Frequently Asked Questions

Early stage of black knot disease
Early stage of black knot disease - "twig spindle" - on May Day tree
Photo: © M. Allen
Early maturing stage of black knot disease
Early maturing stage of black knot disease - "crown galls" - on May Day tree
Photo: © M. Allen
Mature black knot disease gall
Mature black knot disease gall
Photo: Internet
Black knot disease stroma
Black knot disease stroma - a part of the gall where fungal spores are released as shown by the lighter coloured structures (apothecia)
Photo: © M. Allen

Who can benefit from using Viburnum Tree Experts services?
Anyone who has a piece of land on which trees and woody shrubs grow can benefit from VTE's services. Where there are trees and shrubs there are bound to some problems with them. This includes owners of homes, cottages, businesses, institutions, or agencies such as government organizations, law firms, insurance adjusters, and home inspectors.

Do you make house calls to inspect private trees and shrubs?
Yes. I will schedule visits anywhere in Manitoba, southern Saskatchewan and north-western Ontario if my schedule permits long distant visits. I charge travel time and mileage for visits outside the City of Winnipeg.

What is Black Knot disease and how do I deal with this disease on my tree?
Black knot disease is infecting many property Schubert choke cherry and May day trees in Southern Manitoba. The mature form of the disease (see image) looks like a black mass of burnt rope often tinged with grey usually located on the branches, but not uncommon in large black blister like openings on the trunk. The black mass is called a gall and it consists of stroma that release microscopic fungal spores when mature (see image). The infected branch should be pruned at least one foot away from the disease towards the main trunk. If possible prune off the branch at a junction with a larger branch or the trunk.

In the spring the first sign of black knot disease will be a swollen new twig. The fungus disease causes the swelling. The swollen area will become ridged and brown in colour. (See image) This is the best time to control this disease in the swollen twig stage. Always sterilize your pruning tools after EACH cut with dilute bleach (1 part) and water (9 parts), or with methyl hydrate or with rubbing alcohol. The early stage can also produce ball like swellings on the twigs instead of the spindle shaped swellings. (See image)

This disease is common on western choke cherry, Schubert choke cherry and May Day tree.

Common pruning objectives
Common pruning objectives
Image: © M. Allen
Where to cut
Where to cut
Image: © M. Allen
Fire blight disease on apple
Fire blight disease on apple
Photo: © M. Allen
Proper place to prune a branch
Proper place to prune a branch
Photo: Internet - Adapted by M. Allen
Homeowner learning how to prune an apple tree
Homeowner learning how to prune an apple tree
Photo: © M. Allen

How do I prune my fruit tree?
Prune fruit trees in the fall (October is best). Remove branches that are:

  1. rubbing against each other
  2. dead or broken
  3. weak and crowding out another stronger branch
  4. over-extended in the crown giving a lopsided appearance
  5. growing straight up (vertical) from a horizontal branch
Watch out for stem and trunk diseases such as fire blight and black rot canker in apple and pear trees which can kill the trees. Plum trees can also get black rot canker as well as fruit diseases such as brown fruit rot and plum bladder gall. Early signs of all these diseases can be pruned before they get serious. Information on these problems and fruit tree pruning techniques are presented in my courses.

Is there any place where I can learn how to properly prune my trees?
Yes. I give detailed instructions in many ongoing courses scheduled in the fall, early spring and in the spring all over Winnipeg. I alternate the presentation of courses that specialize in pruning fruit trees, evergreen trees and shrubs, shade trees, and ornamental woody shrubs. Hand outs are provided in all courses detailing and illustrating many of the key items presented.

Can you show me how to prune my own fruit trees and woody shrubs?
Yes I will work in the fruit tree along with its owner showing how and why specific cuts are made. I allow the owner to learn at his or her own pace until they are comfortable with the task. I also ensure that they are using the proper, sharpened tool for the task at hand.

Spider mite webbing in spruce needles
Spider mite webbing in spruce needles
Photo: © M. Allen

My large fir, pine, spruce or evergreen tree is having its needles turn rusty brown. What can I do?
Your coniferous evergreen tree is likely a spruce or fir. Both kinds of trees have extremely difficult-to-see spider mites. Over the course of two years, the interior needles are often fed on by spider mites on trees about 15 years of age and older. The presence of spider mites can be detected by looking for minute, unstructured webs spun from needle to needle (see image). In the last year of feeding, the needles turn rusty brown and drop off in late summer, fall, or early winter. The solution is to power wash the evergreen tree with water only. The pressure of the water will dislodge the spider mites causing them to fall to the ground where they are ineffective in doing any more damage to the tree. This washing down process needs to be done monthly without skipping a month from May to early October, inclusively.

Spider mites usually produce 5 or 6 generations during the spring, summer, and early fall; so it is important to control each new generation as it appears. The pressure from water also dislodges dead needle debris, leaves, old spruce pollen sacs, bud caps, dirt, black mould, and other pests such as needle miners, bud worms, aphid nymphs, and scale nymphs from the needles and twigs. All of these pests reside in the debris that collects on spruce or fir twigs and branches.

Cytospora or white blister disease producing exudates on spruce branch
Cytospora or white blister disease producing exudates on spruce branch
Photo: © M. Allen
There are other factors that cause needles to turn rusty brown such as Cytospora (white blister) disease, tip blight disease, needle cast disease, spruce aphids, spruce adelgids (wooly aphids) and needle miners. Many problems on trees can mimic each other and only a proper and knowledgeble diagnosis can sort them out for appropriate treatments.


