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Early-bird spring landscaping – now is the time to prevent August ragweed!

March 30, 2015

What is news:

  • The International Agency for Research on Cancer (IARC) recently declared that three synthetic pesticides cause cancer in animals and probably cause cancer in humans, including the weedkiller glyphosate (a key ingredient in the product Roundup), and the insecticide malathion.

What is known:

  • Synthetic pesticides aggravate rather than protect against asthma.
  • Early application of corn gluten meal can stop seeds from germinating, including the common allergen ragweed.
  • Commonly used pesticides are linked to cancers, chronic diseases and child development problems.

Whether your flowers are blooming in the warm west, or sap is flowing in the icy east, as April begins Canadians are turning their thoughts to things green. For those already pondering spring lawn care, thoughts may include pesticides – products to kill weeds or insects. It is important to know that non-essential synthetic pesticides used “cosmetically” to make lawns and gardens look better were not designed for people or animals to romp upon!

Not surprisingly, chemicals meant to be toxic when spread in the environment can harm us as well. IARC just announced their findings that the weedkiller glyphosate and the insecticide malathion probably cause cancer. Bets are that IARC’s June re-examination of the popular weedkiller 2,4-D will conclude the same. The Ontario College of Family Physicians twice systematically reviewed research and linked various pesticides used in urban areas with serious illnesses such as cancer, reproductive problems and neurological diseases. These chemicals also pose heightened risks to children, pregnant women, and those with a health condition such as asthma.

Pesticide-based lawn care proponents often claim that chemicals are necessary to protect asthmatics from common allergens (tree pollen, grass and ragweed), but in fact pesticides actually aggravate asthma. For ragweed, there is a better, non-toxic alternative to the newly declared carcinogen glyphosate. Since ragweed germinates in early spring, a timely application of corn gluten meal as the snow finishes melting can stop the seeds from forming roots. If you miss that window, there are few weeds easier to pull than ragweed, and the corn gluten meal will stop other seeds germinating. Just remember not to seed your lawn at the same time! Corn gluten meal is sold in some garden centres and in stores carrying ‘green’ products.

In the interest of public health, restrictions on pesticide use close to where people live are increasing across Canada. Seven provinces have taken steps to significantly reduce cosmetic pesticide exposure. Ontario and Halifax have model legislation, Quebec’s is moderately protective, and Manitoba is currently implementing strong legislation for herbicides. Saskatchewan, Alberta and BC have yet to take this step.

It is surprisingly easy to have a great looking organic lawn with minimal effort and cost. Briefly, cut the grass high (about 7 cm), water infrequently but deeply when needed, aerate and over-seed. Consider including some Dutch white clover to generate nitrogen fertilizer naturally. There are organic solutions to all landscape and garden problems – solutions that ensure you and your family, friends, pets, as well as local wildlife have a safe place to tread, and a yard in balance with nature.

Prevent Cancer Now will periodically bring you news and topics about leading edge cancer prevention. In the meantime, check out for more information.

Happy, Healthy Spring, Canada!

–The PCN Team


  • International Agency for Research on Cancer. World Health Organization. Monographs Volume 112: evaluation of five organophosphate insecticides and herbicides. CLICK HERE
  • Ontario College of Family Physicians. Bassil et al. Cancer health effects of pesticides. Systematic Review. 2007. CLICK HERE
  • OCFP 2012 Systematic Review of Pesticide Health Effects. CLICK HERE


Prevent Cancer Now is a civil society organization including citizens, scientists and health professionals working to stop cancer before it starts, through education and advocacy to eliminate preventable causes of cancer.

For further information contact:

Meg Sears, PhD
Co-chair and science advisor, Prevent Cancer Now