In vitro evaluation of fungicides and biocontrol agents for efficacy against <i>Neofusicoccum</i> spp that cause dieback of blueberries

Abstract

Several botryosphaeriaceous species have been reported to cause stem canker twig blight and dieback of blueberries with different Botryosphaeria species reported in different parts of the world This research evaluated nine fungicides for their ability to reduce mycelial growth conidial germination and germ tube elongation of four common and pathogenic botryosphaeriaceous species recovered from New Zealand blueberries Furthermore two biocontrol agents were tested against the same species using dual plate assays Fludioxonil carbendazim flusilazole and tebuconazole were the most effective for inhibition of mycelial growth of three isolates each of Neofusicoccum australe N luteum N parvum and N ribis EC₅₀ values for these fungicides were less than 01 mg ai/litre Carbendazim and iprodione (both EC₅₀ 004 mg/litre) were the most effective for reduction of conidial germination of all four species In addition these two fungicides were effective for inhibition of germ tube elongation with mean EC₅₀ values of 004 and 01 mg/litre respectively The biocontrol agents Trichoderma atroviride and Bacillus subtilis reduced mycelial growth of all species tested with a range of macroscopic interactions This study has indicated the most promising fungicides and biocontrol agents for further investigations to protect pruning wounds in blueberries