Fall is a wonderful time of the year especially with the vibrant colours accentuated by the sun’s glow as it changes position on the horizon. What about that evergreen over there why are its needles dropping, is it sick? Needle shedding is common on evergreens, a better term would be conifers in order to dispel the assumption that they stay green forever. In most circumstances old growth on; spruce, pine, fir, cedar or even junipers discolours and is shed from the interior or lower portions of the tree or shrub. Yellowing and shedding is a natural process conifers will go through at least every 5-7 years. What makes the old growth shed is mainly due to the fact that exterior portions of the tree cast shade and limit the amount of sunlight reaching the tree’s interior. Picture an old conifer forest for example where the trees have no live growth near the bottom, the lack of lower branches is caused by them being naturally shed.
Shaped trees and trees planted closely together are also more prone to shedding in the shaded areas. Light means energy for plants, if a portion is not getting and producing enough energy to sustain itself and transfer excess energy to the rest of the plant it is shed. Deciduous trees also have a natural shedding process which results in deadwood. If there is dieback from the exterior of the canopy towards the interior you may be looking at a different issue. What can be done to prevent the shedding? Being a natural process there’s not much that can or should be done to stop yellowing and discolouration in conifers. Some actions can be taken to help reduce the symptoms and severity of shedding with plant health care practices. Proper watering during drought periods is a must and avoiding overuse of high nitrogen fertilizer. If you see an “evergreen” looking a little out of season don’t worry too much they just showing off their fall colours, it just might not happen every year such as their deciduous cousins.
We often get worried calls in regards to a white powdery substance on tree and shrub leaves. Commonly affected species include caragana shrubs, flowering crabapple trees and on occasion turf grass. The problem in question is a fungal disease called powdery mildew, the symptomatic white substance covering the leaves is the fungus and its spores.
In most circumstances powdery mildew is a cosmetic affliction of plants meaning that it will not kill the plant despite reducing its aesthetics and appearance. Fungicides offer little control over curing the disease because fungicides work more as a preventative than a cure for fungal diseases. A fungicide may reduce the spread of the fungus but affected tissues will remain symptomatic.
A better means of control would be to implement preventative cultural practices such as thoroughly cleaning up infected debris in the fall and improving airflow around the infected plant. Another cultural method would be plant health care, ensure that the infected plant is receiving adequate water while being careful not to over water so that the tree can build up energy reserves to naturally combat the disease. Improving root health by using wood chip mulch as a ground cover is also another method you can use to improve the health and growing conditions of the root system.
If the affected tree or shrub has a nutrient deficiency or imbalance it could be more susceptible to disease such as powdery mildew. Nitrogen is a food source for most tree and shrub pests, adding a high nitrogen fertilizer can actually make the problem worse. If you are using fertilizer we recommend a balanced fertilizer containing micro nutrients that is also high in potassium such as tomato and vegetable food. Potassium is the last number of 3 seen on product labels and nitrogen is the first. Prior to using any fertilizer or products it is wise to have a detailed soil or leaf tissue analysis. Samples should be conducted by an agricultural laboratory to determine if there are any nutrient deficiencies or specific soil conditions that could lead to nutrient imbalances.
On a final note please remember that powdery mildew is a cosmetic affliction that will not cause the death of your tree or shrub, try to work on the site conditions leading to the problem rather than trying to find a cure.
Once you have a location selected for your tree consideration should be made towards selecting the most appropriate species of tree for the desired area. If the right tree is put in the right place you and future owners of the tree can earn increasing benefits annually from wise decisions made even before the tree was planted. Things to consider are what is the maximum final height and width of the tree, does it flower? Most flowering trees also bear fruit.
A great choice of tree that stays small, flowers but does not drop fruit or sucker aggressively is the Tree Lilac. If you have a yard limited by space, consider planting columnar or dwarf species of trees and shrubs. An amur maple sold as a shrub can actually reach 15 feet tall and 10 feet wide after a long period of time in the right setting. Far too often we see large Colorado spruce trees planted too near a home or building, a better choice would be a columnar blue spruce or a pine where there are many species of that stay relatively small in comparison to a spruce. People often ask for a fast growing tree because they want an immediate benefit from the tree.
