The willows are weeping

While the willows in northeast B.C. aren't exactly weeping, their dried brown foliage certainly gives them an air of despondency.

What's got the willows down? Or rather, brown? There are a few theories in circulation ranging from fungus to caterpillars, but the consensus pins the area's browning willow foliage on an infestation of willow leaf blotch miners, a moth whose larvae feed on willow leaves.

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The moths have been feeding on willows in the Yukon for the last five years and appear to have migrated southeasterly to the Peace Region in earnest within the last two years.

The willow leaf blotch miners, are native to North America but, unlike the mountain pine beetle, aren't expected to exact much damage on local forests. Usually it takes a prolonged infestation of up to five years to actually impact plant health, but combined with drought conditions or other insect infestations, the willows could die.

Despite the natural inclination to blame the failing health of local willows on the summer's record-breaking rains, local experts believe the infestation's roots reach further into the past.

Local horticulturalist, Annette O'Hanley, speculated the moths moved into the area last fall to take advantage of conditions caused by a five-year drought. She explained the moths spend the winter in the ground, in pupa form, and prefer drier soils. Furthermore, O'Hanley noted, the insects tend to feed on stressed plants - something local willows certainly were, after going so long without a good drink.

Rather than leading to the willow's downfall, O'Hanley explained, the summer's extremely wet weather will likely deliver their salvation.

"They usually only cycle through every ten years and now, because of the wet summer we just had, they'll likely move on," she said.

Like others, O'Hanley's first instinct was to blame heavy rains for the sick willows, but being an avid horticulturalist, she probed deeper.

"At first I thought it was a fungus because of all the rain, but I stopped by a few places and looked at the leaves," she said.

What O'Hanley noticed were signs of eggs laid on leaves then feeding larvae which turn into brown-grey moths, which some residents may have noticed flitting around in abundance lately.

"People shouldn't be worried about this because it's likely going to be a one time thing. If this kept going for say, five years, there would be cause for concern, but this is the first time I've seen anything like this," she said.

As of last year, the Yukon Forest Report documented the infestation as far south and east as Watson Lake, where willow damage seemed to have dropped off.

However, upon an examination of willow leaves along the Alaska Highway corridor, researchers have reported successful larval development with considerable pupal sites on individual leaves.

The miners originally entered the Yukon along the Yukon river corridor from Alaska, where the damage has been widespread since they were identified in 1991. Blotch miners were first noticed in the Yukon in 2007, but the report suggests they had been present in smaller numbers for some time prior to that.

Researchers anticipate the insect will continue expanding its range through willow rich corridors in coming years.

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