DETERMINATION OF PATHOGEN CAUSES AVOCADO STEM-END BLACK ROT AND ANTIFUNGAL ACTIVITY OF CHITOSAN MATERIAL TO CONTROL DISEASE

Abstract

Avocado stem-end black rot is one of the main causes of postharvest losses of fresh avocado fruit globally. The study was conducted to identify the pathogenic agent of avocado stem-end black rot and using chitosan materials to control the pathogen in laboratory conditions. The research content includes isolation, identification, artificial infection of pathogenic fungi and evaluation of the inhibitory and fungicidal effects of different chitosan materials. The research results identified the Lasiodiplodia theobromae as the pathogenic agent of postharvest avocado stem-end black rot with typical symptoms of irregular dark brown discoloration, browning of xylem and phloem tissues, and softening of internal tissues. The chitosan-I₂ complex with a concentration of 1.500 ppm has the ability to inhibit the growth of L. theobromae with an effectiveness of 100% when the pathogenic fungus cultured on PDA medium and 81.94% when avocado fruit artificially infected.