First Report of Phytophthora sojae and its Pathotypes Affecting Soybean in Uruguay

Abstract

Stem and root rot caused by Phytophthora sojae is a disease that causes important losses in soybean worldwide and regionally. This is the first report of this pathogen affecting soybean in Uruguay. Using an international 14 differential set, seven different races/pathotypes were determined out of the 14 isolates of P. sojae obtained from symptomatic plants. Fifty seven percent of these belonged to a single pathotype (vir1b, 3a, 3b, 5), and the remaining six isolates resulted each a unique pathotype including some races known as 4, 14 and 25. Knowing which pathotypes predominate in the country is crucial to select for resistance within a soybean breeding program, and also to test their compatibility on commercial varieties.