GROWTH OF FOUR SOUTHWESTERN LANDSCAPE TREES IN CUPRIC-HYDROXIDE-PAINTED NURSERY CONTAINERS

Abstract

Seedling liners of sweet acacia (Acacia smallii), shoestring acacia (Acacia stenophylla), palo brea (Cercidium praecox), and Chilean mesquite (Prosopis chilensis) were potted on 1 June 1993 into 27-liter (#5) black polyethylene containers filled with a 70% ponderosa pine forest mulch, 15% sand, and 15% silt (by volume) rooting medium. Just before potting, the inner wall of one-half of the containers of each species was painted with a latex paint impregnated with cupric hydroxide; the remaining containers were unpainted as a control treatment. Trees were then grown for 5 months in an outdoor container production nursery at a spacing distance of 45 cm. All trees were irrigated and fertilized according to standard nursery practices. The effect of cupric-hydroxide-painted containers (CHPC) on tree growth was species specific. Compared with nonpainted controls, CHPC caused roots to become more branched and decreased shoot lateral branch number and extension lengths of sweet acacia and shoestring acacia. CHPC also decreased height of shoestring acacia, but did not affect height of sweet acacia or root and shoot dry weight of sweet acacia and shoestring acacia. Shoot and root dry weight, height, and shoot lateral branch number and extension lengths of Chilean mesquite in CHPC were all increased compared with nonpainted controls. CHPC did not affect root branching of Chilean mesquite. Also, CHPC did not affect any measured growth variable of palo brea.