Powdery mildew is more common now with rising humidity, says Vaughn

It really was hard to not see it coming. The cool temperature with all the moisture through almost all of the spring and now it is finally warming up a little bit with higher humidity.

Now it is the time of the year for some plants to do their best impressions of turning into ghosts. That chalky, dusty, grayish white stuff growing on your crape myrtle or dogwood is a fungus called powdery mildew. It is fairly common this time of year, but will be a little extra this year.

Our UGA Ornamental Plant Pathologist superstar, Jean Williams-Woodward does a good job of describing some of the characteristic of powdery mildew. It is the presence of whitish fungal growth on the surfaces of leaves, stems and flowers. Infection of young, expanding leaves or shoots can result in severe distortion.

There are many different fungi in the powdery mildew group. Some are quite host-specific while others can infect a wide range of plants. The fungi obtain nutrients from host plants by penetrating the outermost layer of plant cells.

Powdery mildew spores are easily dispersed by air currents to surrounding plants, infecting plants of the same species. Unlike most fungal diseases, leaf wetness is not required for powdery mildew infection.

Powdery mildew happens most often when it starts getting warmer, dryer and high humidity. Then the subsequent cooler moist nights really get the fungus moving.

Powdery mildew is common on woody plants like roses, crape myrtles, dogwoods and I have often seen them on mophead hydrangeas. On perennials, it is often seen on verbena, gerbera and phlox. On vegetables, take your pick.

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There are some things we can do to prevent it. Thinning thick vegetation areas to allow for better air flow can help. Remove severely affected branches to reduce the disease pressure as well as remove any leaf matter under the plant that might be harboring the fungus. Overhead irrigation can help splatter the spores, so if you can irrigate at the base of the plant, that will help. If your overhead irrigation is rain, you will have to take that up with the Big Guy.

I am a proponent of using fungicide on powdery mildew if you can catch it early enough. Daconil with the active ingredient chlorothalonil is a good contact product that has been in the gardener's arsenal for years. I also like the systemic fungicide made by Spectracide called Immunox with the active ingredient myclobutanil. Both of these products are great if you catch the fungus early. I also like them because they are safe for vegetable use if you follow the label. The label will tell you everything you need to know about how the fungicide works including how soon you can eat that squash after it has been sprayed. Try and mix the uses of these products if you have persistent issues with powdery mildew because they can build resistance when you continually use the same product over and over.

On the bird front, I have a pair of Eastern Phoebe nesting on my back porch. It took me a while to identify the little guy, but I learned they are a type of fly catcher. The next has five eggs and should be hatching soon.