Plants growing in poorly drained soils are far more subject to winter damage than those growing in well-drained ones.
They also tend to grow more readily when the host leaves the ground in spring.
Plants growing in well-drained soil have more luxuriant roots that penetrate more deeply.
Such plants are more resistant to low-temperature injury and heaving.
Of course, many other factors govern a tree’s or shrub’s ability to withstand low temperatures. The maturity of the wood is one.
Feeding Of Trees And Shrubs
Trees and shrubs fed with excessive amounts of high nitrogenous fertilizers or those making considerable growth in late fall are more commonly injured.
Location, natural protection, plant species, and character of the root system are additional factors that govern winter hardiness.
Autumn Frost Damage
The growing season is prolonged in areas where warm autumn follows a cool summer.
In such areas, twigs, buds, and branches fail to mature properly and are more prone to injury by early autumn frosts or unseasonable cold waves.
Frost Cracks: Extensive Damage To Branches And Roots
Aside from extensive damage to branches and roots, unfavorable fall and winter temperatures produce more or less localized injuries on trunks and branches known as frost cracks.
These usually appear on the trunk’s south, and west sides since the sun’s rays heat these areas, and a greater gradient prevails when the temperature drops suddenly during the night.
Deciduous Trees: Frost Cracking
Deciduous trees are more subject to frost cracking than evergreens, among the former.
Norway maple, elm, horse-chestnut, linden, oak, and plane suffer most.
Drying Of Evergreens
Winter injury to such evergreens as rhododendron, laurel, holly, pine, spruce, and fir is rarely caused by excessive winter cold.
The damage results from excessive and rapid temperature fluctuations or late spring freezes after the plants have resumed activity.
Water Loss Of Evergreens
Evergreens lose water continuously. Although water loss is less in winter, it may considerably increase over the usual amount when the plants are subjected to drying winds or are grown in warm sunny spots.
Unless the water lost during this period is replaced by absorption through the roots, the leaves wilt, turn brown and may die.
Thus it is obvious that the ability of a plant to withstand low temperatures depends on many factors beyond man’s control.
Reducing Winter Damage
In some instances, however, certain precautions can be taken to reduce the possibility of winter damage.
To ensure an ample winter supply of moisture for evergreens, the soil around them should be thoroughly soaked before freezing weather sets in.
Using Of Windbreaks For Evergreens
One good way to wind-protect broad-leaved evergreens such as rhododendron and laurel is to use windbreaks of coniferous evergreens, which as a rule, suffer less severely.
Other winds and sun shields that have proved effective for evergreens in some places are evergreen boughs inserted among the shrubs before the ground freezes or a screen of corn stalks.
Used, too, are screens of burlaps or boards to protect the more tender subjects.
The material Wilf-Pruf can be sprayed directly on the foliage of evergreens.
Transparent Coating: Reduce Water Loss
It forms a thin transparent coating, which reduces water loss from the leaves without preventing the normal movement of gases in and out of the leaves.
Heavy Mulches: Prevent Deep Freezing of Soil
In the case of all trees and shrubs, heavy mulches of oak-leaf mold or acid peat moss will prevent deep soil freezing and thus facilitate water absorption by the roots.
This will help significantly to minimize winter injury.
Deer Control
In some sections of the country, wintry weather has arrived. Soon heavy snows can be expected, and many wild animals lack forage with them.
Deer, particularly, will cause heavy damage to unprotected trees and shrubs in the more rural areas.
Spraying Goodrite Z.I.P
Thanks to modern science, a repellent known as Goodrite z.i.p. can be sprayed on valuable trees, shrubs, and berry bushes in late fall to protect deer.
A spray containing a pound of z.i.p. to 25 gallons of water should be applied to deciduous trees and shrubs after most leaves have fallen before the snow.
This spray makes the leaves so unpalatable to deer that only a few bites are enough to convince them.
The animals will not establish themselves in the vicinity of sprayed plants but will move to the unsprayed areas before bad weather restricts their travel.
Goodrite Z.I.P: Prevent Horses From Nibbling
Goodrite z.i.p. has recently been found to repel other animals too. For example, trees and shrubs sprayed with it will prevent horses from nibbling.
And when painted or sprayed on fences, posts, and buildings, it controls cribbling. As a result, some users report that goats, cattle, and raccoons stay away from treated plants.
This repellent does not harm animals that taste-treated plants. Nor is it harmful to the plants sprayed.
In addition, because z.i.p. contains a special adhesive, its effectiveness is not empaired by rain, snow, or wind.
Sawfly Biological Warfare 70+ Years Ago
According to Philip B. Dowden, in 1950, entomologists successfully disseminated a virus disease of the European sawfly in Ontario, Canada.
The next year, the virus was made available in New Jersey, where complete control was effected on a small area treated with a knapsack sprayer.
In 1952 excellent control was obtained in Illinois when the virus was applied with ground equipment and in New Jersey when applied from an airplane.
44659 by P. P. Pirone