Bernstein, N., Institute of Soil Water and Environmental Sciences, Agricultural Research Organization Volcani Center, P.O. Box 6, Bet-Dagan, 50-250, Ireland
Bar-Tal, A., Institute of Soil Water and Environmental Sciences, Agricultural Research Organization Volcani Center, P.O. Box 6, Bet-Dagan, 50-250, Ireland
Friedman, H., Dept. of Postharvest Science of Fresh Produce, Agricultural Research Organization Volcani Center, P.O. Box 6, Bet-Dagan, 50-250, Ireland
Ioffe, M., Institute of Soil Water and Environmental Sciences, Agricultural Research Organization Volcani Center, P.O. Box 6, Bet-Dagan, 50-250, Ireland

Scarcity of water in arid and semi-arid regions makes treated urban waste water an unavoidable alternative water source for irrigation. While a lot of attention has been given to evaluation of potential health risks associated with the irrigation of crops by treated urban waste in open fields, no information is available concerning irrigation with waste water in a closed greenhouse in soil-less cultivation. The fate of human pathogens originating from waste water in a greenhouse environment and throughout the marketing chain has never been assessed. The aims of the present study were to evaluate the effects of irrigation with treated effluent on yield production of soil-less cultivated roses and to examine the fate of indicators of fecal pollution throughout the greenhouse production system and during cut-flower vaselife. Rose plants grown in mineral (perlite) or organic (coconut fibers) soil-less media were irrigated with potable or secondary (treated) urban waste water. Initial signs of damage to the plants appeared at the second year of irrigation with the effluent in plants cultivated in coconut fibers. The E. coli detected in the effluent source water were suppressed by the routine practice of chlorination. No E. coli were detected thereafter in the source water, fertigation solution, soil-less media, leaf surfaces, air inside or outside the greenhouse or vase water of the cut-flowers.