Presence of the bacteria in an area dictates in many cases the success or failure of a vineyard. The bacteria is spread by xylem feeding insects. In other states sharpshooter leafhoppers and spittlebugs have been identified as vectors. In Texas, the exact vector or vectors are not known. The presence of leafhoppers does not automatically mean that they are Pierce's Disease vectors.
Field observations based on plant symptoms suggest that the bacteria spreads from vine to vine.
Disease centers are observed to spread outward from an infected plant. Movement inward from the edge of the field has also been observed in some locations. Losses to the disease are most severe in East Texas, Gulf Coast area, Texas Hill Country and Central Texas. It has also been identified in one vineyard in Jeff Davis county in West Texas. Not all vineyards in counties where the disease has been identified are infected with the bacteria and even in those where the disease has been identified, losses vary in severity.