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Virburnum, Amelanchier, Ants, Lawn seed & Siberian Iris

Bugs on Viburnum shrubs and plum tree; a problem with newly-planted arborvitae shrubs; sawflies on Amelanchier shrubs; controlling ants; comments on ‘Quick Lawn’ seed; and a Siberian iris that is not blooming.
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

July 12, 2009

Above, Three shots of our ‘Pink Sensation’ hardy water lily with its first bloom early this month; the colourful foliage in the background of the top shot is Houttuynia cordata ‘Chameleon’; and our Canada Day display of flags at the front door! Below, our Gloriosa lily (Gloriosa rothschildiana) near our front door; we inherited this red rose which may or may not be a climber, and note the Mason Bee house; a good rock garden plant, Heron’s Bill geranium (Erodium x variable ‘Bishop’s Form’) and lastly, for years we’ve grown the Rose campion (Lychnis coronaria) which re-seeds generously! This year we added the cultivar ‘Rose Blush’ which also re-seeds. It’s a delightful pink/white colouration.
Author photos.

Karen M Shepherd of Saint John, New Brunswick wrote to Donna several weeks ago thanking us for responding to her question on behalf of a friend, about Alberta spruce. She also asked about “How to prune a Hawthorn Bush and when?”

She continued, “Also, I've noticed a lot of leaf curl on my Viburnum bushes (several types), only two years old. And also on the plum tree. I can see a lot of tiny black insects, but don't know what is in the curled part. There were so may on the plum tree that I had to cut away some branches. It is about seven feet tall, in the yard for its second year. Thanks for any help.”

Nothing special to pruning a hawthorn shrub. You could do it now or anytime up to say mid August, or leave it until next late April or early May. It sounds as if your Viburnum shrubs may have an infestation of Viburnum leaf beetle. I have written about it here, as have others such as Leonard Perry. You may check my last item (February 25/05) at  or Leonard Perry’s of June 25/06) at  also, possibly it is a different insect, but the Doktor Doom House & Garden Insecticide should be of help, regardless of what the insect is.

Just on Tuesday this past week J.McCombe of unknown location wrote: “I am wondering if you can give me some info on why my new cedar hedges are turning black in some spots. The leaves are all black and they are not sticky. When I look at the leaves they are healthy looking, but are black in colour. Could this be due to stress from being transplanted from pots? These hedges came from B.C. and we just planted them a couple of weeks ago. The trees are watered every day, if it rains we don’t water them. There is new growth on the trees. Is there anything that we should/shouldn’t be doing? Please respond and let me know what you think might be the cause of this. Thank you kindly.”

Unfortunately Mr. McCombe you did not advise me from whence you were writing, even though you did say the arborvitae (eastern cedars) came from B.C. Nothing from what you describe rings a bell. Is there a possibility you could e-mail me a photo of the affected foliage? Also, if you got them from a nursery or garden centre nearby, I would take a piece of the affected foliage in and ask the manager if he recognizes the problem.

Meanwhile, currently on the ICanGarden forum, there are several questions which have gone unanswered for about a week, including this one from Veronica from somewhere in zone 1: “Does anyone know how to control sawfly larvae in saskatoons (Amelanchier)?”

A difficult problem Veronica. There at least two insects that cause skeletonizing of the foliage on Amelanchier and other trees. At their worst they can cause major reductions in berries at harvest times, and some berries may actually be hollow or contain a larval form of the insect.

The only insecticide recommended for control of the sawflies is Decis, manufactured by Bayer CropScience. Unfortunately it is not available to the domestic market, and not even sold throughout Canada other than in Eastern Canada and British Columbia.

The first presence of the sawfly is of the adult in May each year just as the Amelanchier are beginning to flower and extending for about a week up to the time when the plants are in full white flower. That would make me believe that any contact insecticide sprayed onto the flowers over that period of time (and likely done three times) would help control the pest. The Doktor Doom product mentioned would be fine. You might also try using high pressure water from a hose sprayer to blast the insects away.

On the same day, Michelle from somewhere in zone 6b, asked: “We seem to have lots of little black ants in our front garden, they're actually in plants, etc. We're preparing the soil to plant some new plants. What can we do about this? Thanks.”

A few ants, even in some plants (not at all uncommon in peony flowers, for example) is not really detrimental. If there are masses of them, you may wish to control them with a product such as Doktor Doom House & Garden Insecticide. It contains the natural Permethrin made from chrysanthemum flowers. Not knowing from what province you are writing, I cannot make any further suggestions, due to the various provincial pesticide regulations.

Yet another question on the site’s Forum came from Lindy in zone 8, who says: “Just wondering if anyone has experience with the lawn seed called ‘quick lawn’?”

I see various of these “miracle” grass seeds advertised in spam e-mails almost daily, and it happens annually. Generally, value-wise they are not as good as visiting a reliable garden centre in your area and telling them what your conditions are, and then purchasing the type of seed they recommend to you. Grass seed in Canada is federally regulated, and while for many of us the bar may not be high enough in certain areas, nevertheless some protection is offered. Hard to predict whether those regulations apply at all to Web-based offers.

Finally from the Forum this week, Sue from somewhere in zone 3b asked: “I have 3-year old Caesar's Brother irises in the recommended location. They bloomed the first year and then not last year. So far this year lots of healthy leaves but no buds coming. Any iris experts out there who can suggest how to promote blooming in irises?”

I don’t think I would call myself an Iris expert Sue; for that you should contact someone such as Chuck Chapman ( ). ‘Caesar’s Brother’ is a Siberian iris, and a Canadian introduction, as it happens. That means it will grow well along the edge of a pond, or even in a pond if the container is located at the water surface.

Ordinarily, the first suggestion for Iris not blooming is to dig and re-plant them, being sure to clean up the rhizomes and not plant them too deep. For example, in clay soils, the top of the rhizomes should be visible rather than being buried in the soil. Yours however, seem to be only two years in your garden, and re-planting usually need not be done more often than every three years. Since you don’t really say the conditions in which yours are planted it is difficult to make a recommendation.

Perhaps you might check out Chuck’s site and then contact him.

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