If you want to know what problems you have on your trees and how you can treat them, call me at (204) 831-6503 to arrange a visit. Please note that I do not diagnose tree problems over the phone nor give specific treatment information without seeing the tree or shrub first hand.

I also have an entertaining PowerPoint presentation that I give to interested groups of people about the 10 Step Tree Problem Resolution. Contact me at (204) 831-6503 if your group is interested.

Can I rely on one year of treatment to cure the problems on my large evergreen tree?
No. Treating large evergreen trees takes a minimum of 3 to 4 years of adhering to a strict monthly schedule of treatments. It takes years for the tree to get in its present condition; you must expect that it will take a number of years to get back to some health.

Can I do some of the treatments myself, and must I always use chemicals?
I design the treatment schedules to maximize the involvement of the property owner if that is his or her wish. Depending on the time of year I advocate the use of most environmentally acceptable treatments. My philosophy is to try to get you to reduce your reliance on often harmful pesticides.

I have had a lot of problems with tree companies in the past. They spray all kinds of chemicals on my trees and the trees still look sick. What can I do?
First of all stop using these companies if you are not getting the service you want and expect. When I assess and diagnose property trees, I will always provide the property owner a short list of highly qualified recommended arborists. The vast majority of clients are very satisfied with their services. Not all treatments need chemical pesticides.

I get 3 quotes from 3 tree companies. One is low and the other two are higher but similar. Can I expect good service from the lowest bidder?
Definitely not all the time. Some companies will buy down the job to get volume business. They can do this by cutting corners and by using relatively inexperienced, lower paid seasonal workers. In the tree business cheap service sadly can translate into shoddy service. Like all your involvements with contractors, follow the axiom "buyer beware". Check out their written references.

My Mancana ash has lost bark from the trunk leaving wide open sores in the bark of the tree in the spring. Also the leaves were covered with brown spots and then they dried up completely. What's happening?
Description of Problem

Severe frost crack damage is the most obvious of the environmental stresses seen in Mancana ash leading up to your problem. There is initially a deep vertical crack in the bark on the south to south west facing sides of the main trunk as well as to the upper secondary stems arising from the trunk. The crack expands as the tree grows in the spring. This opens up the bark and the surrounding bark and underlying cambial region tissues dries up.

Open sores in spring on a Mancana Ash Tree
Open sores in spring on a Mancana Ash Tree
Photo: © M. Allen
The openings are linear and can be quite long - up to 6 feet. Eventually the bark breaks away from the trunk and stems. The interior wood is revealed. Prominent wound wood or wood callous forms a protective barrier around the wide opening.

Bio-analysis of leaf and wood tissues from these ashes reveal a main canker fungus disease called Botryosphaeria plus a secondary fungus disease called Fusiccocum. Canker diseases usually cause the bark to open up. The disease entered the frost crack and spread quickly under the bark adjacent to the crack. Both diseases are known be present with frost cracks in ash trees.

In addition to the frost cracking there is massive anthracnose leaf disease occurring on the leaflets of most Mancana ash trees that I have encountered. The disease starts out as dark patterned leaf spots on the leaflets which eventually merge causing total leaflet death. The main leaf stalk often stays green even though the leaflets are quite dead.

Since 2007 Mancana ash trees have shown significant signs of stress from environmental factors and fungal diseases. I believe that there are a number of sources of the Mancana ash cultivated variety that are not truly frost hardy to southern Manitoba. Even native ash trees such as green and black ashes growing on the Prairies are known to experience frost crack damage caused by extremes in heat and cold within the living tissues under the bark during late winter. Recent frost damage done to Mancana ash is quite different from what is normally seen on green, black and Manchurian ashes.

In the past I have seen small slit cankers (openings) in the twigs of green and Mancana ash trees that have had heavy leaflet anthracnose fungal infections. The cankers were usually no more than 2 to 3 cm (1 to 1.5 in) in length. They were simply identified as systemic cankers of Botryosphaeria dothidea. No other twig or branch damage was observed. Severe fungal infections can cause the death of twigs and ultimately branches. Now it would seem the disease is changing into a more destructive form in association with Fusiccocum fungus disease.

Treatment

There is no specific treatment to control systemic fungi causing the formation of canker diseases. The best means of controlling anthracnose is to spray dormant lime sulfur fungicide before the buds open in the spring. Mid-April on the Prairies is usually a good time to do this. The buds, twigs and branches should be thoroughly soaked. Early June spraying with a copper based fungicide or any other approved tree fungicide is also very important. Copper fungicide requires at least two spray applications usually 10 days apart. The spring fungicide treatments will help control new infections of the disease that are readily spread by spring rains and winds.

The exposed inner wood will split and crack as it dies owing to its location on the sunny south side. It is important to restrict the entry of wood decay organisms. Apply a wood preservative such as clear shellac or a grafting wax to the exposed wood. Repeat twice a year for two or three consecutive years. Keep the shellac off the sides of the newly forming wound wood. Tree sealant tar or paste, as well as grafting wax can also be used.

Keeping the tree healthy through early spring or fall fertilizing in the first two years (at least) of infection will limit the damage done by the anthracnose and the Botryosphaeria diseases. A sanitation program of collecting early fallen leaves during summer and again in fall, plus pruning dead and dying twigs and branches in the fall will help reduce the presence of the fungal spores that could re- infect the tree. Properly dispose all diseased leaves and branch material as soon as possible so as to prevent the later release of fungal spores re-infecting the ash tree.


© Viburnum Tree Experts
Updated May 27, 2009

International Society of Aboriculture  Ontario Professional Foresters Association  Manitoba Forestry Association