Today's hours: 9:00am-7:00pm

Get Directions

Your Cart

0 items

June 26, 2023

Plant Fungus Prevention & Treatment: Tips for Powdery Mildew and Black Spot

In mid to late summer, some plant problems—like fungus—can start to become noticeable.

powdery mildew aster, plant fungus treatment

In mid to late summer, some plant problems—like fungus—can start to become noticeable. Fungal diseases can look ugly, but don’t worry: they are not fatal to your plants and won’t cause too much damage. Plus, most fungus issues can even be prevented! If you do encounter fungus on your plants, just remember it can be treated, and your plants will more than likely recover beautifully.

Learn how to recognize powdery mildew and black spot, and how you can prevent and treat them in your own garden.


Powdery Mildew

Powdery mildew is a white, powdery coating that can appear on leaves, stems, and flowers. As unattractive as powdery mildew is, it is not fatal to plants—although repeated infections can gradually weaken a plant. Infected areas can turn yellow or brown, and dead foliage can fall off the stem.

Powdery mildew is caused by high humidity and often affects plants like:

  • Zinnias
  • Snapdragons
  • Verbena
  • Delphiniums
  • Peonies
  • Lungwort
  • Bee balm

Black Spot

Black spot appears as black spots on foliage and is most commonly found on the upper leaf surfaces. Leaves turn yellow around the spots and eventually fall off. This fungal disease often affects roses. Black spots can also appear on rose canes—starting purple and turning black.


Prevention & Treatment

To avoid this problem altogether, it is important that you use the proper watering technique when watering your plants. Fungal diseases are often caused by water sitting on the leaves.

Learn the proper watering technique

Remember: “Water the pot, not the plant!” Pour water directly into the soil, not over the leaves or foliage. This prevents fungal spots and wasted water.

Water your plants in the morning so that the leaves have time to dry out during the day. Fungal diseases thrive when foliage stays moist for long periods. Spacing out your plants and removing weeds can also help reduce humidity and improve air circulation.

If you weren’t able to prevent powdery mildew and black spot, don’t worry. You can:

  • Spray the plant with a fungicide
  • Fertilize with a liquid fertilizer to support recovery
  • In the fall, cut back infected plants and discard leaves—don’t compost them if they’re covered in spores
  • Spray a final round of fungicide in fall to help kill lingering spores

Learn how to apply fertilizer properly

Applying fertilizer now will help ensure damaged, stressed leaves can produce enough energy to stay strong next season. Odds are really good that your plants will recover beautifully and come back fresh next year.


Want personalized garden advice? Stop in and speak to our garden team—we’re here to help your plants thrive through every season!

Photo credit

Other Garden Tips

Eco-Friendly Easter Decor: Ditch Plastic Grass for a Greener Easter

When it comes to Easter decor, one of the most common staples found in baskets across the country is Easter grass—the colorful shredded material used to cushion eggs, chocolates, and small gifts. But did you know that traditional plastic Easter grass is a major contributor to holiday waste? This year, make the eco-conscious switch to all-natural Easter grass for a more sustainable celebration.

Learn More
grass, lawn care

Early Spring Lawn Care: Tips for a Healthy, Lush Lawn

As winter fades and spring approaches, it’s time to start thinking about lawn care. A well-maintained lawn in early spring sets the stage for healthy growth throughout the season. Here are essential steps to kickstart a vibrant, green lawn this year.

Learn More
kitchen scraps into compost for your plants and garden

Turning Kitchen Scraps into Compost: A Sustainable Solution

Looking for an easy way to reduce waste and give back to your garden? Turning kitchen scraps into compost is one of the most ethical…

Learn More