Apply adequate water volume to wet the entire vine. The more calcium that can be applied, the better the control, but there is a concentration at which calcium can cause foliar burning. Apply three sprays, 10-12 days apart. Ca formulations containing nitro-gen after the end of July or fruit quality may suffer. The desirable range for micronutrients is quite narrow.
More damage is possible if micronutrients are applied in excess rather than from deficiencies.
For this reason, do not apply micronutrients to fruit crops unless leaf analysis or visible symptoms confirm a deficiency. Only the nutrient that is deficient should be applied in sufficient quantities to correct the problem. Boron deficiency can have an effect on growth and fruiting. There is currently no accredited soil test for boron in Ontario. Use a petiole analysis to check for boron deficiencies.