With recent temperature fluctuations and inconsistent visits from the sun, our hopes for spring are not the only ones taking a hit.
When the sun shines on mild winter days, a tree absorbs heat from sunlight through its bark. The tree’s dormant cells awaken, causing the tree and its bark to expand. A sharp decline in temperature then provokes the bark to cool and contract much quicker than the interior of the tree. This causes the bark to split and fall off, injuring both the tree and its protective barrier.
This is known as sunscald, or Southwest injury, as it occurs mostly on the south or southwest side of trees, where they receive the most direct sunlight. The south side of a tree can get as much as 77°F warmer on a cold winter day than the north side.