A need exists to manage or manipulate plant pathogens for biocontrol of weeds in row crops. Many weed species remain refractory to conventional weed-control technology. Some of these weeds occur in the same families as important crops and are resistant or tolerant to many of the herbicides that are applied for weed control within those crops. Preemergence treatments are needed for some weed species for which only postemergence treatments are now available. The cost of controlling some weeds is so prohibitive that many farmers will not spend the necessary money; therefore, more economical control is needed.