In most cases the faster growing species are also the ones that get the largest. If privacy is desired in a tight location it is better to be patient and plant a slower growing species of tree rather than putting a tree in that will outgrow the area. Tree species selected and planted for the best location also have reduced maintenance and plant health care requirements. Take a bit of time to research what types of insect and disease problems the tree you want is prone to, for example avoid species susceptible to black knot. If you are planting in a full sun open space facing south or west avoid dark thin barked trees such as mountain ash, linden and amur cherry because of their susceptibility to sun scald (tree sun burn). Putting the right tree in the right place is the golden rule which a positive multi-generational relationship with the tree is based on.
A very common myth associated to spruce and other evergreen species such as fir and pine is that they acidify and lower soil pH. There are many remedies for raising soil pH due to the presence of evergreens, do not use these products as they may cause more harm than good to your soil.
Research has proven that evergreens do not have an immediate effect on soil pH but over centuries and millennia they may. Another factor in dispelling the myth is that our soils in the Calgary and area have a high buffering capacity. Buffering capacity is the ability to resist a change in pH, meaning if you try to lower or raise soil pH the soil will return to it’s original pH quickly.
Our soil, and water for that matter, are alkaline and have a high calcium content. Calcium is what gives our soil and water a strong resistance to pH change. The myth came about because, grass and many other plants do not grow under or near a spruce. Competition for light and water is the reason why plants don’t grow well or die under evergreens.
Bergenia is a broad leaf creeping perennial plant that grows well in a dry shady area if you are looking for a suggestion for planting. You can raise the tree canopy to allow for more light at a sacrifice for tree balance, health, value and appearance. Every live limb removed from a tree is an injury, removing live growth from a tree should be done with reason and purpose. What do you value more your grass or your tree? Rather than fight a losing battle with a tree, work with it. Adding mulch under and extending the bed or dead ring around the tree is a great solution. A mulch bed makes a natural healthy environment for the roots and a nice edge that is more maintenance free. If you are adding mulch make sure that it is around 2”-4” deep while making sure not to put any around or bury the tree trunk.
Planting a tree is one of the best long term property improvements that you can make. Trees offer many benefits to you and the community around you including increasing in value as they mature. An improperly situated or inappropriate species of tree can become more of a liability than an asset. Putting the right tree in the right place, this is the golden rule in having a tree that will provide many generations of people and homeowners benefits with fewer maintenance costs and issues.
Before choosing which species to plant, take a look at the tree location as this will influence the decision and list of adequate tree species to choose from. Ideally any tree should be placed in an area where it will have a chance to reach maturity without growing into conflict with other trees or property.
Often trees are placed too close to buildings and require a lot of clearance maintenance or early removal because the tree selected grows too big for the desired location. Trees that often get planted way too close to buildings are columnar aspens, these trees get to be well over 4 stories tall and cause significant damage to rooves and eaves troughs when they bash against them in the wind. Fence lines are also a popular choice for tree placement that can lead to unfavorable results. As the trunk grows the tree may cause damage to the fence. Remember that trees grow to be quite large, if planted too close to a property line a large portion of the tree canopy ends up in the neighboring property.
Trees too close to a property line have been known to cause wars and rifts between neighbors. Trees grow tall, keep this in mind and look up before you plant so that you can avoid future concerns with overhead utilities such as communication and electrical lines. An open area that allows for your new tree to grow in all directions is the most ideal placement to maximize on the benefits provided to you by the tree.
One of the best strategies you can use to manage pests is monitoring. With accurate monitoring you can identify and mitigate pest problems on your trees and other plants in your yard. A pest can be classified as any insect, disease or weed that has a significant impact on human health or crops.
Proper monitoring involves a few key elements. You need to know the plant species you are dealing with, also be familiar with or research which pest problems the plant is most likely to have, including pest life cycles. Now you know what to keep an eye out for. Identification of the pest is really important because there are many insects that are either beneficial or benign. Some insects only cause cosmetic damage to trees, the tree will not die from the insect causing a little bit of damage. Now we are getting into pest thresholds which can be covered in a different article. Most spray insecticides are non selective which means they kill all of the good bugs with the bad bugs.
