Dicotyledonous and grass weeds
Before the treatment in 2019, weeds from two groups-dicotyledonous and grass weeds-were found on the experimental ground. The first group included the following species: catchweed bedstraw (Galium aparine
L.; BBCH 25; 17 specimen/m2
), corn poppy (Papaver rhoeas
L.; BBCH 25; 12 specimen/m2), wood cerastium (Cerastium nemorale
M. Bieb.; BBCH 51; 9 specimen/m2
). The second group included: common wild oat (Avena fatua
L.; BBCH 25; 18 specimen/m2
) and black foxtail (Alopecurus myosuroides
Huds; BBCH 27; 37 specimen/m2
). In 2020, before the treatment, the species composition of weeds was similar, but their total number was less by 17% (77 specimen/m2
Table 3 shows the weed density in control plot during the period of experiment.
Efficiency of herbicides
Table 3: The weed density in control plot.
A significant excess of the efficiency of the combined agent over the single-component one was noted by the effect on two types of weeds: Galium aparine
and, specifically, on Papaver rhoeas
Common poppy (Papaver rhoeas)
Pure pyroxsulam’s effect on Papaver rhoeas
was the least: in the first year of research, the number of plants of this species decreased by 5.5-24.0% and in the second year, the reference standard Pallas 45 OD had no effect on them at all.
As is shown in Table (4) the use of Tarzec WG herbicide against Papaver rhoeas
was significantly more efficient: in the first year of research. The efficiency of both application rates exceeded that of both reference standards (91.8-100%); in the second year, the efficiency of 0.075 kg ha-1
of Tarzec herbicide was equal to that of the reference standard and the efficiency of 0.09 kg ha-1
was the highest in the experiment (89.3-95.5%).
Cleavers (Galium aparine)
Table 4: Efficiency of herbicides against weed species, % to nontreated check (2019, 2020).
The use of Tarzec in both application rates in 2019 made it possible to destroy all plants of Galium aparine
(100%) in 28 and 56 days after treatment (Table 4). The efficiency of reference standard Pallas 45 OD was credibly lower than this level. Reference standard Verdict WG was the least efficient in the experience (72.8-81.5%).
In 2020, the efficiency of 0.075 kg ha-
1 of Tarzec herbicide exceeded that of the Pallas reference standard in 28 and 56 days after application and the efficiency of 0.09 kg ha-1
of the agent under study exceeded that of all other herbicide options during the entire observation period (Table 4).
With respect to Cerastium nemorale
, the efficiency of pure pyroxsulam (93.8-100%) in the first year of research was equal to that of the combined agent in both application rates. All of these options credibly exceeded the performance of reference standard Verdikt WG.
In the second year, with records on days 14 and 28, the efficiency of 0.075 kg ha-1
of Tarzec herbicide exceed that of Pallas 45 OD reference standard and the efficiency of 0.09 kg ha-1
of Tarzec herbicide was the highest in the experiment during all observations (90.3-96.5%).
It is known that Corn poppy (Papaver rhoeas
L.) having developed herbicide resistance to acetolactate synthase inhibitors, especially in Mediterranean countries and Great Britain (Stankiewicz-Kosyl et al., 2020
). Therefore, obvious is the benefit of herbicides mixtures with halauxifen-methyl for the control of Papaver
resistant to ALS herbicides (Group 2) as well as 2, 4-D (Sleugh et al., 202
1). Concerning grass weeds, the use of combined agent in the first year of research had no significant advantage: pure-pyroxsulam efficiency against Avenafatua
and Alopecurus myosuroides
was at the level of the maximum combined-agent application rate. A lesser herbicide application rate was less efficient. Altogether, it corresponds with the available. Furthermore, Morderer et al., (2018)
noticed that Mixing halauxifen-methyl with pyroxsulam and florasulam increases the effectiveness for controlling perennial dicotyledonous in wheat crops. Data that Halauxifen-methyl combination with pyroxsulam succeeded to control both broad and grassy weed without antagonistic effect between them (Morderer et al., 2018).
In the second year of the study, the combined agent had an advantage over the single-component one in both application rates. Identification of chromosomes in Triticum aestivum
possessing genes that confer tolerance to halauxifen-methyl is currently under study (Obenland and Riechers, 2020
) and the herbicides based on this primary material are produced with the safener cloquintocet-mexyl. Safeners associated to ALS inhibitors reduce the sensitivity grass weeds to their associated herbicides (Duhoux et al., 2017
). Therefore, it is possible that the advantage of combined agent was caused by the lesser amount of safener cloquintocet-mexyl (0.02655 kg and 0.03186 kg per ha of Tarzec WG VS 0.045 kg/ha of Pallas 45 OD).
The use of Tarzec WG herbicide, as well as reference standards Pallas 45 OD and Verdikt WG had not negative effect on winter wheat Kalym strain plants. Spots, necroses or other symptoms of phytotoxicity were not found on herbicide-treated plots during the whole experimental period. The winter wheat plants, whether herbicide-treated or untreated-control, were developing simultaneously.
In the untreated control, the yield of winter wheat Kalym strain was 43.9 dt/ha (in 2019) and 46.2 dt/ha (in 2020). In all herbicide options, a significant increase in crop yield was noted: by 9.3-11.8% in 2019; by 8.7-10.4% in 2020 (Fig 1). Despite the stronger inhibition of some weed species in comparison with the reference standard in the options where herbicide Tarzec WG herbicide was applied, the yield of winter wheat in all herbicide options was at the same level.
Fig 1: Winter wheat yield after herbicides treatments (2019, 2020). The vertical bars represent LSD 0.05.