Regaining Yields in the Vineyard

Cover crops in viticulture Fertility management in viticulture Soil cover Pruning and vine training Soil regeneration

What technical levers to regain yields in the vineyard?

Several studies highlight a decline in yields in vineyards of the South-East. However, for a farm, yields that are too low are often the cause of a lack of profitability. Faced with a decrease in production potential, it is therefore imperative to act. The causes of such a decrease are multiple: age of the vines, diseases and decline, inappropriate fertilization... Thus, no solution proves effective if implemented in isolation, and yield recovery will only be possible through a combination of measures.

Regaining yields through a combination of measures

Long-term action levers

Soil preparation
Choice of plant material
Good planting practices
Disease management of decline (Grapevine fanleaf virus, Flavescence dorée)
Appropriate soil rest
Intercropping

Medium-term action levers

Replacement of missing plants

Short-term action levers

Health status
Valorisation of extraction juices
Fertilization
Pruning
Irrigation
Soil maintenance and cover crop
Harvest conditions

Short-term actions

Pruning to regulate load

Pruning allows fairly rapid control of yield, by regulating the number of clusters per plot, according to 3 criteria:

Choice of short or long pruning (+ potential clusters with long pruning)
Number of spurs
Number of buds/spurs^[1]

Two practices of pruning allow yield gain and reduce production costs:

Precision short pruning: this mechanized pruning where 1 to 2 buds maximum are kept, allows a rapid production gain (+41% average yield compared to classic manual pruning).
Minimal pruning: this technique consists of not pruning but only performing summer trimming, it allows obtaining high yield levels in entry-level wine. To implement this technique, it is essential to train the vines in single cordon with robust trellising.

Maintenance fertilization: mineral nitrogen inputs at flowering

Nitrogen inputs mainly affect vigor then plant fertility and cluster weight. To increase yield, annual nitrogen fertilizer inputs of 30 to 50 units of nitrogen/ha are recommended.
Mineral fertilizers applied just before flowering and localized under the row are effective.
Potassium or magnesium fertilizer inputs, based on petiole analyses at veraison, help avoid deficiencies or excesses, which can impact production.

Regulating the grassed area

In a Mediterranean context, the presence of grass in vineyards during the growing season is one of the main causes of yield decline (competition of weeds with the vine row). In case of yield problems, it may be interesting to minimize the grassed area during this period. In winter, grassing is not competitive, on the contrary, it is an asset for soil protection and structuring.

Irrigation

Irrigation applied before veraison improves the functioning of the vine and increases berry weight. However, the resulting yield increase is not proportional to the amount of water applied:

50 to 100 mm of water/year, applied regularly can increase yield by 3 to 5%, depending on the level of water stress and soil water retention capacity.
Beyond 100 mm/year, additional water inputs are no longer converted into production gains.

The drip irrigation system is the most efficient.

Maintaining soil organic matter

Maintaining or even increasing a soil organic matter content between 1.5 and 2% through regular inputs contributes to good soil functioning. Organic matter also helps retain water in the soil.

Adjusting the harvester

Production losses due to poor adjustment of the harvester are not negligible.

Here are some rules to follow:

Properly position the beaters at the fruiting zone.
Advance at a moderate speed (3 km/h) and adjust shaking frequency accordingly.
Align the harvesting head with the row to limit impacts on the vine.

Medium-term actions

Replace missing plants

On non-declining plots where the missing plant rate does not exceed 25 to 30%, it is wise to replace missing plants, by Complantation or by layering. Beyond this threshold, complete uprooting of the plot and replanting will often be more profitable.

Long-term actions

Plot establishment

Choices made when establishing a plot will strongly condition the success of the coming production years. It is essential to be vigilant on the following points to expect good yields:

Site choice

Well-watered soils (useful reservoir > 150mm)
"Cool" exposures
Soil analysis

Soil preparation
- Base fertilization
- Soil preparation work

Manage the previous crop

New soil
Vine
- Devitalization
- Cover crops
- Appropriate rest duration

Planting practices

Early planting (March) with short roots
Watering and physical and phytosanitary protection

Choice of plant material
- Variety adapted to production goals
- Vigorous rootstock
- Productive and non-declining clone

Notes

↑ Leaving more buds at pruning allows a production gain the 1st year. Then, the yield tends to regulate itself, decreasing again from the 2nd year.

Annexes

Sources

This page was created from the PDF document "What technical levers to regain yields in the vineyard?" jointly published by the Chamber of Agriculture of Var and the French Institute of Vine and Wine.

[1] Leaving more buds at pruning allows a production gain the 1st year. Then, the yield tends to regulate itself, decreasing again from the 2nd year.

[1]