Phytophthora species associated with irrigation water in the Culiacán Valley

Abstract

In Mexico there are few studies describing aquatic bodies used for agriculture and the role of irrigation water as a source of inoculum, persistence and dispersal of phytopathogenic parasites, such as oomycetes that inhabit aquatic environments with the capacity to infect a wide range of cultivated hosts. Due to the lack of information on which oomycetes genus and species are present in the water, their identification is of paramount importance in managing alternative management and control of them for agricultural production in the region. In order to determine which oomycetes are isolated in surface waters used for irrigation in the Culiacán Valley, Sinaloa, in the period from September 2018 to January 2019, in different agricultural water networks (reservoir, ponds, rivers and canals), floating traps made with polypropylene bags and two pear fruits that were placed that served as bait. Oomycete isolates were obtained, which were identified based on their morphological characteristics and DNA sequences (with ITS 4/6, COX and NADH initiators), pathogenicity tests were also performed on plants and fruits of the solanacea and cucurbitaceae families. The organisms were isolated and identified: Phytophthora parsiana, P. virginiana, P. lagoariana, P. capsici and P. hydropathica. All Phytophthora species were pathogenic, they had the ability to infect plants and fruits, causing symptoms of wilting and rotting in the inoculated vegetables.