Hydroponic chrysanthemum production: cultural and pathological issues.

Hydroponic culture has not replaced soil culture in greenhouse production of chrysanthemum (commonly known as 'mum'). This study examines cultural or pathological conditions that might have affected the conversion from soil to hydroponic production. Cultural factors investigated included hydroponic container size and shape and oxygenation of the nutrient solution. Disorders encountered during the studies included salt wicking during rooting of the cuttings and severe Pythium infection in the third and successive crops in a hydroponic system. Mums did not appear to respond to various shapes and sizes of containers and troughs in which they were grown. Also, increased oxygenation had little effect on pythium root rot and plant growth. Rooting of cuttings in a polyethylene covered hydroponic system reduced wilting, whereas salt wicking was severe without a plastic covering. Pythium disease was severe in the third and successive crops in the same hydroponic system. The disease could be overcome by raising the cuttings in a peat-based growing medium in perforated plastic cells and then transplanting the seedlings along with the peat moss cubes into a hydroponic system.