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New Zealand Plant Protection 67 (2014): 323

In vitro evaluation of fungicides and biocontrol agents for efficacy against Neofusicoccum spp. that cause dieback of blueberries

K.M.S. Tennakoon, H.J. Ridgway, E.E. Jones and M.V. Jaspers


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 0.1 mg ai/litre. Carbendazim and iprodione (both EC50 = 0.04 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 0.04 and 0.1 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.

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