Organic Answers Column - September 7, 2022 - Tree Care After Storms Cause Damage
Tree Care After Storms Cause Damage
Conditions during the summer of 2022 were so hot (approximately 50 days over 100 degrees) that it created conditions for sudden limb drop, also known as known as "summer limb drop," "high temperature limb drop" and most recently as "sudden branch drop." Follow those harsh conditions with a storm that arrived with the remarkably heavy rains of August 22, when up to 15" of rain dropped on the Dallas/Fort Worth area in a single day, and you have a lot of damaged trees needing a variety of remedies. This column will survey important aspects of the Dirt Doctor's approach to Natural Tree Care when dealing with storm damage.
Trees that were already vulnerable may be planted too deep in the ground, may have areas of decay, damage from insects and animals, disease, and heavy limbs that were hit with storm damage. Let's start with the basics.
Pruning is generally best taken care of in the colder months when trees are dormant, but after a storm cleanup must happen now and may involve approaching broken limbs and cleaning up the damage to help the tree survive. Pruning trees is part science and part art. Don’t try to change the character and overall, long-term shape of a tree, and don’t remove lower limbs to raise the canopy. Low growing limbs exist for a reason. It’s very unnatural to strip tree trunks bare. If you think that looks good, think again. Remove dead, diseased, broken, or damaged limbs and the weakest of crossing limbs. Remove limbs that grow toward the center of the tree and limbs that are dangerous or physically interfere with buildings or activities. Thinning to eliminate a certain percentage of the foliage is usually a mistake. Heavy thinning of a tree’s canopy throws the plant out of balance, inviting wind and ice storm damage. The resulting stress attracts diseases and insect pests. Gutting (heavy interior pruning) is never appropriate.
Examples of bad "flush cut" pruning
Pruning cuts should be made with sharp tools. Hand tools such as bow saws, Japanese pruning saws, loppers, and pole pruners are good for small limbs. Chain saws can be used for larger limbs, but only with great care and a thorough understanding of the equipment.
Never make flush cuts, when the branch is cut off exactly level with the bole it grows from. Cuts leaving a 1/16” stub are also bad. Pruning cuts should be made at the point where the branch meets the trunk, just OUTSIDE the branch collar. The branch collar stub will be as small as 1/8-1/4” on small limbs but can be several inches to as much as a foot or more wide on large limbs. It will also be wider at the bottom of the limb than at the top. Cuts made at the right place leave a round wound. Improper flush cuts leave oval cuts and cause cavities to form in the trunk long term.
It’s scientific fact that cutting into or removing the branch collar causes problems. Flush cuts encourage decay. They also destroy the natural protective zone between the trunk and the branch and can cause several serious tree problems including discolored wood, decayed wood, wet wood, resin pockets, cracks, sun injury, cankers, and slowed growth of new wood. Proper cuts are round, smaller, and heal much faster. Peach, plum, apricot, and other fruit trees are particularly sensitive to flush cuts. Many fruit tree insects and disease problems are related to improper pruning cuts. Long branch stubs can also detrimental sometimes and should be avoided, however, it is always better to err on the side of stubs too long than too short.
Trimmings & sawdust from pruning should not be hauled away
Broken branches or split trees create or reveal cavities in the damaged trees. It is possible that the cavities you're seeing today were caused by the physical injury of past flush cuts. Cavities in trees are voids where fungi have rotted healthy material. Removing only the decayed material is the remedy. Fillers such as concrete and foam are only cosmetic and not recommended. When removing decayed matter from cavities, be careful not to cut or punch into the living tissue. Injuries to healthy tissue can introduce further decay into the healthy wood. When cavities hold water, drain tubes are sometimes inserted to release water. Bad idea. Drain tubes puncture the protective barriers between the rotted and healthy wood and allow decay to expand. I don’t recommend any of the trunk injector systems for fertilizer and insect control because of their puncture wounds, plus they miss the main problems in the soil and root system.
When there are exposed wood and cambium after pruning or as a result from storm impact or breakage, it might seem that pruning paint is a helpful tool, but this is not the case. Research by Alex Shigo, Carl Whitcomb, and the U.S. Forest Service has shown that pruning paint and wound dressings have no benefit and can be harmful by slowing the healing process. Healthy tissue needed for callus formation can be damaged or killed by pruning paint or dressings. Trees have defense cells, much like white blood cells in mammals. These lignin cells are produced on the backside of a wound to naturally prevent diseases from entering fresh cuts. Just as a cut finger heals faster when exposed to the air, so does a tree wound.
Wound dressings have no benefit and can be harmful
Finally, weak crotches between limbs can sometimes be stopped from splitting by installing cables horizontal to the ground so the natural movement of the tree is not completely stopped. This is different than cabling used to hold up low growing limbs, that is poor tree care and a waste of money. Cabling can be very dangerous and should only be done by professional arborists. In most cases, I do not recommend it.
When the work of cleanup is completed, the tree trimmings and sawdust resulting from pruning should not be hauled away. The large pieces should be used for firewood and the limbs and foliage should be shredded and used as mulch under trees or mixed into a compost pile.
After a storm is not the time to be worrying about aeration, fertilizing, or about treating for pests unless they are right there in the damaged wood. You'll find more about those practices in the Natural Tree Care topic and can follow up on those later in the year, if needed. Taking care of trees using common-sense techniques and safe products is easy and cost effective. The results are better than using toxic chemical treatments, which will destroy many beneficial insects while only reducing a percentage of the target pest insects. Imagine being able to spray trees without worrying about wind drift, lawsuits, over-application of material, and the real possibility that the environment is being harmed each time a pesticide is applied. That’s the beauty of tree care using the natural approach – it is safer and it works better - in every way!
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