The plants were just switched over to 12/12 they are only 10 days into flowering. I am not sure of this problem, I haven't seen leaves that look like this. The lamp is a 400 Watt HPS and it's a foot away from the tops of the plants. I have been using nutes but gave them the first blooming nutes on the 15th a week after switching the lights. Is it burn?
The leafs are only infected towards the top of the plant. Should I remove them or leave them alone?
Any advice please help.

The leafs are only infected towards the top of the plant. Should I remove them or leave them alone?
Any advice please help.