What Do You Do When You Don't Know the Answer?

September-October 2003

MY PET PEEVE WITH ARBORISTS is their willingness to diagnosis a tree health problem with insufficient information and knowledge. I hate going onto a property where I am the last of a long line of arborists to look at a problem because I know that I will be giving a different diagnosis than everyone else. There is little worse than an angry client who has a multitude of different diagnoses; she ends up thinking that arborists do not have a clue about trees and their problems.

Arborists need to have the guts to answer "I don’t know." I am willing to say this even when I am getting paid for a consulting call and I don’t have a clear-cut answer. From my observations, I should be able to state what the possibilities are and what the answers are not. Sometimes the answer is not clear. The client cannot, because they have recently moved in, or won’t, because of embarrassment, provide a full history of the tree, the site and construction-type activities. The tree exhibits very broad symptoms that could have a wide range of origins.

If you hate to leave sites with problems unsolved or without any sales made, what can you do? Try the following:

1. Provide the information you gathered plus samples to the Pest Diagnostic Clinic in Guelph. The clinic sees samples of problems from around the province and they have exposure to a huge range of problems. The more complete information you provide, the more precise the answer they will give. I have used them when I am stumped, looking at disease symptoms that I cannot precisely name (sometimes the answer "some sort of fungal leaf disease" does not satisfy people), or to provide an independent second opinion when clients don’t believe what I tell them.

2. Go back to the basic needs of the tree – sunlight, water, oxygen, carbon dioxide and elements (macro and micro-nutrients). Determine which one (or more) is not being met and look for ways to meet it. This is basic Plant Health Care.

We need to think about solving problems with knowledge, not just selling injectors/implants, fertilizers and pesticides.

A) Talk to the client about proper watering techniques. Dr. Kim Coder in Watering Trees (www.forestry.uga.edu/warnell/service/library/for99-009/index.html) states, "Water is the single most limiting essential resource for tree survival and growth. Water shortages severely damage young and old trees alike and set-up healthy trees for other problems."

Most irrigation articles suggest that 1 inch of rain is required per week to replace water in the soil lost to plant uptake and evaporation. Explain to your client that Ontario typically experiences droughts during the summer. Show them that short summer showers (natural or irrigation) do not wet the soil sufficiently for water replacement. Get out the hose and show them how to water properly. The Regional Municipalities of York and Durham are giving out rain/irrigation gauges free of charge that show how much water is being applied. Get one for demonstration purposes or have a supply on hand for freebies.

B) Talk about aeration. With so much human and vehicular traffic occurring in our densely populated cities, soil compaction is a huge problem. If soil pores are destroyed, oxygen (and water) will have a difficult time infiltrating the soil.

What is the best way to aerate? First of all, realize that when the soil structure (the arrangement of pores between the soil particles) is damaged by compaction, it is impossible to recreate that soil structure. The structure took years to develop and will take years to rebuild if compaction is restricted.

The addition of organic matter to the soil will help. Organic matter (OM) is the cement that holds soil particles together to create soil aggregates and this aggregation creates pore space. OM is the food for soil organisms – earthworms, etc, which dig through the soil creating tunnels or oxygen/water corridors.

The easiest way to provide OM to the soil is to mulch – add three to four inches of organic material to the top of the soil over as much of the trees root system as possible. If the client insists grass is the preferred soil surface topping, try a variety of tactics to convince them otherwise. If you do not win this "grass vs. mulch" battle, fine organic matter can be spread over the grass and worked through the grass to reach the soil. Holes or trenches can be dug in the rooting area, filled with organic matter (or organic matter + soil mix) and covered with turf.

Aeration with the Grow Gun or Terralift has been shown to produce a saucer shaped fissure to the soil surface and only creates better oxygen infiltration along this fissure. It may be impressive to watch the earth movement created by the compressed air but be sure, when you are aerating, that you are doing more than just putting on a good show.

C) Add deficient nutrients back to the soil. To do this, you need to have soil testing done. Agri-food Laboratories will provide information on macro and micro-nutrient levels, soil pH, and organic matter percentage (ask for the AFL Complete test). They do not test for nitrogen levels unless specifically asked (and paid) as nitrogen leaches easily and the results that the soil tests show would be incorrect when you received the results in the mail.

With these results, you can create a prescription for fertilization. For those arborists who consider this too much work or too expensive for the average client, you may be correct when you are dealing with the average property where no organic matter is or will be added and no nutrient deficiency is noted. For chlorotic trees, remember that some fertilizers do not contain micro-nutrients so if one of them is deficient, your fertilization will not improve leaf colour (and therefore leaf function). I find that the majority of my soil tests come back with a magnesium deficiency noted, a macro-nutrient, which is not added to the tree fertilizer that my company uses.

We need to think about solving problems with knowledge, not just selling injections/implants, fertilizers and pesticides in the hope that we might hit upon the magic bullet that will cure the problem. These are valuable tools but only if they are used properly. If you set yourself up as the "Tree Expert," you owe your clients correct and responsible answers. Work on improving your knowledge and diagnostic skills. Until then, repeat after me, "I’m not sure what is causing your problem but there are a few things that we can do …"

1. Pest Diagnostic Clinic, Laboratory Services Division, P.O. Box 3650, 95 Stone Road West, Zone 2, Guelph, Ontario N1H 8J7, 519-767-6256, fax 519-767-6240.
2. Agri-Food Laboratories, Unit 1, 503 Imperial Road North, Guelph, Ontario N1H 6T9, 519-837-1600 or 1-800-265-7175.

— Patricia Thomson, B.Sc.F. Consulting Arborist, Kelly’s Tree Care Ltd.

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