Caracterização de Colletotrichum spp. associados à antracnose e avaliação da adubação e controle químico na intensidade da doença e produção da pimenta-de-cheiro(Capsicum chinense Jacq.)

Abstract

The "pimenta-de-cheiro" is a vegetable from the Solanaceae family, with its center of domestication in the Amazon, where a wide variety of fruit sizes, shapes, colors, and pungency are found. One of the major problems associated with pepper cultivation is anthracnose caused by Colletotrichum spp., a disease that directly affects the fruits and can result in production losses of up to 100%. Given its commercial importance and the need to establish more effective management measures, efforts were made to identify species of Colletotrichum causing anthracnose in "pimenta-de-cheiro" using phylogenetic and morphometric criteria, as well as to evaluate the effect of treatments with fertilizers and fungicides in the field for disease management. To this end, this work was divided into two chapters.The first, titled "Morphometric, Pathogenic, and Molecular Analysis of Colletotrichum spp. Associated with Anthracnose of 'Pimenta-de-Cheiro'," presents results of the morphological, cultural, pathogenic, and molecular characterization of Colletotrichum isolates obtained from "pimenta-de-cheiro" fruits with anthracnose symptoms. It was found that the conidial and appressorial shapes of the evaluated isolates fit the patterns described for the Colletotrichum gloeosporioides and Colletotrichum acutatum complexes. These results were confirmed through identification based on the sequence of the ITS, ACT, GAPDH, and β-TUB genes, identifying two species: C. siamense (gloeosporioides complex) and C. scovillei (acutatum complex). Virulence assays showed that all Colletotrichum isolates inoculated into the fruits were capable of infecting and developing typical disease symptoms. The second chapter, titled "Combination of Fertilization and Fungicides in the Management of Anthracnose and Production of 'Pimenta-de-Cheiro'," was conducted through a field experiment using a randomized complete block design with subdivided plots, where fungicides (Control, Flutriafol, Chlorothalonil, and Azoxystrobin + Difenoconazole) were applied to the plots and NPK fertilization (0, 50, 100, and 200% of the recommended dose) in subplots. Evaluations began 90 days after transplanting and concluded at 210 days after transplanting. Biweekly assessments quantified the incidence and severity of disease on fruits, productivity (number and weight of fruits), and plant height.The combination of fertilization doses with fungicides demonstrated a significant effect on productivity, incidence, and severity of anthracnose. Anthracnose incidence and severity were reduced in plants subjected to 100% (150, 200, and 150 kg/ha of N, P2O5, and K2O, respectively) and 200% (300, 400, and 300 kg/ha of N, P2O5, and K2O, respectively) fertilization doses, especially when associated with the fungicide Azoxystrobin + Difenoconazole. Regarding productivity, fertilization had a significant impact, achieving the highest average weights and numbers of fruits at higher doses (200%), even without fungicide. However, the association with fungicides enhanced these effects. The results highlight the importance of the interaction between fungicides and fertilization in the management of anthracnose and the productive performance of "pimenta-de-cheiro" plants.