Rust spots!! Please help

View attachment 1177030Hey all

I have these rust spots on my hash plant leaf. It's only on 1 leaf out of 12 plants. This leaf is on the tallest plant. It started lighter then got darker. Otherwise leaf is healthy. No sign of bugs, ebb and flow flood 2 times a day 10 min, gh nutes.


Any ideas?

Did it start from bottom to top, nute lock, mag def, heat stress. Is it in veg or flower, type of light, feeding schedule, test equip., ect, ect, the more you tell the better people can help you. There are plenty of these on the web also... http://www.drugs-forum.com/growfaq/97.htm http://www.angelfire.com/cantina/fourtwenty/

Best of luck turning it around.

Middle, largest leaf
Canopy is 76 degrees RH 50%
6 days VEG
400w HPS
10 min flood 9 am 5 pm lights out 8pm-8am
oakton ppm meter gh ph kit

It started a few days ago and really hasnt gotten any worse. seeing signs on a few leaves on some other plants. Thinking foliar feed with cal-mag?