Clematis Powdery Mildew ( Causes & Treatment )

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Powdery mildew is a fairly common disease affecting a wide variety of plants, and if your garden plants often get powdery mildew then it is only a matter of time until your Clematis will also be affected.

Symptoms of powdery mildew on clematis include the presence of white powdery patches on the leaves, petioles, and stems, which may cover the entire leaf surface. Later in the season, small dark specks resembling pepper, known as cleistothecia, may develop within the powdery areas. To control this fungal disease, it is most effective to apply fungicides to immature tissues before symptoms appear.

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Powdery mildew is a serious problem for any gardener that is living in a more humid environment. Some cultivars are trying to develop types of Clematis that are immune to powdery mildew, although currently, all varieties of Clematis are prone to getting powdery mildew. The good news is that Clematis Viticella are less likely to get powdery mildew than other varieties of Clematis, although they can still get the disease.

Powdery mildew can easily be treated with a good fungicide, but if you do not address the main issue of why the powdery mildew appears on your plants then it is only a matter of time until it will come back. If you want to keep your Clematis in pots over the winter then check out my recent article Clematis In Pots Over Winter ( In 6 Easy Steps ).

Clematis Powdery Mildew

Clematis powdery mildew is a common fungal disease that affects the leaves and stems of clematis plants. It appears as a white or gray powdery coating on the foliage, causing the leaves to curl, distort, and eventually turn yellow or brown. To manage powdery mildew, it is important to provide proper care and create conditions that discourage its development. Start by planting clematis in well-draining soil and providing adequate air circulation around the plant.

Avoid overhead watering, as wet foliage can promote the spread of the disease. Regularly prune and thin out the plant to improve air circulation and remove any infected leaves or stems. Applying fungicides or natural remedies, such as a mixture of baking soda and water, can also help control the disease.

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What Causes Powdery Mildew On Clematis

The main cause of powdery mildew is high humidity, oftentimes the plants that are affected by it grow in an area with poor air circulation and in partial shade. Powdery mildew is a fungal disease caused by ascomycete fungi. Powdery mildew thrives in wet and dark environments, and once you start seeing it on the leaves of your plants, it is already reproducing and spreading.

The good news is that once the humidity gets lower the powdery mildew will simply die off. Plants that are overcrowded and growing in a corner garden are more prone to getting powdery mildew as the air circulation tends to be somewhat lower in these areas and as there are a lot of plants in one place the humidity will be fairly high. If you do not know what kind of Clematis you have, then check out my recent article What Kind Of Clematis Do I Have ( 6 Ways To Identify Clematis ).

How To Identify Powdery Mildew On Clematis

Identifying powdery mildew on Clematis is extremely simple, all you need to do is to look at the leaves. If the leaves of the Clematis are white or contain white patches then this is powdery mildew. Oftentimes it will look like the leaves of the Clematis are sprinkled with flour, and this is a telltale sign of powdery mildew. The spores of the powdery mildew can travel a fairly long way, and even if you do not have any plants suffering from it, there still might be some spores on the plants waiting for the ideal condition to take over some plants.

Is Powdery Mildew Fatal To Clematis?

The good news is that powdery mildew is not fatal to Clematis. In the worst-case scenario, the Clematis will lose all of its leaves, but it should have plenty of energy to grow new ones. The Clematis leaves that are covered by powdery mildew will start to curl, after which they change color to brown and eventually fall off. Clematis that are suffering from powdery mildew will rarely flower, oftentimes even the flower buds will simply fall off.

Large flowered Clematis like the Blue Angel, Ernest Markham, Fond Memories, and Gipsy Queen are more prone to getting powdery mildews. If the powdery mildew appears once the Clematis is in full bloom, then most of the flowers will turn brown and fall off. This happens because the leaves of the Clematis that are covered by the powdery mildew can not function properly.

How To Treat Powdery Mildew On Clematis

As powdery mildew is caused by a fungus, it can be easily treated with a fungicide. The fungicide has to be sprayed directly on the plant, preferably in the evening. If you spray the fungicide on the leaves of the Clematis in the middle of the day, then the leaves might get sunburned. When purchasing a fungicide, make sure that it is safe to be sprayed directly on plants, and follow the instructions precisely.

If you do not want to use fungicides, then you can use a garlic spray. Garlic has excellent anti fungal properties, and it is also safe to be sprayed directly on plants. In addition to this, the garlic spray will keep pests like aphids, slugs, and snails away from your plants, for more info check out my recent article Garlic Spray For Slugs ( Natural Pesticide ).

Key Takeaways

  • Powdery mildew on Clematis is a fungal disease that is caused by high humidity, and it can easily be treated with fungicides. If your Clematis had powdery mildew in the past, then simply spray it with a fungicide once every two weeks. If you do not want to use fungicides then a simple garlic spray will do the job, as garlic has excellent anti-fungal properties and is safe to be sprayed directly on the Clematis.
  • Powdery mildew is rarely fatal to Clematis, although the plant will probably lose most of its leaves and will not be able to flower.
  • If your Clematis gets powdery mildew every year, then simply replant it into an area where there is good air circulation.