Common Ragweed

Ragweed is the most common cause of seasonal allergies. Pollen from ragweed is the primary cause of hay fever.

What is Ragweed?

  • Common ragweed is an annual broadleaf weed that produces allergenic pollen.
  • Ragweed blooms in late summer to early fall.
  • Each plant makes 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 reach a height of 1 foot - 6 feet.

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Where is Ragweed found?

  • Ragweed is one of the most abundant weeds in southern Ontario.
  • It is frequently found in:
    • gardens
    • poorly kept lawns
    • sidewalk edges
    • fence-lines
    • along roadsides
  • Goldenrod can often be found growing with ragweed.
    • Goldenrod produces pollen too (that is heavy and sticky) however, only in small amounts.
    • Goldenrod pollen is not carried on the wind and cannot be blamed as the source of irritation for ragweed hay fever sufferers.

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How can Ragweed affect my health? 

  • In addition to causing hay fever (sneezing, running nose, itchy eyes), ragweed can also cause a skin rash (allergic contact dermatitis).
  • In general, when you have allergies you may experience some of these symptoms:
    • Sneezing
    • Itchy and watery eyes
    • Coughing and wheezing
    • A scratchy, irritated throat
    • Headaches
    • Difficulty sleeping
  • Coughing and wheezing may be worse in people with asthma and Chronic Obstructive Pulmonary Disease (COPD).

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Is there a Ragweed By-law in Halton?

  • In Ontario, 23 weeds are considered noxious under the Provincial Weed Control Act (R.R.O. 1990, Reg. 1096). Ragweed is included in this list.
  • The Weed Control Act requires land owners to destroy ragweed.
  • Halton Region, Milton and Oakville do not have a ragweed by-law. Halton Hills includes ragweed as a ‘Nuisance Weed’ (requiring removal) under their Community Standards By-law (No. 2008-0138) and Burlington’s By-law (No. 12-2011), which regulates exterior property maintenance, requires that all owners shall destroy or remove weeds (including ragweed) between May 1 and October 15 each year.

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Does the Ontario Pesticides Ban permit municipalities to spray Ragweed?

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How can I get rid of Ragweed?

  • Efforts to eliminate ragweed should focus on preventing seed production (since it spreads by seed).
  • For homeowners, hand-pulling is the best method to get rid of ragweed.
    • The plants are easy to pull, as they have shallow root systems.
    • Gloves are recommended.

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What can I do to protect my health?

  • There are a number of precautionary measures that can be taken to reduce exposures.
    • 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. Use air conditioning at home and in the car.
    • Mow your grass often. 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 to remove pollen.

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How can I treat my allergies?

  • If you experience an allergic reaction, speak to your doctor about over-the-counter/prescription medications for nose and eye relief.
  • Others who should talk to their doctor before taking medication include: those with health conditions, older adults, children, and women who are pregnant or breastfeeding.
  • If your allergies continue to bother you, you and your doctor can decide if you should get allergy shots (immunotherapy) to help control your symptoms.

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Where can I get more information?

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