Treating Powdery Mildew On Leaves

Perhaps the best way to deal with plant diseases and pests is to be observant. Keep an eye on your garden. Regular surveillance will assure that you catch problems before they get worse.

For example, have you walked around your garden and noticed what resembles a powdery substance on the leaves of some of your plants? If you do, then your plants are probably dealing with a fungal disease.

Several varieties of fungi that fall under the class of Ersiphales can cause the disease, but the symptoms are always alike. Regardless of the region in which you live, if you experience humid summers, then you’re going to encounter powdery mildew. It can affect any plant. However, there are some plants species that are most susceptible to it. They include:

  • Apple
  • Begonia
  • California Poppy
  • Dahlia
  • Delphinium
  • Hollyhock
  • Hydrangea
  • Lilacs
  • Monarda
  • Oak
  • Phlox
  • Roses
  • Strawberries
  • Zinnia.

You may not realize it, but many plants that are susceptible to the problem will get it often. In their case, it is virtually unavoidable. Some gardeners who are use to confronting the issue every year may not act upon it aggressively. However, if left untreated leaves could yellow and drop off the plant, a plant could suffer stunted growth or distorted buds, blooms, and fruits. Eventually, the mildew will weaken the plant.

Plant infested with Powdery Mildew.

How It Begins

Spores of mildew appear on plants over the winter and begin asexual production of new spores when the weather gets warm. The wind carries new spores to other parts of the plant or to other nearby plants. Spore production never stops. So, if you don’t confront it, it gets worse.

Treating And Prevention

Powdery mildew flourishes in temperatures between 60°F and 80°F.It gets worse due to humidity and in shady areas where air circulation is poor. Chemical fungicides generally don’t work in eradicating the problem. Your only alternative to dealing with it is to remove or destroy diseased plants and plant parts.

You can save your plants from an infestation if you plant disease-resistant flora and ensure that the area in which the plants grow has good airflow.

Other ways to prevent powdery mildew from occurring include:

  • Plant susceptible species in a location that receive early morning sun. This assures that dew and condensation evaporate quickly preventing the moist conditions that cause development of the fungus.
  • Space plants well apart for optimum air circulation. The better ventilation reduces the chance the disease will appear.
  • Inspect plants frequently during the warm, dry periods and remove any leaves that have signs of infection. Destroy the infected plant parts, but never compost it.
  • Apply a formula of ¼-teaspoon of baking soda and 1-quart of water. Spray plants weekly immediately after you notice the powdery substance. This can prevent any additional damage.
  • Apply neem oil, a commercially available organic treatment. It treats the powdery mildew as well as guards against additional infection.
  • Apply milk spray as a preventative. Mix a ratio of 40% milk and 60% water.

Another effective way of preventing powdery mildew or treating plants that already have it is to spray them with water from the hose everyday. Powdery mildew loathes water. It’s best to use this remedy early in the day to allow the flora to dry before cooler evening temperatures arrive. If you apply the treatment too late in the day, other fungal diseases including black spot could occur.


About Robert Janis

Written by Robert Janis for LawnEq - Your specialists for Lawn Mower Parts and Small Engine Parts. We offer genuine premium OEM parts for Land Pride, Toro and many more dependable manufacturers.