Studies on the effect of the fungicide Euparen on cellulose‐decomposing fungi in Egyptian soil

Abstract

AbstractEuparen when applied to the soil at three doses (0.95, 4.75 and 9.5 mg active ingredient N,N‐dimethyl‐N'‐phenyl‐(N'‐fluorodichloro‐methylthio)‐sulfamide per kg dry soil) was generally suppressive to the total count of fungi and several fungal species. Its toxicity persisted to act till after 10 weeks from treatment with the three doses, but after 15 weeks the toxicity was completely alleviated. Trichoderma spp. were the only fungal species that was recovered from soil when Euparen was incorporated into cellulose‐CZAPEKS agar medium at the three doses (4.8, 23.8 and 47.5 ppm). The decomposition of filter paper buried in Euparen‐treated soil was significantly retarded after 1 week of incubation with the high dose. On the other hand, filter paper sprayed with the fungicide at the high dose and buried in untreated soil was decomposed at a significantly lower rate than the control after all experimental periods (15 weeks) in addition to the medium dose after 5 weeks of incubation. The growth and sporulation of Trichoderma viride on filter papers placed on the surface of carbon‐free agar medium and treated with Euparen were partially increased by the low dose, not affected by the medium dose and partially inhibited by the high dose. The colonization of the other test fungi was partially inhibited or even completely eliminated by the three doses. The mycelial dry weight of Trichoderma viride was significantly increased (nearly doubled) by the medium dose and not affected by the other two doses. The mycelial dry weight and endo 1,4‐β‐D‐glucanase production of the other test fungi were toxicated at least by the higher doses.