Occurrence, productivity and the possibility of Japanese knotweed and giant knotweed control.
Knotweeds (Reynoutria sp.) are native to East Asia and were introduced to Europe. They are considered invasive weed species which acclimatize very well in new environment and displace native species in Poland. Currently knotweeds occur commonly in all regions in Poland. They grow mainly along river banks, roadsides and on borderline habitats. They are rarely found in home gardens, railway and industrial areas as well as on fallow and idle lands. In the years 2013-2016 the places of knotweed occurrences, a productivity of plant fresh mass, and possibility of their control were determined. Three herbicides and mechanical mowing were applied in the trials. The efficacy of weed control was evaluated 4 and 8 weeks after the treatment. Regrowth of plant was analyzed after 3 and 5 months. The best results of knotweed control was achieved after application of triclopyr + fluroxypyr + clopyralid mixtures. Other examined products such as flazasulfuron, glyphosate and mixture flazasulfuron + glyphosate were less effective.