Sneezing? Blame those sexy trees
If you've been noticing that your hay fever symptoms have gone haywire this spring and summer, you're in good company.
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Ripe pollen cone cluster on a pine tree.
(photo: Don White)
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Pollen counts are up across Canada, including the Yukon. And it's the plants that produce airborne pollen (known as anemophilous, or 'wind-loving,' plants) that are mainly responsible for all those sneezes and stuffy noses.
In the Whitehorse area, by far the largest amount of airborne pollen comes from two tree species, both conifers – spruce and pine.
"The pollen that leaves the yellow puddles on the streets, and yellow gutters after showers, and the yellow on your windshield, is largely tree pollen," says retired forester Don White.
"That pollen is off the pine and the spruce, the most common species here."
These trees, like other plants that rely on wind for pollen dispersal, produce large quantities of pollen in order to increase the chances of fertilization.
"The greater the amount of pollen in the air, the greater the chance that all the ovules in the female cones get pollinated," says White.
"There's probably tens of thousands of metric tonnes of pollen that float through the air in the Yukon during pollen season, and probably less than one percent is used in fertilization."
That means a lot of pollen coming in contact with your nose – especially spruce pollen, according to White. "We've got a lot more pollen off the spruce this year than normal, and a slightly higher amount off the pine."
Chief Medical Health Officer Dr. Brendan Hanley says that "anecdotally, we've seen a significant increase in medical visits this spring for both allergic rhinitis and asthma, including emergency visits.
"That includes both new sufferers and those who already had allergic rhinitis but were finding the usual antihistamines weren't helping."
Conifer species found in the Yukon produce both male and female cones on the same tree, but it's the male cones that produce all those tiny pollen grains.
"You can stand on one side of Long Lake," says White, "and watch the wind blowing, and all of a sudden you have this huge cloud of yellow pollen drifting across. It can be carried for kilometres."
Conifers can actually "self" – they can pollinate themselves from their own cones – but White explains that "the offspring tend not to be very good."
The buds that will turn into cones are produced the year before. New buds become either vegetative buds, which will develop into branch tips, or flowering buds, which will develop into male or female cones.
"Last year the Yukon had really good weather at the end of June and the beginning of July, so when those buds started to differentiate we ended up getting a lot of flowering as opposed to vegetative buds," says White.
These buds grow into cones the following year – toward the end of May with the pine, and from early June to the middle of June with the spruce.
The Yukon also had good weather this spring at just the right time for pollen release. "We had a relatively nice May and early part of June when all of the pollen cones started to burst. That's what led to that huge influx of pollen," says White.
"If it had been cool and rainy this year during the flowering period, there wouldn't have been nearly as much pollen flowing."
The really big increase in production this year came from the spruce, leading to a pollen season that lasted for a month instead of two weeks.
"Often we just get the one big whack of pine pollen and we're done," White explains. "But this year we got about 8 to 9 percent more pollen cones on the pine, and a huge increase – about 80 to 90 percent above normal – in pollen cones on the spruce.
"Again, that's because of the really warm summer last year at the end of June and the beginning of July."
Pollen production this year seems atypical to us because "we haven't had a really good cone crop across the territory for about 10 or 11 years," says White.
The last time Whitehorse saw a real bumper crop was in the early eighties, when "the tops of the spruce trees in Robert Service campground were breaking off because of the weight of the cones. They closed portions of the campground down."
But hay fever sufferers take note: chances are things will be back to normal next year. "At the end of June and the beginning of July this year, we didn't get the temperatures in the high twenties that we did last year," White points out. "So next year pollen production from the spruce will be diminished by 90 percent or so, and pine production will be slightly less than this year."
Up around Mayo, though, hay fever sufferers may be out of luck. "Mayo had really good temperatures around the end of June and the beginning of July this year, so it may get a repeat of really good cone production next year," says White. "That will depend on the temperatures in 2011 at the time of pollen release, and if pollen cones are present."
