Do you notice a kind of white fungus affecting the plants in your garden? Then it could be the fungal disease known as powdery mildew. This is a common disease in a lot of gardens as it infects various plant species while lowering the amount and overall quality of the fruits and flowers they bloom and produce.
Powdery Mildew Defined
Powdery mildew refers to a fungal disease affecting the stems, foliage, and sometimes the fruit and flowers of a plant. It comes in the form of a superficial fungal growth covering the plant surface.
This is one of those fungal diseases that affect several of the most popular ornamental and edible plants in the garden. These include apples, peas, cucumbers, marrows, grapes, gooseberries, and blackcurrants.
It also affects grasses considering the fact that powdery mildew is a major pathogen of many cereal crops. Powdery mildews also tend to infect several ornamentals that belong to the daisy family, as well as roses, English oak, honeysuckle, azaleas, and rhododendrons.
This fungal infection also often has a narrow host, which consists of several related plants. For instance, the powdery mildew that infects peas is not the same as the ones that infect apples.
How Does It Spread?
The spores of powdery mildew often spread into your garden and plants through the wind. However, if this fungus already infected your plant in the past, then it is highly likely for new outbreaks to come out of the dormant spores within weeds and old vegetative materials close to you.
Powdery mildew also tends to survive well in areas that have warm, dry climates. It also needs a high relative humidity for the fungus to spread. You can’t also expect this fungus to spread that well in rainy and cooler locations.
Temperatures more than 32 degrees Celsius may slow down its spread. In addition, it affects plants species grown in shady areas compared to those in direct sunlight.
Signs and Symptoms of Powdery Mildew Infection
To determine if the plant species in your garden are infected with powdery mildew, here are some signs and symptoms to look out for:
- White and powdery fungus patches that spread on the lower or upper leaf surfaces – These patches may also appear in the fruit and flowers.
- Distorted or stunted tissues – Examples of this issue are the leaves affected by what we call rose powdery mildew.
- Plants that appear like they were dusted with flour
- Powdery and circular white spots appearing on the fruits, leaves and stems
- Yellowed and dried leaves – This is because the young foliage is more prone to damage.
- Twisted, broken, and disfigured leaves – You will also notice the growing tips, buds, and leaves becoming disfigured. Such symptoms often come out at the latter part of the plant’s growing season.
In several cases, the tissues infected by the fungus will display only minimal reaction at an early stage. However, there are also certain cases, like in the case of Rhamnus, wherein the fungal infection causes a strong change in color among the affected areas. This results in the color becoming purple-brown.
Plants Susceptible to Powdery Mildew
While no plants are fully immune to all powdery mildew species as this infection tends to affect even roses, shrubs, trees, and vegetables, note that there are still those that are more susceptible to them. Among the plant species known to be truly susceptible to powdery mildew are:
- Begonias
- Chrysanthemums
- Roses
- Dahlias
- Sunflowers
- Melons
- Squash
- Zucchini
- Zinnias
- Tomatoes
- Pumpkins
- Peppers
- Grapes
- Potatoes
- Cucumber
- Lettuce
- Parsley
In case you experience recurrent powdery mildew problems, then make sure to search for plant varieties with improved disease resistance. You can often find this information on the plant tag.
Causes of Powdery Mildew
There are several possible causes of powdery mildew. Among those that you have to watch out for are the following:
Shady Spots
Putting the majority of your garden plants in an area that exposes them to full sun is advantageous for them. The reason is that improper and shady location can cause powdery mildew.
Aside from providing enough sunlight for proper growth, it also keeps them protected from specific plant diseases. Moreover, the sunlight will cause some parts of your plant to remain dry, lowering the likelihood of powdery mildew from forming.
If plant growth only happens in shady areas, then be extremely cautious of the mentioned fungus. This is so you can detect an infection right away, allowing you to treat the disease in a timely manner.
