I agree with your assumptions, Dave. We have over 200 rows of trees, about 1/3 being tall spindle. We build out trellises with 12' posts, typically 8" thick posts (6" on shorter rows of 400' or less) leaving 4 feet in the ground.and 8 above with our top trellis wire being on top of the post at 8'. We keep our trees at 8 to 8.5', mostly m9 and m26 rootstock If we leave the posts at 3' depths, frost heave (Illinois/Wisconsin border) will move them out of the ground a few inches each year, even with cross-anchors on the base. We also loosen the tension on the wires, 4 on tall spindle , 2 or 3 on the central leader depending on rootstock, central leader being mostly M7. Our rows run from 300' to 900' and we space the center posts at 50' intervals. We have found that loosening those wires in the late fall after harvest but before the first frost keeps the posts from moving when frost goes deeper than 4'....as it has this winter. If we don't get those wires tightened back up before the growing season starts, the tall spindle trees will start leaning and those end posts will go with them from our prevailing winds. When attaching the wire to center posts, we allow them to slide through the staple, which eventually puts more of the stress on the end post, but we also adjust the tension throughout the growing season. Since we are also a U-Pick operation, we have to be concerned with safety, so we do not use wire stabilizers at the ends of the row to brace the end post. We brace the end of row post with a 6' post angled back into the row as pictured at http://fruit-crops.com/wp-content/uploads/2012/11/3.10-slender-spinle-apple-bolzano.jpg with another post 4' in the ground at the base of the angle post 1' above ground for additional bracing. If we don't get the brace at least 6' long, our posts will start to lean into the row. This system seems to have worked well for us over the years with minimal maintenance from leaning posts.
We have found the publication "Support Systems for High Density Orchards" at http://www.al.gov.bc.ca/resmgmt/publist/300Series/336000-1.pdf to be quite helpful. And, fortunately for us, we were a family of residential home builders prior to getting into the orchard business and my father in law has an engineering degree!! Dennis Norton IPM Specialist/Certified Nurseryman Royal Oak Farm Orchard 15908 Hebron Rd. Harvard, IL 60033-9357 Office (815) 648-4467 Mobile (815) 228-2174 Fax (609) 228-2174 http://www.royaloakfarmorchard.com http://www.theorchardkeeper.blogspot.com ----- Original Message ----- From: David A. Rosenberger To: Apple-crop discussion list Sent: Thursday, February 20, 2014 12:29 PM Subject: Re: [apple-crop] Tall spindle trellis In theory, trellis rows could be “as long as you want them to be,” but in reality there are almost certainly limits to the amount of tension the end-posts can handle without coming out of the ground. Consider the worst case scenario: Trees that have grown to 3-ft above the wire (i.e., 13 ft tall) with 2000 bushels/A evenly distributed over the upper 12 ft of the canopy (i.e., none within 1 ft of the ground). That could mean that 25% of the fruit are above the 10-ft top wire, and in my experience those upper limbs will tend to fall toward the leeward side of the tree due to wind effects. Let’s assume that trees are on 10-ft row spacings and that 10% of the total crop is above the wire and off-center to the leeward side. If I’ve done the math correctly so far, that means that every acre will have 4-tons of apples off-center and at least 10-ft above ground. At 10-ft between rows, it will require 4,356 ft to make an acre. Thus, with rows 1000-ft long, there will be roughly 1 ton of off-center apples 10-ft above the ground. Now add a 40 mph crosswind just before harvest, and (for those in the east) assume that you just had 10 inches of rain due to a hurricane coming up the coast. The line posts will provide some support, but ultimately the greatest stress will be on the end-posts, and that stress will increase with the total length of the trellis. Even on short rows of only 300 ft, I have gradually seen trellises go off-center with time (i.e., line posts begin to lean a bit) due to wind effects, uneven cropping on the two sides of the trees, and slope (which leads to uneven frost-heave effects). If the trellises are tilted just a bit under the scenarios outlined above, then the stresses on the end posts will be multiplied. Admittedly, my observations are mostly with wider trees and wider row spacings, and those planting systems probably was more prone to going off-center than a narrow tree wall. Nevertheless, the side-ways forces on trellises should not be ignored. You may quibble with some of my assumptions, but I really would like to see/hear an engineers perspective on how long rows can be given various soil types, diameter of both line posts and end posts, crop distribution in tops of trees, soil moisture levels, etc. Whatever the answers might be, I can guarantee that when a trellis goes over in a storm, the owner with shorter sections is likely to come out with smaller losses than the person with longer runs if one assumes that construction on shorter and longer sections was equivalent. **************************************************************** Dave Rosenberger, Plant Pathologist (retired) Cornell's Hudson Valley Lab, P.O. Box 727, Highland, NY 12528 Office: 845-691-7231 Cell: 845-594-3060 http://pppmb.cals.cornell.edu/people/dave-rosenberger **************************************************************** On Feb 20, 2014, at 12:43 PM, Hugh Thomas <hughthoma...@gmail.com> wrote: Seems to me, that they could basically be as long as you want them to be. I would calculate the fuel capacity of my tractors so that one doesn't run out of fuel before getting back... On Thu, Feb 20, 2014 at 7:27 AM, Fleming, William <w...@exchange.montana.edu> wrote: We had rows 2200 feet long between end anchors. 4 wires, 10’ high with posts spaced at 42’, 3’ deep. End posts were a larger diameter, 4’ deep at about a 45° angle. Wires and anchors were attached to a 4’ long screw in steel anchor with 8” plate. Ground was basically flat. No problems holding a bumper crop. Bill Fleming Montana State University Western Ag Research Center 580 Quast Lane Corvallis, MT 59828 From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Arthur Kelly Sent: Thursday, February 20, 2014 6:24 AM To: Apple-Crop Subject: [apple-crop] Tall spindle trellis What is the longest length of trellis for tall spindle apple planting that growers have experience with? -- Art Kelly Kelly Orchards Acton, ME _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop ------------------------------------------------------------------------------ _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
_______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
