To prevent this issue, you need to provide your plant with excellent rotation, giving them enough space. This space also has to be clean, so if you see a lot of fallen leaves, it's better to clean the ground from them because rotting leaves are very attractive to fungi. Mulch is not an obvious recommendation, but according to some research, mulched plants are less inclined to various diseases, this one included. This disease often happens when you save seeds from the previous year since the pathogen can overwinter. So it's better to save only healthy plant seeds or to buy the seeds from companies with a good reputation.