Poor Airflow
You have to let air circulate and flow properly to your plants; otherwise, it may develop breeding grounds that cause powdery mildew to thrive. Ensure that the air can easily travel from one plant to another. It should also circulate through each plant. That way, the plants will dry faster after you water them.
High Humidity and Water
One thing that this disease is so fond of is a high level of humidity. It also thrives well in areas with high but not extreme temperatures. It is the reason why a lot of plants in greenhouses are more prone to getting this fungus than those indoors and in outdoor gardens.
They thrive well in closed greenhouses due to the increased moisture there. You also have to water all your plants, whether in the greenhouse or an outdoor or indoor garden, properly to prevent the powdery mildew from taking over your entire garden.
Preventive Tips
Undeniably, powdery mildew causes a huge problem for gardeners as treating their garden once infested by this fungus can be extremely troublesome. This is why you should try to prevent powdery mildew before it ever gets the chance to form and thrive.
Here are some preventive tips that can lower the chance of your plants from getting this disease:
Buy resistant varieties
As much as possible, buy plant varieties recognized for being powdery mildew resistant. If you already experienced this problem before, then pick varieties that were able to withstand it. This helps in preventing your garden from having to fight the fungi.
Apply the right watering techniques
The way you water your garden contributes a lot to how well your plants will thrive. A great tip would be watering from below rather than overhead. The reason is that spraying water over the entire garden may cause the area to turn humid.
If the humidity becomes too high, then it would just cause the powdery mildew to begin developing and spreading. Another valuable tip is to provide your plants with sufficient time to dry before dusk. In case you are unable to water your garden in the morning, then do it early in the evening before sunset.
Prune regularly
Making it a habit to prune the plants in your garden can prevent the formation of powdery mildew. It is because this requires you to cut large plants that can help build space in and between each plant.
What you should do is prune overcrowded places selectively as a means of boosting airflow and circulation around the plants. This is a good thing as it can lessen relative humidity while providing good airflow for your garden plants to thrive and survive.
Try companion planting
If you have a vegetable garden, then a great practice that you can try is companion planting. This involves putting plants prone to powdery mildew next to those known for being resistant. This helps in protecting those plants prone to fungus.
How to Control Powdery Mildew?
If your plants already has this fungus, then you don’t have to fret right away. Note that there are still many things you can do to control powdery mildew. If possible, try non-chemical and organic methods first, including the following:
Manage the environment surrounding susceptible plants
This means picking the ideal location for the plants to prevent the spread of the disease. Make sure to position your plants in full sun as much as possible, except for those guaranteed to love the shade. It is also advisable to avoid putting them in sheltered places, like against fences or walls wherein there is a likelihood for air to stay still.
Make sure to provide good and quality soil
Ensure that you manage and monitor the condition of the soil where you put your plants. It is also important to provide good drainage. However, you also have to water them regularly when the dry periods come.
You may also want to apply mulch as this helps in the retention of water. Avoid applying excessive amounts of fertilizer, too. Never fertilize infected plants until you are one hundred percent sure that you were already able to control the outbreak of powdery mildew.
The reason is that spores prefer young and succulent growth. This means that fertilizing your plants while there is still an ongoing infection can trigger further spread and make your garden even more susceptible to have an existing infection.
Monitor the wetness of the leaves and the humidity
To achieve that, consider doing these tips:
- Avoid planting too densely – Ensure that there is enough space in between each plant. Your goal should be to have an open environment as a means of reducing humidity and increasing circulation.
- Prune shrubs – This should help in providing a more open structure, which is also a good thing as far as reducing humidity and boosting airflow and circulation are concerned.
- Never overwater – If possible, do overhead watering if the weather is dry since it can help in reducing powdery mildew. Also, make sure that infected leaves do not stay wet for a long period as it may lead to other ailments.
