leaf diseases

if it was greater than 950 umol/s PAR across canopy, it was probably a major cause of what you see. If this is an autoflower, you may want to be around 667 PPFD for 18 hours of operation. A good target for a 12h operation is 900PPFD. -- These are both the same DLI, which is what matters, You'd still need to observe and react to the plant. These are values that are meant only as a good starting point with minimal adjustments needed, but adjustments still needed. 950 may be fine, too... but if you were much higher, it's increasingly likely it caused the damage. You need 1300ppm atmospheric co2 to push higher than 35-40 DLI. Read up on "daily light integral" to get the gist. DLI tables are good to download for reference.