Morphological and molecular identification of Phytophthora capsici L. in pipiana pumpkin and its greenhouse management

The pipiana pumpkin is an important element in the diet of south-central Mexico residents. Its seeds are consumed directly toasted and seasoned with salt, and they are also the main ingredient used for making typical dishes such as green mole or pipian, as well as various traditional sweets. Some soil microorganisms cause severe damage in fruit, which reduces yield. The aim of the study was to identify morphologically and molecularly the oomycete causing rot in pipiana pumpkin fruits, and evaluate options for chemical and biological control in greenhouses. During August and September 2011, in the northern region of the state of Guerrero, pipiana pumpkin fruits with rot symptoms were collected. Morphological identification was performed with the keys proposed by Gallegly and Hong (2008), and molecular identification was by polymerase chain reaction (ITS-PCR). Both tests identified Phytophthora capsici as the causal agent of rot in pipiana pumpkin fruits. The sequences obtained showed 99 % similarity with the GenBank-held sequences for P. capsici in watermelon from the United States and pumpkin from Italy. The active ingredients propamocarb + fosetyl and metalaxyl + chlorothalonil delayed the presence of the pathogen in the fruits by six days, whereas the biocontrol agents delayed it by four days. Resumen