Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
4/17/00
Contacts:
Mark Vitosh, Forestry Extension, (515) 294-6739, mvitosh@iastate.edu
Elaine Edwards, Extension Communication systems, (515)
294-5168, eedwards@iastate.edu
Yard and Garden Column for the Week Beginning April 21
Tree Planting Season Has Arrived -- Plan Ahead
By Mark Vitosh
Extension forester
Iowa State University Extension
Many perennials have popped out of the ground, trees are flowering and the grass is growing. During this spring season, we often start thinking about planting new trees in our yard. Tree planting is a great activity, but the experience can turn sour in some cases when trees become unhealthy or die a few years after planting. In many cases these tree problems can be avoided.
Many common problems found on trees are not always related to insect or disease organisms. They are often caused by planting species not adapted to the growing conditions on the site. To avoid unnecessary problems, evaluate the planting area before selecting trees for planting.
Site Evaluation
The first thing you should evaluate on any planting site is the location of buildings, structures, established trees and above and below ground utilities. In Iowa, you are required to call Iowa One Call at 1-800-292-8989 at least two working days before you plan to dig, and they will locate and mark utilities at no charge. Avoid planting trees closer than one-half their mature width from buildings and structures. Also, be sure to look up for overhead wires, and always keep trees a minimum of 35 feet away from these lines.
After you have evaluated the planting space, consider other factors such as soil texture (i.e. sand, silt or clay), drainage and pH. These factors can have an impact on tree survival and growth. For example, a limited number of species adapt to wet soils such as in a low lying, moist area. If the pH of the soil is 7.0 (neutral) or greater, you would not want to plant certain tree species. In Iowa, pin oak often develops a symptom called chlorosis (yellowing) when the soil pH is above 7. This symptom of yellowing can often progress to die-back of branches and eventual tree death. This problem can be avoided by not planting pin oak in most situations unless the pH of the soil is 6.5 or lower. Tree species such as river birch, swamp white oak and red maple also can be sensitive to soils with a high pH.
Other factors to consider while looking at the site include the amount of sun or shade, exposure to the wind and the general direction of the area. North- and east-facing slopes tend to be cooler and moister than south- and west-facing slopes.
Tree Selection
After you have evaluated the site, select the species that best meets your objectives (e.g., shade, wildlife habitat, beauty, screening, etc.) and match the available growing conditions. It is important to select trees adaptable (hardy) to the weather conditions in your part of the state. As you look at potential choices, find out what the mature size of the tree will be, and consider how it will fit into your landscape.
Other things to consider about potential trees include their ornamental shape, bark appearance, fruit, fall color and whether they produce thorns or not. If you are planting near an area with pedestrian traffic, a tree with thorns would be a poor choice. Remember that characteristics like spring flowers only last a few weeks, so you may want to select species that have other interesting characteristics at other times of the year. For example, a number of flowering crabapples have fruit in the fall that is attractive and valuable to wildlife.
There are potential disease problems of selected crabapple trees. For example, some crabapple trees are susceptible to a fungal infection called apple scab that defoliates the trees nearly every year. This problem can be easily avoided or reduced by selecting varieties with resistance to this particular disease. A great place to find information on disease resistance, the needed growing conditions, height, spread and growth characteristics of a specific tree species, is your local nursery.
Two special days in April give Iowans a great reason to plant a tree--the 30th anniversary of Earth Day on April 22 and Arbor Day on April 28.
Check the following Iowa State University Extension publications for more information on selection, planting and care of trees: Community Tree Planting and Care Guide, Pm-1591; Conifer Species of Iowa, Pm-1429G; Low-Growing Trees for Urban and Rural Iowa, Pm-1429D; Street Trees for Iowa, Pm-1429E; and Crabapples for Midwestern Landscapes, Pm-1814. These are available at the ISU Extension office in your county.
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