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PRUNING DECIDUOUS TREES WHY
Central leader - Single, dominant extension of the trunk from which growth in height occurs. Most (not all) trees have a dominant leader. Co-dominant leaders – Two central leaders competing for dominance. Structurally unsound as one of the leaders is typically more weakly attached to the tree. As tree matures junction weakens. One leader usually fails or tree top splits between the two. Epiconnic growth (suckers or witches brooms) - Growth of many weakly attached, spindly branches from site of (usually) damaged branches or those which have been flush cut. Common on incorrectly pruned willows, elms, Russian olives, cottonwoods and fruiting trees. Included bark (between the trunk and branches or between two larger branches) - is a common contributor to branch failure, particularly in larger mature trees. Between co-dominant leaders; the condition worsens as the tree matures. Particularly common between trunk/limb pairs when the angle of limb attachment to the trunk is less than 45 - 50 degrees Lion tailing - Excessive removal of interior secondary/tertiary interior secondary/tertiary branches leaving primaries and large secondarys with growth only on the ends of the branches. A no-no. Always leave some interior growth on all branches (balanced pruning). Subordinate/dominant limbs/branches - Location, relationship and size of tree limbs/branches
Topping and heading back - Cutting back central leader (topping) and in older, mature trees cutting tree back to primary limbs leaving only large stubs as branches (heading back). Both techniques have unpleasant consequences and are NOT recommended, ever. HOW Good tools do a better pruning job and are designed to make pruning easier.
Co-dominant leaders - Remove weaker branch when tree is young. Branches growing low on the trunk - Remove when tree is young. Crossing/overlapping (redundant) branches - They rub against one another causing damage to each, providing entry points for various diseases, and in severe cases interfering drastically with growth. Remove weaker branch. Inward growing branches - These are secondary/tertiary branches which grow into the interior of the crown. Remove. Branches/limbs with large amounts of included bark at their junction with larger branches or the trunk. Identify and watch. If cracks appear around affected parts remove affected branch or limb before it falls off. This is usually a condition restricted to older trees and particularly those with codominant leaders. Diseased branches - Remove well back from the diseased area preferably to a dominant secondary or primary. Don't leave a stub between cut and left branch. Dead branches should be removed in the same way as live branches; respecting the branch-bark collar. Broken branches - If the branch is just cracked tying it back up to its original position - using straps and rope - may permit healing to a degree. The rigging should be left on for at least two seasons. If the branch is truly broken, remove it by pruning back to a dominant branch (or trunk if it is a primary limb). In the latter case try to cut outside the branch-bark collar; if not possible, smooth broken surface and in both cases wrap wounded area with tree wrap and leave it on for a year or so. Crown thinning - Some trees e.g. purple leafed plums, some crabapples and fruit trees develop extremely dense crowns, the exterior branches of which shade the interior of the tree. Resulting poor air circulation in the tree interior plus reduced light results in spindly, often insect infested or diseased interior branches. To correct this, selectively remove branches starting with crossing/overlapping branches and those growing into the crown. Always cut back to a dominant. If more removal is necessary, do it selectively with frequent stops to step away and look. Avoid overpruning and practice balanced pruning by leaving some interior growth on the remaining branches. Removing large (3 inch or more) branches from mature trees, particularly branches higher up in the crown, is a hazardous undertaking which could result in injury or property damage. Consider calling a professional arborist with training, experience and equipment for safe and efficient work. WHEN Generally speaking, anytime you choose. But dormant is better (usually after mid-October and before mid-March)
Visit www.santafebotanicalgarden.org to learn more about how Santa Fe Botanical Garden celebrates, cultivates and conserves the rich botanical heritage and biodiversity of the region.
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