University of Vermont Extension 
Department of Plant and Soil Science

Spring, Summer News Article
line
SELECTING THE BEST TREES


Dr. Leonard Perry, Extension Professor
University of Vermont

Trees are the first plant consideration in most landscapes, form the framework or base to build on and around, and can affect subsequent plantings.  Trees are a major investment, most lasting a lifetime and perhaps longer than those who plant them, so the selection of the right tree for the right place is a major decision. This applies whether you’re building a new landscape, or simply replacing a tree that died from age, damage, disease, or other causes.

Choosing the best tree for a site depends on what you desire from the tree, its traits, its quality, and a proper match to the site.  According to a brochure from the International Society of Arboriculture (ISA) on Tree Selection, the main cause of tree death is not from pests and diseases, but from planting the wrong tree.
           
Before you start shopping for a tree, consider what you want from it.  Will it be for aesthetics?  If so, what are its shape, growth habit, rate of growth, flowers, fruit, or attractive bark?  You’ll hopefully be living with this tree for some time, so personal preferences are important and will vary with individual.
           
Will your tree be for an environmental use such as providing shade, screening winds, providing wildlife food or habitat, reducing noise, or just adding more oxygen?  Evergreen trees provide a backdrop for other plantings, screening from wind, and food or habitat for wildlife in winter. Trees along streets help reduce pavement glare and rain runoff, and filter pollutants from vehicles.
           
Then consider where the tree will go, and the space for its ultimate growth.  This is perhaps the most misjudged or overlooked decision in buying and planting trees, with them ending up too close to buildings or other plantings, or too tall under utility wires.  Or they may block desired views and need frequent pruning, or be of an undesired shape.  Choose the right size and shape of tree, and maintenance will be greatly reduced.  You even may end up deciding you just don’t have room for even a small tree—which is perhaps better than planting one and having to deal with the size in a few years.
            
Consider aspects of the environment, such as hardiness, soil type, and if a small tree if it will be shaded by a building or taller trees.  Often hardiness is given as a USDA zone, referring to average low temperatures, with maps either in catalogs, on labels, in books or online (planthardiness.ars.usda.gov). 
           
Soil type is critical, as trees just can’t be moved easily as can smaller shrubs or flowers.  Poor soil drainage will starve the roots of oxygen, drowning them and leading to root rots.  If you’re unsure about this, dig a hole a foot deep and fill it with water.  If the water doesn’t drain away in 6 hours, you may have a problem and should consult a landscape professional or tree specialist. Or you should choose a tree that can tolerate “wet feet”. 
           
Soil compaction from foot or vehicle traffic can keep water and air from entering the soil as well, resulting in tree decline or death.  Keep in mind that tree roots extend out at least as far as the tips of the branches, or “dripline”, so this should be planned for in tree growth if they’re to be in areas of potential soil compaction. 
           
While many trees will tolerate some level of pests and diseases, and in fact insects on trees provide a huge supply of food for birds, there are some specific ones you should think about or ask your nursery professional for their recommendations.  Crabapple trees, for instance, have varying levels of resistance to scab disease, depending on cultivar (cultivated variety).  With the emerald ash borer insect in many areas of the country, you may want to shy away from ash trees.  Mountain ash and some apple trees easily get fireblight disease.
           
So far, all these considerations have been made prior to even starting your tree shopping.  So when you do visit a plant outlet, nursery, or garden center, look for the best quality trees.  Just as trees are a long-term investment, injuries you may start with on trees (just as ones that happen later) may take a year or more to show symptoms. 
           
When looking at trees to purchase, the ISA says to keep in mind R.I.F.  This is a way to remember to inspect a plant for problems with roots, injuries, or form.  Make sure the tree has plenty of roots to support the top—the larger the top, the larger the pot or “root ball” if a ball of burlap holding soil and roots. 
           
Inadequate roots often are a major problem with trees purchased through large chain stores, and even some nurseries.  Trees are potted “bare root” in spring by growers—just the plant dug with no soil, or from cold storage.  You then buy the plant which is starting to grow on the top, or in full leaf, but with few if any roots formed yet.  This causes stress when planting and subsequently, and can easily result in decline or death. 
           
To check roots in pots, turn them on their side and tap the sides.  Pulling the trunk gently, the roots and soil should easily pull out together.  If the plant starts to pull out, leaving soil behind, put it back and move on. 
           
Even if plants in pots or a root ball seem well rooted, look at the base of the trunk for any roots that are tight and circling the trunk or rubbing against it.  These “girdling roots” are from improper growth, or plants in pots too long, and will eventually strangle the tree. This is a common cause of tree decline in later years in landscapes.
           
Check the trunk and stems for injuries, either broken branches or trunk wounds.  Branches pruned off should not have stubs left, as these lead to improper healing and diseases.  If trunks are wrapped with paper or a tree guard, check under this as it often can hide injuries from improper handling, or insects.  Look for cracks in the trunk below branch unions.  Sunken and discolored areas on trunks may indicate start of a canker disease, so avoid trees with these.
           
Check the tree form as well—there shouldn’t be too many branches on one side and not another, branches should be well-spaced around and up the trunk, branches should not be rubbing or squeezed together, and upper V-shaped angles between branches are weak areas that often result in a branch breaking off. If you want a tree with multiple trunks, as is common in birches, choose one with the trunks well-apart at the soil surface.
          
If buying trees in spring, particularly before leafed out fully, make sure they are what the label states.  A friend bought a tree from a chain outlet, the tree labeled as a pear but when it leafed out it obviously was a peach that wouldn’t have survived a winter!  Thankfully the store had an easy return policy, but it was extra work to dig up the plant and return it to the store.
           
If you want a particular cultivar of tree, this may be more difficult to determine at purchase time.  It may take several years for a form to develop, as in a sugar maple I bought thinking it was the usual rounded species.  It turned out years later to be more columnar, which actually fit my site better, fortunately.  The best way to get the correct plant is to buy from a reputable nursery.
           
Going through these steps in planning for your new tree, then selecting one of high quality, you should be rewarded with one that grows well and gives you many years of enjoyment.  Trees in the landscape also will increase the value of the property, should you decide to sell it and move.  You can learn much more on choosing and care of trees online from the ISA (www.treesaregood.org/). 


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