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.

Sosnowsky's hogweed (Heracleum sosnowskyi Manden.) is known as an invasive, ineligible, harmful to human health, and hardly controlled plant. The purpose of this study was to evaluate the efficiency of chemical control when different herbicides were applied at various development stages of H. sosnowskyi plants. The experiment was carried out in Ukraine over the period of 2013-2020. Two field experiments on the first-year and second-year H. sosnowskyi plants were conducted. All the selected herbicides were applied at the rates registered in Ukraine. The first-year plants of H. sosnowskyi were the most sensitive to the herbicides at the cotyledon stage -the efficacy of herbicides ranged from 97.3% to 100%. Postponing the herbicide application up to a six-leaf stage, the efficacy ranged from 43.2% to 60.7%. The most effective were the following herbicides: Task Extra 66.5 WG (rimsulfuron 23 g kg -1 , nicosulfuron 92 g kg -1 , dicamba 550 g kg -1 ) + Trend 90 at application rates of 385 g ha −1 + 0.2 L ha -1 and MaisTer Power OD (foramsulfuron 31.5 g L -1 + iodosulfuron 1.0 g L -1 + thiencarbazone-methyl 10 g L -1 + cyprosulfamide (antidote) 15 g L -1 ) at an application rate of 1.5 L ha -1 . The second-year plants of H. sosnowskyi were effectively controlled by the following herbicides: Elumis 105 OD (mesotrione 75 g L -1 , nicosulfuron 30 g L -1 ) at an application rate of 2.0 L ha -1 and the tank composition Elumis 105 OD + Roundup Max (glyphosate potassium salt 551 g L -1 ) at application rates of 2.0 + 6.0 L ha -1 . The results of the experiment clearly showed that the sensitivity of H. sosnowskyi plants to herbicides decreased with increasing the stages of plant development of the first-year of H. sosnowskyi. The results suggest that the combination of mesotrione, nicosulfuron, and glyphosate might be a suitable solution for the chemical control of second-year plants of Sosnowsky's hogweed.

As of today, Heracleum Sosnowskyi have expanded from transformed habitats and small areas into natural conditions, where they occupy stable positions and is characterised by high phytocenotic activity, often being dominant or co-dominant. Considering that there are no clearly developed methods of control of this invasive species, there still is an urgent need to develop the methods of control of both annual and perennial plants under conditions of Ukraine. The aim of the study was to determine the effectiveness of different methods of control of Heracleum Sosnowskyi. A field experiment was carried out during 2015-2020 on typical medium loam black soil. Four experiments were conducted: 1 – mechanical measures; 2 – screening; 3 – hot steam; 4 – use of herbicides. A randomised experimental design with four repetitions was used. It was found that an effective approach is the removal of the weeds with the root to a depth of at least 10-15 cm. Complete shading of the plants to the stage of four leaves within 30 days ensured their complete disappearance. The rate of Heracleum Sosnowskyi plants mortality by hot steam ranged from 100% (cotyledon stage) to 85% (6 leaves stage). The most sensitive to herbicides were the shoots in the cotyledon stage, from 97.3% to 100%. The most susceptible to herbicides in the phase of cotyledon was from 97.3% to 100%. To the phase of 6 leaves sensitivity decreased from 43.2 to 60.7%. The most effective herbicides were: TaskExtra 66.5 WG (rimsulfuron – 23 g·kg-1, nicosulfuron – 92 g·kg-1, dicamba – 550 g·kg-1) + Trend-90 at a consumtpion rate of 385 g·ha-1 + 0.2 l·ha-1 and MaisTer Power OD (foramsulfuron, 31.5 g·l-1 + iodosulfuron, 1.0 g·l-1 + tincarbazone-methyl, 10 g·l-1 + cyprosulfamide (antidote), 15 g·l-1) at a consumption rate of 1.5 l·ha-1). Heracleum Sosnowskyi the following herbicides proved to be efficient: Elumis 105 OD, MD (mesotrion 75 g·l-1, nikosulfuron, 30 g·l-1) at a consumption rate of 2.0 l·ha-1 and the following tank compositions: Elumis 105 OD, MD + Roundup Max v.r. (glyphosate potassium salt, 551 g·l-1) at a consumption rate of 2.0 + 6.0 l·ha-1. In further study of this issue, it is advised to increase the efficiency of controlling the number of Heracleum Sosnowskyi plants and reducing the chemical effect on the environment

Goal. Determination of soil contamination of plots planted for planting black poplar and evaluation of seed productivity of weeds. Methods. The level of seed productivity of the weeds was determined by the weighting method in the following sequence. In the experiment, 10 plants of one weed species were cut and manually threshed on a tarpaulin. The purified seeds were weighed and, after determining the mass of 1000 seeds, the average amount (thousand units /plant) of seeds per plant was converted. Results. The problem with perennial plantations of bioenergy crops is that the plants are grown for 10—15 years in monoculture on the same section of the field. Consequently, large stocks of certain weeds in the soil can significantly affect the growth and development and productivity level of cultivated plants. So, before planting a plantation, it is necessary to assess the clogging of the plots for the presence of problematic weed species, which can potentially breed on black poplar plantings and impede effective plant care. Virtually all arable land is mothballed with a different weed seed bank. Weed seed stocks depend on the direction of use of the plot, the culture of agriculture, the quality of agricultural operations on care, crop rotation, culture, etc. However, two areas with the same seed reserves in the soil are difficult to find, although the percentage of the main weed species may be identical. Conclusions. Weeds traditionally have high seed productivity and form large seed banks in the arable soil, reaching 1.5—2.0 million units / ha. Bioenergy crops, especially perennial species, are extremely sensitive to weeds in the first year of growing season. Because they form rather modest growths of vegetative mass and can not receive photosynthetically active energy to the soil, and therefore it is important to ensure the purity of the field from weeds during the first year of vegetation.