I've a 6 ft rubber plant in a pot in my porch. It was getting too tall and I pinched the top out to encourage side shoots which it did. However the main stem has stared to wither and die from where I pinched it out. The rest of the plant below this is healthy and has side shoots but as the withering has moved down the stem the new side shoots have also died. From being 6ft the plant is now 4 ft. Can I stop the main stem from dying back.