sp. and other herbaceous plants.
Fusarium may enter through roots or at the soil line (collar rot). Plants wilt, then turn brown and die. Plants may go "piece meal" or all at one time.
Fusarium lives in the soil. It normally helps break down dead plant material. However, when some plants become stressed, this weak pathogen attacks and often kills the plants.
Control is to fix the stress on the plant (usually a root stress) if the plants are slowly declining. If the plants die, wait several years before planting again with susceptible varieties.