I panted 9 forsythia bushes, potted, and they were about 2 ft tall in the pots. This was in June. They all look great except one, it turned brown almost all over and promptly died. There are a few green areas, but almost all of the leaves turned brown. I am thinking it may have some kind of bacteria or fungus? So my question is, 1. How do I treat it, can it be saved? 2. will winter cold kill whatever it is so that it will come back next spring healthy? and 3 will it spread to the others? Maybe I should pull it out to keep it from spreading and if I plant another one in the same spot will it become infected?