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More than half of the questions we receive through the Master Gardener voice mail and plant clinics are tree related. We can help you with information about pruning, species selection, proper planting and current disease and insect information, but it is often difficult to diagnose a problem over the phone or from a visual sample. Trees are a valuable resource that adds to the value and enjoyment of your property.

Sometimes it is necessary to consult a 'tree doctor' or arborist. The following recommendations are from an article written by Patrick Weicherding, Regional Extension Educator, Natural Resources and Environment that appeared in the July 15, 2005 Yard and Garden news. You can view the entire article at www.extension.umn.edu/ projects/yardandgarden.

An arborist by definition is "an individual who is trained in the art and science of planting, caring for, and maintaining individual trees." Much of the training is acquired through education and certification but a lot of it comes from years of professional experience. A well-informed homeowner can provide proper tree care (planting, watering, corrective pruning, mulching, etc.) to young trees in the landscape but trees grow quickly in size and most homeowners do not have the training, experience or equipment to work safely on large trees.

Ask if the arborists on staff are certified by the International Society of Arboriculture (ISA). ISA offers a range of certification credentials from certified tree worker to certified arborist. To be certified, individuals must pass a voluntary comprehensive exam. Certification must be maintained through continuing education, which means they should be up to date on the latest in arboricultural technology and are knowledgeable of acceptable tree care practices.

Ask about membership in professional organizations such as the International Society of Arboriculture (ISA), the National Arborists Association (NAA), or the American Society of Consulting Arborists (ASCA). Affiliation with these organizations demonstrates a willingness to keep current on the latest techniques and information. When checking the yellow pages look for arborists who list themselves as ISA Certified Arborists or display the official logos of their professional memberships.

A reputable arborist should have insurance to cover personal and property damage as well as worker's compensation. If you hire an uninsured tree worker, you can be held liable for any damages or injuries that occur while they are on the job.

Do not be afraid to ask for an estimate, and it's best to get more than one estimate. Keep in mind, selecting the lowest bid is not the best way to select a tree care company. Rather, when examining the bids, look at all specifications and credentials, and the work to be done to determine which company will provide the best service with the skill and professionalism needed to protect your investment.

When do I need an arborist? If you need a chainsaw and a ladder to treat storm-damaged trees, if there are any downed and potentially energized power lines in the vicinity of the damaged tree, if there is potential for personal or property damage or if you are wondering if the tree is worth saving, you need an arborist. Beware of door-knockers following storm damage. They are often non-professionals who see a chance to earn quick money.

Are there cracks in the trunk, branches or roots? Cracks form when the load exceeds the capacity of the stem to withstand the load. The vast majority of cracks are caused by improper closure of wounds, by the splitting of weak branch unions, or by flush-cut pruning. Cracks can occur in branches, stems, or roots. Several types of cracks can be found in trees and, like other defects, the severity of cracks ranges across a spectrum. Cracks put a tree at risk when they compromise the structure of the tree by splitting the stem in two or when another defect, such as internal decay and a crack do not provide enough sound wood in the outer shell to support the tree. The presence of multiple cracks and decay indicates a very defective tree. You need an arborist.

Are there mushrooms, conks, or bracket fungi growing on the branches, stems or roots? Fruiting bodies of fungi are advanced indicators of decay by sap rot and heart rot fungi. Heart rot fungi decompose both the heartwood and sapwood portions of the living stem and sap rot fungi decompose dead branches and dead portions of the stem. Decay can occur in branches, stems and/or roots. Decay results in less structural strength and reduced stability in the tree. If you notice fungal fruiting bodies on your tree and they are accompanied by other indicators of decay like rotten wood, cavities, holes, open cracks or bulges in the wood, you need an arborist.

Does the tree have dead branches or a dead top? Living trees most often fail at their first defects. Dead trees, however, can fracture anywhere: at the ground line, just above the stump, just below the lowest branch, or anywhere in the crown. Dead tops or branches are symptoms of tree decline. They may remain attached to live trees for several years or may fall off suddenly. If your tree has dead branches or a dead top and you suspect that your tree is declining, you need an arborist.

Has there been any soil disturbance or construction activity in or near the root zone? When a tree has extensive root damage, the whole tree usually tips over and falls to the ground because the roots can no longer provide adequate anchoring. Roots can be lost due to excavation, trenching, soil compaction, grading, paving, fungal decay, or environmental stress. Common symptoms of root problems include: decline or dieback in the crown, leaning trees, and presence of fungal fruiting bodies at the root collar. If you notice any of these symptoms, you need an arborist.

Do you plan to build on a lot with trees, and you want to save some of them? If you plan to build on a lot with trees and you want to save some of them you'll need to develop a landscape protection plan. Careful planning will save you time and money and help to avoid the expense or heartache of later repairing or removing trees damaged by construction activity. In most cases an arborist can be a good addition to your planning team. An arborist will inventory trees on the site, select the trees to be saved, and provide advice on the best way to protect the trees you plan to save. If you don't feel comfortable doing this on your own or if you feel uneasy about the building contractor's tree knowledge, you need an arborist.

Are the leaves on your tree wilting, necrotic, chlorite, malformed or does the tree exhibit early fall coloration? Trees can be injured by biotic and abiotic agents. Abiotic or nonliving agents include environmental, physiological, and other nonbiological factors. Biotic agents are living organisms such as insects, pathogens, nematodes, parasitic plants, and viruses. Whether the cause is biotic, abiotic, or both, an accurate diagnosis is needed to treat the problem. If your tree exhibits any of these symptoms and you haven't got a clue about what might be wrong, you need an arborist.

Are more than the usual number of insects noticeable, or do you see symptoms and signs of their presence? Insects can cause damage to trees in the landscape. They can defoliate branches, mine or stipple leaves, create galls, 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. If you can't identify the insect that is causing the problem or don't know how to control it, you need an arborist.

A couple of good websites that cover some of the basic principles of tree care are ISA's "Trees Are Good" web site at http://www.treesaregood.com and Minnesota DNR's "Minnesota Trees" web site at www.mntrees.org.

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UPCOMING CLASSES

The next class is 'Beneficial Insects in Your Garden' presented by Bud Markhardt, Professor, University of MN, member Board of Directors for the MN Institute for Sustainable Agriculture and the Organic Advisory Task Force, MN Department of Ag. Many who heard him speak at our Gardening Bonanza in March asked us to have him back. The class will be held at the Senior Center in North Branch on June 27 at 6:30 pm.

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PLANT CLINICS

Volunteer Master Gardeners will be available Mondays from 4-7 p.m., at the Extension Office, in North Branch, at 38780 Eight Ave. to answer your gardening questions. You can also call 651-674-4417 during these hours to speak with a Master Gardener. Samples can be dropped off during the day on Monday if you cannot stop in during clinic hours. Please note MONDAY is the only day you can drop off samples, as there is no longer staff at the North Branch Office who can answer gardening questions.

VOICE MAIL: You can leave a question for a volunteer Master Gardener at 651-674-4417. Depending on the volume of calls, they try to respond within a couple of days. During office hours ask for the Master Gardener voicemail, after hours, select ext. 18.

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