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The Systemic Fungicidal Effect of Benzimidazole Derivatives and Thiophanate Against Cercospora Leaf Spot of Sugarbeet. Z. Solel, Division of Plant Pathology, The Volcani Institute of Agricultural Research, Bet Dagan, Israel. Phytopathology 60:1186-1190. Accepted for publication 10 March 1970. DOI: 10.1094/Phyto-60-1186.

Thiabendazole, 2-(4-thiazolyl) benzimidazole (TBZ); a dichloro derivative of thiabendazole, 2-(4-thiazolyl) dichlorobenzimidazole (ClTBZ); benomyl, methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate; and thiophanate, 1,2-bis-(3-ethoxycarbonyl-2-thioureido)-benzene, applied systemically, decreased infection by Cercospora beticola. Leaves were completely protected from infection when their opposite surface was prophylactically treated. Treatments 5 days after inoculation cured the disease by limiting fungus colonization. Application to infected leaves suppressed sporulation on both treated and untreated surfaces. Benomyl and TBZ applied either to the soil or to a part of the plant protected all leaves. An effect restricted to benzimidazole derivatives was an inhibition of spore germination on the opposite, untreated leaf surface. All those results were attributed to penetration of the fungicides into leaves or roots and to their translocation across the leaf, from root to leaf and from leaf to leaf. ClTBZ was fungicidal at 100 ppm, in vitro. At sublethal concentrations of benzimidazole derivatives, spore germination was abnormal, and numerous initial and distorted germ tubes were observed.