Wrapper leaves left behind after cabbage harvest have active black rot lesions. Disease could easily spread to the nearby fall cabbage crop. Photo: M. Grabowski, UMN Extension By September, many crops have accumulated some level of leaf spot, fruit rot or other disease problems. Even if these diseases are not severe enough to reduce yields this year, many plant pathogens are able to survive in crop residue from one season to the next, resulting in disease problems in following years. Several basic cultural control practices can be used to reduce the risk of disease spread to other crops in this growing season and the next. First diagnose any unknown plant diseases in the field. A few plant pathogens, like white mold or Tobacco Mosaic Virus are able to survive exceptionally long periods of time in soil and crop residue. It is important to identify these problematic pathogens early, remove infected plants promptly, and follow sanitation procedures specific to that diseas...