Rapid method for detecting resistance to a QoI fungicide in Plasmopara viticola populations.

ABSTRACT

BACKGROUND: The increasing occurrence of Qo inhibitor (QoI)-fungicide-resistant Plasmopara viticola (Berk. & MA Curtis) Berl. & DeToni populations is becoming a serious problem in the control of grapevine downy mildew worldwide. RESULTS: The authors have developed a rapid method for detecting resistance to a QoI fungicide, azoxystrobin, in P. viticola populations using the nested PCR-RFLP method. With this method, a glycine-to-alanine substitution was discovered at codon 143 in the cytochrome b gene of P. viticola populations found in Japan. CONCLUSION: It is proposed that the nested PCR-RFLP method is a high-speed, sensitive and reliable tool for detecting azoxystrobin-resistant P. viticola populations.