Powdery Mildew🍀

Tammy Johnson
Oct 30, 2023
3 min read

Updated: 6 days ago

Written and edited by Tammy 30th October 2023

image of powdery mildew on Zucchini leaves curtesy of gardenerspath.com

Written and edited by Tammy 30th October 2023 - Updated Nov 2025

Powdery Mildew — How to Spot It, Stop It, and Stay Ahead of It This Summer ☘️

They say you should 'never look a gift horse in the mouth' and Mother Nature has certainly gifted us with some beautiful rain here in the SE this Spring. It's been not only wet, but very mild, grey and gloomy overall, with below average warmth and sunshine, creating the perfect conditions for powdery mildew to thrive.

Ongoing rain events, cool nights, low light, and sluggish air movement tick all the boxes for a fungal paradise!

As we head into summer and our warm-season veggies really start firing, it’s the ideal time to keep an eye out and put a few prevention steps in place before powdery mildew becomes the uninvited guest.

Identifying Powdery Mildew

Powdery mildew is a fungal disease, and one of the easiest to recognise once you know the signs.

You’ll typically notice:

• White, powdery-looking spots on the surface of leaves

• Mycelium (fungal tissue) spreading into a dusty coating

• Foliage becoming yellowed, washed out, distorted, crispy, or wilted around the margins

The tricky part? Spores live on old plant debris in the soil and hang around quietly until conditions are favourable. From there they’re spread by wind, insects, tools, clothing, pets… everything, really.

Favourable Conditions

Powdery mildew absolutely thrives when we get:

• Cool, humid nights, followed by

• Warm, dry, breezy days

Think of mushroom-growing kits, cool, dim, low-airflow environments. Because powdery mildew is also a fungus, it loves the same conditions: reduced airflow + shade + lingering humidity.

And that’s exactly what this spring has delivered.

Most Susceptible Plants

Plenty of plants are vulnerable, especially those we’re growing right now at the end of spring. The most common ones you’ll likely have in your garden include:

Cucurbitaceae — zucchinis, squash, pumpkins, cucumbers, melons
Solanaceae (Nightshades) — tomatoes, eggplants, chillies, capsicums
Strawberries
Fabaceae (Legumes) — beans and peas
Roses
Hydrangeas

Prevention

As always, prevention is better than cure. Put these small steps in place and you’ll dramatically reduce your risk:

Allow maximum light and airflow through the foliage
Avoid overcrowding — give each plant its own breathing space
Remove old, damaged, or diseased lower leaves
Choose a sunny position — 6–8 hours of light is ideal
Water in the mornings so foliage dries before evening
Apply Seasol Health Treatment to strengthen plant immunity

Why not have a go at training your veggies up off the ground and over a mesh arch supported by 4 star droppers? The concept ticks all the boxes for keeping them off the damp ground and allowing maximum light and air circulation. I've watched a few tutorials recently and thought I'd have a go a setting one up for my Spaghetti Squash seeds. A few have germinated so I'll see how I go!! 😁🤞

Treatment

If you do spot any tell-tale signs of powdery mildew, it's vital to act early:

Remove affected leaves and dispose of them (don’t compost)
Treat with Eco-Neem, Lime Sulphur, Liquid Copper, or any fungicide of your choice, always follow label directions
Prefer a natural approach?
Use a 40/60 milk-to-water spray (milk has natural antifungal properties)
Or try the classic bicarb mix:
1 tsp bicarb soda + 1 L water + a few drops of biodegradable dish liquid (the soap helps it stick)

Just remember: these treatments won’t repair leaves already damaged, but they will stop the spores and protect all the fresh new growth.

Watch the newest leaves, if they’re clean and healthy, you’ve turned the tide.

A Final Word

Follow a few of these little hints and you’ll hopefully avoid powdery mildew altogether or, at least know exactly how to deal with it when it appears.

Have a wonderful week,

and enjoy your gardens 😘🌸