Plectosporium blight (Mirodochium blight), caused by the fungus Plectosporium tabacinum (Microdochium tabacinum) is an important disease of pumpkin and squash. This disease was first reported in Tennessee in 1988. It was subsequently reported from most of the pumpkin growing areas in the United States. Plectosporium was first diagnosed in pumpkin fields in Illinois in 2000. The disease was observed in most of the pumpkin fields, causing more than 50% yield losses in some fields (Figure 1). The most susceptible cucurbits to Plectosporium blight are pumpkin, yellow squash, and zucchini squash.