• careful pruning will promote good health and strong structure,
• bad pruning practices such as topping, over-thinning or allowing a tree contractor to climb the tree with spurs, will result in permanent (life-long) damage or death of the tree,
• neglecting adequate preventive care may lead to early decline and in some cases attack by some very detrimental and hard to manage insects (borers) and diseases (cankers),
• diligent supplemental watering of large and small trees during prolonged periods of high temperature and drought will ensure that the tree is able to carry on its day-to-day business and store energy for future needs.

Now a little Q & A...

Let's start with the most common enquiries of the past few weeks:

1. Browning evergreens
Question:
I have a Yew hedge in front of my house. Over the winter it started to turn brown on one side. Its never done this before. What should I do?

Answer:
There's no question in my mind that 2002 will go down in history as one of the worst winters for plants, in recent history, especially for evergreens.

Evergreens need lots of moisture reserves in the soil to keep their leaves alive and healthy through the winter. The chronic droughts of the past few years have diminished soil moisture levels. This winter was particularly bad because it was long and punctuated by mild periods, which resulted in moisture loss from the leaves. Those portions of the foliage that don't get enough moisture die and turn brown. This is commonly referred to as winter burn or desiccation. If all the foliage on an evergreen dies, then whole plant will die. If the browning is limited to one part of the plant and the rest is still alive, the plant may not die totally, and depending on the species, the affected part may die or put out new growth from terminal growth. Generally spruce, pine, junipers, euonymus, boxwood, and ericaceous plants do not recover from extensive winter burn or winterkill. Yews and cedars with partial browning are more likely to put out new new growth from further back on the branch.

Don't be too hasty to cut off what may appear to be dead. Give the plants until mid-June (this year) to complete new growth, then take your signals from what's alive and dead.

The very best place to concentrate your efforts to revive desiccated (thirsty) plants, is generous watering. Most evergreen species prefer cool, moist, well-drained soil all the time.

Road de-icing salt is a common contributor to winter burn. Plants dehydrate from too much salt, whether it's in the soil or on the branches, buds and leaves. The salt sucks moisture out of the plant. The best thing you can do is soak the plant and the soil with water to dilute the concentration of salt.

One word of advice… if you suspect soil-borne salt damage to plants and decide to fertilize them to give them a boost, don't fertilize until you've thoroughly flushed the soil with water to leach de-icing salts. Fertilizers are also salts and you can unknowingly increase the salt level and thus the damage to the plant.

We are lucky this spring to have had so many slow soaking rain events to help reduce salt toxicity:-)

It should be noted here that there are a couple of diseases that will result in similar symptoms on spruce and pine. However the browning will be spotty, and usually starts on one tree and spreads to adjacent trees. Positive identification of these pathogens requires a site inspection and possibly lab culture.

2. Dieback in Norway and Japanese Maples
Question: I have a lovely Norway Maple in my front yard. Its always been very healthy, but this spring there were a lot of dead branches on the lower part of the crown. Do you think its diseased? Is the tree going to die?

Answer: I have noticed unprecedented die-back on Norway and Japanese Maples this spring. Even trees that appeared to be "perfectly healthy" up to now are showing symptoms of "winter-kill". Some buds never broke; some broke but died before fully opening; some came out in leaf and then the leaves wilted.

Most of the die-back I have seen is not related to a pathogenic disease. After close examination of over 150 Norway Maples on different properties around the city, I am convinced that this die-back cannot be attributed singly to the winter. It is the cumulative result of a chain of tree stressors:

• First of all, Norway Maple is genetically pre-disposed to a root disorder called Girdling Root Syndrome which reduces the trees ability to get enough water from the roots to the leaf.
• Secondly, summers of the past few years (in particular) have been very hot, with acute droughts. Norway Maples are not efficient water users and therefore have suffered moisture stress.
• Thirdly, any recent injuries or wounds to the trunk or main branches result in reduced ability to transport water up from the roots to the leaves and buds.
• There are many other factors that may lead a branch or tree to die-back following a harsh winter. Identifying them comes from your observations while monitoring your tree's health throughout the growing season.
• In every case that I examined, the degree of dieback could be directly attributed to the degree of cumulative stress acting on the tree. Trees unaffected by any of the above factors were also not noticeably affected by the winter.
• In the case of Japanese Maples, the primary pre-disposing factor is lack of sufficient climatic hardiness.

3. Delays
Question: Everything seems very slow this spring. Buds were slow to break. Leaves on some trees are still not fully out. Some spring-flowering trees and shrubs are still in flower. How does that affect plants?

Answer: The more time that lapses between bud break and full leaf expansion, the more energy a plant uses to keep everything alive. Early spring for urban trees is often a time of crisis management; precious little stored energy gets sent where its needed most urgently. Until the leaves are fully out and able to store energy from the sun, energy reserves are being used up quickly. Its like a jet circling the airport in a holding pattern, waiting to land after a long trip. · This is just another potential source of stress for trees at this time of year.

There is a difference this year though. Our prolonged spring-like weather, cooler temperatures and lots of slow soaking rain has resulted in unprecedented spring growth. Directly related to this lush new growth will be a noticeable increase in photosynthesis and storage of energy to next year.

