First time grower here. These are two different plants, both about 3 weeks into flowering, grown in soil, and I've been feeding them Advance Nutrients Micro, Grow, Bloom, CalMag, Big Bud and Bud Candy. So far they've had no issues....now this? Anyone have any idea? Both plants are showing this on a lot of the leaves.
Sorry, I've not really figured out how to take pics under these purple lights. Many of my leaves are getting these rust spots on them.
Just use a different light while taking a picture, if it happened overnight I would think something sprayed on the plant, really hard to see much with purple lighting though
Without looking at the pictures, calcium deficiency can cause rust spots. If you have dark leaves with rust spots, manganese excess is the suspect.
It looks like cal deficiency however your list of nutes shows cal/mag. This leads me to believe ph issue causing lockout. There is enough cal in your soil but your ph may be off cause it to be locked out.