Help!!! 1/3 of my cannopy is wilited, and the rest is vigorous??

like the title says i have a large mother plant (about 4 1/2 ft tall) and about 1/3 of the canopy is extremely wilted while the rest of the canopy is looking perfect. i dont know if this is a root problem or a problem on the branch??? all the wilting is coming from the same branch so im thinking it must either be the plants branch has some sort of infection??? or maybe i have some kind've root bugs and thats why this part of the plant is dying?? ill attach the pic so you can see what i do.

the plant is under shoplight type t8's, 5 gal bags of FF ocean forest soil. ph of rez water is fine (6.4 - 6.8 typically). temp and humidity are not an issue.

any input or advice is much appreciated, thanks in advance!!

here is a pic of the wilted branch on the plant!!



here is a pic of the rest of the plant and how its doing!

a few things i forgot to add:

i have been using Azamax in foliar sparys, as a preventative measure, and also i use pyretheum bug bombs about once a month. about a week ago (before wilting started to show) i trimmed all the lower area's on my plant, all the dead leaves and small stuff that was underneath and never going to reach the lights. it seems to me that perhaps could have caused an infection on this certain branch?? i have a few other mother plants in this same room, no others seem to be affected, nor the rest of this plant - it seems to just be this branch?