Control of invasive species of hogweed and goldenrod in Belarus

E. A. Yakimovich, O. A. Shklyarevskaya

Introduction. Sosnowsky's hogweed (Heracleum sosnowskyi Manden.) and Canadian goldenrod (Solidago canadensis L.) are included in the list of invasive plants prohibited for introduction and (or) acclimatization, established by the Resolution of the Ministry of Natural Resources and Environmental Protection of the Republic of Belarus dated 28.11.2008 No. 106 "On certain issues of regulating the introduction and (or) acclimatization of plants." The spread and abundance of these plants are subject to regulation in accordance with the Resolution of the Council of Ministers of the Republic of Belarus dated 07.12.2016 No. 1002 "On certain issues of regulating the spread and abundance of plant species."

Due to the fact that hogweed leaves contain furanocoumarins, which increase the skin's sensitivity to sunlight, specifically ultraviolet light, people have suffered first-to-third-degree burns when working with hogweed. After the introduction of hogweed into crop rotation as a forage (silage) crop, it became clear that the culture was not suitable as a silage crop. For these reasons, the cultivation of Sosnowsky's hogweed was suspended in the second half of the XX century.

Subsequently, the hogweed went out of control and began to grow on abandoned lands, along streams, ditches, and roads, within settlements, and then began to occupy the most fertile lands, displacing local species of herbaceous plants. Non-agricultural lands are one of the main categories of areas where the hogweed is actively spreading.

In the European part of Russia and in Belarus, the European goldenrod (Solidago virgaurea L.) grows naturally. In Belarus, it is found throughout the territory, often in coniferous and mixed forests, especially in dry pine forests, along roads, in forest clearings and edges, in felling areas, fallow lands, waste grounds, and railway embankments.

Invasive goldenrods, native to North America, are represented in the territory of Belarus by a complex of species, among which Canadian goldenrod (S. canadensis L.) is most frequently noted. Giant goldenrod (S. gigantea Ait.) and the cultivar hybrid goldenrod (S. hybrid L.) are also found. Often, all these species are referred to under the collective taxon S. canadensis.

In Belarus, Canadian goldenrod appeared as an ornamental plant in the 1950s. It is a perennial plant, 70–120 cm tall. It is pollinated by insects. Fecundity is more than 10 thousand seeds on a single generative shoot. Due to their small size and good wind dispersal properties, the seeds are scattered by the wind over long distances, which ensures the colonization of unoccupied areas.

Thanks to clonal growth, S. canadensis can create dense thickets, the density of which reaches more than 300 shoots/m2. The maximum projective cover of goldenrod is noted at 5–6 years of age.

The main distribution areas of goldenrod are waste grounds, abandoned lands that were recently used as agricultural land, territories of abandoned residential complexes, lands under power lines, forest park areas, as well as territories of cemeteries; it is partially found in crops of agricultural plants.

Control of the spread of goldenrod and Sosnowsky's hogweed was previously mainly carried out by mowing. More significant results were obtained when replacing mowing with various herbicides registered for use against invasive plants: glyphosate-based herbicides; persistent herbicides based on sulfometuron-methyl and imazapyr; and metsulfuron-methyl. Positive studies were also obtained by specialists from the V.F. Kuprevich Institute of Experimental Botany of the National Academy of Sciences of Belarus when using metsulfuron-methyl against Sosnowsky's hogweed. According to specialists from the Central Botanical Garden of the National Academy of Sciences of Belarus and the St. Petersburg Forestry Research Institute, tank mixtures of herbicides are effective against goldenrod and Sosnowsky's hogweed.

Herbicide Magnum, WDG (metsulfuron-methyl, 600 g/kg) belongs to the sulfonylurea derivatives. This systemic herbicide enters weeds through the leaves and roots. The preparation acts by inhibiting cell division in the growing tips of roots and shoots of sensitive plants. Visible signs appear on the 5–10th day, and complete death of weeds occurs after 15–25 days. The selective herbicide is used in agriculture against annual broad-leaved and some perennial weeds in cereal crops.

The purpose of this work is to designate the priority of the Magnum, WDG herbicide as a herbicide for controlling invasive plant species due to the preservation of the grass cenosis during its application.

Materials and methods of research. The work was carried out at the RUE "Institute of Plant Protection" in 2012–2023 by setting up field experiments in the territory of Minsk and the Minsk region. The studies were conducted on lands heavily overgrown with Sosnowsky's hogweed and Canadian goldenrod plants.

The performance evaluation was conducted at the "Mezhdulesye" agricultural production cooperative in the Beryoza district of the Brest region, the "Zelenstroy" unitary enterprise of the Oktyabrsky district of Minsk, and in the Slonim district of the Grodno region.

