Estudio in vitro de la sensibilidad de Alternaria spp. en pitahaya (Selenicereus megalanthus) a fungicidas comerciales

Abstract

Yellow pitahaya, also known as yellow dragon fruit (Selenicereus megalanthus), an exotic fruit prized its distinctive flavor and nutritional properties. However, in Ecuador, its production faces phytosanitary challenges, including pathogenic fungus presence Alternaria spp. This fungus can cause leaf spot, fruit rot and even significant yield losses if is not properly controlled. Despite popularity of commercial products, efficacy against this disease has not been evaluated a vitro environment, creating a critical knowledge gap when using such products. To address this, sensitivity of Alternaria spp. present in pitahaya crop to different commercial fungicides was evaluated by in vitro tests. The study was conducted at Plant Protection Laboratory of Central Experimental Station in Amazon (INIAP) in Joya de los Sachas Canton, Orellana Province. The fungicides evaluated included Difeconazole, Chlorotalonil, Azoxystrobin, tebuconazole and a biological control with Bacillus subtilis. The variables considered were doses (high, medium and low) and germ tube inhibition. The results indicate tebuconazole (0.10 µm) is the most effective fungicide to reduce Alternaria spp. germ tube length, followed by Chlorothalonil (0.18 µm), Azoxystrobin (0.37 µm) and Difeconazole (0.3 µm). In addition, Bacillus subtilis showed intermediate efficacy (0.73 µm). These findings highlight the importance to use adequate doses to maximize efficacy and minimize resistance risk on pathogens control in agricultural crops.