Why are My Periwinkles Turning Brown?

Periwinkles, also known as Vinca minor, are popular groundcover plants often used in landscaping due to their evergreen nature and ability to thrive in various conditions. However, these plants can sometimes turn brown, indicating an underlying issue. This article explores the potential causes of periwinkles turning brown and provides recommendations for addressing the problem.

Key Facts

Vinca stem canker, caused by the fungal disease Phoma exigua, is a common reason for periwinkles turning brown. This disease causes shoot tips to become dark brown, changing to nearly black as it progresses.
Over-watering may also contribute to periwinkles turning brown. However, if you haven’t changed your watering habits, it may not be the primary cause.
Other possible causes of periwinkles turning brown include stem blight, root rot, and fungus, such as Botrytis blight (Botrytis cinerea). These diseases can occur during periods of cool, wet weather.
Stem blight, caused by the fungus Phoma exigua var. exigua, can infect periwinkles and cause black lesions on the stems, followed by stems turning dark brown to black, wilting, and dying. This fungus thrives in moist soil and plant debris and may persist in the soil for long periods.
Rhizoctonia is another fungus that can cause stem and root rot in periwinkles. Infected plants may turn yellow, wilt, and die, with brown rotted areas on the roots.
To address the issue of periwinkles turning brown, it is recommended to remove all affected foliage, including fallen leaves, as the fungus can remain in them. Avoid composting the dying foliage. If a whole plant is affected, it should be removed. Applying fungicide in the spring may also be helpful.
Minimizing water contact with the remaining plants, improving air circulation, and avoiding overwatering can help suppress fungal infections.

Causes of Periwinkles Turning Brown

1. Vinca Stem Canker:

Vinca stem canker is a fungal disease caused by Phoma exigua.
It causes shoot tips to turn dark brown, eventually becoming nearly black.
The fungus thrives in moist soil and plant debris, persisting in the soil for extended periods.
Damage is most prevalent during cool, wet weather, especially in spring and autumn.

2. Over-Watering:

Excessive watering can contribute to periwinkles turning brown.
Over-watering can lead to root rot and other issues, especially if the soil does not drain well.

3. Other Fungal Diseases:

Periwinkles can be affected by various fungal diseases, including stem blight, root rot, and Botrytis blight (Botrytis cinerea).
These diseases often occur during periods of cool, wet weather.

4. Stem Blight:

Stem blight, caused by the fungus Phoma exigua var. exigua, can infect periwinkles.
It causes black lesions on the stems, followed by stems turning dark brown to black, wilting, and dying.
The fungus thrives in moist soil and plant debris, persisting in the soil for long periods.

5. Rhizoctonia:

Rhizoctonia is another fungus that can cause stem and root rot in periwinkles.
Infected plants may turn yellow, wilt, and die, with brown rotted areas on the roots.

Addressing Periwinkles Turning Brown

1. Remove Affected Foliage:

To address the issue of periwinkles turning brown, it is recommended to remove all affected foliage, including fallen leaves.
The fungus can remain in fallen leaves, so it is essential to remove them.
Avoid composting the dying foliage.

2. Remove Affected Plants:

If a whole plant is affected by a fungal disease, it should be removed to prevent the spread of the disease to other plants.

3. Apply Fungicide:

Applying fungicide in the spring may be helpful in preventing new infections.
Consult with a local nursery for the best fungicide options.

4. Minimize Water Contact:

Minimizing water contact with the remaining plants can help suppress fungal infections.
Avoid overhead watering and ensure the soil drains well.

5. Improve Air Circulation:

Improving air circulation in the area where the periwinkles are planted can help reduce the risk of fungal infections.
Prune nearby plants and overhanging branches to improve air circulation.

6. Avoid Overwatering:

Overwatering can contribute to periwinkle decline.
Water the plants only when the soil is dry to the touch.

By following these recommendations, you can address the issue of periwinkles turning brown and help keep your plants healthy and vibrant.

Sources:

FAQs

What causes periwinkles to turn brown?

Periwinkles can turn brown due to various factors, including fungal diseases like Vinca stem canker, over-watering, and other fungal diseases such as stem blight, root rot, and Botrytis blight.

How can I identify Vinca stem canker?

Vinca stem canker causes shoot tips to turn dark brown, eventually becoming nearly black. The fungus that causes this disease thrives in moist soil and plant debris.

What are the symptoms of stem blight in periwinkles?

Stem blight causes black lesions on the stems of periwinkles, followed by the stems turning dark brown to black, wilting, and dying.

How can I prevent fungal diseases in periwinkles?

To prevent fungal diseases, avoid over-watering, improve air circulation, and apply fungicide in the spring. Additionally, remove affected foliage and plants to prevent the spread of the disease.

What are the signs of over-watering in periwinkles?

Signs of over-watering in periwinkles include yellowing leaves, wilting, and root rot.

How can I improve air circulation around my periwinkles?

To improve air circulation, prune nearby plants and overhanging branches.

When should I apply fungicide to my periwinkles?

Apply fungicide in the spring to prevent new fungal infections.

What should I do if a whole periwinkle plant is affected by a fungal disease?

If a whole periwinkle plant is affected by a fungal disease, it should be removed to prevent the spread of the disease to other plants.