Blackberry Anthracnose: A Common Fungal Disease
Blackberry anthracnose is a common fungal disease that affects blackberries and other brambles, such as dewberries, loganberries, and raspberries. It can cause poor fruit quality and production, and in severe infections, it can weaken or even kill canes.
Symptoms of Blackberry Anthracnose
The first signs of blackberry anthracnose are small purple spots on the shoots of new canes in the spring. These spots will increase in size, become oval-shaped, and eventually turn a gray or buff color. You may also find small spots with light gray centers and purple margins on the leaves. In heavy infections, the spots on the canes and stems can merge together, forming large cankers with cracks.
Causes of Blackberry Anthracnose
Blackberry anthracnose is caused by the fungus Elsinoe veneta. The fungus overwinters in diseased canes and releases spores during rainy periods in the spring and summer. The greatest risk of infection is between bud break and pre-harvest, as the fungus targets mainly new growth.
Treatment for Blackberry Anthracnose
The best way to control blackberry anthracnose is to use a combination of cultural practices and fungicides.
Cultural Practices:
- Plant resistant varieties of blackberries.
- Space plants properly and prune to improve air circulation.
- Remove any wild brambles in the area, which can harbor the disease.
- Remove weeds and prune back blackberry bushes to promote good air circulation and light penetration.
- After harvesting blackberries, remove and destroy any canes that have been infected.
Fungicides:
- Apply a delayed dormant spray before growth starts and while temperatures are still cold.
- Use a lime, sulfur, copper hydroxide, or foliar fungicide.
- The recommended type of fungicide may vary depending on your area, so check with your county extension office for the latest information.
Prevention of Blackberry Anthracnose
The best way to prevent blackberry anthracnose is to start with healthy plants and to follow good cultural practices.
- Buy disease-free plants from a reputable nursery.
- Plant blackberries in well-drained soil.
- Water blackberries deeply and regularly, especially during hot, dry weather.
- Fertilize blackberries according to the soil test recommendations.
- Mulch around blackberry plants to help retain moisture and suppress weeds.
- Avoid overhead watering, which can spread the fungus.
- Inspect blackberry plants regularly for signs of disease.
Additional Information
Life Cycle of the Anthracnose Fungus:
The anthracnose fungus overwinters in diseased canes. In the spring, the fungus produces spores that are spread by wind and rain. The spores infect new canes through wounds or natural openings. The fungus then grows inside the cane, causing the characteristic symptoms of anthracnose.
How to Identify Blackberry Anthracnose:
Blackberry anthracnose can be identified by the following symptoms:
- Small purple spots on new canes in the spring
- Oval-shaped, gray or buff spots on canes and stems
- Small spots with light gray centers and purple margins on leaves
- Cankers with cracks on canes and stems
Home Remedies for Blackberry Anthracnose:
There are a few home remedies that may help to control blackberry anthracnose, but they are not as effective as fungicides.
- Baking soda: Mix 1 tablespoon of baking soda in 1 gallon of water and spray on blackberry plants.
- Apple cider vinegar: Mix 1 cup of apple cider vinegar in 1 gallon of water and spray on blackberry plants.
- Garlic: Crush garlic cloves and mix them with water. Spray the mixture on blackberry plants.
Organic Treatment for Blackberry Anthracnose:
There are a few organic fungicides that can be used to control blackberry anthracnose.
- Serenade: Serenade is a biofungicide that contains the bacterium Bacillus subtilis.
- Actinovate: Actinovate is a biofungicide that contains the bacterium Streptomyces lydicus.
- Mycostop: Mycostop is a biofungicide that contains the fungus Trichoderma harzianum.
When to Use a Delayed Dormant Spray:
A delayed dormant spray is applied before growth starts and while temperatures are still cold. This is the best time to apply a fungicide to control blackberry anthracnose because the fungus is most vulnerable at this stage.
