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Common Ragweed

 
Common ragweed can be hazardous to our health. Learn how to recognize ragweed and protect yourself against its harmful effects.
 

What is Ragweed?

  • An annual broadleaf weed that produces allergenic pollen
  • Ragweed blooms in late summer to early fall
  • Each plant produces about a billion pollen grains per season
  • With the help of the wind, ragweed can travel distances greater than 200 kilometres
  • Ragweed has a jagged leaf and tannish-green flower stalks
  • It can grow to a height of anywhere from 1 - 6 feet

Where is Ragweed found?

You can find ragweed all over Southern Ontario, often growing with a plant called goldenrod. Goldenrod pollen is not carried on the wind like ragweed pollen.

You can find ragweed in:

  • Gardens
  • Poorly kept lawns
  • Sidewalk edges
  • Fence-lines
  • Along roadsides

How can Ragweed affect my health?

Ragweed can cause a number of health problems for some people:

  • Hay fever, which includes sneezing, runny nose, and itchy eyes
  • A skin rash (allergic contact dermatitis)
  • Coughing and wheezing
  • Scratchy and irritated throat
  • Headaches
  • Difficulty sleeping

Is there a Ragweed By-law in Halton?

The Provincial Weed Control Act (R.R.O. 1990, Reg. 1096) requires land owners to destroy ragweed.

Milton No By-law
Oakville No By-law
Halton Hills Included as a “nuisance weed” requiring removal under Community Standards By-law
No. 2008-0138
Burlington Require removal of weeds (including ragweed) from May 1 to October 15 each year.
By-law No. 12-2011
 

Does the Ontario Pesticides Ban permit municipalities to spray Ragweed?

Yes, the Ontario Pesticides Ban (external link) contains exceptions to certain plants to protect public health and safety.

How can I get rid of Ragweed?

Since ragweed spreads by seed, eliminating this weed should focus on preventing seed production. We recommend hand-pulling the ragweed as the plants are easy to pull out with their shallow root systems. We recommend using gloves.

What can I do to protect my health?

Use the following precautionary measures to reduce exposure.

  • Minimize outdoor activities when pollen count is highest (10 a.m.- 4 p.m.)
  • Monitor local weather report for local pollen counts
  • Keep windows closed and use air conditioning at home and in the car
  • Mow your grass often and wear a dust/pollen mask while you mow
  • Wear wraparound sunglasses to prevent pollen from blowing into your eyes
  • Avoid places with lots of weeds and tall grasses, like parks or fields
  • Clean your furnace/air-conditioner filter frequently

How can I treat my allergies?

If you experience an allergic reaction, speak to your doctor about over-the-counter or prescription medications to help control your symptoms.

Diagram of common ragweed showing various growth stages  

Common ragweed. A. Seedling, top and side views. B. Portion of stem with 2 leaves. C. End of flowering branch. D. 1-sided "raceme" with 7 heads, each with 1 female flower.

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