Sorry I thought the mods didn't like the spread of false information? Pity now they're actually helping to spread it.
I'll leave you with a quote from the great Uncle Ben...he's got his name as a contributor the Jorge Cervantes Indoor/Outdoor Medicinal Grow Bible,so believe him,not me.
"Popular thought says that's the way they are supposed to look, but most times in cannabis forums, "popular" is nothing short of pure bullshit. *Folks use the ruse of yellowing leaves as *a cover up for not understanding plant culture.....not having the experience and/or knowledge to be able to retain a lot of healthy foliage until harvest.
It's not the leaves dropping off that determines the prime time to harvest, it's several factors including the rate of new calyx/pistil development, bulkiness of the colas, color of the resin heads, etc. *Bottom line - keep the leaves green until harvest and have as much foliage going into the flowering response as you can. *It's the leaves that will drive bud production.
Time to think outside of the box. *Welcome to the Uncle Ben No Spin Zone. *"