The efficacy of herbicides in controlling invasive species was assessed in accordance with the Methodological Guidelines…. The herbicide was applied by broadcast spraying using a "Jacto" knapsack sprayer according to the experimental design. Simultaneously, the impact of the tested herbicide on the phytocenosis was evaluated.

Clearing land of invasive plant species, such as Sosnowsky's hogweed, requires a selective approach. Popular non-selective herbicides based on sulfometuron-methyl, imazapyr, or glyphosate completely destroy all herbaceous vegetation. At the same time, selective products for cereal crops and rapeseed (Galera Super 364, SL; Dianat, SL; Lancelot 450, WG; Lintur, WDG; Saniflor, WG; Starane Premium 330, EC; Fenizan, SL) show low efficacy against hogweed — no more than 6.0–56.5%. In such a situation, the solution is to use the herbicide Magnum, WDG based on metsulfuron-methyl, which combines high efficacy with the ability to preserve grass stands.

• Magnum, WDG application rate — 20–300 g/ha
• Hogweed height for tank mixtures — 20–30 cm
• Reduction in weed mass by mixture — up to 95.8%
• Reduction in population by mixture — up to 80.3%

Standalone application of Magnum, WDG herbicide against Sosnowsky's hogweed

In the experiments, the Magnum, WDG product was tested at dosages ranging from 20 to 300 g/ha on two plots with different levels of infestation. On the first plot, the initial weed population was 10.7 plants/m² with a mass of 1122.7 g/m², and on the second, it reached 25.3 plants/m² with a mass of 13029.3 g/m². The results of counts one month after treatment showed a gradual suppression of plants with increasing product dosages.

Two to three months after treatment, the biological efficacy of the product increases significantly. On the first plot, after 2 months, a dosage of 20–30 g/ha reduced the hogweed population by 43.0%, and the mass decreased by 65.4–77.1%. At the same time, on the second plot, after 3 months, with application rates from 50 to 300 g/ha, a 100% weed mortality was achieved.

On average, according to the test results, treatment with the herbicide Magnum, WDG at rates of 20–30 g/ha after 2–3 months reduced the hogweed population by 54.0–70.3%, and their mass by 80.2–87.5%. At rates of 40–50 g/ha, these indicators were 84.2–87.5% and 92.2–94.9%, respectively. Maximum doses (100–300 g/ha) ensured a reduction in population by 87.5–93.8% and mass by 97.7–98.8%.

Use of tank mixtures to accelerate the effect

When treating Sosnowsky's hogweed at early stages of development, when the plant height is 20–30 cm, it is advisable to use tank mixtures. The combined application of Magnum, WDG and Volnik Super, SL herbicides allows for a significant acceleration in the death of weed vegetation. Just one month after spraying, the vegetative mass decreases by 85.4–90.9%, and after two months, the efficacy by mass reaches 92.3–95.8%.

For comparison, the isolated application of Magnum, WDG at doses of 10 and 20 g/ha yields a slower effect. After one month, the hogweed population decreases by only 11.0–21.5%, and its mass by 57.9–75.3%. After two months, the indicators are 34.0–38.5% for population and 65.0–76.2% for weed mass. Adding Volnik Super, SL to the tank mixture allows for rapid control of the invasive species in a short time.

The influence of the tank mixture of metsulfuron-methyl with a glyphosate-containing herbicide compared to pure metsulfuron: after one month, hogweed mortality increased to 28.5%, mass to 15.6%; after two months – to 41.8% and 19.6%; the hogweed in the experiment did not regrow, as it did with the application of glyphosate.

Using tank mixtures (Magnum, WDG + glyphosate-containing herbicide) allows for a significant increase in the efficiency of chemical treatments. The effectiveness of these tank mixtures was also confirmed in field evaluation trials.

The herbicides we studied were also used in hogweed populations of different ages (in areas difficult to mow). The height of the hogweed plants was 30–50 cm, 50–90 cm, and 120 cm.

In 2013–2014, we established that one month after treatment, the Magnum, WDG herbicide reduced the hogweed mass by 60.2%, and when using the tank mixture of Magnum, WDG + Tornado 500, SL – by 73.4%. Table 4 – Influence of herbicides on the population and mass of hogweed (Heracleum sosnowskyi) plants of different ages (field trials, Minsk district, average data for 2013–2014)

Assessment after treatment one month 2 months

Variant population and mass pcs/m2 g/m2 pcs/m2 g/m2 No treatment 9.7 6575.0 12.4 15060.0 efficiency, % Magnum, WDG – 100 g/ha 51.3 60.2 73.1 81.5 Magnum, WDG + Tornado 500, SL –

65.2 73.4 81.1 93.6 100 g/ha + 3.0 l/ha

The addition of Tornado 500, SL helped accelerate the expression of the herbicide's activity: plant leaves turned yellow earlier and began to discolor; plant mortality proceeded more intensely than with treatment by the Magnum, WDG herbicide alone.

