Effects of Cupric Hydroxide-Treated Containers on Growth of Four Southwestern Desert Landscape Trees

Abstract

Seedling liners of four southwestern desert landscape trees, Acacia smallii, Acacia stenophylla, Cercidium praecox, and Prosopis chilensis, were potted into black polyethylene containers either painted on the inner wall with a latex paint containing cupric hydroxide [Cu(OH)2] or unpainted. Tree seedlings were then grown for five months in an outdoor container production nursery and evaluated for effects of Cu(OH)2-treated containers on tree growth. No foliar copper toxicity symptoms were observed on any species during the study. In comparison with unpainted containers, Cu-treated containers increased root branching frequency, reduced shoot extension, and lowered the number of primary shoot lateral branches of sweet acacia and shoestring acacia. Cu-treated containers also decreased height of shoestring acacia. Chilean mesquite grew taller and larger with increased shoot and root dry weights in Cu-treated containers in comparison with those in unpainted containers. However, effects of Cu-treated containers on growth of Chilean mesquite were not related to any changes in root branching frequency. Growth of palo brea and root-to-shoot ratios of all four tree species were not affected by Cu-treated containers.