Effects of conventional pruning with defoliation of the vine head
Source of infection
- Conventional pruning with large wounds creates drying cones of dead wood that extend deep into the trunk, leading to the formation of a voluminous, defoliated vine head (see below).
- The surface area, which is increased many times over by cracks/tears/bark, harbours all kinds of pathogens and thus represents a massive reservoir of infection for the leaf wall.
- The interior is colonised by decaying fungi, which, as ESCA syndrome, can lead to the apoplectic death of the vine within a few hours, a problem that is becoming increasingly widespread in the context of climate change.
- Since the vine, as a liana plant, cannot isolate itself from the fungus by means of callus, a large chronic wound develops internally, against which the vine must constantly defend itself immunologically, which places a heavy strain on it.
Restricted sap flow
- The constant repositioning of the spur/fruit cane over the bare head associated with conventional pruning techniques leads to rarefaction and constriction of the vine's sap flow pathways, so that new, small-calibre bypass circuits have to be formed each year, which can only supply the foliage to a limited extent.