I have written a great deal about the problems with poplar trees, especially the Swedish aspen and Tower poplar -- two of the most commonly planted trees in the poplar tree family. There are larger poplar trees than these two which also can be of great concern for people who own these trees.
I devote much space about poplar tree problems in my book Dr. Tree's Guide to the Common Diseases of Urban Prairie Diseases. There are numerous illustrations of the problems poplars can experience. The poplars I am referring to are the very tall and massive hybrid poplars. These trees have been around for more than 50 years, but are usually hybrids between the native giant cottonwoods growing near river banks and the native balsam poplars that thrive in slightly seasonal low lying areas. Tree breeders have also combined these trees with European poplars to form even more variety of poplars for use as shelter belts in prairie fields.
There is no question some people admire the imposing size of mature hybrid poplars, especially the northwest poplar hybrid. A mature native plains cottonwood can live more than 200 years. Hybrid poplars are lucky to reach 60 years. Although these poplars were destined to be planted as shelter belts and for shade around home and farm buildings, a very large number of them have been planted in urban yards. The hazards of falling dead branches from a giant hybrid poplar in a populated area are obvious. These trees were simply not meant to be planted in city yards. Some people are concerned with the height of these giant trees and have them 'topped' by someone in the tree business. Topped trees will usually produce new shoots at the cut locations. The thickness of the new shoots (referred to as "suckering shoots") is smaller than the stem or branch they originated from. The new shoots in these circumstances may or may not be strong enough to grow very large and long branches. Invariably, the branch falls away from the tree at the former cut location.
A few weeks ago I wrote about hazardous trees. When you see the condition of these structurally unsound trees it is easy to see they are no longer an amenity for the yard. Untreatable poplar diseases easily enter all poplar trees as they have very little natural resistance to these disease. A typical common poplar disease is called Hypoxylon. This disease spreads quickly though the tree resulting in the death of branches at first followed by the whole tree. My advice; be very wary about planting these trees in small residential lots.
Michael Allen M.Sc.F., RPF (ret'd) is a consulting urban forester, tree diagnostician and certified arborist.
viburnumtrees@shaw.ca
