Caracterización morfo-cultural y sensibilidad in vitro de aislamientos de Bipolaris sp. obtenidos de arroz (Oryza sativa L.) y pitahaya (Hylocereus undatus Haw.) Britton y Rose a diferentes fungicidas

Abstract

The presence of pathogens such as Bipolaris spp. among economically important crops such as dragon fruit and rice, describes the symptoms they cause in these crops. The main objective of the following work was to evaluate the morpho-cultural characteristics and in vitro sensitivity of Bipolaris sp isolates. obtained from rice (Oryza sativa L.) and dragon fruit (Hylocereus undatus Haw.) Britton and Rose to different fungicides. Morphological characterization revealed significant differences between the isolates: those from pitahaya showed circular or irregular colonies, light to dark brown mycelium, and conidia with 2-4 septa (24.15 x 7.31 µm on average). Rice isolates presented greater variability, with similar colonies, light brown to whitish mycelium, and conidia with 2-9 septa (62.08 x 12.46 µm on average). In vitro sensitivity tests showed that penconazole and pyraclostrobin + metiram were the most effective, achieving 100% inhibition of mycelial growth at 0.25 g/L. Other fungicides such as chlorothalonil, metalaxyl + chlorothalonil, cupric compounds and methyl thiophanate caused moderate inhibitions (40-60%). It is concluded that penconazole has great potential to control Bipolaris, although more studies are required given the variability between isolates. The morphological characterization of Bipolaris sp. showed significant taxonomic differences between rice and pitahaya isolates. This research provides a fundamental basis for the accurate identification and development of crop-specific phytosanitary management strategies.