This is a bit difficult to answer ... for one thing, we'd need to know what you're giving her in terms of nutes... I agree with Aldo90 in that she probably needs more PK - but I also worry that you're giving her a bit too much nitrogen as the rest of this leaf is very dark green - and if she's lacking in PK, it might be the result of a nitrogen toxicity - or it could be that your pH is not at the right level ... Best thing to do is to link your question to the diary it pertains to so we can take a look at the whole picture.. At the bottom of the diary page, there's a box where you can submit a question... this will link the question to the correct diary...
Good luck!