mechanical harvesting in ‘Concord’ vineyards in the early 1970s, labor for dormant vine pruning became the largest production cost ( Morris, 2007 ). Mechanical pruning or prepruning ‘Concord’ grapevine research began in the mid-1970s with the intention of
Bruce W. Wood
-type pruning. Efficacy of mechanical pruning in relatively low-light environments was first tested during the 1970s by Worley (1985) in which it was concluded (based on drip-irrigated ‘Desirable’, ‘Elliott’, and ‘Farley’) that annual cuts to one of each of
low-light environment of the southeastern United States ( Wells, 2007 ). Mechanical hedge pruning has been used successfully in high-light environments to mitigate the effects of orchard shading ( Wood and Stahmann, 2004 ) and has become the standard
Yi Gong, Ronald B. Pegg, Adrian L. Kerrihard, Brad E. Lewis, and Richard J. Heerema
, mechanical pruning has become the most common orchard management practice to improve sunlight penetration into tree canopies. Specifically, mechanical pruning has been demonstrated in some studies to effectively increase light penetration and distribution in
S. Kaan Kurtural, Andrew E. Beebe, Johann Martínez-Lüscher, Shijian Zhuang, Karl T. Lund, Glenn McGourty, and Larry J. Bettiga
mechanical harvesting, it was proven difficult to facilitate mechanical management, such as dormant pruning ( Kurtural et al., 2012 ) and shoot removal ( Terry and Kurtural, 2011 ), with some success in mechanical leaf removal ( Cook et al., 2015 ; Yu et al
J.G. Williamson and R.L. Darnell
Mature `Sharpblue' southern highbush and `Beckyblue' rabbiteye blueberry plants were mechanically pruned at two heights on three dates after fruit harvest during the 1994 growing season. No pruning had occurred for at least 3 years (`Sharpblue') or 5 years (`Beckyblue') before initiating experiment. Pruning heights were 45 and 85 cm and nonpruned for `Sharpblue' and 45 and 95 cm and nonpruned for `Beckyblue'. Pruning dates were 3, 6, and 9 weeks after peak harvest for each cultivar. Regrowth was measured in Mar. 1995 before initiation of spring growth. Pruning `Sharpblue' bushes to 45 cm increased new shoot number and mean and total shoot length but decreased fruit yield compared to the 90-cm pruning treatment. No difference in yield occurred between the 90-cm pruning treatment and the nonpruned control. As time between fruit harvest and pruning increased, new shoot number, mean and total shoot length, plant height, canopy volume, and fruit yield decreased. There was no difference in yield between the earliest pruning treatment and the control. For `Beckyblue', mean and total shoot length of regrowth and flower bud density decreased with increasing time from harvest to pruning. Yield data for `Beckyblue' were not collected in 1995 because of gall midge infestation.
Stephen M. Southwick, W. Krueger, J.T. Yeager, and J. Osgood
French prunes (Prunus domestica L.) on myrobalan seedling rootstock were planted in 1981 in an east-west direction with 4.9 m between rows and 2.7 m between trees on a poorly drained Class II soil in Glenn County, CA. A randomized complete block design was used with 8 trees per plot. Trees were pruned by hand to an open-center tree form or pruned by machine to a pyramid form in the dormant or summer season resulting in 6 pruning treatments. This high density system has led to high yields of good quality fruit (9.18 dry tons/acre in 1989, sized at 78 fruit per pound). Hand pruning led to higher yields, larger fruit, lower drying ratios and a greater dollar return per acre than any of the machine pruned trees. Dormant machine pruning led to larger fruit produced than those trees pruned in the summer by machine. Mechanical pruning may be possible for short time periods, but continued practice led to smaller fruit with lower yields than hand pruning. Certain locations within the tree canopy had smaller fruit size and it is within those lower locations where fruit size needs to be improved. These and additional experimental results obtained from 1987 through 1989 growing seasons will be presented.
