Hey,
yeah there are sprays out there.
Make for damn sure tho they are safe for herbs and veggies, needs to be food grade, you don't wanna smoke toxic shit.
Use sand 1 inch thick over the top of the soil, it will spare your roots from anymore damage, specially if you have fungus gnats.
I use it normally, it's good for your soil when it soaks in later on as well. Make sure it;s not limestone sand.
If you don't know flush than sand really well before using, and do NOT use colored sand.