Vegetable brassica IPM expanding into other brassicagrowing systems in the South Island

Abstract

An IPM programme originally developed for vegetable brassicas is now being adapted and extended into other brassicagrowing systems in the South Island including vegetable fodder and seed brassica crops MAFs Sustainable Farming Fund and various industry partners plus government funding is supporting research into best practices to manage the major foliage insect pests in these brassica crops A pest risk assessment survey was undertaken this year to determine in which seasons areas and growing systems pests are a problem Pheromone trap data showed that diamondback moth (DBM) Plutella xylostella survived overwinter as resident populations in localised brassica crops DBM and leaf miners caused serious problems for many growers DBM is resistant to standard broadspectrum insecticides but growers are still applying these insecticides which disrupt natural enemies of insect pests European leaf miner Scaptomyza flava is the key leaf miner pest and appears not to be attacked by the larval parasitoid Asobara persimilis which could be introduced from the North Island Field surveys also showed that the recently introduced larval parasitoid of white butterfly Cotesia rubecula has spread naturally to North and South Canterbury