There are some downsides to cooler moist spring weather and increased spring growth, but we'll talk about that at a later date. By the way, talking about the season being out of "synch"… Juanita and I went for a walk along the boardwalk at Ward's Island on Sunday and were amazed at what was concurrently in bloom. Magnolia, Forsythia, Eastern Redbud, Honeysuckle, Pin Cherry, lilac, tulips, Lily of the Valley, Alpine Currant. Most of them had never met before.

4. Watering:

Probably the most common factor in poor performance of trees over the past years is prolonged drought. Although we are presently being blessed with generous natural rainfall, I continue to tell clients that good old watering is generally the best investment for the future of their trees. Experts recommend trees receive an inch of water per week. The only way to determine this for your particular garden is to purchase a guage that measures natural and sprinkler rain/water-fall. How you water, how often, how long, and when, are all specific to the plants you are watering, the soil type, and the present weather conditions. If you are interested in the topic, I strongly recommend you visit www.forestry.uga.edu/warnell/service/library/for99-009 for a look at watering trees by Dr. Kim Coder.

5. Mulching:

I am a very strong supporter of the practice of mulching trees and other garden plants. Our tiny garden in south Etobicoke consists of a whopping 10% turf (plus weeds) and that's only because I have not ripped it up yet. The use of mulch has been lauded repeatedly everywhere, so I will spare you that. What many people don't know, is that turf grass (lawn) is the single most aggressive competitor for water and nutrients that a tree has to contend with. Turf under trees is generally a source of long-term stress. I therefore take every opportunity to recommend the replacement of turf under trees with a three to four inch layer of wood chip mulch. You will be amazed at the affect this has on tree vitality. There are some technical details that one should know when introducing a mulch surface. We have lots of experience, and would be happy to share it with you. FREE WOOD CHIPS!!! We generate lots of wood chips on job-sites, and we'd be happy to share them….free of charge. Give us a call. (Note please: This is subject to supply and demand and your location).

6. Fertilizing:

This year I am noticing a lot of symptoms related to soil nutrient problems, particularly inter-veinal chlorosis (yellowing of those portions of the leaf between the veins). In cases like this, the use of a general-purpose tree fertilizer can result in additional damage, so we strongly recommend to our clients that any prescription for nutrient supplements be based on prior soil sample analysis. We offer a soil analysis service backed by years of agronomic expertise.

7. Hazardous Trees:

I mentioned earlier that there are downsides to cool, moist springs and excessive new growth. Excessive new growth results in increased weight on the limbs and trunk, and increased wind resistance. In situations where a large tree has existing structural defects, these added forces may be what ultimately results in failure of the defective part or whole tree. It is very important for tree owners to appreciate the importance of the fact that "A tree can be a picture of health today, but fall over tomorrow as a result of some undetected structurally defect". Structural defects are not always readily visible to even the trained eye of an expert.

8. Ravine Restoration: There has been an increased focus lately on ecological restoration of ravines, flood plains, and other linked open spaces of the "Metro Forest". Due to our focus of interest, our combination of knowledge, experience, and the nature of our existing operations, we are expanding this component of our service to residential landowners with ravine lots. We are presently booking for assessment, planning, management and planting of ravine lots for the 2004 season.

I'll finish up with some tree tips:

1. Planting: When did you last plant a tree? There's no better time than now. Think of it as your legacy to the future. If you need a good reason to plant a tree, give us a call. The only advice I have for you is take the time to do it right. For more on selection and planting, visit the Landscape Ontario and International Society of Arboriculture websites. They are directly accessible from our site. We can advise you on the best trees for different conditions, and we can refer you to reliable planting contractors.

2. Monitoring: Try to get in the habit of doing a regular, systematic inspection of your trees and shrubs to catch insect, disease and other problems before they get out of hand, and just take time to appreciate these wonders of bio-mechanics. We provide a Plant Health Care monitoring service tailored to your trees. Don Carter is very knowledgeable and delivers a first class pest management service for us.

3. Pruning: Pruning is the most common maintenance done to trees, shrubs and hedges. Everybody prunes something at some time or other. How we prune, how much we remove, and when we prune different trees and shrubs has changed significantly in recent years. Dramatic changes in weather, and potentially serious new insect and disease pests require careful consideration, especially when pruning valuable large trees and shrubs.

Of particular concern in Toronto for the past couple of summers, is the probability that a serious disease that kills oaks, could move into southern Ontario from the northern U.S. Known as Oak Wilt, the disease is initially transported to oaks in a new region by beetles which are attracted to fresh wounds (notably pruning wounds). For this reason, City of Toronto Forest Health Care Inspectors are urging people not to do extensive pruning of oaks from early May to late July. The disease is very hard to control once it is established in an area. We specialize in the pruning of trees, shrubs, vines and hedges…. from huge to small….from Wisteria to Magnolia to Copper Beech to Norway Maple and White Oak. Our focus is on species-specific pruning or pruning driven by the characteristic habit and rate of growth of a particular species.

For more information on Bruce Tree Expert Company Ltd., the services we provide, or any of the information presented in this newsletter, check out the rest of our web-site or contact us by phone (416-252-8769) or by fax (416-252-4574).