VIEW ARTICLE

The Effect of Thiabendazole on Spore Germination. David Gottlieb, Professor of Plant Pathology, Department of Plant Pathology, University of Illinois, Urbana 61801; Krishna Kumar, Research Assistant, Department of Plant Pathology, University of Illinois, Urbana 61801, Present address of junior author: Department of Botany and Plant Pathology, University of Maine, Orono 04473. Phytopathology 60:1451-1455. Accepted for publication 22 April 1970. DOI: 10.1094/Phyto-60-1451.

Thiabendazole, 2-(4'-thiazolyl) benzimidazole (TBZ), inhibited germination of Penicillium atrovenetum and Aspergillus oryzae 80% at 20 µg/ml and slightly more at higher concn. Complete inhibition did not occur even at 100 µg/ml. As little as 2 µg/ml prevented elongation or growth of germ tubes but did not inhibit spore germination. Growth of mycelium of P. atrovenetum and P. oxalicum was also inhibited by 2 µg/ml. TBZ is fungicidal as shown by the inability of spores to germinate after being removed from TBZ solution, washed, and placed in Czapek's medium. The fungicide is very readily absorbed by spores, and absorption is directly related to concn of TBZ and to time of incubation. At 100, 200, and 400 µg/20 ml TBZ, uptake by 200 g spores was 75, 140, and 260 µg, respectively. Spore concn of 10, 25, 50, and 100 µg and 200 µg TBZ/20 ml remove 5.0, 4.6, 3.0, and 2 µg/mg spores, respectively. TBZ was found mainly in the cell fluids, from which it was readily removed by adsorption on sand during preparation of cell-free spore extracts. The remainder was distributed among various particulate fractions obtained from ground spores: the cell wall and nuclear 37%, mitochondrial 42%, and ribosomal 20%.