The potential for the Canadian Nursery Landscape Association’s “Canadian Certified Horticultural Technician” programme is great, but how good is the present model?

Two true stories prompted this particular topic.

First, a good friend and past president of the Rhododendron Society of Canada, wrote on June 27th: “This young man by the name of Joe, bought six rhodos and was looking for advice on how best to plant them. He read ARS info on the Web and went to (a large west-end Toronto garden centre) for peat moss and more advice. He was told by some lady (he got the impression that she may be the owner) that rhodies are too difficult to grow and he should take them back.

“Now, how do you like that?

“Fortunately Joe found out that there are public plantings of rhododendrons and he felt that if they can grow in the parks, surely he can make them grow in his garden. He came to my garden yesterday and after seeing my collection of over 150 plants in the back, he was convinced that they are wonderful and easy plants to take care of, if planted properly and in the right location.”

Second, listener Erna Letson of St. Agatha Ontario wrote several weeks ago about caterpillars on her copper beech tree. I replied, in one of my articles that not knowing exactly which caterpillar it was made it difficult to advise just what to use. I did basically suggest Bacillus thuringiensis that is a ‘natural’ control used for many, many caterpillars.

She has since responded, saying (excerpted): “I described the worm to [a gentleman at the University of Guelph Arboretum] and he was able to respond within days [with] the possible ID.”

She went on, “A close look at this minute caterpillar and watching it spinning a web was enough to identify it as a fall web worm. I called a garden centre and was told that the solution was to spray a product called Ambush, (Permethrin). My only concern is, that the tree is 22 yrs old and approx. 35 ft. tall and how could my husband or I possibly do this topical spray safely. I hate to use any insecticides and I wonder if there is a safer way to tackle the problem.”

I advised Erna that the gentleman at the University of Guelph may have been wrong. That early in the spring, I would think the caterpillar was more likely a tent, rather than a fall web-worm. The two make similar though not exactly the same ‘tents’. I believe, as I indicated originally, the insect could well be the tent caterpillar. The telling feature of its tents are the way they are built around the branch crotches of the tree(s) rather than around the foliage as is the case with the (generally) later fall webworm.

More importantly, I was concerned about the recommendation she received from “the garden centre” about just what to spray. Ambush, though still available in some garden centres, is no longer a registered product for domestic use in Canada. It was the older form of permethrin that has now been supplanted by the newer and much less toxic water-based permethrin (i.e. Doktor Doom Yellow Label is 50% permethrin). Obviously it’s the latter that should have been recommended, especially since Erna expressly said she didn’t wish to use strong insecticides! “How-ever,” I wrote, “I go back to my original recommendation of Bacillus thuringiensis. It is the recognized answer for caterpillars--especially those of the eastern tent caterpillar.”

These are just two samples of errors in advice I hear about at least weekly. As far back as April and again in May 1999, I wrote recommending that gardeners looking for the best advice at a garden centre should search out managers or staff that had there “CCHT” designation. As this audience will know, that stands for Canadian Certified Horticultural Technician programme. However, this July I had occasion to read through two major documents relating to that programme. The Training Manual (Retail Garden Centre Professional), for example, is 127 pages (8˝ x 11”) but totally in black and white. In reference to insects there are only verbal descriptions; photographs would have been oh so much better. In the case of weeds, there are nine black and white sketches, but they too leave much to be desired. However, over a dozen other common weeds listed are not illustrated at all!

Many other shortcomings are obvious. For example, the hardiness map used is that of the U.S.D.A. rather than the Canadian Plant Hardiness Zone Map (I still think the 1967 version is the one that should be being used!). There is, however, a chart that attempts to compare the zones of the two maps--a task that is not at all easy, if possible at all. The explanation of the two hardiness maps (on page 5 of the Manual) does not jive with what actually appears in Appendix 1 of the publication, and the explanation of zones having to do with “The minimum winter temperatures that woody and herbaceous plants have demonstrated ongoing survival in the landscape….” is not only lacking, but definitely incorrect, at least when it comes to the Canadian map!

Botanical names are never italicized, as they should be, although cultivar names are shown in single quotes correctly. Oddly enough no mention is made of the newer trademarked names that are soon going to dominate.

As mentioned in one of my opening stories, I have a long-standing concern about pesticide recommendations. On page 49 of the Training Manual they actually suggest only “pet-proof traps baited with metaldehyde” as a solution for slugs. No mention is made of diatomaceous earth or the newer Ferric phosphate product from Safer’s.

I also noted ever so many typos, spelling errors and exclusions. For example, that super aggressive perennial, goutweed (Aegopodium podagraria ‘Variegatum’), is listed as “Aegopodium podograria”--that’s right with incorrect spelling of the species, and no mention of the variegated form although under ‘Features’ they say “variegated white and green leaves”. I guess they didn’t realize there is a solid green form as well. However, I think there should have been more than just the two words “vigorous, aggressive” in the ‘Features’ write-up. Customers in garden centres should likely be told that if they sell this to a new gardener they could well face a highly distressed and angry customer two years or so later! And, they might also have informed: 1) that the plant should be planted in a container, even if in the ground, and 2) that it cannot be killed with either selective (2-4-D/Mecoprop/Dicamba) or non-selective (Roundup) types.

One of the funniest spelling errors is the insect listed as “Bruce Spanworm” which to me indicates rather poor proofreading. Just what the source of some of the information in the Training Manual was, is open to conjecture. But, since one of the spelling errors in “podagraria” is the same as in the Sheridan Nurseries Garden Guide, perhaps we have a clue!

On the other hand, Chris Andrews, CNLA executive director, told me they were working hand in hand with “the Americans” so possibly that explains some of the problems, including the over-use of the USDA hardiness map.

In thinking about improvements for this programme it seems to me that it should be entirely Web-based. There are already mentions in the Training Manual of checking the CNLA’s CD-ROM of plants, so why not continue in that direction? Coincidentally I recently checked the Web and found the University of Georgia’s site ( where they have exams on a huge range of topics including National Nursery Landscape Plants and National Nursery Landscape Disorders. Just compare their colour photos with the text or poor black and white sketches of the CCHT programme!

Chris Andrews, executive director of CNLA, suggested he would get his education and marketing coordinator, Rachel Corbeil, to call me about the CCHT programme since it was her area. Rachel did that and told me she was unaware of the errors and omissions I mentioned to her. She also said the latest revision of the Retail Garden Centre Professional manual was in the process of being developed and that she expected to see some proofs within a month. She also said that they hope, eventually, to sell the manual to the U.S. just as they currently buy the landscape maintenance ones from the Associated Landscape Con-tractors of America.

That one point may well mean boosting the prominence of the U.S.D.A. hardiness map, rather than reducing it in favour of our own Canadian map. I hope that will not be the case! There should be a way of having two editions, one for Canada featuring only the Canadian map, and one for the US, using the U.S.D.A. map.

In preparing for this article, I did contact a number of “sea-soned” garden centre employees in several provinces who have “taken the course” and found a consensus that it could indeed be much, much better. To sum up, the CCHT programme is new, it is a good start, it’s being constantly refined, and according to Chris Andrews, Rachel is looking at putting it on the Web. Hopefully many of the gross errors will be corrected in the next version! And, it seems to me they are years behind the times by not being on the Web NOW!