First report of Alternaria alternata causing the golden spot in xoconostle (Opuntia matudae) in Hidalgo, México

Abstract

The species Opuntia ficus-indica is affected by pests and diseases, one of the most important of these being golden spot. The latter has been reported in various countries, including Mexico. Symptoms similar to those of golden spot in O. ficus-indica have been observed in the xoconostle crop ( Opuntia matudae Scheinvar, cv. Rosa). The objective of this study was to isolate and identify the causative agent that causes the symptoms, which resembled those of the disease described as golden spot in O. ficus-indica. Simple random sampling in the field (10 plots) was carried out on xoconostle plants that presented the described symptoms. Slices of diseased plant tissue were cut and placed in Petri plates with PDA medium. Compliance with Koch’s postulates showed that the isolated (one aislated) of Alternaria sp. obtained from the field samples colonized the cladodes after inoculations in the greenhouse. Through taxonomic keys, Alternaria sp. was identified as the causative microorganism. Molecular characterization of the isolated Alternaria sp. was identified as Alternaria alternata. This is the first report worldwide of Alternaria alternata as the causal agent of golden spot in a xoconostle crop.