deficiency or neem oil burn?

i recently used neem oil on these a little under 2 weeks of flowering, with sm-90 and a pyrethrin insecticide, i didn't imedietly put them under the lights but let them sit for about 15-20 minutes before i put them back under the light. these are all about 3 feet away from 1000w HPS lights temps were around 75 degrees, mixing instructions were followed exactly.

Plants are in 15 gallon tubs, were doing until i sprayed them, but i can't infact remember if the tips looked like this before or after ( damn weed getting to me). Never ran into this problem, i know its not nut burn because iv been using half strength of my flower nuts for this so far, filtered, ph is 6.5, fresh air, everything else is good. just not sure what caused them to do this.

It is pretty hard to see, but i want to find out before i give it more nuts, notice the very tips of the leaves are narrowed into brown think dead spots, and the edges. Im thinking potassium deficiency. but not sure. let me know and ask any questions. thanks.IMG_20110502_232331.jpgIMG_20110502_232513.jpgIMG_20110502_232513.jpgIMG_20110502_232614.jpgIMG_20110502_232529.jpg
 
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