Managing Powdery Mildew in the subtropics

Managing Powdery Mildew

Powdery mildew can be devastating to many crops and it is highly infectious so can spread quickly in your garden if you don’t get control of it. It’s not a pest, it’s not a disease, it’s a fungus. Powdery mildew looks like a white dust on your plants. It can also make foliage looked mottled as it forms on the underside of leaves.

How to avoid powdery mildew

  • Don’t water overhead, water the soil 
  • Make sure there is plenty of airflow between susecptible plants, follow your spacing guidelines
  • Make sure your plants are receiving plenty of sunshine
  • Avoid planting susceptible plants in times of high humidity
  • Opt for varieties that are less susceptible (they can still get it but are more tolerant to it)

Having said that, in humid climates, places that receive heavy dew or rainfall (particularly the subtropics) it can be unavoidable.

Plants that are affected

The most common plants we see it on is zucchini and some varieties of peas. Towards the end of winter we may start to see it on some heirloom tomatoes.

Plants it likes:

  • Cucumbers
  • Pumpkins
  • Zucchini
  • Tromboncino
  • Watermelon
  • Rockmelon
  • Tomatoes
  • Zinnias
  • Nasturtiums
  • Mint
  • Strawberries
  • Peas (sugar snap, snow pea and podded)
  • Mustard greens 

(Our fave Peas that tolerate it are the Greenfeast variety, sugar snaps we only go with the Cascadia and snow peas the Giant Yukama)

How to manage powdery mildew

Once you see first signs of the fungus you need to start taking action as it can spread around very quickly. 

If you can trim any leaves and discard (don’t put into the compost as it can spread it) and treat it with a spray, whether you try a commercial spray or a home made.

Yellow ladybugs, whilst aren’t bad, their presence indicates you have a fungus issue, and when they arrive things it usually means things may be out of hand. 

Sprays for powdery mildew

You can purchase a commercial eco-fungicide or use DIY solutions such as a simple milk spray.

If you’re a Dirt Lover you can access my full tutorial on managing powdery mildew here with instructions on how to make your own DIY solutions.

I’d love to know how you manage powdery mildew in your garden, leave a comment below.

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