Identification and control of fungi causing fruits rot in pipiana pumpkin (Cucurbita argyrosperma Huber)

Abstract

Severe rot symptoms were observed in samples collected during 2012 in a small farm in Cocula, Guerrero, Mexico. One oomycete and two deuteromycetes fungus were isolated from collected symptomatic fruits. In order to carry out the molecular analysis by the amplification of the internal transcribed spacer region (ITS) two representative isolates of each fungus were chosen. The pathogenicity of each isolate was verified with pumpkin fruit inoculation with fungus inoculants and fruits sprinkled only with sterile distilled water as control. The control fruit remained healthy while the fruits which were inoculated with the pathogens were observed to have injuries and rot symptoms five days after inoculation. From the fruits showing injuries and rot symptoms, the oomycete and fungus were re-isolated. Based on the isolation, morphological, and molecular identification, as well as on pathogenicity tests, Phytophthora capsici Leon, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc., were determined to be the causal agents for rot of the pumpkin fruits. Additionally, five fungicides and the biocontrol agent Trichoderma asperellum were assessed against the above fungus in pumpkin fruits in a greenhouse. The fungicides propamocarb + fosetyl-Al, metalaxyl + Chlorothalonil, quintozene, and the biocontrol agent T. asperellum, delayed the presence of P. capsici, R. solani, and S. rolfsii for 6.00, 4.67, and 5.83 days, respectively. Key words: Cucurbita argyrosperma, soil pathogens, fruit rot, fungicides, Trichoderma asperellum.