WHAT IS SHADE TREE DECLINE? - Decline is a term used to describe a tree that is generally deteriorating. This deterioration may be "causes' by many things. The symptoms often result because the translocation system of the tree has been disrupted. The root system may be restricted or damaged. The trunk tissues may be blocked, wounded, or infected by some agent. Decline also results when a tree's food reserves are depleted.
WHAT ARE THE SYMPTOMS OF SHADE TREE DECLINE?- Symptoms are usually subtle and slow in developing. Premature fall coloration, smaller and fewer leaves, and early leaf drop are usually early symptoms. As the condition worsens, some branches may die, beginning at the top of the tree and progressing downward. Leaf scorch can also result from relatively minor drought problems. Trees suffering from decline may survive indefinitely, or they may die within a year or two. Trees most commonly affected are sugar and Norway maple, ash, and oak.
WHAT ARE SOME CAUSES OF SHADE TREE DECLINE? - Decline can result from anything that restricts, damaged, or impairs root or vascular systems of trees. Late spring frosts or summer droughts that deplete food reserves also lead to decline. In many cases, a combination of causes may be involved. some of the factors involved might be:
1) Salt injury from winter use of salt
2) Root cutting - trenches, foundations, etc.
3) Trunk wounding - mower or farm equipment, etc.
4) Soil fill or removal from under tree canopy
5) Soil compaction
6) Air pollutants
7) Natural gas leaks into soil atmosphere
8) Herbicide injury
9) Repeated droughts - thin soils that undergo widely fluctuating water
10) Excess soil moisture
11) Repeated defoliation's - perhaps due to insect damage or hail
12) Fertility imbalance
13) Girdling root
HOW CAN THE CAUSE OF DECLINE BE DETERMINED? - Because of the varied causes of decline, it is difficult to pinpoint the cause without an on-site examination of the entire diseased tree. The trees should be carefully examined. Careful observing or digging around the lower trunk and root area may often reveal the cause. In some cases, the tree may have to be removed and examined further before the cause is known. It is extremely important to attempt to find out the environmental history of the affected tree. To determine the period of stress, use an increment borer to look at annual rings. Check the pattern of branch elongation. Attempt to find out whether there has been drought in the area, construction or soil filling, water table changes, or herbicidal usage. Check surrounding vegetation to see if a general environmental stress or toxic condition exists. Trees can't talk, but their story is vital.
HOW CAN DECLINE BE CHECKED OR CONTROLLED? - The best control approach is to determine the specific causal factors and attempt to correct them. Of course, where this cannot be determined, a more general control program must be undertaken. Most good general tree care practices should contribute to control of shade tree decline. Fertilize trees in late fall or spring. Water during droughts. Prevent wounds as much as possible. If decline begins in a tree, thin out the top by selective pruning. Aerate the soil if needed. If a tree has been removed due to decline, do not replant with another of the same type unless the cause has been determined and corrected.
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8793 Kenwood Road, Cincinnati OH 45242
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