Common Flower Diseases ~ Powdery Mildew on Leaf

Phlox ~ You can see the mildew on the leaves. This is after two treatments of baking soda water mix. Before the leaves were fully covered with the fungus.

We got a request to answer a flower problem one of our readers asked. The reader was questioning what a powdery mildew was on her phlox leaves. I took this as an opportunity to answer that question for anyone who may be dealing with this in their flower beds.

In Mid to late summer is when gardeners will begin to see signs of plant diseases. Powdery mildew on your plants leaves is just one of the diseases you may encounter. Over a period of seasons, this mildew will weaken your plant until it no longer produces or dies.

This condition can be isolated to just the flowers leaves, but if severe can move onto the plant stem and flower as well. Although not instant detrimental to your plant, it isn’t very attractive and if left unattended will eventually kill off your plant.

Annual flowers that are particularly susceptible to powdery mildew include zinnias, snapdragons and verbena. Perennials that are commonly infected include delphiniums, lungwort, bee balm and garden phlox.

This fungal disease is spread by wind and splashing water. To help prevent the onset of this fungus avoid getting water on the leaves and flowers, water in the early am to give leaves plenty of time to dry during daylight hours.

Most fungal diseases are spread by microscopic structures called “spores” that are transferred on wet foliage. However, powdery mildew flourish in high humidity. By keeping plants well-spaced and removing weeds will help ensure good air circulation and reduce the humidity around plants thus lowering risks of this fungus. .

To control this fungus there are several different things you can try – use a horticultural oil, insecticidal soap or another spray. Begin applications at the early onset of the disease and when treating make sure to treat all foliage. Repeated applications are usually necessary right through the duration of the growing season

A home remedy that works for some is a mixture of baking soda and warm water. Mix 1 teaspoon baking soda per quart of warm water and spray on plants every seven to 10 days.

If you have a gardening question, feel free to ask! If we don’t have an answer for you we will get one!