I think a big problem is that, like magnesium, nitrogen deficiency has sort of become an automatic assumption on here. If any foliage is yellow, up the grow. It's just not the case and the sooner people realise this the better for not only that grower, but the one after who he passes that knowledge on to.
N def shows clearly on the lowest leaves first. It's gradual and it's usually a problem in isolation and, like I say, treated by just upping the feed a bit.
These threads are a good learning tool not just for the op, but for me, and anyone else reading them. Like I said at the beginning, I only really read this to validate my own opinion. When I saw the problem on the first page I made my own mind up. I only carried on reading to see the results of the advice given. That way it helps me to understand the problems a bit better so I can apply that to my own grow.
Diaries are a blind test if you like, where the end pages are the results and whether you were right or not. For example, I read someones diary the other day. I saw their end product and it gave me an idea of what had happened earlier in that diary, so I read back over the earlier pages to see.
It's all confirmation and it all helps to understand the basics of growing, because that's really all it is.
In the first pictures in this thread, the very tips of the leaves are curling down. That's usually the sign of an excess in N. I would never up the N in a plant which showed that sign, ever. It will, in my experience anyway, always lead to burn and worse problems to follow.
What I'd have done at that point is dependent on what you were feeding at the time. It depends on what they looked like at the very end of veg, and what symptoms they showed first. A lot of the time the ability to treat and diagnose problems just depends on how early you spot something is wrong, and how quickly you post that picture. A plant with an excess of nutes for example, might first show a curled or burned tip. Show a pic at that point and you might get an easy and quick answer. Let it go further and the leaf might pale or other nutes might get locked out, and then people might misdiagnose a nute deficiency and advise you to up your feed.
I'll show you one of my plants now and you can see what I mean.
This post has been edited by papaduc: 15 March 2012 - 12:57 PM