Weed controlSoils that are acid, compact, poor and deficient in calcium and magnesium are ideal conditions for the establishment of the weed.

How to reduce the presence of weed:

  • Deterrent factors:
  • Check the soil’s pH and add lime to counter acidity.
  • Break up the soil with a lawn aerator. This will allow water and nutrients to infiltrate better into the roots.
  • Re-seed annually to keep your lawn thick and free of bare spots. The thicker coverage will compete with the seeds of undesirable plants.
  • Keep the grass long (8 cm) to prevent seeds from germinating in the soil. Grass that is mowed very short is three times more likely to have weeds than grass that is kept longer. Adjust your lawn mower to a higher setting.

Giant hogweed is harmful to health and the environment. It hampers the growth of other plants in the habitats it colonizes. It destabilizes ecosystems and contributes to bank erosion. It should never be seeded, planted, propagated or transported. Contact with its sap can cause painful skin reactions similar to burns. If required to handle it, you should wear gloves, long pants, and long sleeves.

Description of the plant

Giant hogweed (Heracleum mantegazzianum) is a poisonous, invasive, exotic species. It is a perennial in the carrot and parsnip family like cow parsnip, which it resembles, although it is much less poisonous. Giant hogweed can measure from two to five meters high, or thirty centimetres to one meter after mowing. Its very robust stem is covered with stiff white hairs and numerous, very distinct, extensive, raspberry-red to purple spots. Its leaves can be up to 1.5 meters wide and three meters long.
Giant hogweed is a spectacular, impressive plant. It is also very appealing and intriguing. Children may hide or play in it, or use the stem as a flute, peashooter, or telescope. Adults may appreciate it as an ornamental plant.

hogweedHabitats colonized by the plant

Giant hogweed first appeared in Québec in 1990. It has been found in a number of regions in the province, including Bas-Saint-Laurent, Capitale-Nationale, Côte-Nord, Chaudière-Appalaches, Gaspésie–Îles-de-la-Madeleine, and Lanaudière.
Giant hogweed prefers cool, damp habitats and is found in the following types of disturbed habitat: Along the banks of waterways, in ditches, along railways, on roadsides, in fields and in vacant lots.

Health effects

Although contact with the sap is not painful in itself, the toxins it contains are activated by light (UV rays), making the skin extremely sensitive to sunlight and causing a type of damage to superficial skin cells called phytophotodermatites.
Phytophotodermatites can develop up to 48 hours after exposure to sap. It is characterized by localized rash and oedema (red, swollen skin), blisters, or even burns. Once healed (in approximately a week), brown spots can persist and the affected region can remain sensitive to sunlight for several months.
All parts of the body can be affected, but the back of the hands, arms, legs, and face are the most commonly injured because they are more likely to be exposed to the poisonous sap and to sunlight.

The risk of exposure is high for the following groups of people:

  • Children and their parents
  • Horticulturalists
  • Farmers
  • Personnel doing brushing work
  • Anyone living or spending time in areas where the plant is found.

To reduce the risk of exposure to the sap, these individuals should be able to recognize giant hogweed.

What to do in the event of exposure
If your skin has been in contact with sap

  • Remove the sap as quickly as possible without spreading it. Use a sheet of absorbent paper and do not rub. Wash the affected area with soap and rinse thoroughly with water. Then wash your hands.
  • Change and wash your clothes to avoid contaminating other parts of your body or other people.
  • Cover affected areas (gloves, long pants, and long sleeves) to avoid exposing them to light (including artificial light) for at least 48 hours.

If your eyes have come in contact with sap

  • Rinse your eyes thoroughly with clean water for ten minutes.
  • Wear dark sunglasses to avoid exposing your eyes to light.
  • See a doctor as soon as possible.

If you have burns

  • Avoid any exposure to sunlight for at least a week.
  • Use sunscreen for six months.
  • Call the Info-Santé helpline at 8-1-1 for more information on how to treat burns.

If you think you have been in contact with giant hogweed or if you would like more information on what to do in case of burns, contact Centre antipoison du Québec at 1-800-463-5060 or the Info-Santé help line at 8-1-1.

You should see a doctor in the following cases:

  • A child is affected;
  • Eyes are affected;
  • The affected person is running a fever;
  • Large lesions develop;
  • Red, swollen skin over an area greater than one-third of the affected body part; Presence of blisters 25 millimeters or more in diameter (larger than a quarter); Several affected body parts;
  • Pus (yellow opaque liquid) in the wounds.

hogweed-1How to control it

Giant hogweed should be controlled to protect not only public health, but also the environment for the following reasons:

  • It disrupts the balance of the ecosystems it invades.
  • It reduces biodiversity.
  • It promotes bank erosion.

