Effect of pruning intensity on the growth in diameter of hybrid walnut shoots

Abstract

Yielding quality timber is possible only if trees are pruned in their young age to produce a straight and knot-free bole (at least when trees are not planted with a high density). Shoots must be pruned as small as possible to avoid decay problems. However pruning can modify tree growth and particularly lead to an increase of shoots diameter growth which counterbalances the objective of pruning only small shoots. This problem appears from a certain threshold of removed leaf volume, which is in part still undetermined. The study reported here aimed to specify the relationship between pruning intensity and shoot diameter growth of young hybrid walnuts in central France. Results showed that pruning can effectively increase shoot diameter growth but with a magnitude depending not only on pruning intensity but also on climatic and growth conditions. Further experiments and modelling tasks will be necessary to end in a more rational pruning management of forest trees.