Resolving the status of Monilinia spp. in South African stone fruit orchards
Geographical distribution records of pathogens and pests are the basis for phytosanitary decision-making. Monilinia fructicola, one of the three Monilinia species responsible for brown rot of stone fruit, is listed as a regulated pest for South Africa. Many disputes about the justification of this classification have arisen during the past years as records have been published regarding the presence of this pathogen in South Africa. Results of several surveys conducted from 1985 in stone fruit orchards, revealed that M. laxa is the only causal agent of brown rot in South Africa. However, another notification of non-compliance (interception of regulated pests) was received by the National Plant Protection Organisation of South Africa in 2003 stating that M. fructicola was detected on consignments of South African Prunus fruits (P. domestica) in the United Kingdom. A detection survey according to inspections and sampling relevant to the biology of Monilinia species were conducted in the identified orchards at various stages throughout the year. Molecular techniques with species-specific primers for M. fructicola, M. laxa and M. fructigena based on the EPPO Diagnostic Protocol for M. fructicola were used for the identification of presumptive positive Monilinia isolates. The absence of M. fructicola from South African stone fruit orchards was again confirmed by this survey and its status in South Africa can be reported as: absent, not known to occur, confirmed by a detection survey. The regulated status of M. fructicola in South Africa is therefore scientifically justified by the results from this survey.