Identification of sources of resistance of Passiflora rootstocks to fusariosis in areas with disease outbreaks in Mato Grosso state, Brazil

Abstract The aim of the study was to identify sources of resistance of Passiflora rootstocks to Fusarium sp. in two experimental areas with histories of disease foci in Mato Grosso state, Brazil. The experiment was carried out from June 2012 to December 2015 and was of randomized block design with eight treatments in which susceptible cultivar P. edulis was grafted onto hybrids CPAC MJ-H-87, CPAC MJ-H-76, CPAC MJ-H-86 and CPAC MJ-H-88, the commercial cultivar and native P. edulis, P. nitida and P. alata. Mortality rates of grafted plants were evaluated up to 640 days after transplantation. All Fusarium sp. isolates were identified as F. oxysporum f. sp. passiflorae. Plant mortality occurred earlier in the clay area than in the area with sandy clay loam. Grafted plants involving P. edulis as rootstocks were highly susceptible to Fusarium sp. with overall mortality rates above 56.25% considering both soil types, while plants with CPAC MJ-H-76 or native P. nitida rootstocks were more resistant with mortality rates below 12.5%. Grafted plants with CPAC MJ-H-86 as rootstock were highly resistant in clay soil but highly susceptible in soil with high proportion of sand. Only grafted plants involving CPAC MJ-H-76 as rootstock showed moderate resistance.