David C. Ferree and W. Timothy Rhodus
Annual mechanical hedging in August or root pruning at bloom was used to control the growth of four apple (Malus domestica Borkh.) cultivars in two orchard systems planted at half the recommended in-row spacing. Trunk cross-sectional area (TCA) per hectare on the trellis system was 30% higher, a result that correlated (r = 0.80) to a 40% higher cumulative yield per hectare over 10 years compared to the central leader system. Over 10 years, the cumulative yield and TCA per hectare of `Smoothee Golden Delicious', `Empire', and `Redchief Delicious' were higher in the trellis than the central leader system, while these characteristics of `Lawspur Rome Beauty' were not influenced by orchard system. `Lawspur' had the highest TCA per hectare, cumulative yield per hectare, and greatest tendency toward biennial bearing of the four cultivars. Root pruning reduced all tree-size measurements, while hedging did not influence tree height or average shoot length. Yield and yield per TCA were reduced by hedging and root pruning, with the greatest reduction in yield caused by root pruning. Hedging increased cumulative yield per hectare with root-pruned trees intermediate between hedged standard-spaced trees. Trellis trees had a higher density of spurs and shoots and a higher leaf area index than trees on the central leader system. An evaluation of the treatment combinations using net present value analysis indicated that none of the treatments was a profitable investment. Of the top twelve treatments, as evaluated for 10 years, nine were the central leader and three the trellis system, with none of the trellis and only four of the central leader treatments being hedged or root-pruned. Results of this study indicate that orchard intensification is accomplished best by choosing appropriate planting distances and not by attempting to control growth mechanically on trees planted too close for optimum performance.
Guofan Liu, Kent Kobayashi, H.C. Bittenbender, and Loren Gautz
Pruning methods 1.5 × 1.5 m (topping and hedging) and stumping to 0.70 m were used on coffee cultivars Guatemalan, Red Catuai, Yellow Caturra, and Mokka. In the hedged treatment, `Mokka' had the longest laterals, followed by `Guatemalan', with `Red Catuai', and `Yellow Caturra' having similar lengths. `Mokka' had the most nodes/lateral. `Guatemalan' showed the fastest growth (height), followed by `Mokka', with `Red Catuai' and `Yellow Caturra' having similar growth. For 0.70-m pruning, vertical lengths of `Guatemalan' were the longest. `Mokka' had the most vertical nodes. `Guatemalan' had the longest vertical internodes, followed by `Red Catuai' and `Yellow Caturra', with `Mokka' having the shortest. `Yellow Caturra' had the most laterals/vertical, followed by `Red Catuai' and `Guatemalan'. `Mokka' had the fewest. Lateral lengths, nodes/lateral, and internode length were similar for all cultivars. Two-meter pruning height may be best for `Red Catuai' and `Yellow Caturra' because of slow growth, shorter laterals, and fewer nodes/lateral. These two cultivars grew well after being stumped due to faster regrowth and more laterals remaining on new verticals. 1.5-m pruning appears optimum for `Guatemalan', but it grew very well after stumping. It may be better to prune `Mokka' to a 2-m height with a narrow canopy remaining because of its good multiple verticals, fast lateral growth from new verticals in canopy but not in full sun, and more vertical nodes but less laterals regrowing from new verticals on main trunks exposed to full sunlight.
Scott W. Dunn and James E. Klett
Perennials grown in 5.7-cm containers received two root treatments (mechanical root-pruned and non-pruned) prior to field planting. During the 1996 season, the two root treatments and five irrigation treatments, (0%, 25%, 50%, 75%, 100%) ET0 (reference crop evapotranspiration), were tested on Delosperma cooperii, Delosperma nubigenum, Polygonum affine, and Veronica liwanensis and evaluated on the basis of plant growth and visual ratings. No significant change in height occurred in any species for both root or irrigation treatments. No significant change in width or density occurred in D. cooperii, from root treatment; however irrigation treatments below 50% resulted in a significant decrease in width. Significant deceases in width also occurred in all species from irrigation treatments. Mechanically root-pruned plants resulted in a significant decrease in density of D. nubigenum, P. affine, and V. liwanensis and a decrease in width in P. affine.