Introduction of Anthracnose
Anthracnose (Latin name: Colletotrichum spp.) a fungal disease that attacks trees, vegetables and the grasses due to experiencing stress from the environment. The security of the infection can range from cosmetic to deadly, depending on a wide variety of unpredictable scenarios that are extremely difficult to diagnose.
What is Anthracnose?
Anthracnose is a group of fungal diseases that attack the roots, leaves or fruits. They spread quickly in warm, moist environments. The diseases generally follow a similar pattern of symptoms. Basal rot is when the disease affects the crown tissue and root tissue, while the leaves are affected by leaf rust or leaf scorch. Once the disease has reached the basal rot stage, the goal of fungicide treatment changes from control to prevention of further infestation.
Basal rot is when the disease affects the crown tissue and root tissue, while the leaves are affected by leaf rust or leaf scorch. Once the disease has reached the basal rot stage, the goal of fungicide treatment changes from control to prevention of further infestation.
Causes of Anthracnose
Colletotrichum sublineola is a fungus from the family Glomerellaceae. Colletotrichum sublineola has a parasitic lifestyle and feeds itself with fungal threads on grain plants where it resides. This is how the Colletotrichum sublineola causes its host plant to become ill.
When does anthracnose occur?
Periods of high humidity: for an infection to occur, a thin layer of moisture (film) must be present around the roots or leaves. Therefore, periods of high humidity or a lot of water in the topsoil are favorable for the development of fungi.
Cool & wet periods: basal Rot is often a symptom of Anthracnose during cool, wet periods.
Periods of higher temperatures: leaf rust or leaf burn are more common during higher temperatures and can be confused with the result of drought. Extreme temperatures can be beneficial for development. However, this disease is most noticeable during a hot summer in a cool temperate region.
Anthracnose is most common in Ash, Birch, Black Walnut, Butternut, Buckeye, Elm, Maple and mostly in Oak trees. Especially during the rainy season we have been experiencing the last few months of 2024 here in MN, it is something that we’ll be keeping a close eye on.
Symptoms of Anthracnose
First, it is important to know how anthracnose can be recognized. The symptoms of this disease vary from plant to plant; during warm and humid weather, when the topsoil is wet, the leaves of infected plants first turn yellow and eventually light brown and then brown before dying. Young leaves often turn red.
Affected plants are easy to pull out of the soil. This disease kills plants in irregular patterns. The general color of the affected areas is reddish brown turning yellow and then light brown to brown. There is often a black spot at the base of the plant. This is caused by acervuli, which are involved in the reproduction of pathogens. If your plants show some of these symptoms, it’s time to act.
Prevention of Anthracnose - Best practices
- Reduce stresses on trees by adequate watering throughout the growing season. This means more than what you would typically water your lawn. Sprinkler systems are for grass, not for trees.
- Use fungicides as part of your IPM program. Keep in mind that you risk causing resistance to a whole group of chemicals through regular use of fungicides.
- Wet conditions promote disease, so redirect sprinklers that splash water on trees leaves.
- Do not fertilize trees unless a soil test shows the need for it.
- Rake up and destroy fallen leaves before the first snowfall to eliminate locations where the fungus can survive to re-infect the tree the following spring.
- Prune to remove infected twigs, increase light penetration and improve air circulation throughout the tree canopy.
Prevention of Anthracnose - Use of resistant grass varieties
- When overseeding lawns, choose fewer sensitive varieties, and use a 5 seed blend.
- Irrigate early in the morning to prevent the leaves from staying wet for a long time overnight. Use a good penetrating wetting agent to ensure that the water can penetrate the bottom and the surface remains dry.
- Use fungicides as part of your IPM program. Keep in mind that you risk causing resistance to a whole group of chemicals through regular use of fungicides.
If a plant is in the right soil and receives the right amount of water, light and nutrition, it will be strong in its fight against anthracnose.
Treatment of Anthracnose
- Advantages and disadvantages of different methods
- Fungicides are unnecessary unless a tree has lost most or all of it’s leaves several years in a row due to Anthracnose.
- They are protective and need to be applied before symptoms appear on the leaves.
- The proper timing of a fungicide application can vary widely from growing season to season.
- For large trees, it’s best to hire a professional that has high pressure spraying equipment to get to those hard-to-reach areas of the tree.
Continue monitoring your plants
Be sure to continue monitoring your plants after taking anthracnose control measures. Keep your plants clean and dry and continue to check regularly for signs of anthracnose. If necessary, repeat steps 1 to 4.
Conclusion
With these steps and tips you will be better prepared and able to control anthracnose on your plants. Make sure you recognize the disease quickly, prune off affected branches and leaves, pick up debris and provide your plants with plenty of light. If these measures are not sufficient, you can always consider using fungicides. Remember to check your trees regularly and, if necessary, take measures to prevent further spread of the disease.
Of course you can also contact one of our experienced arborists to give you advice.
Frequently Asked Questions (FAQ) about anthracnose
- Can anthracnose be prevented?
Yes, anthracnose can be prevented by choosing healthy plants and ensuring good light and air flow. In addition, it is important to regularly clean up fallen leaves and fruits.
- What can I do if my plant is overloaded with anthracnose?
If your tree is heavily infested, it may be best to remove it completely to prevent further spread of the disease.
- Are fungicides safe?
Fungicides can be used safely when labels are read carefully, and instructions are followed. However, it remains good to use biological fungicides as much as possible.