Which of the following is not a true pathogen of turfgrass?

The option indicating slime mold is not a true pathogen of turfgrass is accurate because slime molds are not classified as true pathogens in the context of turf diseases. True pathogens typically target a plant's living tissues, causing diseases that manifest in specific symptoms like wilting, discoloration, or dieback. In contrast, slime molds are not plant pathogens; rather, they are saprophytic organisms that feed on decaying organic matter. They can be found on turfgrass, but they do not invade the plant tissues or cause the same types of disease symptoms associated with true pathogens.

The other choices listed—dollar patch, stripe smut, and white patch—are indeed true pathogens recognized for causing diseases in turfgrass. These pathogens can lead to significant damage and visibly affect the health and aesthetic quality of the grass, which is why they are significant concerns for turf management.