Identification of Avocado Fruit Disease Caused by Diaporthe phaseolorum and Colletotrichum fructicola in China

Abstract

Persea americana (avocado) is a healthy fruit, rich in unsaturated fatty acids, various minerals, and vitamins. As avocado cultivation continues to expand globally, its development is increasingly constrained by concomitant diseases, among which fruit rot and anthracnose have emerged as significant threats to fruit quality. Menglian in Yunnan Province is the largest avocado production area in China. In November 2024, fruit rot was observed on avocado fruits in Yunnan, China, characterized by reddish-brown discoloration, premature ripening, softening, and pericarp decay, with a field infection rate of 22%. Concurrently, anthracnose was detected in avocado fruits, presenting as small dark brown spots that developed into irregular rust-colored lesions, followed by dry rot depressions, ultimately leading to soft rot, peeling, or hardened dry rot, with a field infection rate of 15%. Infected fruit samples were collected, and fungal strains were isolated, purified, and inoculated via spore suspension, followed by re-isolation. The strains were conclusively identified as Diaporthe phaseolorum (SWFU20, SWFU21) and Colletotrichum fructicola (SWFU12, SWFU13) through an integrated approach combining DNA extraction, polymerase chain reaction (PCR), sequencing, phylogenetic reconstruction, and morphological characterization. This is the first report of D. phaseolorum causing fruit rot and C. fructicola causing anthracnose on avocado in China. In future research, we will test methods for the control of D. phaseolorum and C. fructicola. The identification of these pathogens provides a foundation for future disease management research, supporting the sustainable development of the avocado industry.