Occurrence of branch canker and stem-end rot in avocado trees in São Paulo orchards

• DOI: https://doi.org/10.22533/at.ed.9735112503071

• Palavras-chave: Persea americana, dieback, Botryosphaeriacea, Phomopsis

• Keywords: Persea americana, dieback, Botryosphaeriacea, Phomopsis

• Abstract: Branch canker and stem-end rot of avocado trees were characterized in 15 commercial orchards in the State of São Paulo, evaluating factors such as incidence of diseased branches and fruits, presence of pathogens, phytosanitary management, and foliar and soil chemical analysis. Fungal pathogens were isolated on potato dextrose agar medium from fragments of diseased branches, identifying the fungal genus by conidial morphology. The disease exhibited a high incidence, with an average of over 97% symptomatic plants in orchards, varying significantly among orchards and in the number of diseased branches per plant. Disease prevalence increased with plant age, predominantly affecting older branches. The presence of diseased branches associated with wood-boring beetle attack and the absence of protection of pruning wounds with fungicides were observed in most orchards. Fungi of the Botryosphaeriaceae family and Phomopsis sp. were the main causative agents of the disease, with an average incidence of 49.0% and 32.0%, respectively. Stem-end rot was the predominant postharvest disease compared to fruit body rot, with Colletotrichum sp. being the most frequent pathogen, affecting more than 15% of the fruits, followed by Lasiodiplodia sp. and Fusicoccum/Neofusicoccum sp. However, no significant correlation was observed between the incidence of diseased branches and the occurrence of fruit rot. Nutritional analysis revealed imbalances in soil and foliar levels of certain nutrients in most orchards. The results highlight the need for more effective management strategies, especially in phytosanitary and nutritional management, protection of pruning wounds and removal of infected branches, to minimize the spread of the disease and its implications on avocado productivity.