After two months, the efficiency of the Magnum, WDG herbicide in controlling hogweed was at the level of 73.1% by population and 81.5% by mass. In the tank mixture of Magnum, WDG + Tornado 500, SL, hogweed mortality reached 81.1%, and its mass decreased by 93.6%.

Thus, the use of tank mixtures allows for a significant increase in the efficiency of chemical treatments compared to applying the products separately at the maximum permitted application rates.

In 2013, the Magnum, WDG herbicide was applied to actively growing Canadian goldenrod plants 30–50 cm in height. One month after treatment, the efficiency of Magnum, WDG at rates of 100 and 200 g/ha was 84.6% and 92.3% by population and 89.2% by mass. At a rate of 300 g/ha, the Canadian goldenrod died completely.

In 2014, the Canadian goldenrod was represented by both young first-year plants that had emerged from seed and perennial specimens regrowing after a scheduled mowing of the plot (at a goldenrod height of up to 30 cm).

After treatment with the Magnum, WDG herbicide at a rate of 40 g/ha, the goldenrod population decreased by 79.4%, mass – by 89.6%; at 100 g/ha, the plant died completely.

Figure 2 – Biological efficiency of the

Magnum, WDG herbicide against Canadian goldenrod (field trials, Minsk district)

When using a tank mixture of Tornado 540, SL (3.7 l/ha) + Magnum, WDG (10 g/ha), the Canadian goldenrod population decreased by 90.2%, and its vegetative mass – by 95.8%. A tank mixture of a glyphosate-containing herbicide with Magnum, WDG (20 g/ha) ensured the total mortality (100%) of the Canadian goldenrod. Table 5 – Efficiency of tank mixtures against Canadian goldenrod at a plant height of up to 30 cm (field trial, Minsk district, 2018)

Variant pcs/m2 g/m2 No treatment 51.0 817.0

Efficiency, % Tornado 540, SL + Magnum, WDG – 3.7 l/ha + 10 g/ha 90.2 95.8 Tornado 540, SL + Magnum, WDG – 3.7 l/ha + 20 g/ha 100 100

The mortality of herbaceous vegetation when using the Magnum, WDG herbicide was quite high; almost all dicotyledonous species died completely (stinging nettle, Canadian horseweed, perennial sowthistle, common yarrow, sheep sorrel, etc.).

The effect on monocotyledonous components of the phytocenosis was not entirely uniform. Upon application of the product, an increase in the population and mass of couch grass and sedge species was noted. At the same time, the mortality of barnyard grass and annual bluegrass was observed.

The Magnum, WDG herbicide at rates from 10 to 100 g/ha inhibited first-year grass crops: meadow fescue, red fescue, and perennial ryegrass. However, as the turf density increases in perennial meadows, lawns, and pastures, the phytotoxic influence of the Magnum, WDG herbicide on grasses decreases, and the application of the product at this rate has practically no negative impact on the grass cenosis.

In a number of trials, perennial grasses (orchard grass, timothy, perennial ryegrass) were periodically suppressed and periodically spread, therefore trials were established to evaluate the efficacy and duration of the phytotoxic effect of the herbicides Magnum, WDG at application rates of 100, 200 and 300 g/ha, Terrsan, WDG at application rates of 200 and 300 g/ha, and Grader, WGR at an application rate of 2.5 l/ha on herbaceous grass plants.

Herbaceous plants were present in the natural phytocenosis. Observations conducted in May of the following year (2014) showed that plots treated with the herbicides Terrsan, WDG and Grader, WGR were completely free of herbaceous plants; in variants where the herbicide Magnum, WDG was applied, the growth of perennial grasses – orchard grass and timothy – was noted, although their above-ground vegetative mass was 33.2–67.8% lower compared to the untreated variant.

Figure 3 – Effect of herbicides on the phytocenosis (field trials, natural herbage, Priluki agrotown, one year after treatment,

Visual observations showed that the overgrowth of plots treated with the herbicides Terrsan, WDG and Grader, WGR by monocotyledonous and dicotyledonous herbaceous plants occurs 1–1.5 years after application. Three months after treatment, the effect of Magnum, WDG (at an application rate of more than 100 g/ha) on wood small-reed, orchard grass, and timothy is noted; however, after six months, the herbaceous cenosis is completely restored and practically indistinguishable from the untreated area.

