hahaha....a spec here and there. Yeah, for today. Tomorrow and the next day are going to be 'a dozen here and a dozen there'.
In direct answer to your question, do not spray when the lights are on. No doubt, there would be burn marks if the light is being used properly. Don't worry about mold or fungi. Provided your all other conditions are within range, spraying your plants, per bottle instructions, will not cause those types of problems. Remember, in natural conditions, it rains outside.
- support
(ps...contrary to popular belief, if done correctly, an entire crop can be irradicated of mites in only two applications.
The key is to use a pressure sprayer!! Without a pressure sprayer you'll most likely control
the mites, not irradicate them.)