Caracterização morfológica e patogênica de isolados de Fusarium solani associados à podridão-do-colo do maracujazeiro no estado do Ceará

Abstract

The Northeast region stands out in the production of passion fruit in Brazil, especially with the 'maracujá-amarelo' variety (Passiflora edulis f. flavicarpa), with Bahia being the main producer, followed by Ceará that is the second in fruit production in Brazil. Among the phytosanitary problems that affect the crop, the Fusarium root rot, caused by the fungus Fusarium solani stands out. Thus, the objective of this work was to characterize morphologically and to test the pathogenicity of F. solani isolates associated with symptoms of root rot on passion fruit in Ceará State. Passion fruit plants that were observed in the field with symptoms of root rot were collected in the municipalities of Guaraciaba do Norte, Tianguá, São Benedito and Ubajara, taken to the laboratory, where indirect isolation was performed. Sixteen isolates of F. solani were obtained from symptomatic plants, being preserved in sterile water (Castellani). In potato, dextrose and agar (PDA) the average mycelial growth rate of the 16 isolates was obtained, varying from 3.28 to 4.61 mm.day -1. The colors of the colonies were beige, white, light gold and saffron. In synthetic nutrient-poor agar (SNA) all isolates were characterized morphologically, observing the variation regarding septation, length and width of the microconidia and macroconidia. Presence or not of chlamydospores and simple or branched conidiophores, where all 16 isolates had structures typical of F. solani. In the pathogenicity test, the 16 isolates induced root rot symptoms. The isolates UFCM-0678 and UFCM-0679 were considered to be most virulent in both necrotic lesion formation and wilt symptom. These results can be considered for future studies with the breeding of the passion fruit crop for the control of the Fusarium root rot.