Evergreens need water to thrive in the summer, in the fall and during dry spells in the winter.
The dry winter air winter weather can cause your evergreens to dry out and develop a winter burn. When the ground is frozen, evergreen trees cannot take in water. The dry weather causes moisture loss through their needles. This can kill your evergreens.
Desiccation, or winter burn, often doesn’t become evident until the weather warms up in spring. At that point, the damage shows up pretty quickly but, unfortunately, it’s too late to do anything about it.
You’ll start to notice “burned” leaves with whitish patches (they look like they’ve been bleached), leaves with a paler green or yellowish color that doesn’t look “right,” and brown or yellow needles on conifers. Eventually, the leaves or needles dry up, turn brown, and fall off.
An anti-desiccant (also known as an anti-transpirant) is a spray that provides a protective waxy coating to reduce water loss from an evergreen’s foliage. Desiccation means “the removal or loss of water,” so an anti-desiccant prevents this.
Anti-desiccants are most often used to protect broadleaf evergreens from winter desiccation. Some broadleaf evergreens, such as Arborvitaes, rhododendrons, boxwoods, andromeda, hollies, and laurels, are particularly susceptible to winter injury from desiccation.