Scientific and practical developments were widely applied in agricultural organizations of the Republic of Belarus. In 2012, at the "Mezhdulesye" Agricultural Production Cooperative of the Berezovsky district of the Brest region, a tank mixture of the herbicide Tornado 500, SL (5.0 l/ha) + Magnum, WDG (20 g/ha) was applied to non-agricultural lands using a tractor sprayer on an area of 5 ha when the hogweed height was 10–30 cm. One month after treatment, the reduction in plant density was 85%, and the reduction in biomass was 95%.

In 2018, a production trial was conducted on the territory of the "Zelenstroy of the Oktyabrsky District of Minsk" unitary enterprise on an area of 13 ha using the herbicides Grader, WGR, Magnum, WDG and a tank mixture of Ballerina, SE + Magnum, WDG, depending on the height of the hogweed plants. Two to three months after treatment, the herbicide Grader, WGR (2.5 l/ha) reduced the density of Sosnowsky's hogweed and other herbaceous plants by 99–100%. The use of the herbicide Magnum, WDG (100 and 300 g/ha) and its tank mixture with Ballerina, SE allowed not only to effectively destroy Sosnowsky's hogweed (by 90–100%) but also to preserve the grass cover.

The herbicide Magnum, WDG confirmed sufficiently high efficacy in the Slonim district of the Grodno region: in 2020, the treatment area against Canadian goldenrod was 166 ha, and against Sosnowsky's hogweed – 10 ha; in 2021, the treatment area against Canadian goldenrod was 5.6 ha, and against Sosnowsky's hogweed – 9.5 ha. The herbicide was applied at a rate of 250 g/ha against Canadian goldenrod and 300 g/ha against Sosnowsky's hogweed. The preparation showed high biological efficacy in suppressing populations of invasive plants (> 90–95%). Preservation of grasses was noted.

Based on the results of the studies conducted, the herbicide Magnum, WDG was officially registered for the suppression of invasive plant species. This preparation is recommended for use on industrial lands (gas and oil pipeline routes, embankments and exclusion zones of railways and highways, airfields, etc.) at an application rate of 100–300 g/ha, as well as in parks, squares, recreation areas, and in territories occupied by herbaceous vegetation at an application rate of 40–100 g/ha. The herbicide is also approved for use in populated areas. The use of tank mixtures with glyphosate-containing preparations is recommended in areas with mixed-age populations of Sosnowsky's hogweed, with a height of 30 to 120 cm.

Conclusion. The herbicide Magnum, WDG (metsulfuron-methyl, 600 g/kg) was effective against Sosnowsky's hogweed (Heracleum sosnowskyi Manden.) and Canadian goldenrod (Solidago canadensis L.) 2 months after treatment of industrial lands. At the maximum application rate of 100–300 g/ha, the mortality of hogweed and Canadian goldenrod reached 100%. Application of the herbicide at a rate of 40–100 g/ha also guarantees the almost complete destruction of Sosnowsky's hogweed and Canadian goldenrod while preserving the grass stand. The herbicide should not be used on lawn grasses in their first year of life. With the compaction of the sod, on perennial meadows, lawns, and pastures, the phytotoxic effect of Magnum, WDG on the grass cenosis is practically absent (when applied at a rate of up to 100 g/ha).

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E. A. Yakimovich, O. A. Shklyarevskaya RUE «Institute of Plant Protection», Priluki, Minsk region

APPLICATION OF HERBICIDE BASED ON

METSULFURON-METHYL FOR INVASIVE PLANT

Annotation. The herbicide, based on metsulfuron-methyl (Magnum, VDG®) in 2 months after industrial land setting treatment have been effective against Sosnowski’s hogweed (Heraculum sosnowsky Manden.) and goldenrod (Solidago canadensis L.). At the maximum rate of herbicide application of 100–300 g/ha, the hogweed and goldenrod kill has made 100 %. The application of herbicide at the rate of 40–100 g/ha also guarantees the almost complete hogweed and goldenrod control with the preservation of grassy species. The herbicide should not be used on lawn grasses of the first year of life. With the compaction of turf, in perennial meadows, lawns, pastures, the phytotoxic effect of Magnum, VDG® on grassy cenosis is practically absent (applied normally up to 100 g/ha).

Key words: Heraculum sosnowsky Manden., Solidago sanadensis L., herbicide, metsulfuron-methyl, high biological efficiency.