Treatment for Powdery Mildew on Plants: Identification, Causes, and Prevention

At least for once you must have come across Powdery Mildew in your garden. But still, if you haven’t, then you are lucky! Gardeners like us become really frustrated to see Powdery Mildew in our gardens. 

The plants become inefficient to thrive due to this disease. Thus we need to inspect the reason for its spread and take an instant action to treat and prevent such infection. 

If the plant is diagnosed with Powdery Mildew at its early stage, it becomes easier for us to treat them. But we need to start the treatment proactively for our plants. 

It is good to plant resilient varieties of crops, adopt good watering techniques, maintain good airflow, and use effective fungicides to prevent the spread of such diseases. 

In this article, I have briefly discussed this issue with its preventive measures.

An Overview Of Powdery Mildew

Common Name	Powdery mildew
Family	Erysiphaceae
Origin	Mostly occurs in climates with high humidity and shaded areas.
What Plants It Affect	Various flowering plants, shrubs, edible plants, weeds & grasses.
Remedies & Treatment	Use of Proper irrigation, pruning at initial stage of infection, sulfur fungicide, neem oil and potassium bicarbonate

What is Powdery Mildew?

Powdery Mildew is a fungal disease that impacts multiple plants. A powdery mildew genus is there, which is proven to be hazardous for many plants. 

Plants like tomatoes, cucumber, squash, watermelon, roses, peppers, peas, beans, etc., are mainly affected.

This fungal disease is highly contagious and can easily spread from one plant to another. The fungi are spread through airborne spores or infected soil. It blooms mainly in warm climates. 

Overcrowded planting, bad air inflow in the plants, and high humidity result in the emergence of Powdery Mildew. 

Due to Powdery Mildew, your plant would not be able to grow and develop properly, which results in low harvest, and the production quality is compromised.

How to Identify Powdery Mildew on Plants?

Identifying powdery mildew on plants is easy. Plants Infected due to Powdery Mildew show the following signs:

• The plants will look coated or dusted with a flour-like substance.
• The plant’s leaves, stem, and flowers develop a whitish or grayish powdery coating. 
• Commonly the upper surface of the leaves is affected by powdery Mildew. Sometimes leaves underneath are also affected. 
• It mostly targets new leaves and results in yellowing, browning, and dry leaves.
• It also results in premature leaves dropping, curling, breakage, and uneven figure of leaves.
• The white spots always try to cover most of the leaves and other parts of the plants.
• The shape of leaves, buds, and growing tips becomes uneven. It occurs mainly in growing seasons. 
• It can also leave the plant weak and sticky. 

Symptoms of Powdery Mildew

Stagewise symptoms of Powdery Mildew have been explained briefly below, and you will be able to understand how powdery Mildew thrives at early and later stages.

Early Detection

Powdery Mildew initially infects a very little part of the plants, and these fungi spores commonly flourish in moderate climates. 

If you can’t spot these fungi spores on your plants, then they can rapidly spread all over it, and if not controlled, mycelia is formed, which looks like a network of fine white thread. Mycelia encourages the fungus to spread all over the plant.

Later Progression

With the rapid increase of powdery mildew fungi, the whole plant system is disturbed and becomes inefficient in absorbing necessary nutrients and water. As a result, the growth and development of the plant is also compromised. 

The plant’s immunity is also reduced, and plants become less resilient to diseases. Leaves’ shape seems uneven and is turned yellow or brown and eventually drop from the plants. These fungi also develop fruiting bodies which totally hampers the yield of the plants. 

Species of Powdery Mildew

I have listed the names of a few plants which are highly susceptible to powdery Mildew. But the infection prevention method remains the same for all the plants.

Sunflower: The lower foliage of the healthy plants is infected, which leaves white spots on the plants, and later black spots also appear, resulting in the total destruction of the plant. 

Wheat: Lower leaves of the plant are attacked first. Then small blisters are formed on the whole surface of the leaves, resulting in the leaves’ death. 

Barley Plants: Powdery Mildew infects the plant the same way it infects wheat. But it develops blisters that are more stippled. 

Legumes: The developed white spots seem like talcum powder on the plants at the initial stage. The leaves appeared to be wrinkled and brown. 

Grape: It infects the leaves, fruits, canes, and flowers. Initially, the lower surface of the leaves develops green-white patches.

Onions: Whitish and gray patches are formed on the leaves and mycelia is developed. It reproduces and increases and destroys the affected leaves of onions. 

Apples and Pears: Leaves of apple plants get impacted and eventually turn red. Fruits of pear are mainly affected due to powdery mildew and they turn black and result in its rotting. 

