During my recent chat with international pruning expert Marco Tessari, we talked about all things shoot thinning, and in today’s blog post, we recap an abbreviated Q&A from my time with Marco. Be sure to tune into the episode to hear Marco’s full in-depth answers along with his overall expert advice on shoot thinning.
What is the purpose of shoot thinning?
The purpose of shoot thinning is to focus the energy of the vine where you want production for the current season and where you want the vine to grow and develop in the years to come.
Shoot thinning focuses on removing unwanted things from the vine, namely:
- Removing shoots that are not fruitful unless they are needed for future vine structure.
- Removing shoots that are in the wrong position for future growth.
- Removing shoots that will cause shading or clutter for the canopy.
How do pruning and shoot thinning go hand-in-hand?
Pruning and shoot thinning are linked in an ongoing cycle. When you prune, you prune so shoots grow in a specific position and specific spacing on the vine. When you shoot thin, you remove everything that is not growing (or not growing fruitfully) in those specific planned positions and spaces. And, then the following dormant season you will prune where you left shoots the previous spring to complete one full cycle.
How or why is shoot thinning important for not only the success of the season but also for vineyard longevity?
Every pruning cut causes a wound to the vine even with proper pruning practices, and pruning wounds are susceptible to trunk diseases which are one the biggest threats to the longevity of the vine.
Green growing shoot removal does not cause scarring or wounds to the permanent structure of the vine if done timely, and no evidence suggests that vines are not susceptible to trunk disease from green growing shoot removal.
So, the more shoots you remove as green growing shoots in the spring the fewer dormant pruning cuts you will have next season, and in turn, your vines will have fewer wounds and fewer entry points for trunk diseases.
What types of vineyards need to shoot thin? Are there vineyards that don’t need to shoot thin?
Every vine needs to be shoot thinned because there are always shoots that grow where you don’t want them to grow. Ideally, you would make a couple of shoot thinning passes to make sure all of the undesired shoots are removed (at minimum from the vine trunk) to allow the energy of the vine to focus on growing the desired vine structure for the next season. Shoot thinning also ensures that the vine can ripen the crop for the current season without crowding or shading.
If you can only make one shoot thinning pass, you can focus on just cleaning the vertical trunk, the easiest to remove unfruitful shoots from the fruit zone, and the shoots that will shade or clutter the canopy or fruit.
When should growers shoot thin – what is the optimal timing?
Shoot thinning timing can be very tricky, especially for growers who only make one shoot thinning pass. If you shoot thin too early, more shoots are likely to pop out after you shoot thin. If you shoot thin too late, the shoots will be well attached to the trunk or cordon, and you risk damaging the trunk when you remove them. Additionally, it will take much longer as you may have to use snips to cut out the shoots and remove them through a heavier canopy. If you are making only one pass, the ideal window is small and should be timed when your shoots are 6-10 inches long.
Did you know… Shoot thinning is beneficial not only for vineyard health but also for your bottom line.
Shoot thinning is faster for a crew to do than pruning, so spending the money on shoot thinning labor in the spring will save you money on pruning labor next season. Additionally, a well shoot thinned vineyard is much faster to prune, so your pruning labor costs will be even further reduced from proper spring shoot thinning.
Listen to all of Marco’s expert advice on shoot thinning as well as tips for shoot thinning in an organic vineyard from Ken Swegles of Rhizos Viticulture Consulting – vineyardundergroundpodcast.com/vu019.