Effect of metalaxyl, fosetyl‐al, dimethomorph, cymoxanil on development and controlPhytophthoraon peachtree in vitro

Four fungicides were evaluated for their effectiveness against Phytophthora diseases of peach trees and their ability to absorbed and translocated by roots of peach tree in laboratory. Meta‐laxyl suppressed the development of P. cactorum and P. citwphthora on segments. Fosetyl‐Al showed variable fungicidal activity against P. cactorum and P. citwphthora. Both dimetho‐morph and cyraoxanil were not effective to inhibit the growth of fungi on segments. Section of tree trunks in 2‐yr‐old GF 677 trees were painted with one of the test fungicides. Strips of bark were removed 10 and 20 days after painting within treated area and inoculated with P. cactorum and P. citwphthora. Generally, the results agree with them obtained with excised stem and excised twig methods. Exception is the dimethomorph that reduced the development of P. cartorum and P. citrophthora. This study indicated that application with metalaxyl to the peach tree appears to be an effective procedure to control Phytophthora diseases on peach trees.