Gourds and Melon: Zucchini powdery mildew develop white spots in the Centre of the leaves. Cucumber powdery mildew also impacts in the same manner but it also infects the fruits. Squash powdery mildew also impacts in the same way but it causes more infection to fruits. 

Lilacs: The top portion of the leaves of the plant form cloudy patches and it is seen as the primary symptom in lilacs. 

Strawberries: The leaves begin to curl and powdery mildew spread underneath the leaves and then spread to the fruits as well.

Tree Leaves: Underside of old leaves are impacted due to powdery mildew. It can develop cloudy white dust like spores and it can be carried from top to bottom foliages. 

Arabidopsis: Hydrangea powdery mildew is developed underneath the leaves and turns the leaves color to yellow and then brown and finally causes leaf curling.

Cannabis: Whitish flour like dust appears on the upper leaves area then leaves turn yellow, then it is dried and finally falls on the ground. It also results in Irregular bud shapes. 

Roses: White spots on the leaves and upper shoots are formed and later turn it to purple texture.

How Does Powdery Mildew Spread?

The release of airborne spores from pre-infected material of the plants is the vital cause of powdery Mildew in the plants. The spores are spread by wind and water.

It mainly flourishes in warm and humid climates at 60-80 degrees Fahrenheit (15-27 degrees Celsius). They cannot spread in cooler and rainy climates. 

When the temperature reaches 90 degrees Fahrenheit/32 degrees celsius, powdery Mildew starts to leave your plants. 

The plants that remain in the shade are more susceptible to this infection than the plants that get direct sunlight exposure. 

Common Susceptible Plants To Powdery Mildew

Almost all the plants may get infected due to powdery Mildew, but some of the plants are more prone to get infected due to powdery Mildew.

The list of susceptible plants is as follows:

• Begonias
• Sunflowers
• Chrysanthemums
• Dahlias
• Roses
• Zinnias
• Melons
• Zucchini
• Squash
• Lettuce
• Cucumbers
• Potatoes
• Parsley
• Pumpkins
• Grapes
• Peppers
• Tomatoes

Powdery Mildew Treatment

How to Prevent Powdery Mildew Infection?

You can prevent powdery Mildew if good cultural practice is adopted and proper plant care is ensured. 

Please go through the below-mentioned points. It can definitely help you to control the Powdery Mildew.

1. Always prefer an area where your plant can receive at least 6-8 hours of direct exposure to sunlight. 
2. Choose to plant Powdery Mildew resistant varieties of tomatoes.
3. Maintain a good facility of air circulation in the plants. You can also adopt the pruning practice but always ensure to disinfect your gardening tools before and after pruning your plants. It reduces the chance of the spread of diseases in plants. 
4. Pluck the infected leaves and dispose of them immediately. Remove all the residuals left on the ground.
5. Use Garden Compost or mulch your soil with leaves, straw, and bark chips after cleaning the area. Mulching helps reduce the water splash on the leaves, and powdery Mildew is reduced. 
6. Avoid overhead irrigation and choose drip irrigation or soaker hoses to water your plant. Never water the leaves of the plants, ensure watering in its base and soil. 
7. Use fertilizers with moderate content of Nitrogen. Excessive use of Nitrogen can set more leaves and even makes your plant bushy. New, soft leaves are more prone to get infected with powdery Mildew. I recommend using slow-release and organic fertilizers.

How To Get Rid of Powdery Mildew? (Treating Powdery Mildew)

Milk Spray

Take 40% milk and 60% water to make a solution. You can spray this solution on your plant once every 10-14 days and get rid of powdery Mildew. 

Baking Soda

Baking soda works well in the treatment of these fungal diseases. You must take one tablespoon of baking soda, a gallon of water, and half a teaspoon of liquid soap. Mix everything and pour the solution into a spray bottle. Now you can spray this solution on the affected areas of the plant.

You can use this solution as a preventive measure or on the already infected part of the plants to reduce infection.

Wash Plant Foliage

Spores releasing cycle of the fungi is broken if the leaves of the plants are washed at times. 

Neem Oil has antifungal properties which is helpful to cure powdery mildew.

Apply them on your plants once every seven days, and fungal infections in the plants can be prevented. 

Sulfur or Copper-Based Fungicide

Sulfur fungicides possess broad spectrum activity which can control widespread fungal diseases. Copper-based fungicides release copper ions which reduce fungal growth on your plants.

It is best to apply these fungicides on your plants at the early stage of the infection. 

You can spray these fungicides on your plant every 8-10 days until harvesting for better results. 

Potassium Bicarbonate

Applying Potassium Bicarbonate to your plants raises the pH level of the leaves surface, making it more alkaline and reducing fungal growth and other diseases. 

