(35) Foliar Mineral Nutrition of Colorado Spruce Trees after Digging Affects Shoot Growth in the Landscape

Abstract

The goal of this study was to determine if nutrient treatments applied to Colorado spruce (Picea pungens Engelm.) trees while they were held in a mulch bed one season after digging affected subsequent shoot growth of the trees after they were planted in the landscape. Sixty 1.5- to 1.8-m-tall trees with 61-cm (24-inch) diameter root balls were heeled into a holding bed of fresh pine bark mulch. The nutrient treatments applied to the root balls were a control (pine bark without fertilizer), 114.2 g Osmocote 15–9–12 distributed over the top of the ball (label rate), one Ross Gro-Stake 10–10–10 Evergreen fertilizer spike per ball, one-half cartridge of Ross Root Feeder 10–12–12 evergreen fertilizer injected into the root ball at four points, or a 50:50 mixture (by volume) of Eko Compost mixed with pine bark. After one growing season in the mulch bed, the trees were transplanted to a landscape site. The height increases of the terminal leaders on all trees were determined for the next 2 years. Changes in tree height by the end of the growing season in the mulch bed were unaffected by the nutrient treatments. By fall, needles from trees treated with the mixture of 50:50 compost: bark had the highest levels of foliar N, Mg, Ca, S, Mn, and B. Trees treated with one fertilizer spike had the second-highest levels of foliar N and S. Leaders on trees that received the compost:bark or fertilizer spike treatments grew at least 70% or 36% taller, respectively, than those receiving the other treatments by the end of the second growing season in the landscape. The compost:bark mixture and to some extent the fertilizer spike improved tree foliar nutrition during the first growing season after digging, which later promoted tree height increases in the landscape.