Bacteria have no means of penetrating cells, so they must enter plants through natural openings or through wounds. Once inside plants, they cause injury by producing toxins, or they can plug vascular tissues.
Initial symptoms appear as wilting, and the leaves develop a blue-green color.
This stage is short-lived. Individual infected annual bluegrass plants then turn reddish-brown or yellow and die in spots about the size of a dime. Large areas are destroyed in a non-uniform pattern within a few days. The disease should be confirmed by a pathologist. Bacterial wilt is on the rise, primarily in the mid-Atlantic and Northeast, the increased incidence due in part to the trend for very low mowing heights and a higher frequency of topdressing.