Common Practices That Harm Trees, Part 1

Trees contribute numerous benefits to a landscape, but the methods for maintenance performed on trees and their surrounding landscape can impact this ability much more than one might think. Before performing work on or around trees, Urban Forestry recommends first doing some research on proper techniques… and practices to avoid. Read below for information about three harmful practices that Urban Forestry frequently observes affecting trees in Edmond.

Topping


According to the International Society of Arboriculture, “topping is the indiscriminate cutting of branches to stubs or to lateral branches that are not large enough to assume the terminal role”. This practice causes a great deal of stress in trees, for reasons such as:
  • Removing a large amount of the canopy, reducing energy production and storage. Starvation mode can then trigger responses such as excessive sprout production
  • Numerous wounds from stub cuts leave the tree vulnerable to decay
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Topping also increases risk. Fast-growing, weakly-attached sprouts quickly reach the same height as branches that were removed, but these sprouts are more susceptible to breakage in ice and wind events.

Do this instead:


  • Make pruning cuts just outside of the branch collar
  • Prune back to limbs that are at least 1/3 the diameter of the branch being removed. 
  • Remove no more than 1/3 of the canopy at once.
  • Hire an ISA Certified Arborist to prune your tree
Find out more about this practice at Why Topping Hurts Trees, and learn correct technique at Pruning Mature Trees.

Lions-tailing


Lions-tailing is a misguided canopy-thinning practice that involves removal of inner limbs along a branch, leaving denser foliage at the branch’s end. The result looks like a slender tail with a tuft at the end, like a lion’s tail (hence the name).

It’s true that foliage along the length of a branch does result in more movement in the canopy on a windy day, but an even distribution of foliage along the branch results in an even distribution of force when the canopy catches winds or weight from ice. A branch that only has foliage on its ends will experience all of the force at that point, weakening the branch and increasing the likelihood of breakage. The excessive pruning will also likely result in production of sprouts along the length of the limb, increasing future maintenance needs. Previously shaded bark that is now exposed to the sun is susceptible to sunburn and subsequent wounds, and stress results from the amount of canopy removed (similar to topping).

Do this instead:


  • Do not remove all branches along a limb. Instead, selectively choose branches to remove, making sure there is an even distribution along the parent limb. Remember, less is more!
  • When choosing which branches to remove, look for those that may contribute to future defects. Is a branch rubbing on another? Does it have a narrow branching angle? Is it cracked or decayed? Pruning these can help to reduce structural issues, in addition to accomplishing your goal of thinning the canopy.
  • Remove no more than 1/3 of the canopy
  • Hire an ISA Certified Arborist to prune your tree

Excessive Irrigation


In Edmond, many residential areas have native blackjack oak and post oak trees growing within fescue lawns. We frequently receive calls from residents in these areas, reporting concerns such as sparse, yellow foliage, branch dieback, and sometimes tree death. These observations are often linked to lawn irrigation practices.

Turf grass irrigation systems are often set to run frequently, for short periods of time. Our native oak trees are adapted to drought, and when soil conditions stay consistently moist it can cause stress, with potential for root rot and tree decline. In order for trees and lawns to coexist, property owners must find a balance that meets the needs of both.

Do this instead

:
  • Like trees, lawns can benefit from running irrigation less frequently for a longer period of time. This allows for a deeper soaking, but also prevents soil from staying constantly moist. Adjust your irrigation system accordingly based on your site conditions.
  • Consider removing grass beneath trees and instead spread mulch using proper mulching techniques beneath tree canopies. Perhaps take it a step further and create a woodland garden by planting shade-tolerant, locally-adapted perennials within the mulched area.
Read about additional considerations related to Trees and Turf.

Overall, these discouraged practices will continue to proliferate for as long as people continue to see them performed by others and assume that they are acceptable methods. Sharing this information with our neighbors and improving practices in our own yards can help to reduce unnecessary tree harm. In next season's issue of Tree Mail, we will share Part Two of Common Practices that Harm Trees.

Check out other topics from the Winter 2019 edition of Edmond Tree Mail