Biological Characteristics and Fungicides of Cherry Leaf Spot Disease Pathogen

  Objective  Biological characteristics of Colletotrichum salicis, the pathogen that causes the leaf spot disease on cherry plants in Qinghai Province, were studied and effective fungicides evaluated for the control.

  Methods  C. salicis were examined by the cross and spore counting methods. Its sensitivity to 26 fungicides was determined in the laboratory according to the growth inhibition on culture media.

  Results  PDA medium was found to be optimal for the C. salicis mycelial growth and sporulation. Inositol and glucose were the optimal carbon sources for sporulation, while beef extract the nitrogen for colony growth and peptone for spore production. The pathogen could grow between 5 ℃ and 40 ℃ but most rapidly at 25 ℃ and died at 58 ℃ in 10 min; between pH 4 and 12 but optimally at pH 7; and well under a photoperiod cycle of 12 h light/12 h dark. Among the tested antifungal agents, 10% phentermine methiconazole aqueous dispersion or 0.3% eugenol dissolvable solution had the greatest inhibition with EC₅₀ of 0.6 mg·L⁻¹ and 1.151 mg·L⁻¹, respectively, whereas 20% allicin oil emulsion, 80% manganese zinc wettable powder, and 500 g·L⁻¹ isobaric urea suspension the least efficacies with EC₅₀ up to 301.44 mg·L⁻¹, 679.36 mg·L⁻¹, and 1 012.52 mg·L⁻¹, respectively.

  Conclusion  The conditions and nutrients for optimal C. salicis culture were determined and the effective fungicides were identified.