Fungal Pathogens of Cheatgrass
Cheatgrass has many natural enemies, since it can be an abundant source of food. Its leaves, roots and seeds are eaten by insects, such as grasshoppers or ants, as well as by rodents and other animals. A host of microorganisms also use cheatgrass as a resource, with varying impacts. Out of this diverse array of natural enemies, fungal pathogens are the most promising for biocontrol.
The third fungal pathogen, (Pyrenophora semeniperda), which we call BFOD, attacks seeds in the seed bank. It has a broad infection window, and so far it shows great promise as a biocontrol agent. It could be used to remove the carryover seeds that cause problems in restoration seedings of other species.
We have investigated the biocontrol potential of
three fungal pathogens on cheatgrass. Two of them, head smut (Ustilago
bullata) and chestnut bunt (Tilletia fusca), infect
seedlings, then grow inside the plants as they mature. Instead of
producing seeds, the plants then produce spores of the fungus. These
pathogens have very narrow infection windows, which limits their usefulness
as biocontrol agents.