I a grow journal in my sig but here are current details: Blackjack and Maui Wauix Hawaii are the two strains High humidities the past two weeks near 40-60%. Past week has been 40-45%. Temps are 77-82. I have a large box fan on it's medium setting and an inline fan pull 240CFM from the 100sq ft room. SIP style so it's automatically watering/wicking. 4 27 W cfl and a 250W HPS. What im seeing is this dampening off type work being done on now my 6th stem. Skim through my journal to see more but here is just one example. I havent read a single thing about stems doing this in flower..so any suggestions are welcome!
Oh yeah! You got bugs bad, Bro. That might be why this is happening. I see that other brown crispy leaf in the pic, too. It might be because of low light under the canopy. I wouldn't worry about that branch too much. Sometimes it happens. The more important issue is the bugs. Get some neem asap. Spray everything in there top and bottom of leaves as soon as your lights go out. Spray the dirt too. If there are thrips in there also, which it does look like. They lay eggs in the soil where as the mites lay eggs on the underside of the leaves. Good luck!
So I'm surprised you noticed that as mite damage so quickly to be honest as i didn't have a lot of questions raised in my journal abut them. Those leaves, from what i've seen over my grow have continuously been like that. I just pulled a leaf that had yellow spots all on top of the leaf but not on bottom, which seems to be a bit newer and getting worst as flowering professes. All i see is white flakey substances that don't rub off and aren't accompanied by eggs or insects. I have done two full sprays now using Azamax. Mites arent abundant..as ive spent almost an hour with my scope today and only coming accross like 4. More than i want of course! I have some pepper spray coming my way and i will spray using that instead of the azamax until i dont need to anymore. I've never seen a thrip on my plants btw! I also attempted to check the soil using my scope and came with nothing.
Well that's good. Its probably old damage we are seeing or its just the way the photo came out. The branch could possibly be from being hurt or damaged. Maybe you had accidentally bumped it at one point. It actually looks a lot like low light to me though. If that is the only branch doing that then its obviously the plant cutting of flow to it for some reason or another.
If I count them right, it has happened now 6 times. There's no real movement in there except occasionally me and then the fan.