Peach Latent Mosaic Viroid Reduces Tree Growth and Affects Fruit Quality in Peach

Abstract

`Coronet' peach on Lovell rootstock was planted near Clemson, S.C., in Dec. 1995 in 4 rows (= reps) 6.1 meters apart with trees 2.2 meters apart in-row. Trees were trained to a Kearney-V. In the 2nd leaf (Aug. 1997), `Ta Tao 5' buds were grafted to half (= 6-tree plot) the trees in each row. These trees received 2 `Ta Tao 5' chip buds infected with Peach Latent Mosaic Viroid (PLMVd) per scaffold at ≈0.75 to 1.15 m above ground. Dot blot hybridization confirmed that the chip buds successfully (100%) inoculated the treated trees, whereas the controls tested negative. Data collected in 2003 included bloom date, tree size, dormant and summer pruning times, fruit maturity date, fruit yield, mean fruit weight, skin color, soluble solids, flesh firmness, titratable acidity, and pH. 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 had been larger in PI trees in previous years. There were no differences in yield efficiency in 2003, but PI trees were 26% smaller in trunk cross-sectional area and 9% 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. PLMVd increased fruit firmness, and PLMVd fruit lost firmness at a much slower rate. PLMVd did not significantly affect skin color, but PLMVD fruit were slightly less red. Soluble solid levels were higher in PLMVd fruit than control fruit during the first harvest, but were lower by the last harvest. Acidity was significantly higher and the soluble solids to acidity ratio significantly lower in PLMVd fruit. Control fruit had a slightly higher pH.