Winter burn on tips of boxwood (Buxus); note undamaged interior leaves
Winter burn on bayberry (Myrica pensylvanica)
Frost crack in bark
Scorch can indicate more serious problems, as on this fragrant snowbell (Styrax obassia) that died from stem cankers, which possibly entered through a frost crack.
Frost heaving can cause plants to rise up out of the ground as these hens and chicks (Sempervivum) did.
Frost heaving of lily bulbs (Lilium)
Overview
Ice, snow, drying winds, and cold temperatures can cause a wide range of problems for plants. Following are some of the most common problems that can be the result of winter injury. Sometimes the damage may not be evident until early summer or even years after the injury has occurred.
Winter Burn/Dessication
Desiccation or winter burn is primarily a problem of evergreens and results when these 3 situations occur: low soil moisture, freezing temperatures, and blowing wind. With these 3 factors in place, evergreens lose moisture through transpiration faster than their roots can replace it from the frozen ground. Damage will be more severe on the side of the tree exposed to sun and wind. Broad-leafed evergreens like rhododendrons show browning of leaf margins.
Integrated Pest Management Strategies
1. Water adequately. This is 1 inch per week or saturation to the depth of 12 to 18 inches. Watering needs to be continued through late autumn into early winter as long as the ground is not frozen.
2. Provide a barrier to wind. A burlap barrier can deflect wind from the plant.
3. Mulch. Put organic mulch around the plant so the entire root zone is covered. This will reduce moisture loss.
4. Provide good culture. Watch the amount of moisture in the spring when the plant is coming out of a period of frozen ground, and low moisture availability. Water as needed if the rainfall is less than an inch per week.
Organic Strategies
All of the recommended IPM strategies are strictly organic approaches.
Frost Cracks
Frost cracks develop in late winter to early spring often on the southwest side of a tree at the site of a previous wound or branch stub. They occur when the daytime sun heats the bark and underlying wood causing tissue expansion. Then with a sudden, sharp temperature drop, the outer bark layer contracts, more rapidly than the inner layers.
The splitting itself can sound like a rifle shot. The area involved shows as an elongated, vertical crack, or sometimes bulge, in the trunk. The area may callus over only to re-open the next winter. The area can also allow entry of insects and disease organisms.
Susceptible species include: maple, sycamore, apple, crabapple, ash, beech, horse chestnut, tuliptree
1. Treat trees well. Avoid trunk wounds: mowing injuries, weed whip injuries, improper pruning. Do not use wound paints/tar on the crack. They actually interfere with healing. Prune properly.
2. Do not fertilize late in the growing season. Wait until after the last leaf drop in the fall or until after the early spring thaw.
3. Provide a clean wound area. If the crack is ‘clean’ with neat edges and no loose hanging bark, leave the trunk alone. It will callus on its own. If there is a ragged tear with shredded bark, trim off the affected bark. Then trace around the wound with a sharp, sterile knife. This cut stimulates cambium growth and speeds healing. A half-inch margin of bark around the wound can also be removed to give a clean edge around the crack. The edges will callus and eventually close over the wound.
4. Serious damage. If there is a large, serious crack, a professional arborist can do ‘lip bolting’ to save the tree.
Strategies 1, 3, and 4 are strictly organic approaches. Using an appropriate organic fertilizer would be a viable organic approach to Strategy 2.
Frost Heaving
Wide temperature fluctuations, with repeated cycles of freezing and thawing, cause the water in the soil to expand and contract. These repeated expansions and contractions push and turn plants and their roots. The result is the heaving of the crowns. They are pushed up out of the soil breaking some roots and exposing other roots above soil level. The elevated crowns and roots are exposed to cold temperatures and drying winds. They may be seriously damaged, stunted, or killed. Perennials with shallow root systems or those that have been planted recently and have not had time to establish adequate root systems are prone to frost heaving.
1. Controlling frost heaving starts with well-drained planting beds. Both surface and subsurface drainage are essential to prevent water from pooling in planted beds. A soggy ground will freeze and thaw repeatedly and susceptible plants will heave. The addition of organic material, when the beds are prepared, helps loosen soil and promotes good soil drainage.
2. Plant early in the fall. Planting perennials at least 6 weeks before the first autumn frost date gives the plants time to establish adequate root systems to anchor themselves.
3. Mulch. Mulching with organic material (compost, ground leaves, straw, or pine needles) will help moderate soil temperatures reducing the heaving of root systems. The mulch should be applied after a hard frost and at a depth of 4 inches. Excess mulch can lead to soggy ground and rodent infestations. Avoid burying the plant’s crown as the mulch is put down.
4. Monitor the plants. Keep a careful eye on susceptible plants. The mulch can hide an exposed, heaved crown. When a problem is found, cover the exposed roots with a layer of soil and re-apply mulch.
Updated 10/2024