Comparative analysis of Monilinia fructicola and M. laxa isolates from Brazil: monocyclic components of peach brown rot

Abstract

ABSTRACT: Brown rot is the most important disease of peaches in Brazil. The objective of this study was to compare the brown rot monocyclic components from Monilinia fructicola and M. laxa isolates from Brazil on peaches, due to the detection of M. laxa in the São Paulo production area. Conidia germination and pathogen sporulation were assessed in vitro under a temperature range of 5-35oC and wetness duration of 6-48h. Incubation and latent periods, disease incidence, disease severity and pathogen reproduction on peach fruit were evaluated under 10, 15, 20, 25 and 30oC and wetness duration of 6, 12 and 24h. Six of seven parameters of a generalised beta function fitted to conidia germination of M. fructicola and M. laxa were similar. Only the shape parameter was higher for M. fructicola indicating that the range of temperatures and wetness periods favourable for germination is wider for M. laxa than for M. fructicola. The optimum temperature for brown rot development caused by M. fructicola was 24.5oC and for. Monilinia laxa was 19.8oC. At 10oC M. laxa lesions produced more conidia than M. fructicola, and the opposite occurred at 30oC. The estimated maximum temperature for lesion development was also higher for M. fructicola than for M. laxa. M. fructicola is favored by warmer weather than M. laxa and the presence and impact of this specie in Brazil must be investigated especially in the South states.