ISHS Acta Horticulturae 705: V International Walnut Symposium
WALNUT TRAINING AND HEDGING FOR EARLY PRODUCTION AND PROFIT - FINAL REPORT |
| Authors: | W.H. Olson, B. Lampinen, S. Metcalf, W. Micke, D.E. Ramos |
| Keywords: | English walnut, Juglans regia L., tree training and pruning, mechanical hedging |
| Abstract:
Standard training of young “English” walnut (Juglans regia) trees in California consists of removing branches below 1.5 – 1.8 meters from the ground, heading the leader as well as desirable scaffold limbs and leaving some less desirable branches temporarily for early nut production. A modification of this system, called “low scaffold” training, which potentially can increase early nut production and early trunk size, is to keep and annually prune back the leader and all low scaffold branches above 0.9 meters from the ground that make good growth and leave all other short branches alone for early nut production. Both methods of training begin in the second leaf and continue until trees are near full desirable size, at which time branches below 1.5 – 1.8 meters are removed and crowded branches thinned out. The performance of the two training systems was compared through the eighth year in a J. regia “Chandler” walnut orchard on two rootstocks: Northern California Black walnut (J. hindsii) and Paradox (J. hindsii × J. regia). With the “low scaffold" training system trunk size was significantly larger in the early years of the experiment and production was significantly greater until the last year of the experiment. Annual or biennial pruning of mature walnut trees is expensive and time consuming. The use of a mechanical hedger in place of hand pruning can get pruning done quickly and at less than half the cost of annual hand pruning. Various hedging strategies were evaluated for eight years in a mature Chandler walnut orchard. Final production and nut quality comparisons indicate that certain hedging strategies are more advantageous than others and more advantageous than the non-hedged/non-pruned treatment. Solar light interception data suggest that production is directly related to canopy light interception. | |
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