Activity of the novel fungicide SYP-Z048 against plant pathogens

In in vitro tests with 18 plant pathogens, the fungicide 3-[5-(4-chlorophenyl)-2,3-dimethyl-3-isoxazolidinyl] pyridine (SYP-Z048) was highly effective on inhibiting mycelial growth of various ascomycota and basidiomycota, with EC(50) values ranging from 0.008 to 1.140 μg/ml. SYP-Z048 had much weaker activity against growth of oomycota with EC(50) values > 100 μg/ml. In a second in vitro test with Monilinia fructicola isolates, SYP-Z048 inhibited mycelial growth (EC(50) = 0.013 μg/ml), germ tube elongation (EC(50) = 0.007 μg/ml), and sporulation but did not affect spore germination. In a detached pear fruit assay inoculated with M. fructicola isolates, SYP-Z048 showed protective and curative activity. Field tests indicated that SYP-Z048 was an efficacious fungicide for control of brown rot disease in two peach orchards. When applied to a single spot on a tomato leaflet in a compound leaf, SYP-Z048 suppressed the growth of Botrytis cinerea isolates on the rest 4 leaflets, indicating that the fungicide has systemic movement in plant tissues. These results indicate that SYP-Z048 has potential for management of brown rot causing by M. fructicola and other diseases caused by ascomycota and basidiomycota.