The 2012 ASHS Annual Conference

Irrigation water in ornamental greenhouse and nursery operations can be a source or dispersal mechanism for diverse biological problems including algae, biofilm and pathogens.  Growers face the challenge of selecting between alternative treatment technologies such as chlorination, copper ionization and ozone for control of waterborne microbial problems.  An online modified Delphi survey was carried out to identify the perceived key attributes of water treatment technologies for control of [algae, biofilm, and pathogens] that growers should consider in technology selection.  A panel of three Expert Types (43 ornamental growers, 28 water treatment industry suppliers, and 34 research and extension faculty) was asked to rate their level of agreement, on a Likert scale from 1 (strongly disagree) to 5 (strongly agree), on the importance of 23 listed financial, social, technical, and environmental Attributes when selecting between treatment technologies.  Response rate was 60%, including 27 growers, 15 suppliers and 21 faculty.  There was a significant interaction between Attribute and Expert Type (P < 0.05).  Attributes with an average rating above 4.5 for all Expert Types included residues that are not phytotoxic,  effective control of plant pathogens; effective control of biofilm; ease of monitoring; worker safety; low risk of environmental impacts; and suitable for large operations.  Cost was also perceived as an important attribute, with low operating cost per volume having a higher rating (4.17 ± 0.64, mean ± standard devn.) than low installation cost (3.37±1.15), with no statistical difference between Expert Types.  Control of target microorganisms varied in perceived importance from plant pathogens (4.63 ± 0.56), algae (4.39 ± 0.781), and biofilm (4.31 ± 0.81).  A lower rating for human food safety pathogens (3.61 ± 0.90) was probably influenced by this ornamental grower population and nursery application of the technologies.  All 23 attributes had an average rating of at least 2.9 both across and within Expert Types.  Results suggest that selection of water treatment technologies for the control of waterborne biological problems encompasses technical, economic, environmental and social attributes.