Field Susceptibility of Four Peach Rootstocks to «Phytophtora citrophthora» and «P. syringae»

Abstract

Four two-year-old peach rootstocks were assessed for susceptibility to Phytophthora citrophthora and P.
syringae. Peach rootstocks reacted differently to each Phytophthora species. GF677 rootstock was the less susceptible
to P. syringae. The other rootstocks inoculated with this fungus did not differ significantly in the average necrosis
length produced. Also peach rootstocks inoculated with P. citrophthora showed different level of susceptibility. Inoculation
of GF677 plants with P. citrophthora produced the largest necrosis of all rootstocks tested. There were no
significant differences in the lesion lengths of PR204, GF305, and KID I plants. The results from laboratory experiments
with both fungi were similar to those from the field experiments: any observed differences can be attributed to
differences in the physiology of the plant tissues and in the aggressiveness of the fungi.