THE PEACH LATENT MOSAIC VIROID IN THE KEARNEY-V TRAINING SYSTEM FOR PEACH

'Coronet' peach trees on 'Lovell' rootstock were planted near Clemson, South Carolina in December 1995 in 4 rows (=reps) 6.1 meters apart with trees 2.2 meters apart within each row. Trees were trained to a Kearney perpendicular-V system. In the 2^nd leaf (August 1997), 'Ta Tao 5' vegetative bud grafts were applied to half (=6 trees or 6-tree plot) the trees in each row. These trees received two 'Ta Tao 5' chip buds infected with Peach Latent Mosaic Viroid (PLMVd) per scaffold at ~ 0.75 to 1.15 m above the ground. Dot blot hybridization confirmed that the chip bud grafts successfully (100%) inoculated the treated trees, whereas the controls tested negative for PLMVd. Data collected in 2003 included bloom date, tree size, dormant and summer pruning times, fruit maturity date, fruit yield and mean fruit weight. Flowering and fruit maturity were delayed by ~4 days in PLMVd-inoculated (PI) trees. PI trees produced larger fruit, but yield was 23% less than that of non-inoculated trees. Both fruit size and yield were larger in PI trees in previous years. Cumulative yields per tree after 8 years were statistically higher in PI trees than the controls (101 vs. 90 kg). There were no differences in yield efficiency in 2003, but PI trees were 26% smaller in trunk cross-sectional area and 7% shorter. PI trees took 34% and 23% less time to dormant and summer prune, respectively and had 34% and 28% less wood removed by dormant and summer pruning, respectively, than control trees. PI trees in the Kearney-V system had lower pruning costs and yielded equal to or better than non-PI Kearney-V trees in 5 of the 6 crop years.