Tuesday, November 14, 2006

Agronomic Production of Hybrid Poplar under Short-Term Intensive Culture in Western Colorado.

Calvin H. Pearson, Colorado State Univ., Western Colorado Research Center, 1910 L Road, Fruita, CO 81521

Hybrid poplars (Populus spp.) are produced for pulp, lumber, oriented strand board, plywood, fuel, conservation and ornamental plantings, wildlife habitat, and more recently for phytoremediation. In the mid-1980s, production of hybrid poplar was initiated in short-term rotations on farmland where agronomic crops have been traditionally produced. Compared to traditional poplar production, short-term rotations of hybrid poplar are planted at high tree densities using production cycles that are completed in less than 7 years. A hybrid poplar clone evaluation study was initiated in 2000 at the Western Colorado Research Center at Fruita. Plantings were on 2.4 by 2.4-m spacing. Eight hybrid poplar clones with a diversity of adaptation and plant architecture were included in the 6-year study. Most hybrid poplar clones established well with low mortalities (< 2% mortality). Tree height during the first year, averaged across all eight hybrid poplar clones, was 2.5 m. Poplar Hybrid OP367 was the tallest at a height of 3.1 m  (n = 64) and a 4.3-cm trunk diam. at the base of the tree and a 2.3-cm diam. at a one-meter tree height. The incidence of cottonwood leaf beetle, Chrysomela scripta (F.), was low in 2001, but in 2002 beetles needed to be controlled using an aerial insecticide application. Beetles were concentrated on Hybrids NM6 and 52225, which flushed leaves before other hybrids. Borer damage caused by carpenterworms [Lepidoptera: Cossidae: Prionoxystus robiniae (Peck)] was first observed during 2004 and only on Hybrid 52225. OP367 had the highest yield at 72.4 Mg ha-1 and 14272 had the lowest yield at 51.7 Mg ha-1. Single tree weights for OP367 were 86.6 kg and 58.2 kg for 14272. On average, hybrid poplars partitioned aerial phytomass by weight into 12% leaves, 20% branches, and 68% trunk.  Wood moisture content, averaged across all hybrids, was 500 g kg-1.