Watering trees now can prevent winter damage
Protecting our trees from winter damage begins in summer and fall by making sure they have adequate water. While this has been an exceptional year for young trees with the abundant rainfall, it is especially important that right before the ground freezes solid in November, those trees are well-watered. This allows trees to take up sufficient water to help prevent winter drying from wind and sun.
Browning or bleaching of evergreen foliage during winter occurs when the winter sun and wind cause excessive transpiration (foliage water loss) while the roots are in frozen soil and unable to replace the lost water. Bright sunny days during the winter also cause warming of the tissue above ambient temperature which in turn initiates cellular activity. When the sun is quickly shaded, foliage temperatures drop to injurious levels, and the foliage is injured or killed. During bright, cold winter days, chlorophyll in the foliage is destroyed (photo-oxidized) and is not resynthesized when temperatures are below 28 degrees. All these result in the desiccation, bleaching and browning of the plant tissue.
Foliage damage normally occurs on the south, southwest and windward sides of the plant, but in severe cases the whole plant may be affect. Yews, arborvitae and hemlock are most susceptible, but winter browning can affect all evergreens.
The first way to minimize winter injure is proper placement of evergreens in the landscape. Yew, hemlock, and arborvitae should not be placed on south or southwest sides of buildings or in highly exposed (windy, sunny) places. Winter injury can often be prevented by constructing a barrier of burlap or similar material on the south, southwest and windward sides of evergreens. If a plant has exhibited injury on all sides, surround it with a barrier, but leave the top open to allow for some air and light penetration.
Sun scald is characterized by elongated, sunken dried or cracked areas of dead bark, usually on the south or southwest side of a tree. On cold winter days, the sun can heat up bark to the point where cambial activity is stimulated. When the sun is blocked by a cloud, hill or building, bark temperature drops rapidly, killing the active tissue. Young trees, newly planted trees, and thin-barked trees (cherry, crabapple, honeylocust, linden, maple, mountain ash, plum) are most susceptible to sun scald. Older trees are less subject to sun scald because the thicker bark can insulate dormant tissue from the sun's heat, ensuring the tissue will remain dormant and cold hardy.
Sun scald can be prevented by wrapping the trunk with a commercial tree wrap, plastic tree guards or any other light-colored material. The wrap will reflect the sun and keep the bark at a more constant temperature. Put the wrap on in the fall and remove it in the spring after the last frost. Newly planted trees should be wrapped for at least two winters and thin-barked species up to five or more winters.
Rabbits and rodents can cause severe damage to plants in winter. These animals feed on the tender twigs, bark and foliage. They can girdle trees and shrubs and eat shrubs to the ground line. Trees can be protected by placing a cylinder of 1/4-inch mesh hardware cloth around the trunk. The cylinder should extend 2 to 3 inches below the ground line to repel mice, and 18 to 24 inches above the anticipated snow line for rabbit protection. Hardware cloth can be left on year-round, but must be larger than the trunk to allow for growth. Small trees benefit from plastic tree guards. You can protect shrub beds or groups of young trees from rabbits by fencing the beds with chicken wire; however, check such fenced areas frequently to ensure a rabbit has not gained entrance and is trapped inside.
The last week in September and the first week in October are the times to plant garlic cloves for harvest next July. The stiff neck garlic, which has fewer and larger cloves, does better in our area than the soft neck variety, which has many but smaller cloves.
Kyle Schulz is a Wadena County Master Gardener from Sebeka and the regular gardening columnist for the Wadena Pioneer Journal.