Deicing products damaging to plants, trees
By Jackie Buckley
Morton County Extension agent
Dates to remember
Jan. 13 – 4-H/FFA Livestock and Crops Judging Workout, Mandan High School, 7 p.m.
Jan. 14 – Temple Grandin, Mandan Seven Seas, Pre-registration required, Call 701-677-1163, ext. 3
Jan. 14 – Temple Grandin, Mandan Middle School, 7:30 p.m. Please call 701-667-3340 to register
Deicing salts cause injury to plants, trees
Deicing salt can burn plants. Apply deicing compounds down the middle of walks and drives, avoiding the edges near grass and shrubs. Sand or cat litter can provide traction and minimize the need for salt. Salt damage does not stop with the roots. When passing vehicles spray salt on the plants, it can damage a plant’s leaves, needles, buds and small twigs, which in turn can reduce the plant’s cold hardiness, making tissue more susceptible to freeze damage. Root growth and reduced seed germination can occur in grasses and flower plantings.
On deciduous trees, salt spray affects opening of buds and twigs in the spring, with the flower buds being the most sensitive. Injured buds are slow to open or fail to open. Factors that influence sensitivity include bud size, nature of the bud scales, twig thickness and bark covering. Trees with thin bark, such as mountain ash, are highly susceptible. Trees with resinous buds, such as cottonwood, are fairly resistant to injury, as are trees whose buds are submerged in the twig, such as black and honey locust. Generally, plants with naked buds are injured more than trees with scaly buds.
Salt symptoms on deciduous trees include reduced green leaf coloration, smaller leaves with scorched margins, thin crowns with dying twigs and branches, early fall coloration and leaf fall, tufting and clumping of foliage and sparseness of leaves, and small growth rings. The irregularity in foliage thickness from year to year reflects both the growth conditions and differences in the amount of injury each year. Subsequent shoot growth results in the development of “witches’-brooms” (tuft-like growths) from the basal section of branches facing the road. The symptoms become evident when growth resumes in the spring. In addition, salt-damaged deciduous trees and shrubs leaf out later in the spring.
Soil salt damage to deciduous species often becomes evident late in the summer following the growing season in which the salt damage occurred, or during periods of hot, dry weather. However, many years of high soil salt accumulation may pass before injury becomes apparent. The symptoms initially include an abnormal foliage color, needle tip-burn, and marginal leaf burn progressing toward the mid-vein of affected leaves. Progressive symptoms may include a reduction in leaf, flower and fruit size; premature fall coloration and defoliation; stunting; and a general decline in health.
On evergreens, injury from salt spray first appears as browning of the needles facing the road. The browning occurs at the tip of the needle and progresses to the base. Browning is evident in February and March and becomes more prominent through the spring and summer. As injury continues, needles drop prematurely and the branches become bare. As needles die, the photosynthetic capacity of the tree is curtailed. Over several years, the amount of new growth is reduced, causing the tree to weaken, die back and perhaps die.
For a list of more salt tolerant plants please contact the Morton County Extension Office at 701-667-3340.