It’s Finally Spring

5 Things to Look Out For

No one would argue that this has been a tough winter, but, in the end, it may have been toughest of all on plants, shrubs and sensitive trees. According to the arborists at ZEN Associates, here are five things to look out for after this brutal winter.

Desiccation: Plants that keep their leaves all year like hollies, boxwood and rhododendron are prone to damage during extreme cold and wind during the winter months. During the growing season, plants take water up through the roots, use it in the chemical reaction that makes the plants food, and expels the water though the leaves. During extreme cold, plants that do not drop their leaves continue this process, but cannot replace the lost water because the ground water is frozen. In the spring the plants leaves will take on a burnt look, the damage is actually often referred to as “winter burn”. Winter burn rarely kills plants but can leave them looking unsightly for many months. ZEN Associates’ solution: Damage can be minimized by making sure the plants are well watered just prior to the hard frost. Another solution is to apply and anti-desiccant – a liquid solution sprayed onto the leaf surface in the fall that seals the pores on the leaf surface so the plant loses less moisture to the air during the winter. The product slowly degrades over the course of a few months so that by spring the plants are ready to become fully active.

Frost cracks: Thin barked and young trees can be susceptible to frost cracking. Similar to the formation of potholes, the tissue of the plant tends to warm in the winter sun and expand, but when the sun goes down and temperatures drop, the tissue rapidly cools and contracts. This cycle of expansion and contraction can cause the bark to split and crack. Frost cracks become evident in the spring as long vertical splits in the bark. They are not only unsightly, but can also allow for invading insects and diseases. ZEN Associates’ solution: When possible install sensitive plants in sheltered locations away from wind and avoid south facing exposure. Or, for sensitive plants or plants in an exposed location, protect the bark by lightly wrapping the trunk with a light colored fabric or specially designed trunk wrap. It is important to promptly remove the wrap in the spring to minimize moisture against the bark surface. Make sure the plants are properly fertilized and are receiving the correct amount of water to facilitate the recovery process. The damage caused by frost cracks will be walled off in a process known as compartmentalization. As long as the plant is kept healthy and vigorous it will generally be able to thrive after a frost crack event although the damage may be unsightly for years.

Broken/cracked branches: Winter wind and snow loads can often cause breakage and small cracks in tree branches. The damage caused can often go undetected until the spring when the plants begin to wake up and the water and nutrients begin to flow again. Breaks and cracks can disrupt the water flow and the leaves on damaged branches will begin to look yellow, or the leaves that emerge will be smaller and less vigorous. ZEN Associates’ solution: Prune out damaged branches making proper pruning cuts. Cracked branches may also tear causing more damage. By making a proper pruning cut, the plant can more quickly recover from the injury.

Rodent damage: In winters with extended periods of snow cover, rodents like mice and voles will often make extensive tunnels throughout the snow. When these tunnel networks reach sensitive, thin-barked trees, such as apple, maple, cherry, linden, walnut, and willow, the rodents often make an easy meal of the bark at the base of the tree. A mouse feeding on the thin bark of one of these trees can often chew a strip completely around the trunk. Called girdling, this can cause the tree to die quickly in the spring because the flow of water and nutrients from the ground is interrupted. ZEN Associates’ solution: Place mesh cages around the trunks of susceptible trees to help protect from damage. If a tree is completely girdled, it is difficult, possibly impossible, to save. If it is partially girdled, an expert may be able to apply a graft – obviously, the less damage done, the better the chance for success.

Damaging insects: Many of the insects that attack landscape plants spend the winter in the ground or leaf litter. In winters with extreme cold and no snow cover the insect populations can be significantly reduced as the insects are killed by cold temperatures. But in winters like this year, the deep snowpack acts like an insulating blanket keeping the insects warm and safe. It is a good bet that insect pests like winter moth will be out in full force this spring. ZEN Associates’ solution: Rake out and dispose of leaves that accumulate under trees and shrubs, they serve as a refuge for the overwintering insects. Also, chemical treatment can control insects actively feeding on your plants, however, unfortunately, insects like winter moth blow in on the wind, so even if your trees are treated, pests from miles away can re-invade.

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