Plant Care
Do I need Anti-Desiccant Spray?
| Nov 17, 2022
Anti-desiccant spray is a protective, waxy, foliar-applied product that is sprayed on evergreen trees and shrubs in the late fall/early winter.
Evergreen trees and shrubs continue to transpire (give off/lose water vapor through the needles or foliage) in the windy, winter months. In our cold climate, a completely frozen ground prevents the tree or shrub from taking up water through the roots to replace the lost water vapor.
The result? Something commonly called “winter burn.” This refers to completely dehydrated, dried out trees or shrubs with brown needles (or leaves) that do not green-up again in the spring.
“Winter burn” may effect just one part of the plant or can cause the plant to die entirely.
The Arborvitae “Emerald Green” trees above are already planted in a challenging location. They have a restricted root zone which limits water and nutrient uptake. They are also completely exposed on the front side with a flat walkway and driveway that doesn’t mitigate harsh winter winds. No mulch was used to insulate this bed of trees either.
Particularly vulnerable trees and shrubs include those that are in exposed sites that receive a lot of sunlight and wind. In a natural, heavily planted or forest environment, desiccation is rare because the surrounding trees and vegetation mitigate strong winds. Furthermore, woody twigs, branches and leaf liter is left undisturbed to decay on the ground, providing insulation against freezing temperatures.
By contrast, our suburban environment commonly features a larger lawn area with a single row of evergreens such as Arborvitae “Green Giant” that line the property to provide privacy from neighbors or a standalone shrub such as the Rhododendron above.
Because the lawn doesn’t provide any protection against strong winds, and fall mulching or allowing our leaves to decay on the lawn aren’t widespread practices, this exposes our evergreens to the harsh winter wind and frozen ground conditions that can cause “winter burn.”
Although anti-desiccant spray isn’t needed for every single evergreen tree* or broadleaf evergreen shrub (such as holly, laurels, rhododendron and boxwood), you might consider an application if your plants are in an exposed location, have had “winter burn” in the past, or otherwise challenging environment such as a limited root zone.
*Note: Waxy blue conifers, such as Blue Spruce, already have a protective waxy coating on their needles and should not receive anti-desiccant treatment.
I often observe winter burn on holly bushes in the early spring.
Other ways to mitigate “winter burn” risk include mulching in the fall (we just finished mulching our own property!), wrapping valuable trees and shrubs in burlap, and planting more trees and shrubs around the property to slow down heavy winds.
As always, one of the best ways to mitigate any plant health care problem is to preventively maintain the plant’s health, vitality and robustness. This reduces risk should a problem arise and enables the plant to withstand any problem more readily. You can achieve this through regular mulching. Among other benefits, as the mulch breaks down, it replaces valuable nutrients into the soil that feed the tree throughout the season.
If mulching isn’t an option or if you’d like to give your trees and shrubs an even greater boost, we can deep root feed your plants with a soil-injected, liquid fertilizer. The slow-release, low-nitrogen fertilizer that we use enhances root growth and helps with water-retention. It can be applied in the fall and early winter (until the ground freezes) and again in the spring and early summer (until the temperatures are above 80-degrees).
If you have any questions about anti-desiccant spray or if you are unsure whether your property may benefit from anti-desiccant, please send me an email.
Happy Thanksgiving! Alex and I are grateful, as always, for our wonderful customers and the opportunity to care for your beautiful trees and shrubs.