Botrytis cinerea causes serious damage to rose plants mainly during the winter and flowers bearing visible symptoms are discarded. However latent infection may be symptomless with visible symptoms developing only after shipment and handling. Research undertaken in Israel and Holland has found that susceptibility of flowers to Botrytis decreases with increasing Calcium concentration in the substrate/nutrient solution. Additional of Boron during the night-time irrigation in a low-Calcium solution, also reduced the susceptibility of flowers to Botrytis. www.phytoparastica.org E-mail: elady@netvision.net.il