Plants By Type
Disease, Insects, and Other Problems that Affect Trees
Trees, like all living organisms, are subject to a host of health concerns. Here, we explain the common causes and treatment of tree injury due to damage or disease.
As a conscientious homeowner, you provide your trees and shrubs with all the necessities. However, insects and diseases may still cause issues. Fortunately, most healthy, mature trees and branchy bushes can defend themselves against minor threats from insects and other hostile forces.
In most cases, leaf-producing trees and shrubs have the ability to tolerate substantial foliar loss. This can be caused by feeding insects or fungal disease. Interestingly, a healthy and well-rooted plant can suffer a total leaf loss one season and return with a renewed vigor the next. Most trees have latent buds that only sprout when necessary, meaning a few missing leaves here and there will soon be replaced. Chances are, you’ll never know the difference. Leaves that sustain heavy damage still conduct photosynthesis, meaning that they still do their job, even if they’ve been snacked on by hungry inhabitants.
However, vegetation can only handle so much abuse. If a tree or shrub is constantly subjected to defoliation it may become susceptible to disease or infestation. Severe fungal infection or insect invasion may require treatment.
Fortunately, disease and insects usually steer clear of healthy trees and shrubs. But, even a healthy plant under stress can still have problems. Factors that can stress an otherwise healthy plant include poor pruning, drought, nutritionally insufficient soil, and flood conditions.
Young trees are at highest risk of damage from insects or disease. Buying trees from a reputable online nursery helps to ensure the healthiest stock.
There are many types of disease that present with similar symptoms. It is imperative to properly assess a plant’s situation in order to effectively identify the root cause of concern. Often, a tree exhibiting outward issues is suffering from more than one affliction, as secondary invaders are attracted to already-stressed leaves and emerging greenery. Problems to look for when diagnosing a tree’s condition include:
- Incorrect soil conditions – This may include improper moisture content or nutrient deficiencies.
- Poor fertility
- Climate extremes – Most climates tend to have a gradual change from season to season but, when there is a sudden and significant shift, it can wreak havoc on young plants. Climate issues are most common around late spring, when winter may arrive unexpectedly for a brief visit.
- Environmental concerns – The air, water, and soil surrounding a tree or group of trees can change at any given time. Underground water sources are subject to pollution from run-off chemicals, especially in spring and summer when pesticide usage on crops is at its peak.
- Physical injuries – Trees that are subject to municipal topping (to prevent downed wires) sustain major damage that’s visible to the eye. Other damage can occur in less obvious ways including the placement of heavy trenches within the range of the tree’s root system.
- CODIT - Compartmentalization of Decay in Trees is a situation that occurs when a tree has been wounded, usually by limbs being improperly removed. As a tree releases sap and resins to “seal” the wound, the living tissue on the outside heals while the inside may continue to decay.
- Cavities and drainage tubes – Despite outdated beliefs, tree cavities do not require drainage tubes. Instead, allow the cavity to remain open and control insect populations as necessary.
- Wound dressing – Trees, including fruit-bearing varieties, have the ability to naturally treat most minor – and even some significant – wounds. Never attempt to dress a wound, as exposure to open air is the best way to encourage new growth and wound closure.
- Injections/implants – Many insects, nutrient deficiencies, and diseases can be controlled via tree-safe chemical agents. Injections of these chemicals should only be considered a last resort as they require careful drilling. Drill holes are an open wound for trees which, if improperly inflicted, can actually further damage the plant’s delicate base. Injection holes should be kept to a minimum; annual re-treatment is only recommended in extreme cases and only for large, well-established trees.
- Cabling/bracing – Severely damaged trees may be saved by the cabling or bracing of structural defects. This is not something that should be performed by an untrained group of people. A professional arborist familiar with the technique should be consulted. Improper bracing will create an unsafe environment, especially if the tree is located in close proximity to a home or other area prone to human or animal occupation.
Damaged trees are considered a liability by most insurance companies. Accidents that result from improper care or neglect may not be covered under your homeowner policy, leaving you to foot the bill for any property loss or human injury.
The best way to ensure lasting tree health is to buy from an online nursery that takes pride to prevent damage from seed to sapling.