Differential susceptibility of three grapevine cultivars to Phaeoacremonium aleophilum and Phaeomoniella chlamydospora in California

One-year-old wood of grapevine cv. Thompson Seedless, Grenache, and Cabernet Sauvignon were pruned and the pruning wound immediately inoculated with a spore suspension (approximately 1 x 10(6) spores ml(-1) of water) of Phaeomoniella chlamydospora or Phaeoacremonium aleophilum. Based on the incidence of esca 3 years after inoculation, Thompson Seedless was rated as the most susceptible of the 3 cultivars. The results are consistent with the observed incidence of naturally-occurring esca in California vineyards on these three cultivars.