Powdery Mildew Control: How to Identify and Get Rid of Powdery Mildews

Powdery mildew is another common fungal disease that attacks a wide array of hosts. It can be a headache for both home gardeners and commercial growers. It deprives the plants of the nutrients that are necessary for its survival. Because of this, the plants suffer from loss of vigor. To prevent the problem from escalating, it is important to treat powdery mildew as soon as possible and to execute the necessary preventive measures.

What is Powdery Mildew?

While this is a fungal disease, it is different from many others in the sense that moisture is not a prerequisite for the disease to spread the infection to other plants. To add, this can survive even in a place with warm weather. With this, regardless of what season it is, powdery mildew can be a significant threat.

Powdery mildew is brought by a variety of fungi species, each attacking a specific plant. Golovinomyces cichoracearum is one of the most common species of fungi causing powdery mildew. This is unique because of the diversity of its hosts. Regardless of the species, they are all obligate parasites. This means that live tissue is necessary for their survival and reproduction.

Powdery mildew forms several spores in its host plant, which will transfer to other plants through wind. While it can survive almost any time of the year, humidity is favorable for them. Irrigation and rain are some of the things that they hate, making them unable to survive. This is unlike many diseases that are more common when there is water supply or moisture. The most favorable condition for them is a cool temperature at night and warm temperature in the day.

Powdery Mildew

Powdery Mildew Forms Several Spores in Its Host Plant

Identifying Powdery Mildew’s Damage

Host Plants

Powdery mildew has diverse hosts, which include indoor houseplants, ornamental plants, deciduous trees, and agricultural crops. To be specific, this is a common disease in apple, grape, cucumber, pea, daisy, gooseberry, snapdragon, lilac, oak, zinnia, begonia, and marrow, among others.


Unsure if your plants are already suffering from powdery mildew? Below are some of the signs that you should watch out for:

  • From the name of the disease, the most obvious symptom is perhaps the appearance of flour-like dust on the top of the plant. They are common on the lower leaves, fruit, and flowers of the host plant.
  • The leaves will also experience discoloration. In most instances, they may turn red or purple. The change in color will be specifically noticeable in the specific portion where there is an infection.
  • If it is too late to act on the damage, the leaves will turn yellow and it will fall off the plant. This can lead to defoliation.
  • Aside from changes in color, leaves can also twist and distort as a result of fungal infection.

Results of Infestation

Most of the time, powdery mildew will lead to superficial damages in their hosts, especially for flowers and ornamental plants. In cases of severe infestation, the problem will be more than just cosmetic. The plant can suffer from distortions, especially in the late part of the growing season. The infection will be more common in young parts of the plants. Because of the latter, this will disrupt the growth of the plant, depriving it of the nutrients that are essential for survival.

Powdery Mildew

Rose Plant Leaves and Flower Buds Infected by Powdery Mildew

How to Get Rid of Powdery Mildews

Natural and Organic Solutions

Thinking of the best way to treat and prevent powdery mildew without the need to resort to toxic methods? Below are some of the solutions that can prove to be promising:

  • The best and easiest way to prevent powdery mildew from being a problem is to grow plants that are resistant to the disease. A perfect example of this is Super Sugar Snap pea. Do your research before you grow your plants and see to it that it can resist fungi carrying powdery mildew and other common diseases.
  • Powdery mildew can happen throughout the year, even when the weather is hot. In the summer, the plants can experience stress and can make them more susceptible to diseases. With this, regular watering is recommended to provide the moisture that the plant needs. Avoid overwatering.
  • Pruning is also a must, especially if the plants are overcrowded. In the same way, it will be good to pay attention to making sure that there is generous space in between plants. This is to encourage air circulation and for the reduction of humidity.
  • If there are plants that are already showing signs of infection, uproot them as soon as possible. The longer they stay in the plant bed, the higher is the possibility that they will spread the disease to other plants. Throw these plants away from the garden and do not use them as compost.
  • While fertilizing can help to provide a healthy soil for the plants, this is one thing that you need to do in moderation. Especially in the case of nitrogen fertilizers, avoid using them in excess.

Chemical Solutions

Even if chemicals have a bad reputation for the treatment of powdery mildew and other plant diseases, it is still a popular choice. Especially for commercial growers, the use of chemicals is common for protecting their crops and making sure that they will not suffer from economic losses. When using chemicals, be sure to follow the instructions from the manufacturer. Apply it at the right time. Also, wear protective equipment as they contain toxic ingredients that can lead to irritation and other skin problems.

One thing that you can use is a bug bomb or fogger. A popular product for the treatment of pests like spider mites, it can also be effective for fungal diseases. One of the best products is Fungaflor TR, which uses imazalil as its main active ingredient. A single canister of this fogger can treat an area that is up to 1,500 square feet.

If you are going to use fungicides, on the other hand, some of the most common active ingredients that you should look for include thiophanate methyl, dinocap, and myclobutanil.

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