Vine tying may seem simple, but growers often make avoidable mistakes that ultimately may mean wasted time and decreased productivity, according to Michigan State University viticulture extension educator Thomas Todaro. He offered the following advice for tying vines on a vertical shoot position (VSP) training system.
Tip one: Go vertical with the training system.
During initial vine training of a newly established vineyard, this involves gathering shoots (green, growing vine stem) from the trunk base (or crown) and tying them so they are trained upward.
Growers may tie the shoots to a metal, wood or bamboo stake, or to a piece of twine, but no matter what the support is, they should make sure the shoots extend as vertically as possible from the trunk base, he said.
“If the shoots bend downward or sideways from the trunk base at all, that bowing is going to increase when it hardens off, and sooner or later, that bow may end up touching the soil or growing toward the middle of the row so that tractors can’t get through easily without damaging the vine trunk.”
Tip two: Use the whole expanse of the horizontal fruiting wires.
In a typical trellis setup, growers select two shoots from the vertical center group and extend them out onto each fruiting wire — one shoot reaching to the left and one to the right.
These shoots become either permanent cordons or annual canes, depending on whether the vineyard is using spur-pruning or cane-pruning, respectively. Todaro instructs that the two shoots be tied so they nearly abut before beginning to extend away from one another.
“A lot of times growers will leave a space between the shoots, but that means they’re not using all of the fruiting wire that they could,” he said. The gap may only be an inch or two, but over the whole vineyard, that can really cut into the amount of crop that can be produced, he noted. “You want that space to almost be nothing, because you want to take advantage of all the sunlight that hits that trellis.”
Tip three: Limit ties in cane-pruning systems.
Vineyards often go overboard on tying, he said, noting that he has vineyards that have annual canes tied every few inches when they really only need two: one tie where the cane starts to extend sideways from the vertical center group (as described in tip two) and one tie at the free end to keep it in place. Even a single additional tie in the middle of the cane is usually unnecessary.
After all, he said, the fewer the ties, the easier it is to remove the canes each year. For growers who prefer wrapping the canes around the fruiting wire rather than tying, he recommends wrapping only once. In other words, the cane dips beneath the wire a single time near its center, and reaches above the wire at the free end to secure it.
Multiple wraps — like multiple ties — just mean more work. “Why make it harder for yourself?” he asked.
Tip four: Limit ties in spur-pruning systems, too.
Because the permanent or semi-permanent cordons remain from season to season and continue increasing in girth, each tie presents a potential for girdling.
“There’s no issue with girdling when you tie near the end because there’s nothing beyond that, but every time you add an extra tie elsewhere, you run that risk,” he said. For that reason, the cordon should have no more than three ties: one where it first begins its horizontal run from the vertical center group, one at the free end, and one more in the center if it needs it.
In addition, all ties on cordons should be fairly loose to allow for growth without girdling. For growers who prefer wrapping to tying, he directs them to wrap only once around the wire (as described in tip three).
“You don’t want to wrap and wrap and wrap,” he said, noting that this not only can lead to girdling, but also can result in considerable difficulty when the time comes to remove an old cordon. “By then, the cordon is usually really woody, and it’s a real job to get them off the wire if it’s wrapped multiple times.”
Tip five: Check the ties in spur-pruning systems.
Since ties can cause girdling, he suggested walking the vineyards each year and snipping off the ties that are becoming too tight. In addition, because cordons eventually become very sturdy, he also advised removing any ties that are no longer necessary. Both, he said, eliminate issues with girdling. •
—by Leslie Mertz
For more information about tying grapevines, including the variety of ties that are available, see this series of online Michigan State University videos produced by grape expert Tom Zabadal at msue.anr.msu.edu/news/how_to_tie_grapevines