In this article I would like to discuss some common tree stresses. This topic seems fitting to me as we are having an exceptional year for tree pests and diseases (P & D). The dark, cool and wet spring (and summer thus far) has created the perfect environment for P & D to thrive. However, the focus of this article will not be on P & D but instead identifying the initial stress which makes them susceptible to P & D attacks.
Similar to people, when trees become stressed or fatigued their defenses weaken and there is an increased chance of sickness, Consider P & D attacks like a cough, the cough itself isn’t the problem but it does indicate other underlying issues. Discovering these issues can be difficult as trees have a storage of energy primarily found in the roots. This stored energy can postpone any indications of injury or stress for several years.
Here is just a short list of common causes for trees to be stressed:
Improper Planting – I find it amazing how many tree problems can be traced back to improper planting. Although tree and site selection is vital, site preparations and proper planting techniques are extremely important.
Root Compaction – This is especially a problem in urban areas and high traffic areas including parks and construction sites. Roots in these areas not only get physically crushed but are also unable to access nutrients and water due to the compacted soils. Two techniques to alleviate compaction are to install barriers to divert traffic and the application of mulch to lessen compaction and to retain moisture.
Nutrient Deficiency – Trees in a forested setting have the benefit of obtaining nutrients from the decomposing organic matter (fallen leaves, fallen trees, etc.) on the forest floor. In an urban or manicured landscape the leaf or “thatch” layer is removed to allow turf and create a more aesthetic landscape. Trees constantly compete with turf for moisture and nutrients and often loose to the shallow rooted grass. Placing mulch around the base of trees when possible and providing supplemental fertilizing can increase the vigor of the root system.
Raised Grade – This is a situation usually affiliated with newly landscaped or construction sites. Problems can arise when soil is mounded or raised around the base and root zone of a tree. This can cause root starvation and suffocation as well as cause rot to form at the base of the tree. To avoid this always make sure the pedestal flare (area around the base of the tree where the trunk meets the roots) is always visible.
Wounds and Improper Cuts – moisture, insects, pathogens and decay can all enter in the tree through wounds. These wounds can be caused by an impact from machinery or improper pruning cuts. These wounds can stress the tree by expending precious energy as it attempts to seal the wound and form barriers to avoid infections. This process can take years or even decades depending on the vigor of the tree and the size of the wound. It is suggested to never dress a wound with paint or sealant as it can actually create a positive environment for P & D. Proper pruning cut placement is vital to ensure the wounds are sealed as quickly as possible.
Of course this is just a simplified short list of possible causes of stress but they are some of the things that I look for when a client calls me with a tree problem. I hope this had shed some light and answered a few question. Till next time, take care.