Ideally monitoring for pests should be done early and frequently throughout the year. Early observation will allow you to catch pest populations and implement any control measures if required before you see significant damage to your plant. Early detection and control can also help prevent minor infestations from becoming severe infestations.
You should also monitor regularly throughout the season, if you are not familiar with what plant you have or which insects to look for keep an eye on the overall vigor of the plant. A great time and schedule to follow for monitoring would be while weeding or watering the garden and yard. Besides monitoring do what you can to keep your tree healthy with regular watering and fertilizing if the plant is showing signs of deficiency. The words plant and tree are being intermixed in this article because monitoring for pests and integrated pest management applies to all plants especially food crops including trees.
Some useful tools used for monotiring include a magnifying glass and a keen eye with attention to detail. One of our favorite tools to use to check for insects like mites, aphids and other small insects is a sheet of paper. Shake a branch over a sheet of paper to observe if any critters end up on the paper. Keep an eye on the underside of leaves and at leaf/stem intersections as many insects like to hide in these areas.
Oystershell scale is affecting many cotoneaster hedges throughout the city of Calgary. We have also seen this insect pest affect; apples, mountain ash and hawthorn trees. In most cases if an infested hedge looks like it’s dead or dying, rejuvenation and post application of oil and monitoring are required. Prior to application carefully examine your tree or shrub to identify the target pest or problem. Most spray insecticides are non-selective and will also kill beneficial insects. Dormant oil must be applied early in the spring prior to leaf out. The reason applications must be made while trees and shrubs are dormant is that the product will cause damage to the leaves. Never spray on evergreens as this will cause permanent damage and sometimes discoloration of blue species.
A few exceptions are Pure Spray Green because the product label states that application is safe on leafed out plants, the next exception would be on a cotoneaster hedge that has been freshly rejuvenated. When applying make sure that you coat every portion of the plant until the product begins dripping off of the plant being treated. This assures that you get all of the insect shells covered with the insecticide. Make sure to read and follow the product label and wear appropriate personal protective equipment.
You will need
1 Hose, you probably already have one if not get a professional non kink hose they’re worth every penny
2 Dial calibrated hose end sprayer +/- $20
3 Horticultural oil or Dormant oil or Pure Spray Green +/-$20
1 Read labels
2 Wear personal protective equipment (plastic dish gloves, eye protection, hat, clothes to cover your skin)
3 Set the dial to 20 on the hose end sprayer and fill it with the oil
4 Thouroughly spray the plant until every portion is covered
5 Continue monitoring pest activity and reapply if required when plants return to a dormant state
People often ask how to water a tree, when and how much. Is there a regular schedule that one should follow to water trees and most plants in general? The answer is simple, check the soil regularly and water when dry. Do not overwater as this prevents the roots from having access to oxygen, low oxygen levels to the roots will encourage them to rot. Trees take up water through the roots by osmosis and transpirational pull which means water evaporating from the leaves is pulled up from the roots. Trees transpire throughout the day and mostly respire during the night, this is important to know when deciding what time of day to water.
The best time to water is during the morning so that the tree can have access to water when it needs it. Avoid watering during the hottest period of the day as much of your water will be wasted by evaporation from the ground. How much to water is also an important factor, ideally the best way to water your trees is to apply a large volume of water over a long time period, water heavily and less frequently.
A soaker hose is perfect for watering trees because it allows for water to be applied slowly so that the soil can be watered to its full capacity instead of just watering the surface with a sprinkler. Where you water should also be considered because you want the water to be where the feeder roots are. Let’s consider roots for a moment, roots can grow out as far as a tree is tall so you need to water where the fine roots are.
