Trunk Wounds


Other than root damage and the resulting stress, one of the biggest problems associated with transplanting large caliber trees is bruising -- trunk wounds. The thin living formative (cambial) tissue just beneath the bark can be easily injured by rough handling (especially from impact), but the permanent damage often does not manifest until later, often a year or more. Some specimens are fitted with a protective trunk sheath while being transported and during installation. Unfortunately, the protective barrier is often inadequate and its presence gives the handlers and installers the sense that they can be less careful. The damage is more likely on 2-4+ inch caliber specimens because they usually require machinery. The root ball mass on large caliper specimens is substantial compared to the development of the protective bark. The heaviness makes delicate handling more difficult. Moreover, the damage may have occurred earlier -- when the specimen(s) was (were) being processed by the grower or during the unloading or placement at the retailer/wholeseller.


The above picture (taken in early 2021) is from a parking lot median at a relatively new hospital in Fishers, IN. I was shocked by the number of damaged and permanently spoiled specimens there. I counted over 100 -- approximately 50% of the specimens! Given a replacement cost of at least $500 per specimen, this was an expensive administrative oversight, never mind that some of the species used are ill-advised in this situation, and their spacing is wrong. [I cite this location as an example, but this issue is common elsewhere] Once the trunk damage occurs there is little that can be done to remedy the problem. The tissue will die, (1) defacing the trunk, (2) reducing the vascular capacity of the specimen, (3) opening it to fungal infection/disease, as well as (4) weakening/stressing the tree, and (5) shortening the life of the specimen. Depending on the severity of the damage, the tree could die relatively soon. Given time, we are talking years here, and assuming the specimen does not die, the tree will attempt to seal over the wound by producing new protective woody tissue from the perimeter of the wound (see the striped area {left center} -- for this species {a red maple} it can look something like a shell or caterpillar) but there will be permanent scaring. The curative paints and salves you see offered for sale will NOT help. In fact, they actually cause more harm. However, it does help to snap or cut away the dead and dried tissue, allowing the underlying surface to dry and be exposed to sterilizing UV radiation. Notice (left center in the pic) the fruiting bodies of a white-tan fungus (Schizophyllum commune) often associated with trunk wounds. This fungus is a saprophyte living off the dead bark and wood. The gray and yellow structures are epiphytic foliose lichens which cause no harm and are not related to the wound, rather they are indicative of where grown (location) and age of the specimen (how long the surface has been available for pioneering). FYI: The damage is so severe in the six inch diameter tree pictured above it either has already been removed, or dead, or soon will be. Moreover, red maple, while commonly chosen, is not a species I recommend (various reasons). There are much better options.


My advice: as with many situations, prevention and avoidance. If having trees installed, ask for references. If you see this damage on trees the business you are considering has installed, do not use them. One can also insist on language being inserted into a contract that would cover such damage, or insist on installation supervision by someone qualified to do so. Better yet, learn the proper method/outcome and do the supervision yourself. Moreover, when purchasing also consider an insurance option, and remember that the damage often does not appear for a year or more. Reality is that the places you buy the trees from are far more interested in getting your money than the well-being of the specimens. Their attentiveness increases if the situation causes them a problem (takes money out of their pocket or if the matter could besmirch their reputation; again, a financial incentive rather than the well-being of the specimen -- business first). If you get lucky, there might be a sincere horticultural concern. Caveat emptor, and know that trunk wounding is one of the reasons it is usually a much better idea to start with smaller caliber specimens. Other reasons to start smaller include: (1) limited selection (species) when trying to start big, (2) less expensive, (3) easier to transport and plant, (4) more likely to survive, and (5) quicker to recover from the transplant shock.Because of the last point, not many years later the smaller is often as big or bigger than the immediate gratification (bigger) choice.


Once installed, careless use of maintenance machinery is another common cause of trunk wounding. In addition to mowers, string trimmers also can produce permanent trunk damage and tree death. Maintenace activity damage is a primary reason I recommend the creation of a no mow zone (mulched or ringed planting) around all trees. I often refer to it as an apron or ringing. Mind you, I am not suggesting the creation of the too common ring of hostas, tulips, impatiens, or wave petunias bordered by tipped bricks or some other tacky barrier option. I prefer a more naturalistic approach/look. I will elaborate in a future post.


Finally, the specimen in the pic as well as numerous others in the area, were planted too high, which (if they lived long enough) would result in a pleated exposed root system, especially maples. The improper planting is the result of unsupervised installation as well as ignorant, uncaring, and lazy installers. They did not want to do the additional digging. [You should also learn about the importance of the root flare in determining planting depth]


The poor result I described above is common both in commercial and residential situations. Again. caveat emptor, and if the recipient of a poor installation, leave an appropriate review online. Do the same if the work was well done. As I tell my consultees, you get just one chance to plant a tree properly, so do it right. Be discerning. I do all my own planting to avoid the expense and to insure the task is done correctly.

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