Powdery mildew, just starting on my zucchini
As it turns out there is a lot of information on-line. This year I'm prepared or so I hope.
It thrives in hot, dry weather, see heat wave alerts all through July, and then bursts into flower when the humidity is right, covering your plants in a downy grey film. Plants with heavy, dense foliage are particularly susceptible It spreads like wild fire and in a day or two it can be very well established. Here is where what I read and what I have experienced differ.
Everything I read says it doesn't survive/thrive in full sunlight or water. It always hits my zucchini first, full sun all day and watered every day if there is no rain???
There are several ways to combat it.
The most obvious is a commercial fungicide. I do not use them in my gardens. They are toxic and you have to be very careful about application before harvesting. I try to keep things like herbicides, pesticides et al out of my soil. I have enough problems with out adding to it.
There is an organic fungicide available called Serenade that is a wide scale fungicide that I may check out next year if what I try this year isn't effective. The active ingredient is a soil bacteria, Bacillus subtilis.
Sulfur is very effective and garlic is high in sulfur so a garlic spray can be used. Soak 3-4 crushed garlic cloves in 1 quart/litre of water overnight, strain into a spray bottle add a couple of drops of liquid dish soap and use on your plants making sure to get the underside of the leaves as well.
Sodium bicarbonate/baking soda is also recommended and that is what I am trying. Mix 1 teaspoon of baking soda into 1 quart/litre of water, add a couple of drops of liquid dish soap and mix until the baking soda is dissolved. Spray onto your plants making sure to get the undersides as well. This is a contact fungicide so I should know by the weekend if it worked or not. It should be applied every 7 to 10 days as long as the infection continues.
Have you ever tried to make sure you got a complete covering of a zucchini plant. Those leaves are prickly. I'll be happy if I can get most of it and can keep it under control. I'll keep you updated.
So here is the update, it didn't not work. It killed off the worst of the mildew but not all of it. At worst it has bought me time to try another method of control. My father used a powdered sulfur spray, that's my next line of attack. Just as soon as the rain stops.
How do you do battle with the various challenges your garden throws your way? Let me know, I can always use the help. Good luck and happy gardening.