New Primocane Raspberry Experiences and Potentials - Update for Year 2002

Virginia Vegetable, Small Fruit and Specialty Crops
February 2002; Volume 1, Issue 2

Charlie O'Dell, Extension Horticulturist Emeritus, Grower of U-Pick
Strawberries, Blueberries and Summer-Fall Primocane Raspberries
Blacksburg, VA

Part 2: Notes on Construction and Annual Use of Harvest Aid Trellis for Primocane Raspberries.
Editors note: Last month Charlie provided insight into primocane raspberry varieties and the top 15 considerations for growers who are thinking about of getting into growing this crop. This month Charlie provides details and budget information on portable trellis construction for this crop, as well as some great ideas for post-harvest handling and eating.

During the dormant season after mowing off canes in the first late winter the year after planting, before really heavy harvests begin, we cut 12" lengths of 2" diameter schedule 40 PVC, then cap the lower end of each 12" length piece. We drive each 12" length of pipe vertically or straight down into the raised row beds, slightly off-center of the buried drip irrigation tubing that is centered in each raised bed of raspberry plants. The lower cap may be glued onto each lower end to keep soil from filling the pipe as it is carefully driven into the soil down to the soil line. Cap, but do not glue the top cap, to keep soil and plant debris from clogging the pipe when it is not in use. Then, we obtain from our local building supply company 8' lengths of treated 1.75" X 1.75" pickets (sold as "2" X 2" pickets"), #1 grade kiln dried, beveled edges, (current cost is $2.69 each here, but they will endure for multiple-years use). Then we cut part of them into 4' lengths, part into 24" lengths for cross-arms. Our raised beds and rows of primocane raspberries also are 24" wide, so the 24" long cross-arms keep the fruiting canes growing straight up, not angling out into the row middles. The middles space is needed by pickers, so keep those traffic lanes open. A 24" cross-arm length is double-bolted near the top end of each 4' length of picket. Three-eighths" diameter holes are drilled in the ends of each cross-piece for threading the support twine. Then, each year in early summer after most primocanes have grown 3' in height or longer, before fruit weight pulls them downward, top caps are removed and saved as each piece of temporary trellis is placed upright into the PVC pipe. Then, heavy nylon twine is run through each end of each cross-arm so twine runs down both sides of each row to form a containment or harvest-aid trellis.

This harvest-aid trellis will keep fruiting canes upright and easily accessible to pickers, and also will keep row middles open so folks have room to travel up and down the length of each row to easily reach all fruit. Harvest efficiency is greatly improved along with customer satisfaction, especially with U-Pick enterprises. Place an upright trellis post every 30' going down each row, about 160 to 180 t-bar posts per acre where rows are on either 9' or 8' centers.. Growers have found it necessary to brace the end posts, since there is real weight on the twines going down the rows lengthwise as the fruit load develops. I use a 16" earth anchor at each row end angled into the ground until only the eye-bolt upper end is visible so late winter mowing can be accomplished after twines are cut and posts removed. A heavy rope or removable wire is tied from this eye-bolt to the top center of the crossbar of each end post. After harvest in the fall, cut the twine to remove it , then pull out the upright T-bar posts and store them in a barn, re-capping the top of each piece of PVC pipe as soon as you pull the post. Such a temporary harvest-aid trellis, stored inside when not in use, will last for many, many years of use.

Plant costs, drip irrigation in-field costs and trellis materials costs are shown below, totaling overall about $6,600. Per acre. Trellis materials will cost in the range of about $1,000/acre, but should last the expected 8 year or longer life of the planting. Current costs, winter of 2001 include:

1. $364. For 135 of the 8' length pcs. of treated 1.75"X 1.75"' needed per acre sold as pickets. 90 of them are cut in half, into 4' lengths. 45 of them are cut into 2' lengths for cross-arms.
2. 360 4" bolts, each with 2 flat washers and 1 threaded nut, $144.
3. $145. For 180' of 2" diameter PVC schedule 40 pipe needed per acre, priced in 10' lengths which you carefully cut into 1' pieces;
4. One or two three-eighths" diameter wood drill bits, $2 ea.
5. 5,445' of heavy nylon twine, similar to that used for string-weave tomato production, $12.
6. 360 pcs of 2" pipe caps, PVC Schedule 40, $0.79 each = $285. Use a wood block or other pipe driving device to avoid splaying top end of each length of pipe when driven into ground, so pipe caps can be easily removed from top of pipe ends annually.
7. $115. For 40 earth anchors, 16" length, order from vineyard/orchard supply dealers.
8. Plant costs/acre at 2' X 9' spacing = 2,420 plants @ 2./plant = $4,840/acre.
9. In-field drip irrigation, heavy 17mm Ram Drip-In Tubing plus header, fittings, $700/acre.
10. Your labor to prepare land, bed, install drip irrigation, plant, cut, construct and install the harvest trellis.

Concerning trellis needs: I have seen it tried by growers both ways, with and without a harvest trellis. Growers, including myself, have always harvested several hundred dollars more fruit per acre where the trellis was used, simply by reducing loss from unpicked fruit. This is especially necessary to have the trellis wherever U-Pick customers harvest the crop. Berries that are left unpicked, because of inconvenience getting to the canes, will quickly mold and rot, serving as inoculum sources for the rapid spread of Botrytis Gray Mold fruit rot. Thus growers quickly find that the harvest trellis does not, therefore, cost money, it saves and makes money, each year!

Some Notes About Handling the Fruit and Eating:
When it comes to eating, growers and consumers, along with our family, says that primocane raspberry jelly and jams are some of the best they ever tasted! Here's another idea I discovered that allows us to enjoy this tasty and healthful fruit year-round, just like blueberries!:

1. Quick-freeze fresh-picked primocane raspberries in smaller 1 or 2 quart size specific freezer bags, in the quick-freeze portion of your deep freezer.
2. Don't use over-ripe berries and don't bruise them during picking for this use, handle gently!
3. If done with a good freezer that freezes fast, berries will remain separate and not melt together from loss of juice during freezing, try it first on a small scale with your freezer.
4. When ready to use during the winter months, keep the package frozen, may need to drop on floor to loosen and separate fruit, then open and remove 1 cup of frozen berries to microwave-safe bowl. Quickly place unused portion of package back into the freezer.
5. On time defrost in microwave, defrost 1 cup berries for 1 minute.
6. On medium heat in microwave, heat this cup of berries for 40 seconds or so, until fruit is thawed, but texture remains similar to fresh- harvested berries. Vary the time for your particular microwave oven.
7. Pour fruit over bowl of cereal, add milk, close eyes and enjoy! Warning: May become healthily 5-A-Day addictive, may necessitate purchase of additional freezer just for raspberries and blueberries!

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