Good weed control is critical, especially in the establishment years. Weeds compete with the newly planted trees for water and nutrients. Weeds should be controlled by maintaining a grassed inter-row area with mulching along the tree rows. Mulch not only minimizes weeds, it also reduce soil moisture loss, maintains a more even soil temperature and improves the soil surface structure. Weeds that then grow through the mulch can be spot sprayed with an herbicide. The mulch should be placed around the tree 2-3 feet (60-90 cm) away from the trunk, when the ground is still moist to retain soil moisture and help with weed control. The mulch layer should be 3-4-inch (7.5-10cm) layer.
CAUTION: Care must be taken that all obstacles including mulches, are not in the way of future harvesting machinery operation.
It is recommended to use mulches such as sawdust, wood chips, aged horse manure or any material that have high concentrations of tannins (cedar, juniper etc.). Darker materials will heat up the soil faster, promoting root development. When selecting a material, be aware that when organic materials break down, they take up nitrogen, so additional nitrogen fertilizer is suggested. Plastic mulches are not advised as they can interfere with harvesting procedures.
WARNING: before using any herbicides (pesticides) carefully read the label and follow the instructions.
See table 8 (PDF) with list of herbicides registered for use in Hazelnuts in the Weed Management section