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Effects of pyriofenone on the infection of wheat plants by Blumeria graminis f. sp. tritici

Shigeru Mitani: Ishihara Sangyo Kaisha, Ltd.

<div>Pyriofenone (Property, Kusabi, Prolivo) is a new fungicide discovered and developed by Ishihara Sangyo Kaisha, Ltd. It is highly active against a broad spectrum of powdery mildew diseases including wheat powdery mildew at 90 g a.i./ha. The purpose of this study was to understand the biological mode of action of pyriofenone against <em>Blumeria graminis </em><span>f. sp. <em>tritici</em></span> on wheat plants. Wheat seedlings in polyethylene pots were sprayed with test solutions before or after inoculation with <em>B</em>. <em>graminis</em>. At 2 to 8 days after inoculation, leaf segments were observed with a light microscope. Pyriofenone inhibited all stages of the infection process (including appressorium formation, haustorium formation, mycelial growth, and conidium formation) except for conidial germination; however, it exhibited a greater effect on haustorium formation than on appressorium formation. In addition to its strong preventative effects, pyriofenone exhibited strong curative and inhibitory effects on conidium development. These data indicate that pyriofenone can help suppress powdery mildew epidemics and confer a high level of field control over fungal infestations.</div>