St. Jacobs – The wild temperature swings of the last 10 days
threaten to ruin this year’s tree-fruit crop before spring arrives.
Todd Leuty, agroforestry specialist for the Ontario Ministry
of Agriculture and Food, told an audience of more than 100 maple syrup
producers here recently that radical temperature changes kill tree buds,
including maples and fruit trees.
He said radical temperature swings – and we’ve gone from minus 40 wind chills to
plus eight within five days – are far more damaging to buds than either
prolonged cold or warm weather.
He explained that there are two types of winter dormancy
protecting buds until spring arrives.
The outer layer is the one that’s most damaged by the wild
temperature swings.
If it’s destroyed, or responds to warmth to begin opening
for spring before winter is over, it leaves the inner bud exposed.
The inner dormancy responds to the tree’s hormonal balances,
Leuty said, and operates much like heat units measured for corn-crop
development.
In this case, it’s an accumulation of cold that eventually
reaches a tipping point to trigger and end to dormancy and the beginning of
spring growth.
Leuty said farmers can check the health of buds by cutting
them in half, lengthwise, to see whether the interior is brown and dead or
green and alive.
He said fruit-tree farmers will probably be checking their
orchards next week to determine the degree of damage caused by the recent
extreme temperature fluctuations.
