Plants are susceptible to 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.
Deer thrive in the natural areas in and around Grande Prairie and seem to particularly enjoy feeding on ornamental landscape trees. The City cages young trees to protect them from this damage, but one of the best strategies to keep deer damage at bay is to choose plants they avoid.
Deer damage and kill trees two ways: feeding damage (left) and rubbing damage from antlers (right)
Caging trees until they develop thick, mature bark protects them from this.
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 with a trunk guard.
|Protect your young trees from rabbit and mouse damage with a trunk guard and mulch|
Beavers can kill a fully grown mature tree in a matter of hours. Keep beavers away from high value trees by wrapping the trunk 1 meter high with metal mesh fencing. Just remember to loosen it annually so you don't girdle your tree.
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 3. 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.
|The winter of 2018-2019 saw wind chills down to -50 that truly tested Grande Prairie's trees. Many trees showed dieback (left) and some died entirely from winterkill (right).|
Symptoms of drought include leaf margin burn and early leaf drop. Many tree insect outbreaks, such as bronze birch borer and western ash bark beetle, can 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.
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 reentering 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.
Winterkill is common in plants exposed to winter winds. Plant trees and shrubs with west protection whenever possible to prevent winterkill.
|Protection from our prevailing west winds often prevents winterkill.|
High winds can cause trees to lose limbs or 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 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 with a trunk guard.
Human activities account for much of the tree dieback and death seen in Grande Prairie.
Explore below to see what damages occur and how you can help keep our trees alive!
Construction damage to root zones is common where sidewalks or roads are renovated in established neighbourhoods. Tree Protection Zone protocols are used by many municipalities to help prevent this damage.
Mower and string trimmer damage causes 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.
Surround your tree with wood chip mulch to the dripline and maintain this ring weed free. This will both keep lawn equipment away from the tree to prevent damage and ensure all the rain that falls on the mulch provides water for the tree, not grass.
|Mower (left) and trimmer (right) damage kill trees every year in Grande Prairie. Maintain a weed-free ring of wood mulch around your trees to their dripline to prevent this 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.
If you spray your lawn for dandelions, keep the spray away from under the tree so its roots won't take up the herbicide from the soil, and do not spray on windy days to prevent drift onto leaves.
Glyphosate (e.g. Roundup) is deactivated upon contact with the soil, so as long as you don't actually hit your tree's leaves, you can spray it right up to the trunk of your tree.
Roadside soils are typically high in salt because of winter sanding operations. This salt ties 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.
Putting boulevard trees into mulched beds set back from the road provides them more moisture and helps them overcome salinity damage. City crews also wash salt spray off boulevard trees to prevent witches brooming.
Often, human caused damage is caused by collisions or accidentally driving too close to trees. It takes over forty years to grow a tree to a significant size in Grande Prairie; please treat them with care and respect to help our urban forest remain healthy and vibrant.
Unfortunately, vandalism towards trees is all too common in GP. Caging small trees helps keep them safe from purposeful damage while they grow. Trees planted near playgrounds or on school grounds are usually planted as large as possible and pruned up high to help prevent broken branches.
Teaching children to respect and love trees will help them realize how valuable they are to our urban landscape. A new tree costs upwards of $1000 to purchase, plant and maintain in the first year. Let's work together to keep our urban forest safe!
Urban soils are by definition highly disturbed. Most likely the soil that exists in your yard hardly resembles what was there originally. If your soil is hard clay, amend it heavily with compost, rotted manure, peat moss and sand. Then mulch around your plants to help improve soil structure and promote soil organisms. Topdressing with good quality topsoil and aerating also helps soil structure.
High water tables 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 drowning may result.
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 eventually becomes 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, compost and other organic matter. Mulch around your trees to prevent foot traffic over their roots and to improve the soil as it breaks down.