Pruning and Training
Hazelnut trees usually do not require pruning until the second year. Do not prune young trees excessively so as to avoid removing too much wood. One recommendation is to remove one-half the fruiting area from one-fifth of the trees annually, while leaving as large a branch framework as possible. Bushes can also be coppiced (cut to the ground) if the growth form or size becomes undesirable; re-growth is dependable. Prune hazelnuts in late winter and early spring before dormant buds begin to grow. Pruning during late fall may result in tree injury, where fresh large cuts can dry back to main scaffold branches before these sites heal during the following spring. In moist climate areas such as the coastal regions, this is important since pruning sites that are exposed to wetness for too long time may allow fungal or bacterial rot to establish resulting in systemic damage to the trees.
Remove all pruned cuttings from the orchard before the trees begin to grow in spring to prevent the possible spread of disease.
After the first growing season the process of scaffold selection can begin. The goal is to select 3 to 5 scaffold branches that are evenly spaced around the tree. Hopefully one can achieve some vertical distance between branches. Avoid selecting two branches that are emerging from the trunk at the same height. This situation would ultimately make for some weak branches, as they grow older. Also, scaffold branches should be high enough so as not to interfere with maintenance and harvesting, but not too high up to make trees top heavy.
After the scaffold branches are selected, it helps to come back the following year and support them by removing any strong competing branches. Once the scaffolds get a “head start”, they usually do all right. After the scaffolds have been established, trees are generally left alone. Excessive pruning of young trees can delay or reduce their early yields. After the trees are ten years old or older, they may require more corrective pruning, depending on their vigor and spacing.