VIEW ARTICLE

Physiology and Biochemistry

The Effects of the Fungicide, Iprodione, on the Mycelium of Sclerotinia sclerotiorum. Charles C. Reilly, Research plant pathologist, U.S. Department of Agriculture, Science and Education Administration, Agricultural Research, Metabolism and Radiation Research Laboratory, Fargo, ND 58105, current address of senior author: U.S. Department of Agriculture, Science and Education Administration, Agricultural Research, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; Gerald L. Lamoureux, research chemist, U.S. Department of Agriculture, Science and Education Administration, Agricultural Research, Metabolism and Radiation Research Laboratory, Fargo, ND 58105. Phytopathology 71:722-727. Accepted for publication 29 December 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/Phyto-71-722.

The growth of Sclerotinia sclerotiorum in solid and liquid medium was inhibited by 3 μM iprodione. At 24 μM, the growth of early log phase liquid cultures was inhibited completely within 4 hr. At the same concentration, however, iprodione had no effect on mycelial respiration 2 hr after exposure. Uptake of ¹⁴C-labeled acetate, glucose, glucosamine, uracil, or thymine was affected only slightly by 60 μM iprodione. Incorporation of ¹⁴C from glucose into nucleic acids was inhibited within 10 min by 3 μM iprodione. DNA incorporation of ¹⁴C from thymine and uracil was inhibited 32%, whereas RNA incorporation of ¹⁴C from uracil was inhibited only 15%. Purine and pyrimidine nucleotide incorporation of ¹⁴C from aspartic acid and glycine and subsequent incorporation into RNA and DNA was not inhibited by 2.5 μM iprodione. It appeared unlikely that iprodione directly affected any major biosynthetic pathways or caused a major disruption of membrane permeability. The effect of iprodione on DNA synthesis appeared to be indirect.