This measure (including leaf cutting, summer cutting) in the vineyard may be carried out several times. A limited number of Scroll removed from the grape zone. The measure is recommended for short-stemmed, thick-leaved vine varieties with compact, dichtbeerigen Grapes and thin berry skins, for example Pinot Noir. Gewurztraminer. Kerner. Müller-Thurgau and Scheurebe (Seedling 88). Defoliation promotes air circulation in the grape zone so that the grapes dry much faster after rain. This ripens the ripening fruit prematurely Botrytis protected. You begin to defoliate two to three weeks after blossom, however, not too many leaves should be removed, because up to veraison (Ripening) the green berries are still very strong sunburn endangered.
Shading through dense foliage provides very effective protection against intense solar radiation and thus triggered grapes wilt, In August to mid-September, however, individual leaves are also removed, thereby improving the air and light conditions. This also works bunch rot counter and also leads to better color formation in red wine grapes. Defoliation is already done mechanically in large wineries. However, defoliation is not allowed too much, because healthy leaves are sufficient for photosynthesis and sugar production is important.
An unfavorable ratio between fruit and leaves is shown in the reduced content glucose (Dextrose) and phenols in the grape and may worsen wine quality. In addition, external circumstances such as hail or frost, Pests like locusts or vine diseases such as the wrong one mildew during the growth cycle lead to unexpected leaf loss. The Rebstock responds to too much leaf loss with the expulsion the epicormic shoot (Secondary shoots). Carbohydrate reserves are used up first. Extreme, repeated defoliation can lead to death.
If, at the end of the vegetation cycle in late autumn, the vine has replenished its carbohydrate reserve, the following occurs leaf fall, This natural process usually takes place with the first frost. Complete defoliation by chemical means shortly before vintage in order to facilitate mechanical harvesting has proven to be unsuccessful. Because after the harvest until the natural leaf fall, the leaf wall still contributes considerably to the good maturation of the one-year-old shoots and the storage of reserve materials in the vine. See also under pruning as well as a list of all activities under Weingarten Care,
Picture: ERO GmbH