![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
Strains of Botrytis cinerea resistant to dicarboximide fungicides were isolated from glasshouse vegetable crops in the Auckland region in 1980. The isolates showed cross-resistance to 4 dicarboximide fungicides (dichlozolinate, iprodione, procymidone, and vinclozolin), to dicloran, and to quintozene, and most were also resistant to benzimidazole fungicides. Growth was reduced, but not stopped, on media containing 10-1000 mg/litre of dicarboximide fungicides. The resistant isolates varied in their ability to invade plant tissue. In the glasshouses sampled, presence of dicarboximideresistant strains of B. cinerea appeared to reduce fungicide efficacy slightly. Strains of Phytophthora infestans resistant to metalaxyl were isolated from poroporo and potato crops where blight control based on the use of this fungicide was no longer effective. These isolates attacked poroporo or potato plants sprayed with 500 mg/litre metalaxyl, and a poroporo isolate also attacked plants sprayed with either ofurace or RE 26745. Isolates from crops where metalaxyl appeared to be giving adequate protection did not infect metalaxyl-treated plants. All of the isolates tested in vitro grew well in media containing up to 100 mg/litre of the fungicides. Metalaxyl-resistant isolates persisted in the poroporo seedbeds 8 months after use of the fungicide had been greatly reduced. Isolates of Penicillium italicum resistant to guazatine in vitro were obtained during trials to develop postharvest treatments for the control of blue mould on stored lemons. The isolates were not resistant in vivo.