Plants are susceptible to environmental stress just like humans are. Drought, drowning, heat, and cold can all damage trees and may even be mistaken for insect or disease damage.
Trees are essential to the existence of many species for food and shelter or just as a good scratching post. The activities of birds and mammals may therefore result in the damage or destruction of trees.
Sapsuckers are medium sized woodpeckers that drill rows of tiny holes in the trunks of both deciduous and coniferous trees. They feed on the tree sap that leaks from the holes and on insects attracted to the sap. Sapsuckers prefer to stay on an individual tree and the resulting damage may be extensive. As a result of the frequent wounding the stressed trees are sometimes colonized by insects or diseases that enter these holes. Tree death, though infrequent, sometimes occurs.
Control of nuisance birds in urban environments is not easy. They are best tolerated. To discourage sapsuckers from feeding on a favourite shade tree, wrap hardware cloth or burlap around the area being tapped or smear a sticky repellent material, such as bird tanglefoot, on the bark.
Moose and deer thrive in the natural areas around Grande Prairie and seem to particularly enjoy feeding on ornamental landscape trees. They are best managed by not planting trees they enjoy feeding on.
Beavers can cause extensive damage to a grove of trees in a short time. Squirrels, mice and rabbits strip bark off branches and may cause girdling and tree death. The easiest control for small rodents is to maintain a ring of bare earth or mulch around each tree to prevent rodents tunneling to the tree, and to wrap the tree's trunk each fall with fine mesh. Make sure to remove the mesh each spring to prevent girdling the tree as it grows.
Here in Grande Prairie, we live in one of the northernmost agricultural areas in the world. This presents some special challenges to us in choosing the proper ornamental trees, shrubs and plants for our yards and gardens. It may be tempting for you to try and push the climate envelope and plant trees not fully hardy to Zone 2b. However, sooner or later low winter temperatures or an early frost will cause severe winterkill or may even kill your tree outright. In order to have a landscape full of healthy plants, use only what can live in this area.
Symptoms of drought include leaf margin burn and early leaf drop. Many tree insect problems, such as bronze birch borer, western ash bark beetle, and yellow-headed spruce sawfly, occur in response to trees being drought-stressed. During dry spells, it is recommended that you water your trees deeply once every two weeks to keep them healthy and growing.
Early frosts may catch a plant before it is fully hardened off for winter, resulting in branch tip kill. This situation may be aggravated if trees are fertilized too late in summer or when heavy fall watering is coupled with unseasonably warm weather. Never fertilize trees after August 1 and taper off your watering through late August and early September. Only water in conifers for winter once cool temperatures have arrived that will prevent them entering a growth cycle.
Late frosts may catch plants after they start coming out of winter dormancy and sap is flowing. Shoot death or blasted flower buds may occur. Watch for frost warnings and cover susceptible plants overnight.
High winds can cause trees to lose limbs or even topple entirely. Also, standing dead trees quickly begin to rot and become hazardous if left. Contact a local tree removal company to remove any dead or weakened trees on your property as soon as possible to prevent them falling on houses, vehicles or people.
Thin-barked trees, such as maple and cherry, are prone to a disorder called sunscald on the southwest side of their trunks. This occurs in the winter on cold, sunny days, when rapid temperature fluctuations kills the cambium bark layer. This eventually flakes off, leaving an unsightly cavity that compromises the tree's structural strength and provides entry points for insects and disease. Prevent sunscald by wrapping the trunk from the ground up to the first set of branches from late fall until spring.
Construction damage to root zones is common where sidewalks or roads are renovated in established neighbourhoods.
Mower and string trimmer damage may cause open wounds, which impedes water movement throughout the tree and increases its susceptibility to disease and insect attack. Trees can be severely stunted or killed from this type of damage.
Herbicide damage may be evidenced by browning, curling, dying leaves or irregular growth patterns. It may be difficult to definitely diagnose herbicide injury, since these symptoms mimic many other environmental stress symptoms.
Roadside soils are typically higher in salt content because of winter sanding operations. This salt tends to tie up available moisture and aggravates drought symptoms on boulevard trees.
Airborne pollutants such as salt spray, vehicle and industrial emissions can produce a variety of symptoms like leaf edge burn, stunting, yellowing and witches'-brooms.
Often, human caused damage is caused by collisions or accidentally driving too close to front yard trees. It takes upwards of forty years to grow a tree to a significant size in Grande Prairie; Parks Operations asks you to please treat them with care and respect to help our urban forest remain healthy and vibrant.
Native soil variability means that a given tree species - although hardy to this climatic zone - may not excel equally at all locations in the city. Native plants growing on site are often an indicator of soil suitability for landscape plants. Plants should be chosen that tolerate local soil conditions. If you are unsure of soil conditions on your growing site, or if you are having difficulty establishing plants, a soil test from an accredited lab may help.
Acidity is measured using the pH scale, which runs from 0 (extremely acidic) through 7 (neutral) to 14 (extremely alkaline). Fairly acidic soils with pH 5.5, though suitable for evergreens, may result in pale green leaves on some deciduous hardwoods. The elemental balance that these hardwoods require is more readily available at neutral pH levels (pH 6.5 – 7.5). Pine trees will thrive in sandy, acidic soils and may struggle in alkaline, clay gumbos.
High water tables may also influence trees because plant roots require oxygen. Combine a high water table with slow draining clay soils and tree roots may become oxygen-starved during extended rainy periods or under excessive irrigation. Stunted new growth or tree death from drowning may result.
Compacted urban boulevard soils often suffer from salinity problems, due to a combination of added salt from winter road maintenance and lack of drainage to flush the salts away. As salinity increases, it becomes more difficult for many plants and trees to thrive, as the salt prevents plant roots from taking up water.
Current urban engineering practices for new roads and subdivisions involve stripping the topsoil from the land, laying in all services and road bases, then replacing the topsoil before completing landscaping. This promotes a layer of severely compacted subsoil called hardpan, which is often so compacted that plant roots cannot penetrate it at all. As boulevards are driven over and sidewalks replaced, even the topsoil will eventually become compacted, preventing plant roots from spreading properly and accessing oxygen and water. Regular aeration will help alleviate compaction, as will amending heavy clay soils with sand to improve drainage and break up hardpan.