Best Tree——????

A frequent question of both new and well established homeowners is “What is the best tree to plant?” I find this question hard to answer because there is no tree without problems. For example, one of the trees, green ash, is at the top of my list. Green ash is native, drought tolerant, and sustains itself through our harsh winters. These are good reasons for it being a native tree for this area.

However, the ash plant bug and ash/lilac borer can be problems for green ash. Occasionally I find some ash trees devastated by the borer. The plant bug very early is the primary cause for the demise of ash trees. The other concern I have with green ash trees is that this tree accounts for a very large percentage of our tree population. Should a dominating pest like the emerald ash borer arrive in this area the green healthy appearance of our community will take a big hit. There are just a whole lot of green ash trees in communities like Tioga, Ray, Grenora and Williston along with most farmsteads.

When making a selection such factors as hardiness, moisture requirements, insect and disease resistance, mature size and freedom from insects and diseases should be considered. For this area plants generally should be labeled for U.S. Department of Agriculture hardiness Zone 3. Plants labeled for warmer (higher numbered) zones may develop dieback of branch tips if they survive the winter or may grow well for several years only to die in a year that exceeds their hardiness limits.

For a lot of trees insects and disease are secondary to environment stresses. Many pests are opportunistic and only attack trees under stress. In this area I think the primary environmental stress is water, both quantity and quality. Most trees are underlaid with grass which, because of its shallower root system, will get the first drink. So the tree must depend on water that leaches through the root system of the lawn.

In many areas we do have water quality issues. Usually the problem is high soluble salts but there are instances when the water source is high in sodium causing the soil surface to become hard. Soil “hardening” is due to dispersion of the soil particles by sodium when it displaces calcium and, magnesium ions that normally saturate the soil and help maintain its structure. The high sodium reduces ability of water to penetrate the soil surface and reach the tree roots.

If you suspect a water quantity problem, I suggest digging down 4-6 inches. Dry soil at this depth is an indication the tree may be under moisture stress.

Knowledge of trees growing around your home or those you intend to plant will be a great aid in maintaining or managing the tree’s vigor. I encourage homeowners to view the North Dakota Tree Handbook at http://www.ag.ndsu.edu/trees/handsbookd/ndhand-1,htm#ndth or purchase the book “Trees and Shrubs for the Northern Great Plains”. Both sources give excellent information about individual plant species characteristics and applications, tree care and maintenance, along with plant pictures and descriptions. The book costs $10 and is available from this office. Call us at 701-577-4595.