Havnt got a clue what this is but it's on about 3-4 leaf..on 2 of my plants..I originally thought it was nitrogen toxicity because there's a few leafs on each plants that are clawing too..an a few days ago before I flushed them with Ph'd water they was noticably darker green..also 1 plant is drooping fairly bad!someone said on get though that it's not nitrogen toxicity..also they have purple stems..i know some strains naturally have purple stems..but these seem to have got a darker purple..might be how they're ment to be I'm unsure.. the strain is white widow X big bud. so what could it be? I'm baffled!