Sensitivity of hyperparasitic fungi to alternative products for use in the control of papaya black spot

Abstract The use of more than one control technique can maximize the reduction of the damages caused by the fungus Asperisporium caricae causal agent of the black spot in the papaya crop. The objective of this work was to evaluate the sensitivity of the fungi Hansfordia pulvinata and Acremonium spp. to alternative products with potential for use in the control of the black-spotted ptarmigan. Three isolates of Acremonium spp. (A-598, A-602 and A-617) and an isolate of H. pulvinata (H-611) were grown in BDA medium containing Agro-Mos®, Bion®, Ecolife®, Hortifospk®, Matriz G®, Vitaphol® separately. The Amistar 500WG ® fungicide was used as a positive control and pure BDA as a negative control. The toxicity of the tested products was determined based on the values of the biological index, derived from the means of mycelial growth, sporulation and germination of conidia, in each experimental unit. In this way it was possible to select the products classified as compatible for all isolates, and to test them in vivo. In the greenhouse, only the isolates and isolates with selected products, were applied in papaya plants with foliar symptoms of black-spotted. The incidence of leaves with hyperparasites and the percentage of black-painted lesions colonized by the tested isolates were evaluated. Thus, the H-611 isolate proved to be compatible with most of the alternative products tested, except with Hortifos®. Bion® and Matrix® products were compatible with all tested isolates and could be used in conjunction with Acremonium spp. and H. pulvinata to control the papaya black spot, since these products did not present toxicity on the hyperparasitic fungi.摘要 联合多种防控技术，可最大程度减轻番木瓜作物黑斑病病原菌番木瓜黑斑病菌（Asperisporium caricae）所造成的危害。本研究旨在评价汉斯福德霉（Hansfordia pulvinata）与支顶孢属真菌（Acremonium spp.）对潜在可用于防控番木瓜黑斑病的替代产品的敏感性。本研究选取3株支顶孢属真菌（编号A-598、A-602、A-617）以及1株汉斯福德霉（编号H-611），分别接种于添加了单一商品制剂Agro-Mos®、Bion®、Ecolife®、Hortifospk®、Matriz G®、Vitaphol®的BDA培养基中进行培养；以Amistar 500WG®杀菌剂作为阳性对照，以不含任何添加剂的纯BDA培养基作为阴性对照。供试产品的毒性以各试验单元中菌丝生长、产孢量及分生孢子萌发率的均值计算得到的生物学指数为评价依据。通过该方法可筛选出对所有供试菌株均兼容的产品，并开展活体试验。温室试验中，仅对带有叶部黑斑病症状的番木瓜植株分别接种单一供试菌株，以及接种结合了筛选出的兼容产品的供试菌株，随后调查带有重寄生真菌（hyperparasites）的叶片发生率，以及供试菌株定殖的黑斑病病斑占比。结果表明，除Hortifos®外，H-611菌株与绝大多数供试替代产品兼容。Bion®与Matriz G®可与所有供试菌株兼容，可与支顶孢属真菌及汉斯福德霉联合用于番木瓜黑斑病的防控，因其对重寄生真菌无毒性作用。