What to do with broken tree branches, how to treat fire blight and more

Gerard Fournier, president of For Trees in Didsbury and a teacher at Olds College, joined Alberta at Noon guest host Jim Brown on Friday to answer caller questions about trees, bushes and shrubs.

What's your advice for getting trees through these hot, dry days? 

Water as much as you possibly can, said Fournier. If you live in a community with water restrictions, look into possibilities to conserve rainwater. Mulching is a good idea, as is watering early in the morning before the heat of the day sets in.

"Generally, trees and shrubs benefit from about an extra inch of water above ground once a week in the absence of sufficient rainfall," said Fournier. 

How you water matters, too. Avoid putting a hose down by the base of the trees and leaving it to trickle.

"The tree gets its water normally in the form of precipitation, which is rain, and rain is spread over a wide, wide area," said Fournier. So you're better to mimic rain by using any kind of lawn sprinkler or soaker hose.

What should you do with with broken branches from storm damage?

"A broken branch sometimes can create a larger wound than if it was just pruned properly," said Fournier, so you'll want to be careful if a storm causes damage.

"Try and make the smallest surface area wound that you can close to the trunk of a tree," he said, but watch that you don't injure the tree right at the branch collar (where the branch meets the trunk).

In the case of a high branch or a potentially hazardous situation, call a good arborist. Fournier suggests researching their credentials at Trees Are Good or the International Society of Aboriculture, where you can also search for a certified arborist in your area by postal code. 

How can you transplant conifer 'volunteer' trees?

"Volunteer" trees, which pop up in your yard or garden without being planted there, can be a great source of trees. You can transplant them to a different area even if they're clustered close together.

"You want to wait until about the middle of August when all the new growth is done and the buds are made for next year," said Fournier. Then, "water the heck out of those trees, like get them absolutely saturated and make the soil even muddy."

With more water on hand, and new holes dug, carefully lift the trees up, separate the individual root systems and transplant them into their forever home.

"Very seldom are [roots] totally knotted together so that they cannot be separated," said Fournier.

How do you treat fire blight?

Fire blight is an extremely serious disease that can affect apple trees and mountain ash. It's caused by a bacteria called Erwinia amylovora.

"The Latin name means that 'I eat starch,' basically," said Fournier.

The bacteria eats all the starch and cuts off the flow of water to leaves, causing clumps of brown leaves. The signature symptom is when the ends of branches curve over, blackened — "almost like being scorched by fire," said Fournier. 

The only treatment is to prune out all affected areas as soon as you notice symptoms.

Fire blights is communicable with your hand tools, so you'll want to have a way of cleaning your pruners. Fournier said that Pinesol, Lysol, wood alcohol or diluted household bleach can work. Soak a rag and wipe your tools off between each cut.

When should you prune trees of deadfall?

When to prune is complicated question, said Fournier, as lots of species of tree don't follow the rules. That said, there are a couple of general guidelines to follow.

"The two times of year where you don't really want to do a lot of pruning is in spring and fall, when leaves are forming and when the leaves are falling," said Fournier.

At those times, the phloem layer under the bark is swollen from distributing sugars, and it's easier to injure.

Instead, get rid of deadfall in summer or winter.

"There's a lot to know when it comes to pruning," said Fournier. "But the time of pruning is probably the least important thing. An arborist friend of mine that hired me for my first job as an arborist, he said the two best times to prune a tree is when your saw is sharp and when you know what you're doing."

With files from Alberta at Noon.