Abstract: Bacterial canker of kiwifruit (Actinidia spp.), caused by Pseudomonas syringae pv. actinidiae (Psa, Biovar 3), seriously affected the New Zealand kiwifruit industry and requires new disease control products. Yeast isolates were screened for suppression of Psa and an effective isolate (YBCA5), identified as Aureobasidium pullulans (de Bary) G. Arnaud, was formulated and evaluated in field trials (2014 to 2017) and mode of action studies. Psa leaf spotting and bud browning were significantly reduced in the field trials across four years of study. Priming of plant host defence genes, leaf surface colonisation and altered pH are suggested as possible modes of action. Commercialisation of a product is progressing.