اثر علف‌كش هاي تريفلورالين و اتال فلورالين بر ويژگي هاي رشدي بيمارگرهاي قارچي پنبه

Effect of Tifluralin and Ethalfluralin on Growth Characteristics of Fungal Pathogens in Cotton

The objective of this study was to investigate side effects of two widely used soil-applied herbicides, Trifluralin (EC 48%) and Ethalfluralin (EC 33%) in 0-500 and 0-300 ppm concentrations, respectively, on biological activities of five pathogens of cotton (Gossypium hirsutum c.v Sahel) viz. Rhizoctonia solani, Pythium ultimum, Fusarium moniliforme, Alternaria alternata and Verticillium dahliae. The parameters, including fungal mycelial growth inhibition (%), prapagule germination, virulence, seedling disease and saprophytic growth of R. solani (by use of baiting method), were determined in laboratory as well as in greenhouse. Results showed that, growth inhibition rate was affected by type and concentration of herbicides. The herbicide treatments reduced mycelial growth in nearly all pathogens with various intensities. Verticillium. dahliae and F. moniliforme showed low vs very high susceptibilities, respectively. The growth of other fungi was suppressed in a range of 4.8-66.3%. The herbicides increased germination percentage in F. moniliforme chlamydospores and either decreased or inhibited formation or germination percentage in P. ultimum sporangia. Also, Trifluralin was observed to have more addetive effects than Ethalfluralin on saprophytic activity of R. solani. Itʹs finally concluded that tested herbicides caused the cotton seedlings to get predisposed to infection (by Pythium and Fusarium species) thus and increasing the incidence of diseases.