what kind of issue is this **pics**

Im 38 days into flowering. nice buds are really forming. but on a couple of plants i have this issue (pics below). plant is sour candy and i have a skunk thats starting to follow with the same condition. but the rest of the other 6 plants are not showing sings of this yet. just them 2. This browning is at the top not so much on the bottom leaves but the little cola leaves got it. . i havent change but two things there whole life and that was the last watering i added 1 more tsp. per gallon of tiger bloom. i was adding 2 per gallon and uped it to 3 per gallon. and the heat in my area has been pretty high to 90 at times. might be causing it to. so take a look and give me an idea please. As far as p.h it is soil so it generaly stays 6.5 to 7.5. there in 3 to 5 gallon bags. under 600 watt light abut a foot above them its not burning it at all.
nutes are:
tiger bloom 2 tsp (last wattering i added 1 more tsp.)
fox farm grow big. 1tsp per gallon
dark energy half tsp per gallon
bush doctor 2 tsp. per gallon.
could it be heat or burn?? how do i change it
to me from doing research it really is looking like mag. def. especlly with the info provided here
http://www.icmag.com/ic/showthread.php?t=11688
But im really unsure and dont want to go doing shit i didnt really need to.

i got to do something with this by tonight so i need some help here guys. I'm doing alot of searching and I'm comming up with mag. deff. anyone see anything different? like i said temps have been high for the past week. upper 80s. not cuz of the light either it cuz of the environment there in cant control Temp that well. but its gonna be colling down to the 70 again out side.
I also want to add molasses to my plants. Ive been Reading about that and a tsp per gallon seems to be good for them about now. so should i clear up the mag. deff. first or jus continue to add my nutes and throw 1 tsp of Epsom salt in as well? i did give then jus a little water p.h last night. so/ help here guys please.

hate to ask instead of answer, but what are you growing in, and where did you get the nute concocksion?

but really, i think your over doing it.

guy at the hydro store. gave me the nute set up and instruction. and its growin in a store bought mix of perlite and coco and soil. i water about every 5 days 2 3rd if a gallon maybe per plant

im thinkin that those measurments are per ingrediant not all at once. sounds more like a hydro concocktion.

i put all 4 in per gallon of watter and have been since they were small per the guys at the store telling me to do so

Im new at this too and when i asked, he gave me one margarine type container of 10/30/20. Enough for 10yrs @1/2 teaspoon per 2 liters. Later i went and got a 20/20/20 same container, same measurements, just for veg. The 10/30/20 for flower.

could be the same thing, just together in one.

probly. so does anybody at least know if i gotta flush them before adding epsom salt? im sure its mag. deff..

im pretty dissapointed in RIU. nobodys is giving me an answer for shit..

i was having the same issue just feed straight water and c if they come around can u pull the plant out from under the light to get a better pic the hps is yellowing the pic hard to c

so this happened after u upped the tiger bloom u might of over did it like i said just straight water for a few waterings and c what happens

bought some epsom salt and added it to my water 1 tsp a gallon. well see what happens