Examining Rootstocks and Vitis Species for Non-host Resistance to Pierce’s Disease

Major Objectives:

  1. To screen the following commonly used rootstocks for the ability to be symptomless carriers of, or non-hosts to, Pierce’s Disease Bacteria (PDB): St. George, 5C, 5BB, 161-49, 3309C, 101-14, Schwarzmann, 44-53 Mgt, 11 OR, 1103P, Ramsey, Freedom, Harmony, 039-16.
  2. To screen selections from rupestris X rotundifolia seedling populations for resistance/non-host status to PDB.
  3. To screen 4 accessions of each of a range southern Vitis species for susceptibility to PD; the ability to act as non-disease expressing carriers of PDB; and the ability to be non-hosts to PDB.
  4. To test the possibilities of grafting vinifera scions onto an infected stock/trunk combination, and grafting to non-hosts identified above under greenhouse and Davis field conditions, in preparation for future field studies.


We have prepared plant materials for PD screening, developed the inoculation system, have optimized the PD – PCR detection system, and have seedlings from a cross of Chardonnay X (rupestris X rotundifolia). These plant materials will be inoculated with PD during summer 1998 and results should be ready near the end of 1998.