KLETT, J.E. 1990. 1900 Crabapple evaluations. Colorado Green 6(3):16-17.
Colorado State University is one of 20 cooperating sites evaluating about 60 different crabapple taxa for disease resistance and ornamental characteristics. Data from each of the sites are tabulated and summarized at the Morton Arboretum in Lisle, Illinois. Eventually, a national publication will be published featuring this information. Six clones appear to have good ornamental characteristics and fairly good disease resistance in Colorado: Centurion, David, Hennengi, Indian Summer, Prairiefire, and Velvet Pillar.
DOUGHTY, S.C. 1990. Pruning properly. Am. Nurseryman 171(1):103-104, 110, 112, 114, 116.
Proper pruning in the nursery is important because trees are unlikely to receive it in the landscape. Most homeowners and commercial landscape owners or managers don’t know how to prune or train their trees. Selecting excurrent trees when possible saves labor in the nursery. Excurrent trees have tall, straight central leaders and need only minimal pruning. Decurrent trees have weak central leaders, and their lateral branches grow as fast as, or sometimes faster than, the terminal shoot. These trees often develop codominant leaders that create a multitude of V-shaped crotches and, consequently, many structural weaknesses. Pruning creates wounds. Genetically superior trees are better able to surround wounds with chemical barriers to limit the spread of decay. Selecting superior cultivars will allow your nursery to grow more serviceable, attractive trees that can be pruned with less chance of decay. After planting, the primary objective is to encourage the tree to become root-established as soon as possible. Research suggests that shoot pruning decreases root growth. Remove any basal suckers, epicormic shoots and crossover branches.
- © 1991, International Society of Arboriculture. All rights reserved.