Identification and pathogenicity of fungal pathogens on avocado 034 in Vietnam

Avocado (Persea americana Mill.) is a popular fruit because of its high nutritional content and high economic value. However, this fruit is susceptible to microbial invasion, especially diseases caused by fungi, causing heavy post-harvest losses. The study aimed to determine the origin of fungal pathogens through isolation and identification based on microscopic morphological characteristics, pathogenicity tests, and gene sequences. Significant fungal pathogens causing spoilage diseases on avocados were identified by isolating spoiled avocado samples from five regions in Lam Dong province. Samples of avocado 034 (Persea americana Mill. Cv. 034) with natural disease symptoms were collected with 138 representatives of six genera, including Lasiodiplodia spp., Colletotrichum spp., Aspergillus spp., Fusarium spp., Geotrichum spp., and Mucor spp. The growth rate of mycelium showed the genus Mucor spp. had the fastest growth on PDA medium at 30oC, followed by the genera Lasiodiplodia spp., Colletotrichum spp., Aspergillus spp., Fusarium spp. and Geotrichum spp. However, the pathogenicity test evaluation indicated that the genera causing the most severe damage on avocados were Lasiodiplodia spp and Colletotrichum spp., with 77.78% and 67.90% of the spoilage rate, respectively. Next were the genera Fusarium spp., Aspergillus spp., Geotrichum spp., and Mucor spp., with damage ranging from 40.74% to 42.59%.