News / Toronto

Heads up! Extreme hot weather can make trees snap

Long, dry spells are generally to blame for the phenomenon known as "summer branch drop," says at expert at U of T's urban forestry department.

Fall colours in High Park. Long dry seasons could cause tree branches to pop and crash, says a Toronto forestry expert.

Eduardo Lima / Metro Order this photo

Fall colours in High Park. Long dry seasons could cause tree branches to pop and crash, says a Toronto forestry expert.

Trees have always shaded you from the hot sun, and now it's your turn to take care of them in this heat wave — lest their branches spontaneously crack and fall.

Long, dry spells are generally to blame for the phenomenon known as "summer branch drop," said Sandy Smith, head of urban forestry department at the University of Toronto.

"The trees are trying to cool themselves off because they do heat up," she said. "In a dry season like last year, not only were trees not able to cool themselves, but they were losing water they didn't have."

In response, the tree starts shutting down branches with less foliage.

Last year a tree limb popped and fell in Trinity Bellwoods Park, killing a 30-year-old man sitting underneath. A city spokesperson said at the time that summer branch drop does happen even in healthy trees, though it wasn't determined whether that was the cause.

Smith said it's unlikely this three-day heat wave will cause such serious damage, mainly because the summer has been relatively cold and the trees are still able to suck enough water from the ground.

She advised people have arborists check on their trees regularly to ensure they're well pruned and in good shape. However, watering is always the best way to prevent this "sudden death."

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