It is very important to limit its spread by avoiding seeding, planting, propagating, or transporting it. As far as possible, it should be eliminated and its regrowth prevented.

hogweed-3If you must handle the plant, protect yourself:

  • Cover your body head to toe with protective, nonabsorbent clothing (synthetic, waterproof material): long pants, long sleeves, and waterproof gloves with long cuffs.
  • Pay special attention to areas where your protective clothes overlap (wrists, ankles, neck).
  • Remove your clothes and gloves by turning them inside out. To prevent contamination, avoid putting soiled clothes in contact with other objects or clothing and wash them well before any further use.
  • Protect your eyes or, even better, your entire face (visor).
  • If you are mechanically cutting the plant, make sure that no one is standing where they could be hit by the sap or plant debris thrown off during mowing or cutting. Use a knife or round shovel to cut stems and roots.
  • Wash tools that have been in contact with sap (pruning shears, brush cutter, etc.).
  • Wash your hands and face.

Source : ministère de la Santé et des Services sociaux.

For more information on controlling giant hogweed, contact Centre d’information du ministère du Développement durable, de l’Environnement et des Parcs:

  • Telephone: 418-521-3830 (Québec City) or 1-800-561-1616
  • Fax: 418-646-5974
  • Email: info@mddep.gouv.qc.ca


By-law concerning the application of pesticides
The use of pesticides for esthetic purposes is cause for concern to more and more citizens. The adoption of the provincial Pesticide Management Code in March 2003 recognizes this and imposes restrictions on the use and sale of pesticides. Montreal City Council unanimously passed a pesticide by-law applicable across the island at the April 2004 meeting. Our City Council adopted an ordinance at the meeting of May 4, 2004 specifying that this by-law come into effect immediately and further limiting some of its provisions.

The rule: The use and application of pesticides is prohibited outside buildings on the whole territory of the City.

The use of a biological control agent, as designated by the Pest Management Regulatory Agency, mineral oil or active ingredients authorized under schedule II to the Pesticides Management Code is permitted except for the control of vegetation.

The exception: The use of pesticides is permitted within a radius of 5 m of food company warehouses and production plants to ensure vermin control, subject to the issue of a permit.

Permits: A temporary pesticide permit is valid for a period of 3 days; the pesticide application must be carried out between 9 a.m. and 3 p.m. on a Monday, Tuesday, Wednesday or Thursday; Clear explanatory signs must be posted on the site for 72 hours before and after the application, using signs provided by the City.

City Council authorizes the inspector to issue a permit for use of pesticides in case of emergencies and health hazards, in all areas. The use and application of herbicides to destroy weeds is prohibited except for public health reasons.

This by-law and ordinance aim to protect the health of residents while allowing some flexibility in methods to preserve the beauty of our gardens and green spaces. A total ban does not address problems such as wasp nest or ant infestations, but there are several non-toxic solutions available to resolve these types of situations. The Public Works inspectors would be pleased to advise you on the types and uses of ecological products as well as local sources of supply.

Click here to download our   Pesticide Ordinance

Ragweed pollen causes hay fever and, occasionally, chronic sinusitis or asthma in people allergic to it. By pulling up or cutting the ragweed down to ground level before the end of July, this will help improve the health of over one million Quebecers who are allergic to ragweed pollen.

For more information, visit: www.herbeapoux.gouv.qc.ca

Solar energy is energy from the sun in the form of radiated heat and light. The sun’s radiant energy can be used to provide lighting and heat for buildings and to produce electricity. Historically, solar energy has been harnessed through passive solar technologies. Typically, these involve the strategic location of buildings and various elements of these buildings, such as windows, overhangs and thermal masses. Such practices take advantage of the sun for lighting and space heating to significantly reduce the use of electrical or mechanical equipment. Solar energy can be harnessed only during the day and only if the sunlight is not blocked by clouds, buildings or other obstacles.

Today, two active solar technologies that involve electrical or mechanical equipment are becoming more common. First, solar collectors or panels are used to heat water or ventilation air for use in buildings. Second, solar photovoltaic technology uses solar cells to convert sunlight directly into electricity.

Source: Natural Resources Canada

Thinking of buying into solar energy? Click here to read an article on this topic published by the Canada Mortgage and Housing Corporation.