The Effect of Some Fungicides on Conidial Germination and Mycelial Growth of Beauveria bassiana and its Efficacy against Cotton Whitefly, Bemisia tabaci Gennadius

Various fungicides and pesticides often have been used in agriculture for controlling diseases and pests. These pesticides may have detrimental effects on entomopathogenic fungi which have pesticidal ability. In this study several experiments were performed to assess the effect of 10 fungicides on mycelial growth and conidial germination rate at different rate using serial dilutions on PDA and SDAY media. Also effect of three fungicides, copper oxychloride (35% WP), Benomyl (50% WP) and Iprodione熪�睚츩 (52.5% WP) on the efficacy of Beauveria bassiana in controlling the cotton whitefly under laboratory and greenhouse conditions at recommended rate, twice the recommended rate and half the recommended rate were investigated. By evaluation of conidial germination of the fungicide-treated fungi, benomyl with IC50 value of 0.218 mg L-1 showed the highest inhibitory effect and copper oxychloride with IC50 value of 1381.94 mg L-1 showed the lowest inhibitory effect. Carbendazim with IC50 values of 0.076 mg L 1 and 0.112 mg L-1 had the highest inhibitory effect on B. bassiana mycelial growth after 3 and 7 days, respectively, Benomyl and iprodione熪�睚츩 at two times recommended field rates showed the highestand copper oxychloride at half the recommended field rate had the lowest effect on the fungal efficacy against the whitefly. Based on the present results, some systemic fungicides such as benzimidazoles were found to have detrimental effects to this entomopathogenic fungus.