Jenna’s Blog: What to do about Powdery Mildew

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mildewIt’s that time of year again. When the monsoons arrive, powdery mildew comes to town.

Powdery Mildew is a fungal disease that affects pretty much everything in your garden. The good news is that while gross and concerning to look at, powdery mildew is rarely fatal, though it does put significant stress on the plant and often causes premature leaf drop due to inhibited photosynthesis.

Now you might be wondering, “What can I do to prevent P.M from wreaking havoc in my garden?”

Well, first we have to discuss the conditions in which powdery mildew thrives…

What Powdery Mildew Loves

  • High Humidity
  • Dampness
  • Crowded Plants
  • Poor Air Circulation 

How to Prevent and Treat Powdery Mildew

Keep a tidy garden

  • When you first notice Powdery mildew popping up, quickly remove infected leaves and discard, this will help slow down the spread.
  • Keeping your garden clean at the end of the season is another useful way to prevent powdery mildew. Making sure you pick up and destroy all fallen debris from affected plants. If infected plant scraps are left to overwinter on the ground, the spores may survive in your garden.

Allow for air circulation

  • If your tightly packed annual containers are becoming infected, you can carefully remove some of the plants to allow for more air flow.
  • Divide perennials every couple of years so that they don’t become too tightly compacted.
  • Prune your trees and shrub

Apply a Fungicide

  • Already got P.M? At this point spraying your plant may be your best option. Most fungicides are great at stopping the spread of powdery mildew but less effective at actually eradicating the disease.
  • Fungicides can also be applied before you first notice powdery mildew as a preventative.
  • Our recommended products:
    • Serenade Garden Disease Control – organic (can be applied up to and on the day of harvest); good for roses, vegetables, fruits, flowering plants, trees and shrubs; broad spectrum, preventative biofungicide; best if applied prior to foliage disease or at first sign, then repeat at 7-day intervals as needed. 
    • Ferti-lome Triple Action Plus – Safe to use on citrus, fruits, vegetables, ornamentals, shrubs, flowers, and houseplants; Miticide, Insecticide, and Fungicide; contains neem oil; may be applied up to the day of harvest on all fruits and vegetables; apply every 14 days to prevent disease.
    • Copper Fungicide – for flowers, fruits, and vegetables; begin treatment 2 weeks before disease normally appears or when it first appears; Repeat at 7-10 day intervals for as long as needed (reapply after rain).