Early every spring, when the vines are still dormant, we begin pruning at Tassel Ridge Winery. The ground may still be frozen, there may still be snow on the ground or the vineyards may be muddy, but as long as it isn’t snowing we start the pruning process on March 2. This takes roughly ten weeks every year to complete.
Pruning is the most time-consuming activity in the vineyard each year. When asked, most visitors to our vineyard assume that harvesting is the most time-consuming activity, but pruning takes significantly longer.
So why do we invest in pruning? Without pruning, the vine will grow every which way to have its grapes exposed to the sun. If possible, vines will grow up trees or posts so that a few of the grapes reach the top to soak up the sunlight. After a few years, the vines become entangled and bear less and less clusters of fruit. The amount of harvestable fruit falls dramatically. By pruning, we can direct the vine to grow along a trellis wire where it will be exposed to the sun and be easy to harvest.
During pruning, we also remove any deadwood. Deadwood can include a single cane, an entire vine arm, or even the vine trunk.
During the pruning process, we spray the vine trunks and arms with a lime-sulfur solution which kills any fungus spores that have wintered in cracks along the bark. After most of the pruning is done, but while air temperatures are 40°F or less, we will also spray Spur Shield®, a chemical that acts like a temporary Band-Aid on pruning wounds, preventing fungus spores from entering the wound. We will frequently combine the Spur Shield with a fungicide that kills fungus spores that float in the air at temperatures above 40°F.
Our vineyard crew consists of two people who work year-round, plus up to four seasonal workers who work from March through Thanksgiving. Also, up to three students work from May until early August. With 75 acres of vineyard, we can’t finish the pruning in the ten weeks we’ve allowed with manual pruning.
Consequently, we’ve invested in mechanical pruning which allows us to prune 90% faster than that of manually pruning. The mechanical pruner has seats for two operators who control the cutting heads with joysticks—the pruner is pulled through the vineyard by a tractor. A total of three people move up and down the rows at about five miles per hour. Still, the canes must be removed manually by hand; nonetheless, it is still much faster than manual pruning.
Not all vines survive our winters and some that do survive lose an arm during the winter, reducing the quantity of grapes they can produce later in the season. This has been happening for the past ten years but we just assumed it was winter damage.
In the spring of 2018, we learned that many of our vines had grapevine trunk diseases that were causing much of the arm damages. Grapevine trunk diseases are caused by fungus that get into the trunk through pruning wounds, damage from equipment hitting the trunks as well as from extremely cold weather. Once an infection is present, it tends to move at a rate of 2-6 inches per year down the arm and trunk towards the roots of the vine. Once it is in the roots, the vine can’t be saved and must be replaced.
Our plan going forward is to replace our vine trunks every 7-10 years. We do this by cutting the vines off at the ground while they are still dormant. Then, we train “suckers” that come up to become replacement vines. Though we lose production for one year, we’ll have healthier vines. And, for each grape variety, we will replace approximately 20% of the trunks each year as to not seriously deplete our harvest quantities. In 2020, we will replace about 20% of both the Marquette and Edelweiss trunks.