I’ve been using neem oil preventively on my tomato plants because I get nasty cases of powdery mildew on them. It’s the only thing that I’ve found that works (although open to other options). I also use I occasionally on my hydrangeas for powdery mildew. PM is the bane of my gardening.
When I use it preventively, I only spray once a week in a light mist, before the sun hits my plants, and before the bees start coming out. From what I’ve read, it’s not harmful to bees unless they are directly sprayed. I’ve been doing this for the last few weeks and the bees have been buzzing around my marigolds with no issues. If the plant has powdery mildew, I make sure to remove the affected leaves and spray directly around where the leaves were cut off.
I also use it for aphids, but not when vegetable plants are close to harvest and even then, I’ll wash the tomatoes with dawn soap when they come inside and before eating them. I have a young hibiscus that was recently planted and I give it a spritz of neem oil once or twice a week because it has aphids. It’s much smaller than the other hibiscus around it, so I’m trying to give it every chance it can have to get bigger. Netting isn’t a big option for my garden spaces except for the wheeled garden beds, which I do net when they are growing.
I had a really bad aphid infestation on my lettuce box recently. I ended up using mildly soapy water because the lettuce is meant for my bunnies and I don’t want them exposed to any pesticides. I’d rather I was exposed to it myself than my little bunny butts.