Pruning efficiency, fruitfulness, and yield and quality of raisins of `Thompson Seedless' (Vitis vinifera L.) grapevines subjected to several canopy separation and defoliation treatments for DOV raisin production were evaluated. Canopy separation treatments, tested in vineyards at Easton, and at the Kearney Agricultural Center (KAC), Parlier, Calif., were as follows; horizontal canopy separation with vine sections of fruiting or renewal zones (Peacock), horizontal canopy separation with vine sections of fruiting zones of one vine adjacent to renewal shoots of the next vine (wave), or non-separated (control). Defoliation treatments included burning or blowing leaves (Easton), application of concentrated solutions of calcium ammonium nitrate or Etherel to leaves (KAC), or no defoliation (both vineyards). Canopy separation treatments did not affect berry size, soluble solids, or raisin yield. Vines subjected to Peacock training had more cluster layers than vines subjected to wave training, at Easton, and more cluster layers than vines subjected to control training at KAC. Canopy separation reduced harvest pruning time by 20% at Easton, but not at KAC. No treatments affected raisin moisture at Easton but, at KAC, raisins of vines trained in the Peacock style had 10% higher moisture contents at harvest than raisins of wave or control vines. Vines subjected to conventional training and leaf blowing had about 40% higher “B and better” raisin grades than vines with separated canopies that were not defoliated, and about 30% higher grades than vines with conventional training and leaf burning. However, raisins of vines subjected to blowing had about 60% more mold than raisins of non-defoliated vines. Defoliation treatments at KAC did not affect any variables measured.
Canopy Separation and Defoliation for Dry-on-the-vine (DOV) Raisins on Traditional Trellises
