Zieslin, N.

Botrytis blight, caused by B. cinerea is a widespread problem in rose {Rosa hybrida) flower production in greenhouses. Despite efforts to reduce damage caused by the disease by modification of environmental conditions and use of fungicides, many flowers carry latent infections and these become visible during shipment or storage. The physiological status of the flower probably inf luences the change from latency to development of spreading lesions. The effect of ethylene inhibitors and calcium nutrition on susceptibility of rose flowers to the disease was studied and both factors were effective in controlling the disease. Exogenously applied gibberellic acid also showed potential for disease control.