Rob Smith on why mouthwash or milk zaps powdery mildew
Why not try a minty fresh approach to tackling disease?
To say this year has been a challenge in the vegetable garden is an understatement. From a cold start to a baking summer, we’ve had some real challenges to face throughout the country. One crop that has done particularly well for me, though, is courgettes.
But now sadly it has come to that time of the year when the weather has changed and the rain has arrived, creating a warm atmosphere with high humidity, the perfect environment for powdery mildew fungus. To help lessen the humidity, always water the soil around plants, never the foliage. Powdery mildew can be a problem for many plants, including squash, cucumber and more noticeably… courgettes!
The white, dusty-like markings on leaves can spread quickly and although not normally fatal to plants it can weaken them and affect yield if not dealt with. One of the easiest methods of treatment is to remove and destroy affected foliage, burning or binning the leaves, as composting will spread the problem in the following years because spores will survive through the winter.
If you do remove leaves, don’t be tempted to feed the plants with a high nitrogen feed as this creates new foliage, which is especially susceptible to powdery mildew. Instead leave the plants to their own devices and consider picking your fruit when it’s a little smaller, giving the plants chance to ripen future crops.
If you want to try and slow the spread of the fungus, there are a few ways you can do this. Firstly, you can try a spray of one part milk, nine parts water; this is a method shown to me by Terry Walton. We don’t know exactly how the milk stops the spread, but it seems to work on lightly affected plants, just make sure to re-spray after every rain shower.
Alternatively, you could use mouthwash! Mouthwash is an antibacterial and antifungal for your mouth so why not try the same ratio as with the milk, and watch how it helps slow the spread on your plants. Don’t use a whitening mouthwash, these can be too harsh and I’d prefer my plants to stay green, even if they smell minty fresh!
Snip off mildewed leaves to lessen the spread
Winner of The Big Allotment Challenge and a seed guardian for the Heritage Seed Library