Control of Heracleum sosnowskyi in Lithuania

Sosnovsky’s hogweed (Heracleum sosnowskyi) is a dangerous perennial, invasive alien plant in Lithuania. Control of this plant is complicated due to well-developed biological properties. To achieve efficient control of the species, it is crucial to choose highly efficient herbicides and their combinations. Field experiments, designed to compare the efficacy of different herbicides and their mixtures used to control Heracleum sosnowskyi, were conducted in 2016 and 2017 in Lithuania, Varnupiai (54° 29' 19.54", 23° 30' 45.9"), Marijampolė distr. The efficacy of the herbicides and their mixtures applied for Sosnovsky’s hogweed control was different. The use of both lower and higher rates of glyphosate did not have the expected result, as 4-6 weeks after application new plants started to emerge. A mixture of glyphosate with triasulfuron showed better effect. The efficacy of dicamba and its mixtures with fluroxypyr and triasulfuron, fluroxypyr, triasulfuron and their mixture, fluroxypyr + clopyralid + MCPA mixture depended on the experimental years’ meteorological conditions. In 2017, the effect of the above mentioned herbicides and their mixtures on Sosnovsky’s hogweed stood out 4-6 weeks after application. Both the smaller and higher rates of tribenuron-methyl + metsulfuronmethyl mixture gave effective control of Sosnovsky’s hogweed. The effect of fluroxypyr + metsulfuron-methyl mixture was more rapid, and 6 weeks after application only single plants remained in the plots.