The time to prepare your trees for winter is now, before the ice and snow storms. Trees should be inspected at this time for defects such as:
Road construction, severing for utilities, soil erosion, trampling damage, debarking, and root disease are some of the considerations here. Certain conditions are widely agreed upon as very serious:
- Any diagnosable root disease that kills and decays roots.
- A recent, uncorrected lean, often visible by soil irregularity associated with tipping of the root system. This indicates that a tree has lost its grip on the earth and is beginning to fall.
- More than half the major roots have been severed, severely damaged, or have decay.
This does not mean that other root conditions are not serious. Any decay found in roots should be carefully examined and considered.
Poor Crown Architecture
This may be caused by poor pruning in the past. Sharp bends or crooks in the branches are naturally weak, liable to failure. If a tree is topped, multiple branches may come out just below and they are usually weakly attached. Failure potential is considered high when a tree leans more than 45° or when it leans and has another defect in the main stem. A significant lean that appears to have occurred recently and has not been corrected by negatively geotropic top growth (“unnatural lean”) should be taken seriously.
A leaning tree may or may not be a substantial hazard. It is necessary to distinguish between two types:
1. Natural lean
This means trees that have been leaning for much of their life. You can see sweep (curvature) of the stem, or maybe even a crook, where the tree corrected the lean. The upper stem is vertical, not leaning. There is no evidence of recent change, such as soil/root plate movement, cracking or stress bending of the stem.
2. Unnatural lean
Here we mean a lean that is due to a relatively recent change in the orientation of the stem. You may see evidence of soil/root disturbance indicating that the root system has shifted in the soil. You may see cracking in the stem as it gives way. There may even be bending of the stem going on, usually associated with decay. The upper stem in an unnatural lean is mostly not vertical, but leaning. Trees with an unnatural lean have already begun to fail and are extremely hazardous.
Decay in stems and branches is a major cause of failure. Conks and decayed knots or stubs are definite indicators of advanced decay. Indicators that suggest decay may be present include cracks, seams, and large old wounds.
Failure potential is considered high when there is canker-rot in the main stem or decay associated with weak branch union or open crack. Any decayed branch also has a high failure potential.
Cankers, Wounds & Cracks
Cankers and wounds must be considered not only from the perspective of their direct contribution to failure potential, but also as infection courts for stem decay fungi. A canker (or scar or cavity) that involves more than 120° of the circumference is serious. Generally a tree with half or more of the circumference occupied by an individual wound or canker should be considered for treatment. The potential for failure is higher if a canker is accompanied by decay or if it is connected to another defect.
Vertical cracks in the trunk, often accompanied by callus that may or may not be ruptured, are taken seriously. They are an indication that tree failure has already begun. They arise from stress related to internal defect such as decay or buried scars or from strain associated with forks. They may be triggered by wind or cold temperatures (thus the term “frost crack”).
Callus forms at the margin of injured cambium and grows outward to cover the wound. If all is well, the callus margins will meet and seal over the wound. Sometimes, the callus tends to curl inward, or inroll, during growth. If this happens, the callus never meets and seals properly. Instead, the bark-covered surfaces of the callus rolls meet. As growth rings are added, the callus sides push against one another, leading to formation of cracks. Also, tension generated in the stem can lead to formation of secondary cracks elsewhere. Inrolled callus might be expected where the wound surface is concave. The callus margin follows the concavity as it grows, increasing the likelihood that the callus surfaces will meet before the margins.
Once these elements are inspected professionally, a plan to properly treat any problems found can be formulated.
For more detailed information on how to prepare trees for the winter season call us at (845) 354-3400.
Information via www.forestpathology.org