Four Varying Questions From Previous Years That Are Still Appropriate For This Year
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

May 4, 2014

Above, an aerosol can of Doktor Doom House & Garden Insecticide Spray; three shots of tree labels, the first showing the type used by botanical gardens, the second, showing a label that has not been loosened frequently enough and will now be difficult to remove, and thus will cause damage to the tree, and the third a unique label painted on a polished stone. Below, two shots of gall mites attacking Dayna Law’s maple trees; and finally two shots of Japanese umbrella pine, the first a close-up of the foliage, and the second, a large specimen tree.
Author photos.


Yet again this week I am going to repeat here some questions I have received in recent years, knowing full well that many readers may have the same question on their minds.

The first this week is from Caroline Onishenko, Edmonton, AB. “I understand you are the expert on gardening questions and wonder if you can offer a solution for my infestation of fungus gnats in my home. I have had most of my plants for 15 years or more and never had any type of bug, but last fall I transplanted all of my plants using potting soil which I purchased at Walmart in bags. Alas, all of my plants are now infected and the pests are flying around my house.

“I googled the problem and was directed to a product which contains Diazinon 2% in a dust form to work into the soil. I have now discovered that this product has been pulled from the market in Canada. Can you recommend any other product that might work to eliminate these pests? Thank you for your help.”

This is an old problem that goes back several decades, and when I was on the air in Toronto, the question came in virtually every week! You are correct, the larvae of those flies comes into your house via bagged soil and soil amendments, but one cannot really blame it on any particular store, or in fact, any specific brand. You are also correct about the use of a powder product containing Diazinon; alas no longer available.

My suggestion is to use a product such as Doktor Doom House & Garden Insecticide Spray containing .25% Permethrin. This is a liquid spray, and is best applied when the soil in your pots and containers is slightly damp. Rough the soil surface up a little bit and then generously spray the entire soil surface, and immediately cultivate the soil surface once again so the (unseen) ingredient is mixed with the top few mm of the soil. You may need to do this this three or four times approximately once per week. That should definitely slow down the activity. If you start seeing them again, just repeat the treatment. The Doktor Doom product is readily available at garden centres in Edmonton.

The second question this week came from Doug Moulton. “Wondering if there is a problem nailing or screwing things (such as bird houses) to our trees. We have mostly maple trees on our property and don't want any of them to die. Thank you for your previous advice about 'weed and feed'. We brought some back to Ontario from the US and it works great....just like the old stuff we used to have here! Regards.”

When it comes to nailing or screwing things to trees we are always better to err on the side of what is best for the tree(s). However, if you think about trees in an arboretum, almost always they have labels attached to them—often a special type of attachment is used whereby the labels are held away from the tree bark by springs on the two screws (or nails). In addition, those institutions generally have a policy of going around and loosening the two screws (or nails) on each tree label annually. That is the important part—the screws or nails should never be allowed to penetrate the tree completely so that they cannot be removed. As I see it, by attaching bird houses to trees, you run the risk of the attachment screws or nails becoming imbedded so they cannot be removed, and that would be a negative. Also, as the tree grows, a closely attached birdhouse would begin to be forced into the bark of the tree causing a larger area of disturbance. These happenings are not going to kill the tree(s), but they are not the best policy.

The one way around this would be to use the botanical institutions’ method of loosening the attachment screws (or nails) annually, but the springs behind the birdhouse might cause it to be too movable which would not be liked by the birds. So, I’ll leave it to you; if you can devise a way to prohibit the attachment screws (nails) and the birdhouses themselves from damaging the tree, then by all means give it a try.

The third question this week is from Dayna Law, Prince Edward County Ontario. “We have two beautiful groves of maple trees (‘Autumn Blaze’), approximately 21 trees, planted 5-6 years ago. We are alarmed that they are showing some sort of stress on the leaves as shown in these photos. Naturally we are worried and would like your opinion as to what action we should take. Thanks.”

Your problem is quite a common one for which we once prescribed various controls, but now it is generally considered best to leave them untreated. It is one of the gall mites which are really only visible through use of a hand lens. Though entirely different, we tend to relate many of these ailments (including the tar-spot of maples) and the only recommendation is to be sure to rake up and dispose of all the leaves in garbage each fall. Even burning them may spread the problem. Do not leave any leaves on the ground over the winter.

Finally, the fourth question this week came from Joye: “I live near Lake Huron and this year I planted a Japanese Umbrella Pine which is lovely. As my house is very exposed to the winds during the winter, I was just researching on the net regarding winter protection when I came across an article that you wrote saying that evergreens get wrapped when they don't necessarily need to. Would this young tree need protection? I would rather be able to look at it, but don't wish to harm it by leaving it exposed.”

You ask about a tree with which I am quite familiar—Japanese umbrella pine (Sciadopitys verticillata) does grow in many provinces, including southern Ontario, Nova Scotia and here (we have two of them). Some consider it a difficult tree to grow but others have few problems. It is difficult to estimate whether it will be hardy under your conditions. Certainly for the first year I would erect a double thickness burlap screen all around the tree to protect it. After a couple of winters of this, you might want to reduce the screen’ thickness and erect it so it only is on the windward side of the tree. Do let me know how it fares this winter.

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