Botrytis cinerea, THE CAUSAL AGENT OF TWIG DIEBACK OF Vaccinium corymbosum L. CV. BILOXI IN OAXACA, MEXICO

Abstract

Twig dieback is a disease associated with plant pathogenic fungi that causes significant losses in species of the genus Vaccinium. This disease was observed in blueberry (V. corymbosum L.) cv. Biloxi plantations during the 2018 productive cycle at Sierra Norte of Oaxaca, Mexico. The aim of this study was to identify morphologically and molecularly the causal agent of twig dieback of blueberry plants cv. Biloxi, as well as to describe the histological damages induced by the pathogen. Fungal isolates were obtained from samples of twigs with necrosis symptoms and cultured in potato-dextrose-agar 2 % medium. The causal agent of the disease was determined using the Koch’s postulates. The pathogen induced wilting and necrosis in twigs after 10 days of inoculation. The fungus was identified morphologically and molecularly as Botrytis cinerea; in addition, histological sections of symptomatic twigs were performed using the paraffin embedding technique and safranin O-fast green differential staining. In the histological sections degradation, lysis and cellular disorganization of cuticle and epidermis were observed; inside these, amorphous red bodies were observed, probably corresponding to polyphenols. There was no evidence of penetration structures of the pathogen. This document constitutes the first report of B. cinerea causing twig dieback in V. corymbosum cv. Biloxi in Oaxaca, Mexico. Morphological and molecular characterization of this pathogen contributes to the knowledge of the causative agent for the search of control strategies and integrated management.