Thesis Title

Studies on Potential of Resistance Development By Monilinia Fructicola to Selected Fungicides and Isolation of Uv Induced Cga 64251 Resistant Colonies

Date of Graduation

Fall 1980


Master of Science in Biology



Committee Chair

James Moore


UV irradiated conidia of Monilinia fructicola were screened for resistance to 5 μg/ml benomyl, 20 μg/ml vinclozolin, 60 μg/ml captan, 4 μg/ml CGA 64251 and 24 μg/ml fenapronil. No isolates resistant to benomyl, vinclozolin, captan or fenapronil were found. From about 1.2 x 10⁶ conidia 137 colonies resistant to CGA 64251 were found. Of the isolated characterized all showed pathogenicity on peach fruit treated and untreated with CGA 64251. Resistant isolates was not inhibited on peach fruit submerged for 1 minute in solutions up to 100 μg/ml CGA 64251, whereas growth of a non-resistant isolate was prevented on fruit treated with 50 μg/ml CGA 64251. The concentration of the solution of CGA 64251, in which peach fruit were treated, necessary to prevent formation of necrotic areas was found to be greater than that concentration required to prevent mycelial growth on potato dextrose agar. Resistance to CGA 64251 was lost by M. fructicola isolates after three to nine passages from isolation of resistant colonies in UV trials.

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