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Patrick Weicherding, Regional Extension Educator, wrote an article on knowing when to hire an arborist. Parts of this article are taken from that writing.

An arborist by definition is one who is trained in the art and science of planting, caring for, and maintaining individual trees. There are several reasons why one could hire an arborist.

One reason would be because of storm damage to your tree. The summer has been one of high winds and lightening strikes. If you wonder if your tree is worth saving you may need an arborist. In a situation where there is potential for personal or property damage it is very important to call your city forestry department or a reputable tree care company to remove potential danger. Beware of door knockers following storm damage. They are often non-professionals who see a chance to earn quick money.

You may want to hire an arborist if there are cracks in the trunk, branches or roots. Cracks form when the load exceeds the capacity of the stem to withstand the load. Most cracks are caused by improper closure of wounds by the splitting of weak branch unions or by flush-cut pruning. The presence of multiple cracks and decay indicates a very defective tree.

If you have mushrooms or fungi growing on the branches, stems or roots, you may need an arborist. Fungi are advanced indicators of decay by sap rot and heart rot. Heart rot fungi decomposes both the heartwood and sapwood portions of the living stem and sap rot fungi decomposes dead branches and dead portions of the stem.

Living trees most often fail at the site of their first defects. Dead trees, however, can fracture anywhere. Dead tops or branches are symptoms of tree decline. They may remain attached to live trees for several years or may suddenly fall off. If your tree has dead branches or a dead top and you suspect that your tree is declining, you may want to contact an arborist.

You may notice the leaves on your tree are wilting or the leaves are malformed. Another sign of stress is if the leaves turn to fall colors very early in the season and/or if the leaves fall prematurely. If your tree exhibits any of these symptoms and you haven’t got a clue about what may be wrong, you may need an arborist.

Insects can cause damage to trees and the landscape. They can defoliate branches, strip leaves, create gulls, bore into the bark and wood and feed on roots and shoots. Most insects are secondary invaders attacking only weakened or stressed trees. Others are primary invaders attacking healthy trees. You may need an arborist if you can’t identify the problem or how to control it.

There may be many other reasons why you may want to call an arborist but it’s more than looking in the yellow pages under Tree Service. If you only need maintenance on large trees or pruning, a tree service will do just fine. However, remember that trees such as maples, elm and oak should be left alone during the summer.

When you hire an arborist, ask if they are certified by the International Society of Arboriculture (ISA). Certification must be maintained through continuing education. If they use the yellow pages or advertise they will state that they are a part of the (ISA). Most reputable tree care professionals do not go door-to-door, so avoid those companies that do. Ask for proof of insurance to cover personal and property damage as well as worker’s compensation. Ask for references of past customers and don’t be afraid to ask for an estimate.

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More information about trees and arborists is available from the Forest Resources Extension homepage at http://www.cnr.umn.edu/FR/exten sion/UrbanandCommunityForestry.html; the Minnesota DNR's "Minnesota Trees" web site at http://www.mntrees.org or ISA's "Trees Are Good" site at http://www.treesaregood.com/

Most arborists are practitioners of plant health care. In other words, they believe in preventative care designed to maintain tree health and vigor. Their plant health care package may provide inspections of your trees for a flat annual fee. This is an excellent way to monitor insect and disease problems in time to take effective action. It can also assure proper early pruning to prevent major, corrective pruning later. Regular maintenance practices will also help your trees remain healthy. For a list of companies with certified arborists in Minnesota check the Minnesota Society of Arboriculture web site at http://www.isa-msa.org.

Upcoming Classes

The last two sessions of the Summer Gardening Series will be held Aug. 11 and 25. The topics are “Butterfly Gardening” and “Attracting Beneficial Wildlife.”

For more information, call 651-674-4417, stop by the Chisago County Extension Office, 38780 8th Ave., North Branch or visit our website to download a ticket order form: www.extension.umn.edu/county/chisago.

In Your Yard and Garden

•Major danger for oaks and elms has passed but given the odd spring, the experts are advising to wait until fall for pruning. While late winter pruning is best for most trees, removing storm-damaged and dead wood now is ok.

•Iris can be divided and replanted starting now. Doing this every few years will prevent the dead circles that can form in the middle of a clump. Digging up the clumps will also allow you to look for iris borers which over time can destroy a planting.

•Avoid herbicide applications. The high temperatures allow the product to vaporize and more easily drift onto other plants. Crabgrass control should also be avoided as such hot temperatures can cause the turf to yellow.

•Finish off any tree or shrub fertilizing chores as you really want to suspend any fast-acting fertilizer applications from mid-July into fall. New growth from later fertilizer applications can result in new growth that will not have enough time to harden off in preparation for winter.

•Wooly aphids and other aphids are busy feeding in deciduous trees and shrubs. The result will often be stunted, misshapened leaves at the tips of branches. You will see frass (insect feces) inside curled leaves and any plants under the trees may have shiny spots of ‘honeydew,’ a substance produced by the aphids as they suck the sap of plants. Webbing indicates that spider mites are probably present.

Ways to Access Information

Master Gardeners will be offering free plant clinics every Monday night from 4:30-8 p.m., at the Extension office, in North Branch. Stop by 38780 Eighth Ave.(the Anderson Chiropractic Building) or call 651-674-4417 to speak with a Master Gardener. During the rest of the week, you can leave a message and a Master Gardener will return your call.

www.extension.umn.edu/county/chisago

Check out the 'Hot Topics' box in the middle of the page for current Chisago County Master Gardener news and events.

You can also click on 'Ask a Master Gardener' next to the cute little flower on the right hand side of the page. Here you can search 1000's of answers from Master Gardeners around the state. If you don't find your answer, you can submit a question online or search for University publications.

Bell Museum of Natural History

For information about snakes, skunks, raccoons or other wildlife around your yard, call the wildlife information line at (612) 624-1374 or www.bellmuseum.org

To see the latest Yard and Garden newsletter, go to: http://www.exten sion.umn.edu/yardandgarden/YGLNews/YGLNews.html.

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