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.