Reduction of the grapes as a quality improvement measure in the vineyard, which is also referred to as Auslichten, blind thinning, green crop and green harvest, as well as French Vendange vert (green harvest) or Éclaircissage. The reason for that is that higher earnings and high quality grapes are mutually exclusive. The removal of grapes will increase the accumulation of various substances in the remaining grapes vine achieved. The effects are increasing the extractives, higher Mostgewicht, Leaf-fruit ratio optimization, higher color intensity red wines and better resistance in drought. Apart from the general increase in quality, a positive long-term effect can be achieved, especially in young plants, because they can develop much better.
Already at pruning You can by limiting to a small number of eyes achieve a reduction. However, an extremely strong bleed entails the risk that poor environmental conditions may cause damage during the growth cycle like late frost or weak blossom there is a drastic reduction. Furthermore, the vine also has fewer leaves in the case of low pruning. Therefore, thinning in the summer is the best way to reduce yields, since many risks are no longer relevant and expected yields are easy to estimate. A desired yield can be calculated with the following formula: average number of grapes per stick x average weight of grapes in kg x number of heads per ha gives the yield in kg / ha.
The optimal time for thinning out is quite different depending on the desired result. Earliest possible, this can be done when the berries have reached pea size. But there is no significant reduction in yield. Ideal is the beginning of the maturity period or veraison because then a required differentiation between ripe and less mature grapes is visually recognizable. This is usually the period from late July to early August. The best way to remove grapes with ripe residue. As a rule, these are the highest grapes on the vine. A commonly used form is leaving the lowest grape per shoot, Up to 50% of the grape mass is removed.
As a rule of thumb, 50% fewer grapes "only" yield about 25 to 40% less. Previously, the green grapes were often left on the ground and served as compost, This is nowadays rarely practiced to one pollution (Contamination) with microorganisms to prevent. Increasingly, the grapes removed are also used for the production of Verjus (Juice of immature grapes) used. As an alternative to manually consuming thinning become growth-regulating gibberellins (Plant hormones) used. Other forms of yield reduction include grapes break or. grapes division by halving the grapes. The video (click to view) shows the thinning at the winery Mario J. Burkhart in the municipality Malterdingen (area Breisgau in the growing area to bathe ). See also other measures below Weingarten Care,
Pictures: Winery Mario J. Burkhart