Is this mold?

my first grow i had run into the same problem once i got good airflow i had no more problems with the molds but my humidity is rarely above 45% idk what your is at but i found airflow really helps keeps those things in check

I use 1 part FF milk to 9 parts H2O and it keep them in check with PM issues. I use it as preventive more than a cure. If the PM is very thick it wont kill it but as it appears spray the area you'll be surprised how well it works and your plants love it. PM starts at a higher humidity but will continue to grow at lower even lower than 40%. I have battled this shit for years and it still keeps coming back over and over. If you look on the net there are trials using milk to combat PM so I thought I would give it a shot and have been using it every since. I'm going to PH milk this morning to see if its higher than 7 that could be why it kills PM not sure. Good luck with that shit!!