Frost damage prevention by alternative pruning methods.

In order to be able to use pruning as a frost prophylaxis, there are three approaches. The first is based on late pruning. The second involves a higher number of shoots, so that sufficient shoots can survive in the event of partial damage. The third approach is based on delaying budding. The pruning methods used in this four- year study comprise all variants. With a frost cane (sacrifical cane), a frost head or a minimal pruning in the trellis, there is an increased number of buds. In the event of late frost events with partial damage, a sufficient number of shoots will remain. The frost cane (sacrifical cane), frost head and minimal pruning methods are therefore primarily based on an increased number of shoots, which are usually not or only slightly delayed in development. The further development has progressed, the more difference there is between the minimal pruning and other pruning variants. Late pruning is variable and could delay the development significantly. Double spur pruning resulted in a significant delay in development in the phase of greatest danger of late frost. In the event of a late frost, there is a good chance that the developing buds will not be damaged. However, the delay in development lasted slightly until harvest and could also be used as a delay in ripening. The delay in ripening was noticeable in lower must weight and higher acid value. Although the sensory impression was slightly abated, it did not differ significantly from the sensory ratings of the best wines. Only the wines of the minimal pruning variant were clearly judged to be of lower value. Due to the greater delay in development, under the current conditions the double spur pruning was particularly suitable for frost prevention.