Ways to Treat Powdery Mildew
There are also several solutions that you can use in treating powdery mildew disease. If you feel like this fungal infection has already drastically affected your plants, then you can use any of the following:
Baking Soda (Potassium Bicarbonate)
Baking soda is a highly effective treatment for powdery mildew. It is also easy to make a treatment out of this active ingredient. Just add a teaspoon of baking soda to a quart of water and mix them well.
You should then spray this mixture on the infected plants thoroughly. You do not have to worry about harsh effects as this baking soda solution is only meant to kill the fungi it gets exposed to.
Fungicide
If you want to use chemical solutions, then fungicides are among your options. These fungicides are chemicals made to damage or destroy the fungi. Apply the fungicide if you suspect that there is already powdery mildew.
Just make sure that you carefully follow the package’s instructions so you can apply the fungicides properly and in a timely manner. Also, make sure to pick organic fungicides to ensure that they are safe for use on plants.
It should also contain neem oil, lime sulfur, potassium bicarbonate, or sulfur as such ingredients have properties known to treat powdery mildew effectively and quickly.
Neem Oil
Neem oil is also a famous powdery mildew solution used by a lot of gardeners over the years as a natural fungicide and insecticide. You can use it by combining around three tablespoons with a teaspoon of soap (liquid). Place it in one gallon of water.
Add it to a spray container then kill the spores of fungi by spraying it onto the leaves. For convenience, you may also want to buy a ready-to-use neem oil concentrate. Prevent leaf burn by using the solution during the early morning.
Apple Cider Vinegar
Another great option is apple cider vinegar. It is a solution used by a lot of organic gardeners as a treatment for fungal infection in plants. It has acetic acid, which can effectively control and kill the powdery mildew.
One advice, though, is to make this treatment fairly weak to avoid burning the leaves of the plant. Just add three tablespoons of this vinegar into one gallon of water then spray it liberally to the plants. This should already help a lot in controlling powdery mildew.
Milk
You can also use milk in removing powdery mildew. Just combine milk and water with a ratio of 40:60. You can then apply this mixture to the infected plants and affected leaves.
After that, spray the milk solution into the plants. Ensure that you cover every surface. Repeat the process after ten to fourteen days or after you get affected by a heavy rain shower. Expect it to work well on cucumbers, squash, and pumpkins as well as powdery mildew susceptible plants.
Frequently Asked Questions (FAQs)
How do you treat powdery mildew?
There are different ways to treat powdery mildew – one of which is to give your plants a proper environment that prevents the fungi from developing. For instance, you have to give them proper air circulation. Your garden should also have moderate temperatures or at least warm, dry climates. You can also use solutions, like milk, apple cider vinegar, neem oil, baking soda, and quality fungicides.
Can plants recover from powdery mildew?
Yes. Fortunately, most infected plants have a high chance of recovering. In most cases, these infections are only mild so it is possible for them to go away on their own.
You can also make them recover by making some changes in their environment, such as providing them with proper care designed to improve the airflow in the garden. Treating the infected plant with organic and natural solutions can also help.
What causes powdery mildew?
Several factors may cause mildew powdery fungus to develop. A common cause is poor air circulation. This is especially true for overcrowded plant spaces that trigger the formation of powdery mildew spores.
Other possible causes of mildew powdery infection are insufficient light, high level of humidity, compromised airflow quality, and overfertilization. You should avoid all those if you want to make sure that your plants grow healthily without the risk of getting such kind of diseases.
How do you get rid of white powdery mildew on plants?
For white powdery mildew that affects certain plants, the most effective solutions are baking soda and milk. Baking soda does not only help in killing the fungi but also in eliminating the white molds that may appear on the leaves. Mixed with water, you can also expect milk to help in fighting and controlling powdery mildew.
Conclusion
Powdery mildew is a common fungal infection affecting plants. If you are into gardening and your plants suddenly got affected by powdery mildew, then don’t fret. There are various ways to handle and get rid of this problem, and even prevent the powdery mildew fungi in the first place, such as the ones that we have outlined in this article.