Manganese deficiency ?

It could be manganese, it could be calcium, it could be phosporous... whatever deficiency it is, it is most likely caused by an imbalance of the PH in your soil. You need to check the PH of your runoff which should be between 6.0 and 6.8 for soil - anything outside of this range will cause the plant to be unable to absorb the nutrients and micronutrients it needs. Once you get that under control, you shouldn't see further problems but the leaves that are affected now will unlikely improve in appearance so don't expect that! Good luck!