Caring for Your Mature Trees

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STC logoWith proper care the life of your trees can be extended and their appearance and health improved. If you have concern about the health of your trees seek the advice of an ISA certified arborist.

Monitoring — By providing regular inspections of mature trees, you can prevent or reduce the severity of future disease or insect problems, and lower the risk of trees causing serious injury to people or damage to property. During tree inspections look for storm damage, which includes large broken and hanging branches, split trunks and roots sprung from the soil, signs of insects and diseases such as defoliation and crown dieback (gradual death of the upper part of the tree), or abnormal leaf size or color. Note that even mature trees can benefit by deep watering during times of severe drought.

Pruning — You can help maintain your tree's health by removing dead, diseased and broken branches. It makes it safer for your family and property. Pruning also can be done for aesthetic reasons, including letting more light onto your property or improving a view. Pruning during the dormant season is ideal because it reveals branch structure and less brush is generated.

Pruning large trees can be dangerous. If pruning involves working above the ground or using power equipment, it is best to hire a professional arborist. An ISA certified arborist will know how to best reduce the size of large trees and cause the least amount of damage to the tree. Topping (the cutting of tree branches to stubs or lateral branches that are not large enough to assume the terminal role) is not a viable method of height reduction and should not be used. In fact, topping can make a tree more hazardous in the long term.

Mulch — Mulching under mature trees is a good alternative to trying to grow grass in heavily shaded areas. A 1 to 3-inch layer of bark, or composted organic material over the soil under the drip line is recommended. Mulch that touches the bole of the tree can promote insect and disease problems under the bark, therefore mulch should be pulled back several inches from the trunk. Avoid mounding mulch around trees; thick layers of mulch can harm trees.

Vegetation management — English ivy and other vines can be detrimental and should be removed from trees. They hide hazardous conditions and the additional weight can cause the tree to fail during high wind and ice storms. Under the drip line of the tree take care not to injure large roots when landscaping. Planting small shrubs and other plants that do not require large holes to be dug will minimize damage to roots. Also avoid rototilling within this area.

Many herbicides or weed killers that are used in turf can cause severe damage to trees when misapplied. While most herbicides do not kill tree roots, some do. Herbicides that can cause tree damage have statements on their labels warning against using the product near trees.

Irrigation — Probably one of the most beneficial things you can do for your trees is to deeply water them during times of drought. A few heavy (high volume, slow application) watering is much better than many light, shallow watering. Water trees once or twice a week in the growing season if drought conditions continue.

Fertilization — Mature trees making satisfactory growth do not require fertilization.

Other damage — Care should also be taken in the use of salt to de-ice walks and driveways. Salt is toxic to trees and shrubs. Use sand or non-sodium de-icing agents such as calcium chloride or calcium magnesium acetate (CMA) as alternatives to salt.

Construction activities around trees can be devastating to trees if no measures are taken to protect them. The visible injuries such as broken branches and wounds to tree trunks are only the beginning. The use of heavy equipment near trees can damage roots and compact soil depriving roots of oxygen. It is the damage to the root systems that often result in tree loss. If construction is planned an ISA certified arborist should be consulted to stake out a no disturbance area around your trees.