Comparison of Slender Spindle and Vertical 

 Axis Tree Training 



Kathleen Williams 



Washington State University 



As the Pacific Northwest tree fruit industry moves 

 into the 2P' century, there will increasingly be an 

 emphasis on improving orchard labor efficiency and 

 fruit quality, as well as promoting early production. 

 Labor for pruning and harvesting operations is, and 

 will continue to be, the most expensive aspect of pro- 

 ducing fruit. Improved labor efficiency depends on 

 improved orchard design. 



Large trees of the Pacific Northwest (PNW) cen- 

 tral leader system pose significant problems in terms of 

 orchard labor efficiency and fruit quality. We as an 

 industry are looking to other orchard systems, primar- 

 ily from western Europe, to improve our orchard effi- 

 ciency. 



Two promising systems, the slender spindle from 

 the Netherlands and the vertical axis from France, are 

 currently under test in Washington State. Both of 

 these systems use a central leader tree with a support- 

 ing framework of laterals. 



However, there are significant differences in prun- 

 ing and training techniques for producing trees in 

 either of these orchard systems in comparison with, the 

 PNW central leader system. 



Slender Spindle 



The slender spindle orchard system was developed 

 in the Netherlands in the mid 1960's and has been 

 refined throughout the past 20 years. The system was 

 developed to optimize light interception and distribu- 

 tion throughout the tree canopy under the low-hght 

 conditions in the Netherlands. Furthermore, the trees 

 had to be physically easy to train, prune, and maintain, 

 because the Dutch labor supply depends on the local 

 people. The trees also had to begin producing early to 

 repay the high initial capital expenditure required and 

 allow growers the option of replanting their orchards to 

 newer, more profitable cultivars. 



The slender spindle and vertical axis systems were 

 developed and continue to be utilized primarily in the 

 management of non-spur cultivars such as Golden 

 Delicious. 



The slender spindle tree is a pyramid-shaped tree 

 that is always planted on a dwarfing rootstock, mainly 



M.9. Trees are supported with either a post or stake. 

 Tree height is maintained at 6 to 7 feet, and tree spread 

 is generally restricted to 3 to 3.5 feet in a single row 

 design. Tree density is 1,000 trees or more per acre, 

 depending on the tree spacing. (See Table 1.) 



Training the Slender Spindle Tree 



Year 1—At Planting 



A branched or "feathered" nursery tree is always 

 preferable to a non-branched "whip" as planting stock, 

 because production wall occur at least one year earlier. 

 The branched tree is headed 10 to 15 inches above the 

 highest retained branch. If there are upright branches 

 present which cannot be trained to a more horizontal 

 angle, they are removed. Branches below 18 inches 

 above the soil line are removed, because they will 

 interfere with herbicide applications, and the fruit will 

 be too low for convenient and clean harvest. If a whip 

 is planted, it is headed 33 to 30 inches above the soil 

 line. 



Year 1 - Summer (First Leaf) 



Vigorous branches are tied or weighted down to 

 the horizontal with non-spur cultivars. For spur types, 

 a less extreme horizontal angle is appropriate, e.g., 45 

 to 60 degrees. It is important with spur types not to 

 train weak branches to a horizontal angle; the branches 

 will be devigorated by fruiting and will eventually 

 "runt out". 



The optimum time for limb positioning, if tying or 

 weighing down, is mid July to mid August. However, 

 earlier improvement of branch angles v«th young 

 shoots three to six inches in length can be achieved 

 with clothespins or toothpicks. 



Care must be taken to keep the terminal ends of the 

 branches at a horizontal or slightly vertical angle; they 

 should not be allowed to bend down, as this can cause 

 excessive vigor in the lower portions of the branch. On 

 spur types, extreme downward bending can be too 

 devigorating. 



The first summer is when most of the pruning is 

 conducted on the young slender spindle tree. Vigorous 



FruU Notes, Fall, 1989 



