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Hi all. My zucchinis are covered in powdery mildew together with the lovely little lady bugs that consume it. I have potassium bicarbonate to spray on it but I’m not sure if it will kill the lady bugs too. I really don’t want to harm them but they can’t keep up with it as it’s so bad.its an organic spray and has a lady beetle pic on the container. Any ideas?
I have always either left the plants to sort themselves out or if the problem gets too much I have used milk. Milk is fairly innocuous and is cheap and easy to obtain. Rinsing out an empty bottle and using that is all it takes here but the climate here is rather dry.
Potassium bicarbonate should not harm the lady beetles too much directly. Clearly once the potassium bicarbonate kills off the powdery mildew the lady beetles will leave/starve but it is best not to over think things like this. Be careful not to over use it as it may alter the pH of your soil.
Also, are you sure the lady beetles are eating the powdery mildew? We have some here that certainly eat the fungi and help us but some other species of lady beetles (eg 28 spotted lady beetle) will eat the zucchini leaves. They always seem to be around whenever a plant is stressed. If you have the bad guys then your plants would be getting hit twice. Lowering the number of leaf eating lady beetles is more difficult than you may think.
Thanks Mukluk. No they’re definitely eating the mildew. Lovely little yellow and black ones. What I ended up doing is removing the badly affected leaves with the lady beetle larvae and adults on them. I moved the little critters from the not so badly affected leaves on to these ones as well. I’ve sprayed the not yet affected leaves with the milk as a preventative. I didn’t want to deprive them of their food source so have left a couple of leaves untouched. Seems to be working so far and starting to harvest a few. I’m not worried about the PH as our soil is pretty heavy and acidy and we regularly need to add lime. I’ve sprayed our cukes with the bicarb as a preventative as a few spots have appeared. Hope I’ve found the middle ground. It’s been a bit of an effort but worth it I think.