Standard methods for inoculations of F. oxysporum and F. solani in Passiflora

摘要

Soil fungi, Fusarium oxysporum FO and F. solani FS (teleomorph: Nectria hematococca), are pathogens of economic importance passion fruit crops. The present work was developed in order to standardize the methodology of inoculation, as an initial step to confirm the etiology of diseases associated with Fusarium wilt and collar rot. Strains of FO for A14, A16, A22, A27, A29, A32, A34, A48, A54, A64 and FS A11, A23, A62, A63 were used; they were obtained from symptomatic crops of P. edulis. Inoculations were carried with and without wounds, on seedlings of two and four months of P. edulis. To assess incidence and severity, a scale designed for symptoms and growth variables was used. An incubation period of 14 to 19 days for FO, and was found highly virulent strains (A54, A64, A34). The symptoms are characterized by vascular wilt corresponded to a pattern of descending necrosis. Cross sections showed discoloration in vascular vessels and roots showed necrotic processes that lead to delayed development of seedlings. FS causes disease but the evolution in most strains is very low and exceeds 100 days. Wounds are further evidence for the fungus required in the plant tissue. Symptoms are manifested in the collar area with redness, mild canker associated with cracking and dry appearance on the injury.