Rusty spots on sugar leaves?

[Crane]

I have four plants under a 315w cmd. Today is day 42 in 12/12. Three of them are HSO choc mint OGs and one is Dinafem Cheese CBD. The problem is only with the Cheese CBD.
They grow in BioBizz All Mix, and I've been feeding them according to the BioBizz chart with BB grow and bloom. They got calmag once at the start of flowering. Day temps 28, night 20. RH has been about 50 but I just stopped humidifying because it's getting pretty crowded, now it's 30-40.

These rusty spots just appeared on the sugar leaves of the Cheese CBD like 5 days ago, everybody else seems fine. What could be the cause? Thanks!!

 

[goofyfoot]

to much nuit`s, give a good flush then let it dry out for 5 days. I am growing Dinafam Blue Haze Autos and I got a little heavy on the P and K as they got going in flower. Had the same thing happen. Less is more sometimes.

 

[Crane]

Thanks! Yeah I've been giving nutes every watering... last grow I gave too little and was trying to avoid that now. Happy medium is where it's at I guess

 

[Conradino23]

Yes this is a burn, most likely too much magnesium. You might've cause a lockout too, so lay off everything for at least two weeks.

 

[Crane]

Thanks everybody.