Replacements for ash trees

Gingko

Ginko. Photo by K. Zuzek, UMN Extension

February 11, 2016 – Kenosha News

Let’s finish this series of columns on choices for replacing ash or other large shade trees with an assortment of species.

Despite its name, Kentucky Coffeetree is native to southern Wisconsin. Small blue green leaflets on compound leaves provide filtered shade. Fall color varies from brown to a so-so yellow. The gray bark features attractive curving ridges, and there are no significant insects or diseases. Kentucky coffeetree can be messy in fall when they drop the rachis (stem) of their compound leaves along with the leaflets. Female trees produce large bean-like pods so male cultivars (e.g. Expresso, Prairie Titan) may be preferred. Kentucky coffeetree is tolerant of compacted alkaline soils common in our urban landscapes.

Ginkgo has become a fairly common landscape tree. The unusual fan shaped leaves attach to the branches in whorls and the “fruit” is actually a naked seed. The 1 to 1 ½ inch round ginkgo seeds are smelly and messy, so male trees (e.g. Autumn Gold, Princeton Sentry) are definitely preferred. The bright green leaves turn bright clear yellow in fall and are the main ornamental reason to plant ginkgo. Fall clean-up is easy because the leaves all drop from the tree within 24 to 48 hours of a hard frost. Ginkgos are notoriously slow growing. Their growth can be accelerated the first few years by sufficient water and fertilizer.

Common Hackberry is a large native tree. From floodplains to dry prairies hackberries will grow just about anywhere. The leaves are elm-like with poor yellow fall color. Birds love the 1/3-inch round purple fruits. Hackberry is distinguished by its warty, corky gray bark. Hackberry nipple gall is very common on the leaves. Although galls do not harm the tree, the leaves are disfigured by the ¼ inch cream colored bumps. In September tiny adult insects emerge from the leaf galls and may become a nuisance if the tree is planted next to your house.

Other good shade trees of which I’m especially fond are Katsuratree, Tuliptree, and Beech.

Before choosing a tree remember to observe the conditions in your landscape, find out your soil pH, consider the characteristics you want, do a little research and avoid planting the same trees as everyone else in your neighborhood.

For lists of recommended replacement trees and previous columns, please visit: Gardening Questions.

 

Kenosha County UW-Extension LogoBarb Larson is horticulture educator for the Kenosha County University of Wisconsin Extension. She holds a master’s of science in horticulture from the University of Wisconsin-Madison. If you have a plant or gardening question, email her at barbara.larson@kenoshacounty.org or call 262-857-1942.