How long into flower and what you are feeding them would also help.
That doesn't look like burn so much as a deficiency of some sort that has been going on for a bit. Nute burn usually affects the edges of the leaves. That seems more like inside out. Or I could just be baked. Either way more info is needed. Jmo
That isn't nute burn, at least not the typical nute burn. Typical burn begins with the leaves curling down like claws. Then the tips off the leaves begin to die (necrosis), looking like someone held a lighter to the very tips off the leaf fronds.
That appears to be a Phosphorous deficiency, but without more details on the grow, its hard to say. It could be a pH issue or over-chem issue that is locking out the P. Or it could be a toxic build-up of salts that is causing that.
My apologies on the delayed response to you all, had to leave town on short notice. Here's a few pics of the entire plant. Also I should tell you that this is the maui waui in which I have pics of the buds in the photography section.
no it's not nute burn. i believe it is using up some of the leaves, but in saying that i believe the plant is looking for something. what are you feeding it? what is your water ph? lets start with these two and go from there.
the only thing i can suggest is maybe a little cal/mag. looks like you have the others covered. the last two grows i did was 10/10/10 all the way through with a little epsom salt and molasses during flower. i had really green leaves all the way and didn't drop that many. by the way nice looking plant.
I see the problem. You need to add some dolomite lime to the soil, or mix some powdered into the next watering and pour into the soil. You are growing in soil using organic nutrients, that means you need to maintain a pH of about 6.5-6.7 for healthy plants and soil. The dolomite lime (needs to be powdered not pellet) will buffer the soil to the proper levels and will provide some magnesium. You need to do this right away, about 2-3 TbSp in that pot and try to stir into the soil before watering (or mix with water then pour into soil)
You are seeing some lower "yellowing-off" which is not at all unusual when late in flowering, or when the leaves are low on the plant and not getting much light. But given the size and age of your plant, I would be more inclined to think the most of the problem is the low pH.