Mix ½ tablespoon of Potassium Bicarbonate with one gallon of water and apply on the bare parts of the plants. Using it in the initial stage of infection of Powdery Mildew is very beneficial. 

Broad-Spectrum Fungicide

You can efficiently cure powdery mildew fungus in your plants with Serenade Garden. It contains Bacillus Subtilis, which can be used for organic gardening. It is secure to apply on your plants, and you can even pluck crops on the same day. 

Sulfur Burner for Indoor Plants

You can use Sulfur Burner, which transforms sulfur prills into dust and improves the foliage’s pH level. It discourages fungal spores and mold from forming on the plants, and it is also researched that it can prevent spider mites.

How To Control Powdery Mildew?

Once your plant is already infected with Powdery Mildew, it becomes very difficult to treat them. So the mantra, “Prevention is better than cure,” fits well here. Ensure all possible preventive measures to control their spread in your plants. 

• Remove the infected stem, leaves, and fruits from the plants and dispose of them. This helps the healthy part of the plants to remain safe.  
• Ensure not to use these infected things as compost, or else it increases the chances of spreading the disease by the wind in the future. 
• Remove all the debris from your garden. 
• Ensure to clean the used gardening tool with alcohol after pruning the infected parts of your plant to prevent the further spread of the disease. 
• While pruning the infected areas, ensure healthy leaves are not touched.

Control Treatments To Avoid

Many chemical treatments are promised to be effective in controlling Powdery Mildew. 

They might control this issue but at the same time, it can harm your plant in either way. 

So it is better not to practice such treatments on your plants. 

1. Sprays containing liquid soaps are hazardous to your plant’s health. Mostly it includes surfactants responsible for reducing Powdery Mildew, but it also destroys the cells of the plants. It also acts as a repellent for beneficial insects, which is a great loss for your plants.
2. Washing the leaves of the plants is also suggested to prevent Powdery Mildew. But the fungus spores are dropped into the soil enough to infect other plants in your garden.

Thus you can choose to apply Neem Oil and milk spray on your plants to prevent such diseases. 

Also, planting resilient varieties is one of the best options. 

Summary

Powdery Mildew is one of the common plant diseases that can infect all types of plants like fruits, veggies, herbs, etc. It forms a white powdery substance on the plants initially and, if left vigorous, can badly impact your plant and reduce their capacity to thrive, develop and produce crops. 

If they are diagnosed initially, it can be easily prevented. So always be proactive and keep inspecting your plant at regular intervals. Use effective and safe fungicides to cure the infection. 

Remove the infected plant debris and dispose of them ASAP. Ensure to maintain good hygiene for the plants. 

If you use all the preventive measures shared in this article, you can definitely get rid of powdery Mildew and free your garden from it.

Frequently Asked Questions

Can plants recover from powdery Mildew?

If the plant is diagnosed at the early stage and is not severely infected due to Powdery Mildew, it can obviously recover. 

You can remove and dispose of the infected leaves, take care of proper air circulation, apply effective fungicides, and take preventive measures (Discussed Above), and your plant will recover from Powdery Mildew. 

What is a natural remedy for powdery Mildew?

You can treat powdery Mildew naturally with Milk Spray, Baking Soda, and Neem Oil. It has been briefly discussed in this article.

Which fungicide is best for powdery Mildew?

I strongly recommend Potassium Bicarbonate and Sulfur or Copper-based fungicides to treat Powdery Mildew. 

Does vinegar help powdery Mildew?

Vinegar can help you to prevent Powdery Mildew. You can prepare a solution by mixing three tablespoons of vinegar with one gallon of water. Now put it in a spray bottle. You can spray this solution on your infected plants once every 10 -14 days. 

Should I destroy plants with powdery Mildew?

It is not always necessary to destroy the infected plants. You can prune the infected areas of the plant and dispose of the pruned parts. Never use them as compost, or spores can come back by winds and spread easily. 

After this step, take all the preventive measures to keep your plant’s infection free and keep monitoring your plant at regular intervals. 

Can I reuse soil that had powdery Mildew?

It is better not to reuse the soil which had powdery Mildew. It can survive in the soil and can re-occur as its spores can stay in the ground for a longer period of time. Still, if you want to reuse the soil, you can plant resilient varieties of crops.

Is powdery mildew caused by overwatering?

Yes, excessive humidity and watering encourage the rapid growth of powdery mildew spores.

Happy Gardening! Share With Your Friends and Family!

References

1. wikipedia.org – Powdery mildew
2. Powdery Mildews, Colorado State University by S. Newman and L.P. Pottorff ^* (5/13)
3. Chuck Burgess, Former HGIC Horticulture Extension Agent, Clemson University