What is this?

What is causing this? It's an older leaf. Plant is on day 50 flower. Sour diesel. Using fox farm nutes. 315 CMH. Seeing it on a few leaves. Buds looks great though.

its cal def. nothing to worry to much about. my advice is to supplement with calmag

iDab666 said:

its cal def. nothing to worry to much about. my advice is to supplement with calmag

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Perfect. Thank you. I've never had that happen before.