Written and edited by Tammy 30th October 2023
image of powdery mildew on Zucchini leaves curtesy of gardenerspath.com
With Spring now in full swing and summer vegetable seedlings going into the ground left right and centre, powdery mildew becomes a hot topic. If you're vigilant and know what to look out for, and perhaps even what precautions to have in place, you'll be able to act quickly if it does show up for the party!
Identifying powdery mildew
Powdery mildew is a fungal disease. The first sign is white powdery looking spots, Mycelium (the fancy word for fungi tissue) spreading all over the leaves. The foliage might also start to look yellow and 'washed out' in colour and become either wilted and or crispy and deformed around the leaf margins as it spreads and advances. Not that you can see them, but the spores live on plant debris on the ground and when conditions become favourable, they're transferred by wind, insects and animals from plant to plant.
Favourable conditions
Cool humid nights in conjunction with warm dry days are the perfect conditions for powdery mildew spores to grow and reproduce. Think of the growing requirements for mushroom kits, they require a cool dark environment, so it makes sense powdery mildew also being a fungus needs the same, an environment that offers low light and lack of air circulation.
Most susceptible
So many plants are susceptible to powdery mildew, and a lot of them are things we grow right now in spring coinciding with those cool balmy nights, and warm windy days.
Here's a handful of the most common ones you'll likely have in your garden right now.
The Cucurbitaceae family including zucchinis, squash, pumpkins, cucumbers, and melons.
Solanaceae the Nightshade family including tomatoes, eggplants, chillies and capsicums.
Strawberries
The Fabaceae Legumes family including beans, peas and soybeans.
Roses
Hydrangeas
Prevention
As always, 'prevention is better than cure' the more measures you can put in place to lower the risk the better.
Allow as much light and air circulation into and amongst the foliage as possible.
Give each plant its own space, don't overcrowd them.
Remove any old, spent or diseased lower leaves. Locate your vegetable patch where it will get at least 6-8 hours sunlight a day.
Water in the mornings so the foliage has time to dry and isn't wet into the cool of the evening.
Routinely apply Seasol Health Treatment to improve disease resistance and maintain a strong healthy immune system.
Treatment
Remove any diseased affected foliage.
Treat with Eco Neem Oil, Lime Sulphur, Liquid Copper or a fungicide product of your choice. Follow the manufacturer's instructions on the label for rates and directions for use.
If you'd prefer a more natural approach, you could try mixing a 40/60 ratio of milk and water. Milk has fantastic natural antibacterial and antifungal properties.
You can also try 1 teaspoon of Bicarb Soda, to 1 litre of water and a few drops of dish liquid (biodegradable with no phosphates) the dish liquid just acts as an adjuvant to help the bicarb to adhere.
Whichever of the above options you choose to go with, you won't reverse the obvious damage to the existing foliage, but by killing the spores that are present, you'll prevent the new emerging foliage from being infected. Watch to see the new foliage looking healthy and disease free to know the infestation has been successfully brought under control and eliminated.
Follow a few of these little hints and tips and hopefully you'll avoid the dreaded 'powdery mildew' or worse-case scenario, know how to treat it if you notice it.
Have a wonderful week,
and enjoy your gardens 😘🌸
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