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Powdery Mildew on Plants

Rajib Singha Apr 17, 2019
Powdery mildew is a common woe of every gardener. It is reputed for jeopardizing a wide range of plants. Read ahead to know more about it.
Caused by a multiple species of fungi, powdery mildew is a fungal disease which tends to affect several varieties of plants. As the name suggests, it manifests itself in the form of white powdery spots, which prevail on leaves and stems. This may be ascribed as a talcum-powder-like growth.
Although it can affect any part of the plant, it seems to do more damage on the lower parts that are close to the ground. With time, these spots tend to increase in size; signaling the production of spores. It is said that no plant has resistance towards it. However, some are known to be less susceptible than others.
Common species of plants which fall victim to this infection include lilacs, crab apples, turfgrass, euonymus, Virginia creeper, phlox, monarda, roses, grapes, squash, and cucumbers, to name a few.

Favoring Conditions

The factors which let the infection take its toll on plants depend upon their type, age, and weather conditions. Warm and dry climates are known to be the ideal conditions that trigger its aggressive growth. Often, it affects more of those varieties which grow in areas crowded with their own kinds or other types of plants.
Lack of air circulation and formation of a damp and shady atmosphere, give the disease enough scope to infect and thrive. Powdery mildew does not need moisture to grow, but needs high humidity levels. So, when the leaves or the stems remain wet, the infection does not occur. Compared to older plants, young succulents, are more susceptible to this disease.


  • The first and foremost thing to do is to get rid of the infected parts of the plant. The best disposal method for the diseased parts would be burning them off.
  • As mentioned, poor air circulation encourage the growth of powdery mildew. So, to counter this problem, thinning and pruning of your plants is advised. It is recommended to disinfect the pruning tool by dipping it in a solution made of 4 parts water and 1 part bleach.
  • Fertilizers promote tender leaf formation, which, as it has been mentioned, attract the mildew growth. So fertilization must be adequate, but at the same time, must not stimulate succulent growth. For this reason, organic fertilizers or slow-release formulations make for a good choice.
  • It is best to water the plant in the morning, as it would have the rest of the day to dry off. This helps in reducing chances of fungal and other plant diseases.
  • Avoid watering plants overhead. This increases the relative humidity and thus, helps the fungus to thrive.
  • Consult your local garden store, and purchase a fungicide that will help combat this disease. Follow the instructions printed on the label, for application and waiting period below reapplying.
To conclude with one last tip, you can also make a homemade fungicide to deal with the problem. Crush a few cloves of garlic and mix them in water. Fill the mixture in a spray bottle, and spray it on the plants. Garlic is rich in sulfur which is helpful in taking care of such plant diseases.