Effects of the herbicides propaquizafop and primisulfuronmetyl on Salix plants and weeds in energy plantations

The foliar-acting, post-emergence herbicides Agil (active ingredient propaquizafop) and Tell (active ingredient primisulfuronmetyl) were tested in two different Salix plantations during the first and second growing seasons. The residual effects on Salix plants and weeds in the year after application were also assessed in one plantation. Overall-spraying of Agil did not result in any visible damage to Salix plants, and stool weight was not negatively affected. Couch grass was controlled by Agil. The use of Tell resulted in severe damage to Salix plants when applied during the first growing season. The damage was expressed by an abnormally high sprouting frequency from the leading shoots as well as retarded growth in the leading shoots. Treatment with Agil combined with Tell resulted in very good weed control, but it increased the growth disturbances to Salix plants compared to Agil or Tell by themselves when applied early during the year of planting, as well as in the one-year-old plantation. An additional effect of the treatment with Agil in combination with Tell in the established Salix plantation was an increased susceptibility to frost damage in the year after application.