Minimum size in viticulture
In order to reduce the costs and time required for pruning the vine, minimal pruning or minimal pruning (Minimal Pruning) is increasingly attracting interest in the wine industry. According to estimates[1], pruning can represent up to 33% of costs, more than half of which is due to manual pruning of vines, potentially representing up to 50 hours of work per hectare. It is one of the last manual labor tasks, while almost all vineyard operations are mechanized or mechanizable (harvesting, leaf removal, soil work…).
What is minimal pruning?
Minimal pruning (Minimal pruning) is defined as not (or almost not) pruning the vine. The only pruning practice allowed in this vine management is topping (in winter and summer). This allows control of the grape load on small clusters, rich in phenolic compounds (anthocyanins and tannins). A significant increase in grape load is generally observed in the year of conversion to minimal pruning or the following year. Minimal pruning self-regulates thereafter, although yields remain slightly higher than with hedge pruning.
Each vine can bear up to 1500 buds.
The vine architecture generally revolves around a single cordon located between 1.5m and 1.8m above the ground.
This minimal pruning is especially suited to a Mediterranean climate although clusters located outside the foliage and exposed to the sun can suffer from sunburn.
In cooler, wetter climates, difficulties and delayed ripening, accompanied by attacks of Botrytis, have been observed, especially if the load is not regulated (hence the importance of topping, particularly in summer).
Characteristics of minimal pruning
| Average of all grape varieties and vintages | Manual pruning | Minimal pruning |
|---|---|---|
| Buds left per vine | 20 to 25 | 300 to 600 |
| Number of shoots per vine | 22.5 | 87 |
| Bud burst rate in % | 90 to 112.5 | 12 to 35 |
| Shoot length in cm | 90 | 39.5 |
| Internode length in cm | 5.8 | 3.7 |
| Number of clusters per vine | 31.3 | 129.7 |
| Cluster weight in g | 158 | 89 |
| Yield in T/ha | 11.3 | 20.3 |
Prerequisites for implementing minimal pruning
Plot selection
- Avoid overly fertile plots
- Avoid plots at risk of severe drought
- Avoid plots exposed crosswise to the wind
- Grape varieties with upright growth such as Sauvignon or Cabernet Sauvignon are easiest to manage with minimal pruning.
Wide planting
- Planting width: minimum 2.5 m
- Avoid rows less than 2.5 m (risk of lateral crowding)
- If possible: 3 m rows (not always compatible with regulatory requirements)
Strong trellising
- Strong head stakes (2.50 m wooden) well driven into the ground
- Strong ties (1.50 m)
- Intermediate stakes every 5 m
- Thick twisted carrying wire to facilitate cordon formation
- Temporary stakes for trunk formation
Careful trunk and cordon formation
- Trunk bud removal (2 passes per year)
- Tying (3 to 4 passes per year)
- Allow an additional year for formation
- Stop pruning once the cordon is formed (avoid cutting back shoots to 2/3 buds after the first year of growth)
Control vigor and water rationing
- Sown cover crop or Managed Natural Cover Crop
- Lengthening cordons (reducing planting density)
- Reasoned irrigation (drip irrigation)
- Reasoned fertilization
To avoid: stopping pruning on an existing Royat cordon
- Insufficient height: drooping growth to the ground, lack of aeration
- Insufficient number of buds, irregularly distributed: poor vigor regulation, strong heterogeneity along the cordon
Available machines
Machine costs range between €9,000 and €25,000 excluding tax.
For more information on mechanical pruning machines on the market:
What are its advantages?
- Lower workload and reduced labor costs due to pruning
- Improved aromatic quality of grapes (richness of berries in anthocyanins)
- Less attractiveness to pests
- Fewer pruning wound infections, less esca, less eutypa dieback
What are its disadvantages?
- Vegetation spreading in width is a drawback as it is hardly compatible with the passage of increasingly narrow modern harvesting machines.
- Significant yield variability has also been observed from year to year
- While conversion of a vineyard to minimal pruning is relatively easy, the reverse and return to a more conventional system systematically involves significant crop losses.
Sources
- Institut Français de la Vigne et du Vin, Mechanization of pruning
- Institut Français de la Vigne et du Vin Occitanie, PRECISION RAZOR PRUNING, HEDGE PRUNING AND MINIMAL PRUNING
- Rousseau J., Carbonneau A., Ojeda H., Minimal pruning
Appendices
- ↑ estimates made by the IFV Sud-Ouest using the VITICOÛT® software
Est complémentaire des leviers
