Articles
EFFECT OF PRUNUS VIRUSES ON GROWTH AND YIELD OF ITALIAN PRUNE TREES.
Each of 50 virus-indexed, 5 year old Italian prune (P. domestica) trees were inoculated with two buds from 12 virus sources.
Prunus ringspot sources were: RS-31, 19NY, M-52 Rugose strain, and V-19, U-437 Chlorotic strain.
Prune dwarf virus (PDV) isolates were V-5 and V-15. Sources of PDV + PRSV were RS-19D, Barbard 3–22. U-494, U-547. All three sources of Recurrent Ringspot Virus (RRSV) originated from S-5009, but one came by way of California, one from Oregon.
The bark splitting virus (BSV) was also used as inoculum.
Myrobolan 29-C that indexed free of known viruses was used to inoculate the control trees.
Growth, over a period of 4 years, was measured as trunk diameter and converted to trunk cross section area.
The PDV infected only a small portion of the tree(approximately 15 cm) and did not appear to effect growth or yield.
Yield was obtained for three consecutive harvests.
Data for each tree was totaled and then averaged for each virus isolate.
No significant differences in growth were found within the strain of any virus or virus combination (Table 1). Therefor, data was calculated to include all trees inoculated with a particular virus or virus combination (Table 2). There was no significant difference at .05% in tree growth among the trees inoculated with either PRSV or PDV or PRSV +PDV isolates (PRSV = 8328 cm2, PDV = 89.9 cm2, PRSV + PDV = 87.1 cm2, PRSV + PDV =86.7 cm2). Significant differences in tree growth were obtained for tree inoculated with BSV (119.2 cm2) and the inoculated controls (203.4 cm2). No significant differences were found in yield between isolates containing strains of PRSV (PRSV = 24.1 kg, PRSV + PDV = 28.3 kg, PRSV + PDV = 24.7 kg). Yield from trees inoculated with BSV were appreciably higher (54.3 kg) than trees inoculated with strain of the PRSV.