Feasibility of Shift Trellis Use for Northeastern Blackberry Production

Feasibility of Shift Trellis Use for Northeastern Blackberry Production

Summary

The goal of our project is to test the feasibility of shift-trellis systems for blackberry production against conventional trellises by measuring fruit yield, quality, and harvesting efficiency over the first three years of production of a new blackberry planting.

Village Acres Farm and Foodshed is a 30-acre organic vegetable and berry farm in Central Pennsylvania. Our primary markets are a 220-member CSA in State College, PA and the Tuscarora Organic Growers’s Cooperative in Hustontown, PA. Both of these markets have been buying organic bramble fruit from us for years – roughly ten years for the CSA and nearly twenty for TOG. One of the main selling points of our CSA has been our berry crops, as few of our competitors grow them, and they are also one of our main wholesale crops as well. In 2010, a fairly average year, we harvested 3,902 half-pints of red raspberries from three plantings, for a total value of about $10,000. 2011 was a less productive year due to extremely heavy rainfall throughout the year, but we still harvested 2,232 half pints.

Roy Brubaker, head farmer at Village Acres, is the project leader and manager. He has been assisted with the project by Steve Freed, who has taken on most of the responsibility of training, pruning, and otherwise caring for the blackberry plantings, and Dave Ruggiero, who has primarily helped with grant paperwork and reporting as well as managing harvest crews. Kathy Demchak, of Penn State Extension, is serving as our project technical advisor, providing information as needed on bramble crop management.

In 2010 we planted four 175-foot rows of first-year ‘Kiowa’ blackberry plants and one row of ‘Prime Jan’ blackberries 12 feet apart in roughly E-W rows following the contour of a north-facing slope on our farm. Each individual row contains roughly forty-five plants and covers 175 feet of ground. These plants grew throughout the year and bore occasional fruits although, as first-year plants, we did not expect significant yields from them.

In early spring of 2011 we fertilized with 20 lbs of feather meal (13% N) along each 175’ row, then applied 1-2” grass and leaf compost in a 2’- wide band over the row. We mulched row edges and mowed the aisles between rows to control weeds. We also did occasional hand-weeding throughout the planting as needed; there did not seem to be any noticeable difference in weed pressure between the two trellis styles, so we didn’t keep track of weeding times.

We built our trellis systems in April 2011; construction began on the 4th and was finished by April 30. Conventional trellises were built on June 21-22. Our shift trellises were built with posts every 25 feet along our rows, for a total of 2 end posts and 6 mid-row posts in each row. Each post consisted of an eight foot section of untreated locust, driven three to four feet into the ground, attached to a 6-foot length of pipe 10 inches above ground level with an 8” carriage bolt. This pipe (the swinging part of the shift trellis) was attached to the wooden post with a short length of flat steel to serve as a brace. The steel brace has two holes in it, allowing it to be swung into place so that it can brace the swinging arm in both the horizontal (pre-bloom) and near-vertical (post-bloom) positions.

The end posts of each shift-trellis row were further braced by the addition of locust tie-back posts driven into the ground and used to support the end posts with double cross-bracing of high tensile wire. This is the anchor for a 3/16”cable which holds the top of the end pipes in place, preventing them from sagging towards the center of the row. Eye bolts through the end pipes and posts anchor the cables.

Conventional trellises were constructed using two rows of 6’ metal posts spaced every 25 feet, positioned to form an open V-shape. Two HT wires were attached on each side of the row, 24’’ and 45” from the ground. Wires were secured to locust tie-back posts driven into the ground at each end.

We first shifted the trellises into the vertical position in mid-July after flowers had opened in primary blossoms on all the canes. Pollination had occurred on some of them by this point and a few berries were starting to grow. The trellises were not shifted back to their horizontal winter position until January, after the period this report covers.

Results
Our blackberry plantings were still relatively immature this year, so harvests are still fairly low. We harvested a total of 26 & a half flats (of 12 half-pint containers) out of our planting this year. Yields and harvest times were split roughly equally between all rows; at this point the shift-trellised rows did not have significantly higher yields and were not noticeably easier to harvest. As the canes grow bushier and more densely, and berry yields increase, we expect this to change. In this first year the main expense associated with the project was labor – we spent around 106 man-hours on shift-trellis construction, shifting, maintenance, training canes to the trellis, and SARE-related recordkeeping (but not including harvesting). Our main accomplishment for this year, then, is getting the trellis constructed – we expect to have higher berry yields, and thus more noticeable differences between trellis types, in the future. We also traveled to a PASA- and SARE- funded workshop in October to describe our project and our experience working with SARE, along with three other SARE farmer grant recipients in Pennsylvania.

2011 was an exceedingly wet year in central Pennsylvania, which no doubt contributed to the low yields from our plants. Our wet April and May no doubt hindered plant growth early in the season, and our wet August and September definitely impacted both growth and the production of high-quality berries in late summer. All of our bramble crops on the farm were very affected by the wet year (our everbearing raspberry yields were down to just 186 flats, as opposed to 327 flats in 2010 and 370 flats in 2009). So, although we expected a low yield in 2011 for our still-young blackberries, it is very likely that both their yield this year and their long-term establishment were impacted by the extremely wet year we had.

It is too early in our study to show any significant economic differences between the trellis types. Right now the conventional trellises are comparing very favorably to the shift-style trellises, but as the plants grow more densely and yield more berries, we expect the shift trellises’ advantages in easier picking and better air flow to become apparent. The shift trellises did take significantly longer to build than we expected (we thought they would take two people a long day to put up – they took closer to a week), which means that they must be a little more efficient than we planned on to make up for that lost cost.

Much of our project is still in the future right now – we hope to have good harvests in 2012 and 2013 that we can use to compare the efficiency of our two trellis types. Having a low-yielding year in 2011 just makes that seem much more important. As we move on to the next two years of our study, we are interested in figuring out more efficient ways to actually shift the trellises without breaking canes, how to time the shifting, and how much training we will have to do over time to keep the canes growing properly on the trellis. We are also hoping to have a PASA-sponsored workshop on our trellis system sometime in this next year, and to present workshops on the completed project at the PASA and PVGA conferences in February 2014.

• Photo 1: Shift Trellis at an angle

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