Grower Experience With Blackberry Adjustable Trellis
May 4, 2012 
Note: This report was originally presented by Steve Bardenhagen, of Bardenhagen Berries in Leelanau County, MI, during the 2011 Great Lakes Fruit, Vegetable & Farm Market Expo.
Our 180-acre fruit farm is located in Leelanau County, MI. We are situated on a peninsula in Lake Michigan which moderates the temperature in winter and provides lake effect snow.
The farm has approximately 15 acres of strawberries, 50 acres of sweet and tart cherries, and 1 acre of blackberries. We deliver strawberries and blackberries to local fruit stands, farm markets, and grocery stores. Typically, the acre produces around 5,000 pounds of blackberries.
The first blackberries were planted in 1988 at a time when no one else was growing blackberries locally. The original cultivars planted were Chester and Thornfree. Chester is winter hardy and resistant to cane blight. The fruit is firm and high quality. Thornfree is also winter hardy and has firm fruit that is tarter than Chester.
In spring 2008, we planted Triple Crown and Lochness, which both produce big, sweet fruit that ripens earlier than Chester and Cancanska. We also planted Ouchita, which is similar to Chester.
Static Trellis System
Our conventional trellis consists of wood posts holding a single wire at the 5-foot level. Each spring, we select up to six of the best floricanes from each plant and prune off everything else close to the ground. Three floricanes are tied in each direction along the wire using short lengths of binder twine.
We usually have snow cover for most of the winter. Our winter snow cover has become increasingly less consistent. In the winter of 1993/1994, a year of minimal snow cover, nearly all the bearing canes were killed.
When we planted Triple Crowns, we were concerned about winter damage and so we decided to try an adjustable trellis along with row covers. In the winter of 2009/2010 we covered the Triple Crowns. Heavier material like DeWitt’s Ultimate 3 ounces per square yard row cover is holding up the best after two seasons. The thinner material is a bit ripped from the wind. We use 8-inch U-pins spaced 1 foot apart to secure the edge of the row cover to the ground, but a layer of snow does the best job of holding things down.
Canes that are covered will often have green leaves in the spring, while uncovered canes will only have brown dried-up leaves. We put out mouse bait before covering to minimize rodent damage. In Winter 2010/2011, we used row covers over the Chesters for the first time. We noticed a significant boost in vitality this spring. The plants have looked healthier and put out more vegetation than ever before.
Adjustable Trellis System
At the North American Raspberry and Blackberry Association conference in 2011, we learned about the Rotating Cross Arm Trellis designed by Dr. Fumi Takeda at the USDA-Agricultural Research Service Appalachian Fruit Research Station in Kearneysville, WV. We contacted Richard Barnes from Trellis Growing Systems, who helped us install 1,200 row-feet of adjustable trellis on Triple Crown the following spring.
Managing an adjustable trellis is significantly different than the static trellis. In order to rotate the canes without breaking them, the emerging primocanes must be trained to grow horizontally. Once the primocane reaches the next plant, it is pinched off, and growth is redirected to lateral shoots. The laterals are then tied to the rotating arm of the trellis. We used ADC bands for tying, which are UV treated rubber bands with a hook. When the arm of the trellis moves, the thick horizontal cane remains in place while the laterals bend.
In early spring, the rotating arm is moved just off the ground to the flowering position. The floricanes send flowering shoots straight up on one side of the trellis. The primocanes begin to emerge from the ground and are trained to a static wire.
When blossom starts, the arm is moved to the upright fruiting position and most of the fruit ends up on one side of the row. The way the laterals are tied up on several wires on each rotating cross arm is a better use of space than the static trellis and provides a wall of fruit. Harvest is faster than on the static trellis, since nearly all the fruit can be reached from one side.
The short arm on the other side of the row helps hold the primocane laterals off the ground. Having floricanes on one side of the row and primocanes on the other keeps things organized. After harvest, the floricanes are removed and the primocane laterals are tied to the rotating cross arm. Before winter, the cross arm lays the primocanes on the ground and can easily be covered.
When placing row covers over the adjustable trellis, there needs to be some structure to prevent snow bearing down on the fabric and breaking the canes. Next year’s floricanes have already been selected and tied to the trellis. With the conventional trellis, the wire can be removed to allow the weight of the snow to push the canes close to the ground. Breaking is not a problem because canes are not tied and floricane selection happens in spring.
Spraying is more efficient with the adjustable trellis because the fruiting shoots are mostly on one side of the row. If adjacent rows rotate in opposite directions, then two rows can be sprayed with a single pass.
We recommend using row covers and adjustable trellis to minimize winter damage in thornless blackberries. The adjustable trellis has other advantages, including increased harvest and spraying efficiency, but has a higher material cost than the static trellis.
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