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Effect of Active Flower, a nutrient spray containing boron, on disease suppression in cucumber (Cucumis sativus L.) and canola (Brassica napus L.)

Li Ni: Simon Fraser University

<div>Active Flower™ (AF) is a fertilizer that contains N: P: K (8:4:12) and boron (B, 3%) with potential for alleviating the severity of plant diseases. Greenhouse cucumber plants ‘Tasty Green’ treated with three weekly applications of AF at 0.3 and 0.5 ml/100 ml had significantly (P≤0.05) lower incidence of powdery mildew caused by <em>Podosphaeria xanthii</em>. Canola (<em>Brassica napus L.</em>) ‘Westar’ treated with four weekly applications of AF at 0.5 ml/100 ml demonstrated reduced development of <em>Sclerotinia sclerotiorum</em> on detached leaves. Nutrient analyses of leaves receiving four applications of AF at 0.5 ml/100 ml showed that N and B levels were enhanced by 22% and 500% in canola leaves, and 25% and 700% on cucumber leaves, respectively, compared to a water control. Neither N nor B had a significant effect on fungal pathogen growth when tested at rates of 250, 500 and 750 ppm in potato dextrose broth. Application of AF at 0.5 ml/100 ml significantly (P≤0.05) increased phenolic levels by 200% in canola leaves and 400% in cucumber leaves compared to the control. Enzymatic activities of peroxidase and polyphenol oxidase were not significantly affected by AF treatment. The mechanism of action of AF in reducing fungal pathogen development may be associated with physiological changes in the plant is response to B, which may include enhanced lignin formation.</div>