Non-chemical control methods of Sosnowsky’s hogweed (Heracleum sosnovskyi Manden.)

Sosnowsky’s hogweed ( Heracleum sosnowskyi Manden.) is an invasive species becoming an increased problem in the Europe including the Baltic region. It is an aggressive weed that poses a threat to human health. It is extremely difficult to control this plant, especially in the locations where chemical control is impossible. The purpose of the research was to evaluate the efficiency of non-chemical control methods of cutting and shading for 1st- and 2nd-year H. sosnowskyi plants as well as thermal control by heating with water steam at different growth stages. The study was carried out in Ukraine over the period of 2013–2020. To test the efficacy of cutting and shading aboveground parts of H. sosnowskyi , two field trials were conducted. Second-year plants were able to regenerate their aboveground part. Cutting of the 2nd-year shoots of H. sosnowskyi reduced the aboveground mass by 89.8–90.3%. An effective control of H. sosnowskyi was root removal in the 10 cm soil layer. Removal of the aboveground part of plant was less effective because of a high H. sosnowskyi regeneration, and the efficacy of control significantly decreased. The 1st-year plants of H. sosnowskyi at the 4-leaf stage were sensitive to covering by a plastic film. Shading for 30 days on juvenile plants ensured the sufficient efficacy of control. Thermal control (at a steam temperature of ≥95°C) was most efficient when H. sosnowskyi plants were at the cotyledon up to 4-leaf stage. Using of two non-chemical methods could have an effective control of 1st- and 2nd-year plants of H. sosnowskyi .