Think of a tree like a petroleum industry, fine roots far from the refinery tap water wells, think of the larger roots closer to the trunk as pipelines to transport the water from the wells all the way up the trunk to the leaves which act as refineries. When you water close to the trunk think of it as pouring oil over a pipeline instead of having it flow through the pipeline. Moisture on the trunk can also cause damage and rotting on the bark of trees growing in a dry climate like our own. You can also follow the dripline example for watering most trees, water at and past the dripline to make the most of your watering efforts.
One exception for watering at the dripline would be columnar trees, I would water these trees wherever they cast shade (the shadeline) as this is where the roots would most likely be found considering the trees height. If a mature columnar tree had all of its roots only within the dripline it would surely fall over. Mature trees need significantly more water than young trees. Remember leaves pull water, more leaves/refineries means that more water is required for the system to work at capacity.
What about watering dormant trees and evergreens during the dormant period of the year should we? Yes if soil conditions are dry then the soil should be kept moist to keep the roots healthy and make water available for when the tree needs it. Watering during dormancy also helps keep a healthy root environment by creating beneficial conditions for microbial activity that promotes healthy soil and root development.
Most importantly is that you water your trees because it’s probably the most important resource that you have at your disposal to keep a healthy tree.
Calgary has had a widespread epidemic of black knot for well over fifteen years and the problem is only getting worse. Apiosporina morbosa is the Latin name for this fungal pathogen which predominately spreads during cool moist weather conditions in the spring. Control of the disease in infected trees is best done by pruning out symptomatic branches that appear as if they have a burned marshmallow on them. Black knot does infect trees systemically which means that even if infected branches are pruned the disease will continue to proliferate within the tree until it is dead and removed.
Because of the natural riparian areas within the city of Calgary it is nearly impossible to completely control the disease as it spreads on native plant species most commonly the western chokecherry Prunus virginiana. The best way to cure tree diseases including black knot in Schubert chokecherry and mayday species is to plant disease resistant trees, in other words the answer is simple do not plant mayday or chokecheery trees because they are guaranteed to get black knot. If you have a tree with a severe infection consider removing and replacing the tree rather than delaying the inevitable. Trees that only have a handful of knots appear per year can be pruned and preserved until the infection worsens.
Keeping a tree healthy will also ensure better chances of success, water regularly when dry, improve soil and site conditions if possible, prune symptomatic and dead branches, avoid over fertilisation and high nitrogen fertilizers.
Trees around the world are faced with the assault of mother natures weather events on a daily basis, in most cases if this occurs in a secluded forest the damage is unnoticed and has little impact on human activity. When storms and strong weather events hit cities however trees are definitely likely to be damaged and have an adverse effect on our daily lives such as the September 2014 snow storm in Calgary. The September snow event wasn’t the first time snow and leafed out trees collided in a bad way in the Calgary, in the early 2000’s there was a snowfall event in May that also caused significant damage to trees throughout the city and I wouldn’t be surprised if such an event occurs again.
Wind is another force of nature which has caused significant tree and property damage throughout Calgary in the past, damage caused ranging from minor twig breaks to complete tree failure. There is a lot that we can do as tree owners to prevent significant damage to trees and reduce the consequences of tree failure leading to property damage.
Firstly properly planting appropriate species in ideal locations is one of the best ways to avoid most conflicts caused by trees whether caused by storms or not. Planting a tree near an overhead wire for example is an extremely poor choice for a planting location or planting any species of tree within 10feet of a building should also be avoided. Have trees regularly inspected and pruned for structure especially young trees, Dr. Ed Gilman from the University of Florida has done extensive scientific research proving that structurally trained trees suffer significantly less damage than unbalanced or improperly pruned trees in severe weather. When a snow event repeats itself the best thing you can do is get the snow off of your trees and shrubs as quickly and safely as possible. You could brush or shake the snow off of smaller trees and shrubs but on larger trees you are putting yourself at risk if you attempt to go near the tree.
I learned from Wade Hartwell, the founder of Golden Acre Garden Centres, that using water is the best way to rid trees of snow and frost on trees and shrubs. Using a garden hose and pressure nozzle spray the branches from the tips inward to alleviate the weight at the end of the branches first, as the water melts off of the snow covered tree you will see the limbs bounce back up before your very eyes.