A common misconception of the general public is that all trees and plants need to grow healthy are water, sunlight, and fertilizer. Caring for plants goes beyond making sure they have sufficient access to their three basic needs. Like animals, plants and trees can also be subjected to poor health brought about by bacteria, fungi, and pests. One of the challenges for new gardeners is learning how to spot symptoms of disease in their plants and how to prevent these from spreading in their gardens.
Whether you are an amateur gardener or an expert green thumb, it pays to be familiar with the diseases that could compromise the state of the plants and trees that you grow.
Here are some of the common illnesses that plague gardens:
Anthracnose
Anthracnose is a common disease that affects many kinds of trees and plants. Anthracnose can attack trees in two ways:
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- Spot anthracnose impacts the leaves and blossoms of plants. Its early symptoms include small, light brown spots emerging on the flowers and leaves of the plants and trees during summer and spring. The spots often develop along the leaf’s vein system.
- Anthracnose canker is a more harmful version that attacks the vascular system of the tree. When anthracnose infects a tree and goes untreated over several seasons, the disease spreads from the leaves and blossoms to twigs and branches. Once it reaches the vascular system, symptoms will also appear in the bark in the form of dark-coloured lesions or indents.
Armillaria Root Rot
Also known as mushroom root rot, shoestring fungus rot, and oak root rot, Armillaria root rot is caused by a fungus present in the soil and attacks the roots of plants and trees. The symptoms of Armillaria root rot include:
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- Dulling of the colour of leaves
- Excessive signs of wilting
- Major branches slowly begin to die
- Lack of fruit production on lower limbs, making fruits only on upper branches
- Root decay
- Brown spots in the lower trunk
When the root rot spreads, small mushrooms and small fan-like plaques can appear around the tree trunk’s base. Plants and trees growing in areas with heavy, dense soil and poor drainage are more likely to be infected. If Armillaria root rot is left untreated, the death of infected plants and trees can be quick.
Beech Bark Disease
Beech bark disease is a devastating two-part disease that affects beech trees. Its cause is a combination of burrowing by the beech scale insect and fungal infection. It starts with the beech scale weakening the tree by burrowing. The fungus then enters these wounds, spreads, and kills the tree. Symptoms of beech bark disease include:
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- A white, fuzzy substance appears on the branches
- Wilting of leaves
- Thinning crown
The fungus has small red or orange fruiting bodies that are especially apparent during summer and fall. Beech bark disease usually affects older trees first. The condition is incurable, so infected wood should not be moved to prevent its spread and infestation.
Blister Rust
With many North American White Pine trees in Ontario, gardeners and arborists should be aware of this disease. Blister rust is caused by fungi, so damaged trees are vulnerable to attack. Trees that become infected have high mortality rates, especially if the infected tree is young.
Botrytis Blight
Botrytis blight is also known as blossom blight, bud light, flower blight, or gray mould. It is a common disease that can infect a variety of plants, including fruit and ornamental trees, shrubs, and flowers.
Botrytis blight is caused by a fungus that grows and multiplies on plant debris like fallen leaves and over-ripe fruits. While the infection is initially limited to dead or dying plant matters, the fungus will eventually replicate and attack healthy parts of a plant. Once infected, you might notice the following symptoms:
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- Decaying fruits and flowers (still connected to the plant or tree)
- Cankers
Cankers
Cankers are dark, sunken areas that appear on an infected tree’s branches and trunk. Often, this is caused by a bacterial or fungal infection in the vascular system of a tree, eventually spreading to its bark.
When a canker appears, the bark around it dies and breaks off. This exposes the tree’s vascular system, making it vulnerable to environmental factors. Canker will also often produces a sticky substance that attracts insects like wasps and ants.
If a canker spreads around the trunk or a major branch, it can destroy the tree’s vascular system. It may cause the death of a limb or even the whole tree. If a tree survives a canker attack without treatment, the tree can be vulnerable to other diseases and insect attacks.
Maple Wilt
Maple wilt is also called verticillium wilt, and it is a common disease that affects many trees. It is caused by a fungus that can be found in the soil called Verticillium. This fungus can spread among plants in many ways, including through water, dirt, and improperly sanitized equipment.
While maple wilt usually infects trees through the soil, the fungus can also enter the tree’s system through a wound. Once in the tree, the fungus spreads throughout the tree’s vascular system and prevents the tree from being able to move nutrients and water throughout the tree. Symptoms of maple wilt include:
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- Random yellowing, then browning, of leaves
- There are barely new leaves growing
- New leaves are undersized or yellow
Parasitic Fungi
Parasitic fungi are incredibly damaging to trees and plants. This type of fungi lives off of their host and results in the death of the host. Parasitic fungi usually attack trees that are already unhealthy, worsening its condition and eventually killing the host tree.
Preventing the Spread of Disease on Trees
The best way to deal with plant and tree disease is to focus on prevention. By preventing an infestation, you can save money that would have been spent on trying to cure your garden of serious conditions. There are some key steps involved in disease prevention:
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- Regularly monitor your plants and trees – Regularly monitoring the plants and trees growing in your garden will help you detect diseases and pests early — when the condition is still in its early stages, or the pest population is small and controllable.
Check your trees’ plants, fruits, branches, bark, and trunk for holes, damages, and other irregularities. Take into consideration the number, colour, and quality of the leaves and fruits produced.
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- Follow good plant care practices – Knowing what your trees and plants need is an essential first step for good plant care. Thoroughly research the different species of plants that you have and figure out how much water, light, and fertilizer they need, the kind of pests and diseases they are susceptible to, and other needs they may have.
- Treat immediately – The moment you notice that your trees and plants have become infected, treat them before the disease spreads. There are different treatments for different diseases and infestations, so consult with an arborist first.
If you need more details on the trees, insects, and diseases that can plague trees, Natural Resources Canada has a database with images, descriptions, and other helpful information available to the public. This is an excellent place to start when researching on tips for caring for your trees.
If the disease and pests have gotten out of control, call a professional to deal with the issue. In some cases, an infected tree or plant may have to be removed to avoid spreading the disease, so a professional tree removal service would be needed.
If you are in the market for trees for sale in Toronto, call Caledon Treeland. We sell a variety of species of trees. We can also help you move trees up to 25 feet tall in Central and Southern Ontario. Make an appointment to visit our tree farm by calling (905) 880-1828.