Mine had a similar problem and was told that it was from stress... With mine I'm thinking it was a quick rise in temperature, as I wasn't home and the temp in the closet quickly rose to 91degrees..
It could be a various amount of things. for anyone to help out and troubleshoot youll need to give alot more info about your grow, everything from ph, ppm, room size, strain, medium and all that jazz
It is in 4x4x8 and it stays between 70-80 degrees. I'm runnin ebb and flow table and using sensi grow advanced nutrients. I have 3 strains brainstorm, superbud, and shark attack and 1 blue dream. Ph stays between 5.5-6.5. And I'm not to Ppm's yet because I don't fully understand ?
If you're not checking ppm's and are having issues in veg such as spotting then I suggest lowering your feed first. Next tell us what additives you are using with the sensi. Is that 70-80 degrees at the canopy or in the room? You are being too vague with your description. We don't even know what week in veg you are and how long your feeding for or really anything we need to know. We're willing to help but you gotta spill your guts. lol
I'm 4 weeks veg right now and I am feeding less vet its only been few days. The climate is not bad still working on better fans and ducting. I use 10 ml of a 10 ml of b and 25 ml of hygrozome root nute in a ten gallon resavoir with purified water.