Deficiency or a burn?

This is a picture of my 5 week old white widow growing in organic soil under 400w MH light. The tips have turned yellow and the new growth on top is yellow. She had her last dose of pure blend 3-1.5-4 12 days ago. It was given at a rate of 1 tsp per gallon. Her soil is a pH of 6.9 and the run-off was a pH 6.5. The problem is just at the top half of the plant. There are no brown spots on the leaves or tips. I'm not sure if this a sulfur or Mn deficiency or a nute burn. I have other WW growing in the same soil mix and had received the same nutes and they are showing no problems. Can anyone offer a suggestion?

no it's not Mg. It's probaly nitrogen. when ever im not sure i give em 1/2 strength fish emulison. It's organic so its easy on them. you will see visual change in about 24 hours.

nitrogen is the most common in veg stage. as well it makes the new growth a lighter green. Mg will cause the lower leafs to yellow intervenualy

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.

were you high when you read his comment?