Pathogen growth inhibition and disease suppression on cucumber and canola plants with ActiveFlower™ (AF), a foliar nutrient spray containing boron

The effectiveness of ActiveFlower (AF), a fertilizer containing 3% boron in reducing pathogen growth and diseases on cucumber and canola plants was evaluated. In vitro, growth of S. sclerotiorum with AF at 0.1, 0.3 and 0.5 mL/100 mL showed pronounced inhibition at 0.5 mL/100 mL. In greenhouse experiments, the number of powdery mildew colonies on cucumber was significantly reduced by AF at the higher concentrations applied as weekly foliar sprays. On detached canola leaves, AF at 0.5 mL/100 mL and boric acid (BA) at 10 mL/L significantly reduced lesion size of S. sclerotiorum. Phenolic content and boron levels in foliage receiving AF applications were significantly increased. There were no significant differences in lignin. These results indicate that boron present in AF contributed to the disease suppressive effect.