Filtration to Eliminate Phytophthora spp. from Recirculating Water Systems in Commercial Nurseries

Abstract

Three filtration systems using slow sand filtration (SSF) and one using lava grain filtration (LGF) were tested for their ability to eliminate Phytophthora spp. from recycled water in commercial ornamental nurseries over four years. Samples were taken in May, August, and October of each year. Phytophthora spp. could not be detected in any of the filter effluents when filters were operating normally. Water stored in clean water reservoirs that were filled only with filtered water and were well protected from contamination via soil and air remained free of Phytophthora. All four filtration systems produced sufficient quantities of water for nursery production. The maximum annual quantity of water demanded by the nurseries ranged from 30,000 to 163,000 m 3 . The cost for 1 m 3 filtered water was lowest for slow sand filtration compared with lava grain filtration. Recommendations for designing systems suitable for large ornamental nurseries with open air recycling systems are discussed. Accepted for publication 20 December 2007. Published 14 March 2008.Three filtration systems using slow sand filtration (SSF) and one using lava grain filtration (LGF) were tested for their ability to eliminate Phytophthora spp. from recycled water under commercial ornamental nursery conditions.