What should you be using to control insects and diseases on your plants in your garden
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

June 11, 2017







Alternate insect control, or natural insect control, has long been a topic of interest to some gardeners. If you listen to a vocal minority of gardeners--those wanting to control insects, diseases and even weeds using only natural methods--the number of gardeners employing these methods is increasing exponentially. It isn't! Both the manufacturers of the chemicals, and the garden centres/home improvement centres that sell them will verify that sales of the chemical products have NOT declined, but continue to grow, and the sales of the so-called natural products, while increasing, is not increasing substantially in comparison with the chemical products.

I'm sure there are many gardeners out there who would like not to have to use chemicals. But many of them have tried the so-called natural methods and found them to be only modestly effective at best. For almost the last four decades there have been insecticidal soap products available. The first such product was developed by Dr. George Puritch at the Pacific Forest Research Centre, near Victoria, British Columbia in the late 70s. Actually, insecticidal soaps for controlling pests have been known for some time but the petrochemical products introduced in the late 1930s overshadowed them.

Dr. Puritch and an old friend Sergei Condrashoff, first president of the Safer Agro-Chem company, told me how, while studying hormonal activity in the balsam woolly aphid in 1973, George more or less stumbled on the fact that fatty acids (soaps) could kill the insects. That lead to further experimentation with varying combinations of fatty acids. His research within a few years showed that insecticidal soaps, WHEN SPRAYED DIRECTLY ON INSECTS, penetrate their bodies causing destruction and disruption of their membranes--usually resulting in death. As well, the insecticidal soaps accumulate in the nervous system and cause paralysis. What he also discovered was that many of the insects that are not killed outright are affected in such a way that they never reach maturity, thus never have the chance to reproduce.

By early 1980, Dr. Puritch's research had indicated that insecticidal soaps were effective in the control of aphids, earwigs, mealybugs, mites and white flies, as well as several disease organisms. At that time, nematodes, spittlebugs, gypsy moth, and pear psylla also showed indications of being susceptible to certain fatty acid salts (soaps). But, that most important factor remained, and still remains the critical point--the spray must actually wet the insects. And, the fact is that once the insecticidal spray dries, it is no longer effective.

Don't disregard insecticidal soaps. They have been improved since my old friend Sergei talked on my radio programmes of the early 1980s, about this new (less harmful) method of insect control. At least one additive is found in some products which causes the spray to remain moist for a longer period of time. And don't forget my suggestion of spraying the subject plant with water first, so the atmosphere in which it is growing is damp. That will mean the insecticidal soap will remain "active" for a longer period of time.

But also keep in mind the use of chemicals should still be in most gardeners' arsenals in the battle to control insects and diseases. If the poisonous petrochemical base (found in most insecticides) concerns you (as it should), then consider some of the newer chemicals such as the water-based Permethrin. It bears no poison label and is widely available, particularly at well-stocked garden centres under the Doktor Doom label. Echoing my advice on one of Canada's Weather Network Lawn & Garden reports back in 1998, don't be fooled by some so-called environmentalists advice "to steep old cigarette butts in water, and use this as a much less dangerous insecticide." What you are doing following this advice is brewing up a strong form of Nicotine sulphate that will probably be much more potentially harmful than any chemical currently on any garden centre or home improvement store shelf.

The natural pesticide Nicotine sulphate was taken off the market decades ago because it was too dangerous! All of this came to mind as I noted this week that a major supermarket chain now has its ladybird beetles in stock. Some garden centres are also offering them for sale. They come from Natural Insect Control at R.R. #2 Stevensville, Ontario L0S 1S0. Telephone 905-382-2904 for their free catalogue of other non-toxic insect controls including purple martin and bat houses. The beneficial live ladybugs come in small burlap pouches of about 1,000 and cost between $6 and $10.

Finally, a word about where we seem to be heading in pest control. The aforementioned water-based Permethrin is just the forerunner of new products on their way. There is already one formulation of Diazinon available where the chemical is encapsulated and only attacks the target insects (cockroaches). It is safe enough to paint on kitchen countertops, and may even be consumed by humans without any effect. The product is expensive, but does work well. Less-expensive water-based Diazinon products and similar formulations of other insecticides should be with us in just the next few years.

If you are looking for a not-so-poisonous insecticide or fungicide, I suggest you check the Websites for Wilson’s and Doktor Doom and read the specific comments the companies make about their various products.


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