LST Stem Problems

Does anyone have any experience with the stem cracking open from LST? My stem on 2 of the 3 plants has broken open within the last couple of days. I haven't tied them down since I started 12/12. It almost seems like it couldn't handle such quick growth. It is literally split open and kind of freaks me out. You can't see through to the other side but you can see the lowest node inside the open wound.

It doesn't seem to be affecting the plant yet but I just noticed it last night.

Also, a lot of my growth under the canopy is wilting and dying. It gets no light down there because of the bushy growth above. Should I just let it all die down there or should I trim some of the bigger fan leaves to get more light below?

lossen the ties on that branch to close the split it will repair itself and grow a big knot there I wrap mine with a small peice of cloth and tie around damaged area...not to tight keep that one loose for a week should be healed or almost then bee more gentle it happens they grow so damn fast....if you cant losen ties cause you screen them just try to crawl under and cover the split dont want it to dry the inner stem hope that help it'll fix itself mine always do...... aarrrrrggghh leave the fans alone let the under growth die off naturaly it feeds the top canopy where growth can use light cutting fans slows growth try to push them down around buds if they shade bud sites but dont cut jus my 2 cent have fun grow on

Thanks for the amazingly fast reply NotMine.
I'll try to cover it with a small strip of cloth to prevent the inside from drying out. I'll also stop clipping the lower fan leaves. I hope it all helps them.