A new method was developed to evaluate in vitro the systemic ability of fungicides against crown rot diseases caused by Phytophthora spp. Excised shoots of peach were inoculated with P. cactorum or P. citrophthora and inserted vertically into vermiculite, 2 cm deep, and flooded with test fungicide, in a storage jar. After incubation, shoots were removed from the vermiculite and stripped of their periderms and the length of necrosis was measured. The systemic fungicides metalaxyl and fosetyl-Al inhibited necrosis whereas copper hydroxide, captan and dimethomorph, which gave protection in bark strip and trunk inoculation assays had no effect. This confirmed that the new assay discriminated between systemic and non-systemic effects. The new method is not laborious, allows ample replications and is inexpensive.
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