Following the posts about courgettes and cucumbers, I need to follow up the depressing facts about powdery mildew with a possible preventative or cure.
I was given ‘Grow for Flavour’ by James Wong as a birthday gift a year ago. In his section about growing cucurbits, James Wong wrote about an interesting concoction he named ‘Supersquash Tonic Spray’ which I was taken by as some of my cucurbits were starting to show signs of that horrid virus, especially my pumpkins. My cucumbers and butternut squashes fortunately escaped unscathed but I was very afraid for the lives of my courgettes (which the disease did eventually slow down to a halt in early autumn) and my pumpkins (that fortunately managed to hang in there until they were ready for harvesting, then the powdery mildew reached the stems and rotted them). James Wong’s spray is for preventing the disease from taking hold of the plants but it was a little late for that last year by the time I got the book. We used it as a way of trying to hold back the disease. We don’t know if it was the tonic or just some strong cucurbits fighting for their lives, but the powdery mildew was kept at bay – it didn’t vanish but it didn’t go out of control and kill of the plants straight away.
This year, we started using the tonic spray on the plants that could possibly suffer from a powdery mildew attack as soon as they were in the ground. The weather has been so odd this year that we really do fear for any plant disease coming along so it is best to be prepared.
If you read the ‘Life’ section that comes with the ‘Telegraph’ paper (my grandma gives them to us for the chicken houses every week), then a slightly recent article written by Bunny Guinness mentioned that she now uses a 50/50 milk and water solution to spray her cucurbits with to cope with powdery mildew too.
Here is the concoction we make to help keep our cucurbits strong and healthy to fight powdery mildew when it attacks, from James Wong’s ‘Grow for Flavour’ instructions (all credit goes to the author):
Supersquash Tonic Spray
Add a splash of seaweed extract to 1 litre (1 3/4 pint) spray can of water along with a 1/4 of 300mg soluble aspirin tablet. Add a splash of full-fat milk for added nutrient content. Spritz the tonic spray over the plants’ leaves whenever you can but at least once a month over the summer. Saturate the leaves as much as you can.
- Trials at the US Dept of Agriculture have shown that a foiler spray rich in potassium improved the quality of melons (squash’s close relative) by improving the firmness and sugar content and increasing vitamin C and beta-carotene levels.
- Trials have demonstrated that chemicals closely related to aspirin can act as a tonic to help boost squash plant defences against drought and cold. Experimental evidence suggests that aspirin spray can improve their resistance to disease such as mildew and mosaic virus.
- Wong emphasises using full-fat milk, not skimmed or soy. The fatty acids in milk have been shown in some trials to inhibit the growth of mildew.
Wong does point out that neither aspirin or milk are approved formally as registered pesticides or for the treatment or prevention of plant diseases. It is entirely legal though to apply them to boost plant growth and crop flavour.
As I mentioned before, all credit for the recipe and facts goes to James Wong’s published work. Give it a go!