crown rot of apple trees i n Chile.