Hello, I planted several plants in the open air, some of them flower in the eighth week and the rest in the fourth week. I want to spray water on the plants because of the dust and some spiders. Is it not harmful for buds and THC?
getting them wet will be greater risk than any benefit you perceive.
you could look into "washing" buds after harvest. This will take off dust and debris. It won't do anything for disease, just to be clear - e.g. it is never gonig to "clean/wash" mold off or rot. so physical dirt and the like only.
needlessly getting them wet will only greatly increase chance of rot.
Don't spray anything on your flowers unless you want to harvest mold.
Water in your buds at this stage is the worst idea. They are like huge sponges and the water that gets into the flower will sit there for ages and cause trouble.
After week 3 you want to keep moisture away from the flowers as much as possible.
The webbing from the spiders might be annoying to clean up during harvest but I say they're patrolling your buds for you! Keep them around if you don't mind. Or maybe I know nothing...