Nutrient Deficiencies of Our Trees
A nutrient deficiency in trees is one of numerous diseases that can affect evergreen and deciduous trees. The key word here is numerous. Many, many causes of odd-looking tree leaves and stems exist; the goal is to figure out the one or ones that are producing the symptoms and take steps to address it. Unfortunately, determining the cause often is difficult, but certainly worth the effort.
There are three main reasons for being accurate, for identifying the actual cause of the malady.
Effectiveness: In order for an action to be effective, it must influence the problem. The old tale of a boy looking under a streetlight for a quarter that he lost somewhere else because the light is better there comes to mind. If a malady is poor soil drainage or winter injury, applications of nutrients won’t help, even though they may be easier to utilize.
Expense: Examples of this include unnecessary pesticide treatments for no problem at all or using fertilizer in an attempt to address a disease, insect or improper planting issue. Clients are much happier spending money that makes actual improvements in their trees health as opposed to ones that are more of a shot in the dark.
Legality: …and possibly fraud. Pesticides are designed to control pests, insects, diseases, weed, rodents, etc. If fungicide is a borer infestation, it may be legal as long as the tree in question is listed as a site on the label, but no real positive results will occur. The same is true for added nutrients. If a customer’s tree has yellow leaves due to being planted to deeply, and a quick fix seems to be the injection of a multi-nutrient solution, the action could be described as fraudulent, which the Nuance iPad dictionary app defines as “deceit, trickery, sharp practice or breach of confidence perpetrated for profit…” In other words, giving the impression of taking appropriate action when one knows that it’s not the right one, or that there may not be of.
How do you know?
The first step in determining if a nutrient deficiency exists is to identify the tree. Many trees have nutrient deficiencies that are commonly associated with them. For example, in the Midwest, pine oak trees growing in high pH soils often develop iron chlorosis. In these scenarios, iron exists in the soil in sufficient quantity to support healthy tree growth, but the alkaline pH ties it up and prevents it from going into the soil solution. Again, there can be many causes of odd-looking tree leaves and stems, so one reasonable place to start is with the known causes. A good next step is soil sampling. Start by taking a representative sample from the tree that you suspect has a nutrient deficiency. What is “representative”? In case of a soil sample for a tree, remove a trowel full of soil from 9 or 10 sites at various levels of rooting. Since most will be in the upper 24 inches of soil, some should be taken at a 4-inch depth, some at a 12-inch depth, some at a 18 inches and some at 24 inches. As well, some samples should be a few feet away from the trunk, some under the drip line and some twice the drip line distance. Overall, the samples should be random in depth and distance from the trunk, and represent the active root zone of the tree. The extracted soil should be mixed together in a plastic (not metal) bucket and taken to a reputable soil-testing laboratory. As best as you can, remove small pieces of roots and rocks before submitting the sample.
Source: TreeServicesMagazine June2015