Blotch on plant

i would raise pH to 6.5-6.8 before adding anything and see if that fixes the problems. simply pH feed and irrigation to that level. It'll raise the soil's pH slowly - the best way. pH, concentrations and ratios of elements are all equally important.. any one of these are off, and you can see symptoms of anything even if it is abundantly presetn -- just not available do to competition or other concepts of chemistry involved. If you have these dialed in, you can react with more confidence to leaf symtpoms... Also, check out my nute spreadsheet that can add up all your products based on labels and spit out some ppms for you. Link is on my profile page - comments. Lots of other great info there that gives a proper perspective on things too. now, as far as that leaf... did you drip anything on it by chance? otherwise, i can't confidently tell you what likely def or tox could cause that.. i'm not as familiar with microbial and pest symptoms. ILGM.com has a pretty good 'symptom checker' you should read through too.