LSD-25 FastBuds =)

@mandragore, I couldn't really tell you man. We would need to know tons of details to try and diagnose it because it isn't one of the more common problems. If it is a single leaf don't worry too much, lots of leaves it might be a systemic problem. My biggest piece of advice for when you run into problems like this is to do a nice flush for the plants depending on what medium they are in then slowly add back in your nutrients but make sure you are using a complete and balanced nutrient line and feed as directed. Lots of these feed lines are specifically formulated to work together so removing one thing and substituting another may leave gaps in your plant's nutritional needs. Don't try to get fancy decreasing this and increasing that until you are very experienced or it is a clear cut issue like Ntox. That will solve 40% of your problems right there . You can solve another 40% of your problems by making sure your ph is spot on. The remaining 20% or so of your problems you are going to need to look at charts that show all cannabis excesses and deficiencies to determine the most likely cause. Also remember that old leaves will most likely never recover after showing damage signs. Look at the new growth and know that your plant is always about 4-7 days behind whatever you are doing. Sorry I can't be more help bud but we need a lot of information. Best of luck and happy growing.

@CANNASIM,as you said, it's hard to tell without seeing the plant and no informations on the life cycle ... @mandragore, is it just one leave ? Is it from the bottom ? What's the plant life cycle ? How often do you water/feed the plant ? You must show us the entire plant bro .

@mandragore, Isolated like that is hard to tell, I suggest you create a diary for her. Judging only by the leaves look, this deficiency could be a mineral lock in Calcium and or manganese thise cause spotting s , seen the plant would help because it could be also Leaf Septoria which is a fungus that causes that type of yellow spotting, then turns brown with time, as I'm not sure you should get other opinions... Guys you have any ideas judging by the leaf only? @JUNGLE_B4RNS @Grimbol

@CANNASIM, I will use this the next time i harvest, thanks