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Organic vs Conventional Produce, Cucumbers & Grapes

Comments about the organic vs. conventionally-produced food are running 50/50; Cucumber foliage turning grey--probably a leaf spot disease; and a ‘stalled’ grape vine!
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

August 9, 2009

Above, we have a good crop of seedless red grapes on our vine here (ready for the raccoons to feast on); and below, a shot of our in-pond Canna lily and the somewhat unusual Zephyr lily (Zephranthes candida) also in the pond. It is brought indoors over our winter. Author photos.

After last week’s release of the British Food Standards Agency’s study done by London School of Hygiene and Tropical Medicine, showing virtually no difference in the nutritive value of food grown or produced using organic principles vs. conventional methods, there has been ongoing fall-out; especially in the form of ‘cries of foul’ from the organic food industry!

Published in the American Journal of Clinical Nutrition a week ago Wednesday Dr. Alan Dangour’s study–which reviewed 50 years of scientific evidence–has polarized opinion between those for whom it has confirmed long-held suspicions about the organic movement and those who believe it was outrageously one-sided. In the London’s Daily Mail, food writer Joanna Blythman, branded the study a "cancerous conspiracy."

Dr. Dangour, who spent more than a year with a team of nutritionists analyzing 162 peer-reviewed studies, said that he had been sent between 250 and 300 emails personally, with hundreds more arriving at the Food Standards Agency and his university. Among the more printable comments were: “Shame on you and this bogus so-called study” and “To the quacks who wrote the study and concluded that organic foods have no health benefits over conventional foods: you blokes are freakin' whacky.”

While Dr. Dangour found the abuse “mildly entertaining”, he was surprised at its vehemence.

“I have received an awful lot of emails,” he said. “Half have been positive saying we really needed this; and I have received a lot of negative emails, some of which have been abusive. I'm not sure I expected that; I was quite taken aback. There have been several things that have come up frequently.

“Some have questioned my integrity and independence; whether I am funded by big agriculture or industry. It's professionally hurtful for people to say: 'You must be funded by industry or otherwise you wouldn't have come up with that finding'.”

Yesterday John Mackey, head of Whole Foods (a British chain of food stores), caused further unwelcome publicity for the organic movement by suggesting his flagship store in London sold too many fatty treats.

“We sell a bunch of junk,” he said adding that there needed to be more health education at his UK division, which lost £36m last year, despite a considerable interest among the public for organic produce.

Nine out of 10 British shoppers buys organic, but debate has long raged about whether it is healthier for individuals as well as better for the environment.

In internet forums, organic supporters have complained that Dr. Dangour's study should have looked at the health impact of pesticides, while others pointed out the work did not nullify the environmental benefit of organic farms, which are generally acknowledged to be good for wildlife.

Others said they bought organic food because it tasted better.

The Soil Association, Britain's main organic certification body, pointed out that while all 162 relevant studies re-viewed found organic to be higher in many nutrients such as beta-carotene, the review concluded there were no important benefits from only 55 "high quality" studies.

Dr. Dangour said the group had been unfair. “The Soil Association obviously have their own point of view but in certain circumstances the way they tried to make their point has not been entirely appropriate,” he said.

“If you pull random numbers from the report and claim that they are significant, that is not helpful.”

* * *

Well, enough already on that topic! There are a couple of letters left over this week, so I’ll deal with those.

Brian, of totally unknown location, wrote as follows: “I am having a problem with my cucumber plants this year. The leaves are turning yellow in spots and then turning grey and then the leaves die off. Is there anything I can do to save the rest of my plants or do I have to give up for this year. Your help would be much appreciated.”

It sounds to me that you have a disease organism present--either powdery mildew, or much more likely a leaf spot (Alternaria sp.). The only real control for leaf spot is a copper fungicide such as copper sulphate, copper oxychloride or copper hydroxide. Various versions of these products (including the old stand-by Bordeaux mixture [a mix of cop-per sulphate and hydrated lime in water]) are available from good garden centres.

You may well encounter suggestions of applying the copper product you choose with a “spreader/sticker”. A common dish detergent is often used. I would ignore that advice, and just use the copper product, mixed (and kept constantly agitated as it is applied) as recommended on the label.

The leaf spot diseases are particularly bad when rainy weather is experienced, such as has been the case in the eastern part of North America this spring and summer. It will also be important not to compost any part of the plants’ foliage, nor to allow them to remain on the ground over the winter. If it is not possible to burn the old vines, then be sure to dispose of them in your household garbage.

The second question came from Tom C. Batty in the Victoria, B.C. area: “We planted a grapevine at our home in Sooke B.C. in the fall last year; it took off pretty good in the spring {about 4 feet} but then came to an abrupt stop about a couple of months ago. Any ideas? Thank you for your time.”

I think I probably need more background information on the grape vines, and the area in which you have planted them before offering any suggestions as to what may have happened. Certainly here, just over two hours by car away, our grape vine has continued its growth, and even now we are trimming it back constantly. In what type of soil are yours planted? Do they receive adequate water (keeping in mind the drought conditions Vancouver Island, and most of B.C. has experienced this year)? What cultivars (varieties) were they? Did the vines flower? Has any fruit been set?

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