Age-Old Wisdom meets Modern Tools
How to Identify and Control Anthracnose
Fungal anthracnose attacks these young grapevine leaves.Photo by CSIRO ScienceImage via Wikimedia Commons
What is anthracnose? This fungal disease affects many plants, including vegetables, fruits, and trees. It causes dark, sunken lesions on leaves, stems, flowers, and fruits. It also attacks developing shoots and expanding leaves. It can spread very quickly during rainy seasons.
Anthracnose is a general term for a variety of diseases that affect plants in similar ways. Anthracnose is especially known for the damage that it can cause to trees. Anthracnose is caused by a fungus, and among vegetables, it attacks cucurbits.
Anthracnose can survive on infected plant debris and is very easily spread. Like rust, it thrives under moist and warm conditions and is often spread by watering.
How to Identify Anthracnose
- On leaves, anthracnose generally appears first as small, irregular yellow or brown spots. These spots darken as they age and may also expand, covering the leaves.
- On vegetables, it can affect any part of the plant.
- On fruits, it produces small, dark, sunken spots, which may spread. In moist weather, pinkish spore masses form in the center of these spots. Eventually, the fruits will rot.
- On trees, it can kill the tips of young twigs. It also attacks the young leaves, which develop brown spots and patches. It can also cause defoliation of the tree.
Photo Credit: Rutgers University. Anthracnose can affect many plants with its brown spots, including this cucumber leaf.
Control and Prevention
How to Control Anthracnose
- Remove and destroy any infected plants in your garden. For trees, prune out the dead wood and destroy the infected leaves.
- You can try spraying your plants with a copper-based fungicide, though be careful because copper can build up to toxic levels in the soil for earthworms and microbes. For trees, try a dormant spray of bordeaux mix.
- Plant resistant plants, or buy healthy transplants.
- Plant your plants in well-drained soil. You can also enrich the soil with compost in order to help plants resist diseases.
- Water your plants with a drip sprinkler, as opposed to an overhead sprinkler. Don’t touch the plants when they are wet.
- Keep ripening fruits from touching the soil.
- Remember to rotate your plants every 2 to 3 years.