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Controlling Efficacy of Strobilurin Derivatives against Wheat Powdery Mildew and Eyespot
Tsuneo ICHIBA, Tetsuya INUTA, Yukio HORITA, Motomu NIIKAWA and Michio MASUKO
J. Pestic. Sci.
27, 127-132 (2002)
Strobilurins are active against a wide range of diseases in laboratory tests, but do not always show the same level of activity under field conditions. We studied the differences in fungicidal activity under laboratory and field conditions of strobilurins and DMIs (14-demethylation inhibitor of elgosterol biosynthesis pathway) against wheat powdery mildew and eyespot, focussing on the systemicity of the compounds. Against wheat powdery mildew, the activity of the test compounds in the field differed from that in the laboratory. In the field, kresoxim-methyl, (E)-2-[2-(3-trifluoromethyl-5-chloropyridin-2-yloxymethyl)phenyl]-2-methoxyimino-N-methylacetamide and triadimefon, which have high level of both systemic activity and vapor-phase activity, showed excellent efficacy to control wheat powdery mildew. The effect is presumably due to the uniform coverage of the leaf surface, even leaves that emerged and developed after fungicide application. On the other hand, against wheat eyespot, (E)-2-[2-(2,5-dimethylphenoxymethyl)phenyl]-2-methoxyimino-N-methylacetamide (SSF-129) and prochloraz showed excellent activity in the field, despite being ineffective against powdery mildew. These compounds had strong mycelial growth inhibitory activity, limited systemic activity and no vapor-phase activity. Therefore, it is assumed that these two fungicides remain in the area where they are sprayed, and show excellent control of eyespot, the symptom of which develop in a limited area of the stem base of wheat seedlings.
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