Pros and Cons of Early Leaf Removal

In my previous post, I wrote about What is Early Leaf Removal? This is the follow up blogpost regarding the pros and cons of early leaf removal. Early Leaf Removal (ELR) is a technique that is still experimental and doesn't replace traditional canopy management activities but can be good for highly-fruitful varieties that produce a high number of clusters (3-4 per shoot) or large clusters such as Grüner Veltliner, Sangiovese, and Barbera.
The benefits of ELR are the following:

• ELR when performed at the onset of fruit-set, may induce a reduction in berry size and an increase in berry abscission due to carbohydrate limitation at the onset of fruit development
• ELR may be employed as a potential alternative to cluster thinning techniques used for crop yield control in highly-fruitful wine grape varieties
• ELR can be more easily mechanized, as opposed to cluster thinning for crop yield control
• ELR decreases cluster compactness by reducing the number of berries per cluster and/or the berry size and can serve to reduce the severity of Botrytis bunch rot infection in susceptible varieties
• ELR of basal leaves increases sunlight penetration and air movement in the fruiting zone, which is important for improving spray penetration within the canopy
• ELR can also reduce methoxypyrazines, ‘herbaceous’ aromas found in higher concentrations among immature grapes at harvest, and may contribute to improved wine color intensity in red varieties

Employing early leaf removal is tricky business because the basal leaves are being removed pre-bloom. During this time, the basal leaves are the one that are photosynthetically active, providing the carbohydrates to the inflorescence as well as the growing shoot.
The disadvantages of ELR may be:

• ELR may potentially exacerbate ‘poor’ fruit-set if extended periods of wet, cool (< 59°F), overcast, or very hot (> 90°F) weather conditions occur following leaf removal
• ELR may lead to bud damage as a result of physical damage during leaf removal and/or reduction of carbohydrate supply during bud development
• ELR effects on carbohydrate storage in perennial tissues and its relation to dormant tissue (buds and canes) cold hardiness development is still unknown and under active research at this time
• ELR use and crop estimation prediction is unknown at this time; cluster thinning is a more conservative approach and can provide a better estimation of final yield

Since we do not have overly fruitful varieties in our vineyard, with the exception of Barbera, which is still not producing any fruit, I think we will be sticking to the standard practice of leaf removal after berry set.
References:
1. Maria Smith and Dr. Michela Centinari, Early season grapevine canopy management, Part II: Early leaf removal (ELR), Dept. of Plant Science.
2. Tommaso Frioni, Shijian Zhuang, Alberto Palliotti, Paolo Sivilotti, Rachele Falchi, Paolo Sabbatini, "Leaf Removal and Cluster Thinning Efficiencies Are Highly Modulated by Environmental Conditions in Cool Climate Viticulture", Am J Enol Vitic., March 2017.

What is Early Leaf Removal?

Late last year, after harvest, my husband forwarded me this link that appeared in Wines & Grape U, Early season grapevine canopy management, Part II: Early leaf removal (ELR) that explains the benefits of leaf removal around bloom. It is now time to revisit this article.
From taking the U.C. Davis online course, I was familiar with the advantages of leaf removal. I was, however, unaware of the timing and the removal of certain leaves as well as the advantages of the canopy management system called early leaf removal.
Leaf removal is an adjustment of total vine leaf area and affects the relationship between photosynthetically active leaf area and yield and can lead to:

• Improved the cluster microclimate
• Additional sunlight penetration
• Higher temperature in the cluster

What is early leaf removal (ELR)? At the moment, ELR is still considered an experimental canopy management technique for crop control of highly-fruitful varieties. ELR is the removal of basal leaves of the main shoots and, optionally, lateral shoots developed from the basal nodes. ELR is typically performed shortly before (pre-bloom) or at the beginning of bloom.¹

Early leaf removal is still an experimental technique for highly-fruitful varieties. The next blogpost will deal with the pros and cons of using this technique during pre-bloom to bloom.
Back to disbudding work for us. Nearly finished with that task!
References:
1. Maria Smith and Dr. Michela Centinari, Early season grapevine canopy management, Part II: Early leaf removal (ELR), Dept. of Plant Science,
2. Tommaso Frioni, Shijian Zhuang, Alberto Palliotti, Paolo Sivilotti, Rachele Falchi, Paolo Sabbatini, "Leaf Removal and Cluster Thinning Efficiencies Are Highly Modulated by Environmental Conditions in Cool Climate Viticulture", Am J Enol Vitic., March 2017.

Vintage 2018: Budbreak

We have been busy pruning our vines in a race against budbreak. We did have a little breather after we finished pruning our last vine on April 29th and were waiting for budbreak. While we were waiting, we got in a round of mowing and we are now weeding in the vine rows.
I never take budbreak for granted and look for signs of life, but this spring has been unusually cold, windy and rainy which delayed budbreak in our vineyard.
Everything happens all at once! We have budbreak! Here is what the various varieties are doing at the moment. The red varieties are behind the white varieties, with the Cabernet Sauvignon 412 being the slowest. For the whites, typically Chardonnay is the first to reach budbreak and the Auxerrois is typically the laggard. In this photo of Chenin Blanc, I can just begin to see the inflorescence (flowers). Exciting!

Done Pruning

We began pruning on March 24th and pruned our last vine on April 29th. While we were doing the job, we constantly told ourselves that next year we will be starting earlier. We will have to, given all of the canes that we laid down this year. Here is what the vineyard looked like before pruning. Before pruning:

Here is what one row looked like after pruning. After pruning:

We are breathing a sigh of relief. Not only that, at the beginning of this week, April 30th, it still felt like a winter chill was in the air, but as of Wednesday, there definitely was a touch of summer in the air. The buds are sensing this change in temperature as well since they have begun their slow but inexorable passage to budbreak.