Identificação de espécies de colletotrichum associadas à antracnose em anonáceas e avaliação de estratégias de manejo

Abstract

Annonaceae are a group of plants of great economic importance in various regions of the world, including Brazil. Among the main cultivated species are the sugar apple, soursop and atemoya. However, the production of these crops faces significant phytosanitary challenges, with anthracnose, caused by the fungus of the genus Colletotrichum, being one of the main problems, resulting in significant production losses. Therefore, the objectives of this work were to identify species of the genus Colletotrichum that cause anthracnose in anonaceae through of molecular and morphological characterization and pathogenicity tests, as well as to evaluate the effects of the fungicides Difenoconazole, Flutriafol, Pyraclostrobin, Azoxystrobin + Difenoconazole and Trichoderma harzianum on the mycelial growth of isolates of Colletotrichum theobromicola in vitro and on seedlings of atemoya, soursop and sugar apple. Fungal isolates of Colletotrichum were obtained from leaves of atemoleira, soursop, and sugar apple exhibiting anthracnose symptoms, collected from commercial plantations in the states of Alagoas, Bahia, Ceará, and Pernambuco. Forty-eight isolates were initially characterized using partial sequences of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes. To corroborate the species identified in the GAPDH gene analysis, eleven isolates were selected and subjected to concatenated phylogenetic analyses with the genes GAPDH, TUB2, and APMAT, as well as the ITS region of the rDNA. The multi-locus sequence analysis, in conjunction with the morphological characteristics and pathogenicity tests, revealed the presence of isolates belonging to the Colletotrichum gloeosporioides complex, closely related to C. theobromicola, C. fruticola, and C. tropicale species. All of the isolates were found to be pathogenic to their respective hosts, as was observed in the cross-pathogenicity test. The fungicide azoxystrobin + difenoconazole demonstrated the highest rates of mycelial growth inhibition in vitro and na efficacious preventive treatment effect on C. theobromicola isolates. Additionally, T. harzianum demonstrated a reduction in mycelial growth in vitro, as well as in mating tests and volatile metabolite assays, for the C. theobromicola.