Evaluation of the Efficacy of Dual-purpose Herbicides Axial One® (Pinoxaden + Flurasulam) and Cassic® (Diflufenican + Iodosulfuron methyl sodium + Flurasulam) Compared to Common Herbicides for Weed Control in Wheat (Triticum aestivum)

Wheat is a crucial crop that plays a significant role in ensuring food security in Iran. Weeds have been one of the major limiting factors for wheat production in Iran and globall. If they are not adequately controlled. Weeds can cause significant damage to wheat crops. Weed damage in wheat fields has been reported to range from 20% to 30% in Iran. The herbicide application is the most important method for weed control of wheat until now. Axial-one@ herbicide, with common names of pinoxaden+ florasulam, has been suggested for weed control of Lollium rigidum, Echinochloa colonum, Alopecurus myosuroides, Phalaris brachystachys, Avena ludoviciana, Stellaria media, Trifolium alexandrinum, Polygonum aviculare, Sinapis arvensis, Ambrosia artemisiifolia, Amaranthus retroflexus, Cirsium arvense. This herbicide has been registered by Syngenta for use in wheat and barley. Pinoxaden (Axial@) belongs to phenylpyrazolines family and inhibitors of the Acetyl-CoA carboxylase (ACC). It has been recorded in the control of narrow-leaved weeds in wheat and barley. Florasulam herbicide belongs to the triazolopyrimidine sulfonamide family and inhibits acetolactate synthase (ALS). Florasolam is the selective herbicide that has been recommended for controlling broadleaf weeds in cereals such as wheat, barley, oats, rye (Secale cereale L.) and triticale (Triticale hexaploid Lart). Also, the Cassic herbicide, which is also known as diflufenican+iodosulfuron-methyl-sodium+florasulam+cloquintocet-mexyl, is a dual-purpose herbicide that has been registered by Syngenta for controlling both broadleaf and narrow-leaved weeds in wheat and barley, oats, rye, and triticale crops. This experiment was conducted to investigate the effectiveness of the herbicides of Cassic and Axial-one in the controlling weeds in wheat fields, determination of the most appropriate dose, comparing their effectiveness with other herbicides commonly used in wheat fields, and evaluating the response of wheat plants to the herbicides.

 An experiment was carried out in weed control in the wheat fields of Karaj, Fars (Darab), Golestan (Gonbad), and Shahrud using a randomized complete block design with 13 treatments and 4 replications during 2020-2021. Experimental treatments included the application of Bromycid AM (bromoxynil + MCPA, 40% EC) + Axial (Pinoxaden, 5% EC) at 1.5 + 1.2 l/ha, Othello (diflufenican+ mesosulfuron methyl+ iodosulfuron methyl sodium, 6%OD) at 1.6 l /ha, Axial One (Pinoxaden+ Flurasulam, 5% EC) at 1.1, 1.3, 1.5, 1.7 l/ha, Cassic (diflufenican+ iodosulfuron-methyl-sodium+ florasulam+ cloquintocet mexyl, 47% WG) at 170, 200 and 230 g/ha with and without cytogit, and control (weed free). Herbicide treatments were applied during the tillering stage (Zadok’s Stage 25(. The plot had dimensions of 8 x 2 m with a plant density of 400 plants m-2. Each plot consisted of 8 planting lines with a row spacing of 15 cm. The distance between the plots was one meter, and there was a two-meter gap between replications. To increase the accuracy of the experiment, each test plot was divided into two equal sections, with the upper half serving as the control without spraying and the lower half being sprayed. The spraying was done using a fixed-pressure back sprayer equipped with a fan spray nozzle (8002) at a pressure of 2 bar and spray volume of 300 L ha-1. Traits such as weed density, weed biomass, and grain yield were recorded. Weed numbers and dry weights were determined by randomly selecting 0.50-m2 quadrats per plot, while grain yield was recorded for 3 m2 in each plot. The data were checked for normality and analyzed using SAS 9.3 software through analysis of variance. The means were separated using the Duncan test at the 5% level of significance. 

 The results of experiment indicated that the herbicide treatments led to a significant decrease in the density and dry weight of weeds, as well as a significant increase in grain yield. The Axial One@ at rate 1.7 L ha-1 was found to be more effective in controlling Avena ludoviciana, reducing its density by 95%, compared to On the other hand, Cassic herbicide at a rate of 230 g per hectare was more effective in controlling Lolium rigidum, reducing its density by 95%, compared to Axial One@ herbicide. Both herbicides, however, led to a significant reduction in the dry weight of Descurania sophia, Polygonum avicular, Sonchus oleracea, Veronica persica and Sinapis arvensis from 85 to 95%. No visual injury symptoms were observed on wheat after the application of these herbicides. Grain yield increased with the application of Axial One (at rate of 1.5 to 1.7 L ha-1) by 5 to 24%, and Cassic (at rates of 200-230 g ha-1 + cytogit) by 8 to 28%. These findings were consistent with the results of previous studies (Minbashi et al., 2020). The application of Oxial herbicide increased grain weight of wheat (Azhar et al., 2013).

 Based on the results of these experiments, it can be concluded that Axial One@ and Cassic@ herbicides showed the best control on A. ludoviciana and L. rigidum respectively, and also led to a significant increase in grain yield compared to half of the control plot. Therefore, the Axial One@ (1.7 L ha-1) and Cassic@ (200-230 g ha-1 + cytogit) can be considered as good to excellent options for weed control in wheat fields. It is recommended to use these herbicides for weed control in wheat fields.