EFFECT OF COCONUT HUSK EXTRACT ON ANTHRACNOSE CAUSED BY Colletotrichum sp. OF POSTHARVEST PAPAYA (Carica papaya L.) FRUIT

Abstract

Anthracnose, caused by Colletotrichum sp., is a major post-harvest disease that significantly reduces the yield and quality of papaya. To develop an effective control strategy, this study evaluated the inhibitory effects of coconut husk extract on Colletotrichum sp.. The fungal isolates were successfully obtained from naturally infected papaya fruits collected in Vinh Long province. Artificial inoculation of papaya fruits with these isolates reproduced disease symptoms consistent with those observed in naturally infected fruits, with strain DD1 exhibiting the disease symptoms. Genetic sequencing analysis revealed that strain DD1 shared 100% similarity with Colletotrichum siamense in the GenBank database. The study demonstrated that coconut husk extract effectively inhibited the mycelial growth of Colletotrichum sp. at concentrations of 100 µg/mL and 200 µg/mL, the maximum inhibition rates were 62% and 78.5%, respectively, though the effect gradually declined over time. Notably, at a 400 µg/mL, fungal growth was completely inhibited (100%) from day 2 to day 10. The extract also significantly suppressed spore germination, with a concentration of 5 mg/mL exhibiting strong antifungal activity. Microscopic observations revealed morphological alterations in fungal hyphae, including thickening, deformation, and the absence of spore formation in treated samples, in stark contrast to the healthy control group. These findings suggest that coconut husk extract holds promise as a natural antifungal agent for managing post-harvest anthracnose in papaya, providing a sustainable alternative to synthetic fungicides and contributing to environmentally friendly disease management strategies.