Powdery mildew may not kill your plants outright, but it can sure wreak havoc. Knowing how to spot the fungus that causes powdery mildew and how to get rid of it will help you win the battle against it in your garden.

Gardening is a relaxing and peaceful hobby most of the time, but it's not without its battles. The first one that you may think of is the one against weeds, but pests and diseases can be just as frustrating. Powdery mildew can be a very annoying problem to deal with, but knowing how to identify and treat this fungus will help you keep it under control in your garden.

Identifying Powdery Mildew

powdery mildew

Powdery mildew is a pretty descriptive term. It appears as a gray or white powdery blotch or spot on the buds, leaves, and stems of plants. It may seem superficial. You may think at first glance that your plants have cobwebs or baby powder on them. Often, this fungus affects the parts of the plant that are shaded or that lack sufficient airflow (usually among the lower branches or on the branches toward the center of the plant). Not having a large enough space between your plants can also contribute to the formation of powdery mildew. Typically, this condition happens outside in places with cooler temperatures and a lot of humidity, but it can still occur in dry, warm climates, too.

If you don't catch the infection right away, your plants' leaves can prematurely turn yellow and fall off early in the growing season. You may notice that some leaves become purple or red in the areas around the infection. Black balls may form in the infected areas later in the growing season, too.

Powdery mildew itself won’t usually kill your plants, but it will stress them and make them weaker. This is because photosynthesis can be impacted if the leaf’s surface is densely covered with the fungi. In addition, it can stop your buds from opening or maturing on their plants. You may even find that your fruit and vegetable crops are affected, as this issue can make them taste less flavorful than they normally would.

Plants Affected by Powdery Mildew

powdery mildew on rose shoots

There's a huge variety of powdery mildew fungi around, and they can actually impact thousands of different plant species. However, specific fungi will often attack specific plants rather than all of the ones in their immediate vicinity. Still, you'll find that there are a few plants out there that are susceptible to several species of this fungus.

Some examples of plants that can be impacted by powdery mildew include roses, maple, oak, crabapples, ash, lilacs, rhododendron, hawthorn, catalpa, cucumbers, squash, grapes, and phlox.

Preventing Powdery Mildew

The best way to avoid powdery mildew is to plant cultivars that are resistant to it. Avoid placing them in the shade, and give each plant plenty of growing room when it comes to spacing. Of course, sometimes powdery mildew just happens in the garden, and the only thing you can do is treat it and move on.

Powdery Mildew Treatment

removing leaves affected by the fungus

This may be painful for many gardeners, but when it comes to powdery mildew, the best thing to do is to remove and destroy the infected plant parts. Depending on how severe the infection is, you may have to remove an entire plant to help keep the rest of your garden healthy. You’ll also want to thin out the growth by pruning your plants to promote better air circulation. Water the ground rather than spraying your garden, as the fungus thrives on the dampness of plant leaves, and avoid working any more fertilizer into your soil until you’ve gotten rid of the problem.

Finally, you'll have to use a fungicide. You can find a wide variety of these at your local garden center or DIY store. Make sure that the one you choose works on the variety of plant you’ll be spraying. Some of the ingredients that you should be on the look out for include neem oil, copper, potassium bicarbonate, and sulfur.

Not sure that you want to purchase a fungicide? Make your own using baking soda or milk! The baking soda recipe is easy, and you probably have all the ingredients for it in your kitchen right now. You’ll just need to mix a tablespoon of baking soda and a half-teaspoon of liquid dish soap into a gallon of water. Apply this mixture to your plants right away, as it doesn't store well. However, you’ll want to avoid applying it in full sun, as it can burn the leaves of your plants. The milk recipe does especially well for squash and cucumbers. It’s one part milk to two parts water, sprayed on every two weeks. Of course, both solutions work well for prevention of powdery mildew.

No matter what fungicide you choose to apply, you’ll want to make sure that you follow the directions carefully. They'll not only tell you how to correctly to apply it, but they'll also tell you how long you’ll need to wait after using it before harvesting your crops. In addition, you’ll want to find out how often you need to apply the fungicide you're using to ensure that your crops have continuous protection against powdery mildew.

No one wants to deal with a pesky fungus that looks so innocuous at first, but knowing about powdery mildew is the best way to tackle it if it ever pops up in your garden.