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Splashes of fall colour begin to show


Changing leaves-- a sign of cooler temperatures ahead. Click the image to see a slideshow of your best fall foliage photos
Changing leaves-- a sign of cooler temperatures ahead. Click the image to see a slideshow of your best fall foliage photos

Andrea Stockton, staff writer

September 26, 2011 — The fall season is beginning to show its true colours. Do you track the fall colours?

First signs of colour in Kearney, Ontario
First signs of colour in Kearney, Ontario

Autumn is often referred to as the “picture perfect” season as splashes of colour fill trees across the country.

The fall colour season has already begun in the province of Ontario with parts of the northern and eastern regions reporting up to 50 per cent change. Pockets of vibrant reds and yellow are beginning to show, but green currently remains dominant across most southern sections of the country.

Travel and tourism officials say colours usually begin to peak by the end of September and into October.

Why do the leaves change colour?

“Temperature plays a factor in the coloration of trees, but the most important factor is called the photo period, or the length of daylight,” says horticulturalist Bob Osbourne of Cornhill, NB.

“The shortening of the number of hours of daylight is the trigger for trees to start shutting down. A cork-like layer forms between the leaf stem and the branch, which will eventually fall off and it also protects the tree from any kind of fungal or bacterial infection. As it shuts down, it begins to stop water and nutrients from coming into the leaf and the chlorophyll dies.”

Osbourne says this phenomenon is what allows us to see the various pigments that have been there all along, but are only visible now because of the lack of green.

Stress is a big factor in coloration. It may be a matter of too much or too little water, or other nutritional factors. You can spot a stressed tree by its leaves, which change color before the others.

Tree stress can affect whether the fall show will be sensational or not. Things like drought, extreme temperatures and air pollution can make the leaves dull.

“The most famous of all the trees is the Sugar Maple,” adds Osbourne, “with its combination of orange, yellow, and sometimes red. One of the most spectacular of the trees is the native Red Maple with its vivid red color. These are the trees we most associate with fall.”

Green continues to be dominant for now in most of southern Canada
Green continues to be dominant for now in most of southern Canada

Colour progression

Wondering how the colours will progress in your area this year?

Saskatchewan, Ontario, Quebec, Nova Scotia, New Brunswick and Prince Edward Island are all helping people track the changing leaves.

If you have a favourite spot to see the fall colours, tell us on The Weather Network's Facebook page.

You can also help us tell this story by sharing your photos. Upload them easily to our Your Weather Gallery.

With files from Kimberly Lamontagne

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