Rusty dry leaves

To me it looks like nitrogen starvation, with the beginnings of fungal attack (black blotches on the leaves). I would be feeding her a combination at half strength of both a mixture of "grow" nutrients and "flower" nutrients, being mindful of the need to keep humidity levels as low as possible. I would also be removing any yellowing leaves with black blotches too. Whatever you do, do not leave the pruned leaves in your grow tent, this will just accelerate the potential for fungal growth and/or mould to grow. Remove all pruned leaves right away from your grow area and wash your hands or wear gloves when pruning and either wash your hands or replace the gloves when moving onto a new plant to prune. This will slow cross contamination. Once your plants pick up and are producing healthier and greener new leaves, you can go back to giving them just plain "flower" nutrients. This won't take long, maybe a week to ten days or 3-4 applications of the "grow" and "flower" combination of fertilizers. Hope this helps... Organoman.