Fall 2015 - Fall Fertilization - Powerful Tool for Arborists

By: Anthony Arnoldi, Board Certified Master Arborist WI-0102B

The Diagnosticians at Wachtel Tree Science are continually asked to assess the state of trees in various stages of decline or trouble. They need to offer a competent diagnosis of the issues affecting the tree, and a reasoned prognosis if current conditions remain unchanged. We are often able to intervene in the decline or eventual “death spiral” a tree may be experiencing through one or several means:

  • We could interrupt the damage done by an insect or disease by treating to control the pest(s). (i.e., Magnolia scale insects, Emerald Ash Borers, Ips bark beetles)
  • Prune out disease agents such as fungal cankers and decay fungi infecting deadwood to prevent decay advancement from overwhelming a tree’s defenses.
  • Improve root conditions by reducing soil compaction through the use of vertical mulching, radial trenching, air tilling, and traditional mulching.
  • Improve overall tree health through Crown Cleaning Pruning that removes weak, dying, and damaged branches, as well as the infested/diseased portions, to increase the trees energy conservation.
  • Pruning to help restore a balanced root to shoot ratio, if too many roots have been lost or damaged.
  • Provide essential nutrients through carefully considered root fertilization. While the previous points remove or mitigate stress, this point adds something positive to the tree system. 

A major aspect of a majority of the root environments that trees in our local urban and suburban settings find themselves is: the tree is trying to make a living on subsoil. Subsoil is what is left after developers transform farm, field or forest land into subdivisions for our homes. The underlying subsoil is great as an anchoring base for homes and buildings (especially after it has been compacted by the heavy grading equipment!) but is nearly devoid of beneficial soil food web life or available mineral nutrients the tree needs to survive. When trees are forced to live off this material, they will become weaker as time goes on. Evidence of this is poor color, growth and defense capability.

We humans do a much better job of fighting colds, flu or other illnesses if our nutritional needs are met. Can you imagine what chance we would have if we were weak from malnutrition? The same can be said for our trees. Fertilization is a wonderful opportunity to correct this imbalance and fortify the nutrient needs our trees have. This supports the trees ability for replacement growth, feeder root production, defense of all sorts of attack from insects and disease, and recovery.

Like anything, there are wrong and right ways to fertilize. Use the guidance of your certified arborist to get the maximum benefit from this procedure. The Fall Fertilization window is before us now. A great advantage of this time is that root growth peaks as the leaves are shutting down and turning color. This root growth peak helps achieve greater uptake and will be used for root growth now, and shoot growth next spring.

Take advantage of your Wachtel Tree Science Certified Arborists knowledge of your trees to make the best selections. 

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