How To Treat Powdery Mildew

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Diseases can completely destroy your plants, so it’s essential you make yourself aware of the different types of plant diseases that may impact the species in your garden. Powdery mildew is one such problem, that’s relatively common amongst hedge plants. Although the fungus is not fatal, it can affect your plant’s growth so is best to be eliminated.

We’ll discuss what powdery mildew is, how to treat powdery mildew and how to prevent it below.

What is Powdery Mildew?

Powdery Mildew is a white fungus that attacks many species of plants. It is extremely common in most plant species and easily recognisable by the growth of white fungus on the leaf of the plant. The growth also extends to a plant’s stems and flowers.

Plenty of species are affected by Powdery Mildew, the most common being roses, grapes, cucumbers, grasses, azaleas, rhododendrons, daisies and more.

The fungus prefers warm and dry environments, appearing as white or grey spots on your plant or hedge. Whilst this does not kill the plant, it is not aesthetically pleasing which can be an issue for many gardeners. When left to grow however it can leech the nutrients from the plant which can cause stunted growth. Therefore, it is best to get rid of powdery mildew where possible.

Is Powdery Mildew Harmful to Humans

Whilst this fungus has no direct negative effects on humans (including human contact), it can cause problems for many people who are allergic to this particular mould or suffer breathing problems.

If you touch or consume the plant and you’re allergic you could have a serious reaction. Again, when inhaled consistently it can cause problems for those who are vulnerable, such as asthmatics for instance.

What are the Causes of Powdery Mildew?

If you know the causes of Powdery Mildew, then it is possible to prevent it. There are three main causes:

High humidity – As mentioned previously, hot and dry environments is where this fungus thrives. This fungus only requires a small amount of moisture in order to survive, which is why it occurs in many different plant species.
Poor airflow – Limited airflow allows for perfect conditions for Powdery Mildew. Bad ventilation in a room or greenhouse encourages its growth where the mould spores can be released and stay in close contact with surrounding plants, aiding its spread.
Leaf-to-leaf contact – If the leaves of different plants are touching the mould is able to spread at a much faster rate. Moisture can form between the leaves which allow for further growth. Providing more space and distance between each plant will decrease the chances of spread.

You can prevent the fungus by eliminating the causes, by increasing airflow, allowing for the adequate distance between the plants (no leaves touching) and decreasing the humidity. This can help reduce the chances of the fungus occurring and keep your plants healthy.

How to Treat Powdery Mildew

Even if you put prevention measures in place it can sometimes be too late or not enough and Powdery Mildew will occur regardless. When this happens, the fungus is very treatable and able to be eliminated. Here are some things you can do to get rid of Powdery Mildew:

1. Destroying fallen hedge leaves

In the autumn, deciduous plants and hedges lose their leaves. Picking these up and disposing of them helps eliminate the humid conditions and also reduces the spread of the fungus.

2. Pruning infected shoots

If you notice that some leaves have started to become infected, you can prune these straight away and dispose of them to prevent the fungus from spreading. This will keep your hedge plants healthy.

3. Manage your planting environment

If you’re starting to see the fungus appear, it may be worth moving the plant into an environment that’s less humid or further away from other plants. If you suspect that one of the causes mentioned above as the culprit and can easily change the plant’s environment, we’d strongly recommend this.

Providing good drainage, preventing over fertilising and watering the plants overhead during dry seasons are all ways you can prevent Powdery Mildew from forming.

4. Chemical Control

You can easily remove this fungus through fungicides. This is a quick way to remove Powdery Mildew without harming the plant itself. However, ensure you consider the surrounding environment including plants and animals before you do this, as the chemicals may be harmful to other plants and animals.

5. Environmentally Friendly Solutions

Whilst a fungicide does eliminate the problem, there are some other more environmentally friendly solutions to treat Powdery Mildew with minimal cost.

Baking Soda – Whilst it can be used more as a preventative treatment, baking soda can also help get rid of Powdery Mildew. Mixed with water and liquid soap, it can be sprayed onto the plants with ease.
Organic Fungicide treatments – there are many of these on the market that do not contain chemicals harmful to other plants and animals. This treatment directly targets the fungus and you know exactly what you’re using, which can help you eliminate the fungus faster.
Lots of water – Since the mould is created in humid environments, lots of watering (particularly overhead) can help prevent and eliminate Powdery Mildew. That being said, overwatering can cause other problems for your plants, so ensure you’re maintaining a balance and watering the right amount for that particular species.
Milk – as strange as it sounds, milk has been known to get rid of Powdery Mildew. Whilst the exact science of why this method works is unclear, it is a common solution that many green-fingered gardeners use. Acting as a fungicide and antiseptic, diluting Milk with water (40% milk and 60% water) and pouring on the plant should do the trick.

About us

Hopes Grove Nurseries are the UK’s leading hedging plant specialists. We’re knowledgeable when it comes to everything hedging related. Whether you’re looking for Box hedging, Privet hedging or anything in between – we can help.

Treating Powdery Mildew is essential for the health of your infected plant and the surrounding plants. Therefore, we recommend you begin treatment as soon as you notice the fungus.