Influence of Copper Ion Concentration and Electrical Conductivity of the Nutrient Solution on Phytophthora cinnamomi in Ivy grown in Ebb-and-Flow Systems

Pathogenic zoosporic fungi cause diseases in many green! house crop species[ Manipulation of the copper ion con! centration and the electrical conductivity in the recirculating nutrient solution was used as a means of reducing Phytophthora!incited root rot in plants[ Foliage pot plants of Hedera helix were grown on ebb!and!~ow benches with separate systems for recirculation of the nutrient solution[ Four nutrient solutions with two cop! per ion concentrations "9[96 and 9[17 p[p[m# and two levels of electrical conductivity "0[4 and 1[1 mS:cm# were used in two experiments[ FeSO3 was added as an iron source in all treatments[ Inoculation with Phytophthora cinnamomi zoospores was carried out via the nutrient solution and with _nal concentrations of 4\ 04\ 49\ or 014 zoospores:ml in the tanks[ Changes in copper ion concentration from 9[96 to 9[17 p[p[m[ signi_cantly reduced disease incidence at all inoculum levels[ In plots inoculated with 4 zoospores:ml\ the mean percentages of wilted plants 17 days after inoculation were reduced from 81 to 7)[ There was a tendency towards a more sup! pressive e}ect of increased copper at electrical con! ductivity 0[4 mS:cm compared with 1[1 mS:cm[ The results suggest that elevated copper ion concentration in the nutrient solution could be an important component of a disease management strategy in ivy production[ However\ methods for control and maintenance of the copper ion concentration in the nutrient solution should be further elaborated[