Application of post-emergence herbicides in the regeneration of pedunculate oak (Quercus robur L.) forests

Weeds are an important limiting factor in the development of pedunculate oak seedlings. Weed control is very important on regeneration areas, particularly in the initial stages of young growth development, when the adverse effects of weeds on oak are greatest. Effective weed control should be based on the combination of several different measures. However, because of manpower shortage, high labour costs and large areas, forest managers frequently decide to use herbicides to control weeds. On oak regeneration areas, a major problem is often broadleaved weeds that grow vigorously. Post-emergence herbicides nicosulfuron, bentazon, imazamox and tribenuron-methyl were monitored in broadleaf weed suppression in pedunculate oak stands during the regeneration process. Field studies were performed at two sites during three growing seasons, i.e. herbicide selectivity was examined on 1-, 2- and 3-year-old seedlings. The study results show that the number and fresh and dry weights of weeds were significantly reduced by tested herbicides in treated sample plots when compared with control plots. The herbicides tribenuron-methyl and bentazon had phytotoxic effects on oak seedlings. In contrast, nicosulfuron and imazamox did not show phytotoxic activity against the seedlings and can be applied in weed control in regenerated pedunculate oak forests.