Thank for the reply but I wan't talking about mg deficiency but Mn (manganese) deficiency. And I thought N def always starts at the bottom and works its way up? I have that "nutrient disorder solver" chart and according to that it is either mn, sulfur or nute burn. The pictures I have seen of these deficiencies are all late stages of the deficiencies and so I can't be sure which is mine because it just showed up. I don't want to wait til they get too far gone before I do something.