Risk assessment of fire blight on pome fruit in South Africa

Abstract

Pome fruit are grown in all temperate regions of the world. However, extensive cultivation of these fruit is limited in many countries due to the highly destructive disease fire blight, caused by Erwinia amylovora. Current control programs of fire blight rely on a preventative approach through effective plant quarantine systems, early detection of the pathogen and well-managed disease control strategies. The inability to effectively control and eliminate this disease has resulted in severe economic losses, particularly during major outbreaks. Complete eradication of fire blight is possible only if a small area is affected, if the disease is detected early and subsequently contained, as was the case in Australia. Countries free from fire blight currently rely on strict quarantine measures to prevent introduction of the pathogen. However, according to the SPS Agreement of the World Trade Organisation, quarantine measures should not be used as technical barriers to trade and should be based on risk assessment (RA) studies. In this study, a RA model was developed for South Africa to determine the likelihood of the pathogen being introduced into the country. Two case studies were discussed. The studies indicated that the pathogen was a major quarantine pest for South Africa and that its introduction may have severe consequences for local pome fruit industries.