Evaluation of the Effect of Mixing Clopyralid with Oxadiazon and Oxadiargyl on Control of Broadleaf Weeds in Rapeseed (Brassica napus L.)

Document Type : Research Article


1 Department of Plant Production and Genetics, Faculty of Agriculture, Agricultural Sciences and Natural Resources University of Khuzestan, Bavi, Mollasani, Khuzestan, Iran.

2 Plant Protection Management Administration, Jahad Agricultural Organization of Khuzestan, Ahvaz, Iran


Rapeseed is one of the most important crops cultivated for oil extraction and has the highest annual growth rate (in terms of production) among the essential oilseeds in the world. Due to its slow growth rate, the rapeseed plant has little competitive ability against weeds in the early growing season, which causes it to be severely damaged by weed interference. Since the long-term presence of weeds in rapeseed could reduce its quality and yield, early weed control is essential to achieve economically acceptable yields.
Materials and Methods
In order to control broadleaf weeds in rapeseed fields, a factorial experiment based on a randomized complete block design with three replications was conducted in winter 2019 in Benvar Nazer region, Andimeshk county, Iran. The experimental factors included two types of rapeseed hybrids (Hayola 50 and Agamax) and clopyralid herbicide (1.5 L ha-1 recommended dose, EC30%, Aryashimi, Iran) application with a fixed dose of 1 lit ha-1 for all treatments along with oxadiazon herbicide (recommended dose of 3 L ha-1 for using in rice as pre-plant before the two leaved barnyard grass, EC12%, Shimagro company, Iran) at doses of 100, 175, and 200 ml ha-1, and oxadiargyl herbicide (recommended dose of 3-3.5 L ha-1 for using in rice as pre-emergence or at the beginning of weed emergence in transplanted rice, SC3%, Herbicide Production Company, Iran) with doses of 100, 125, and 150 ml ha-1. Weedy and weeding control (complete control by manual weeding) were considered as control treatments. Herbicides were applied by a 12 liter back sprayer equipped with a TJET 11003 nozzle, which was calibrated for spraying 200 liters per hectare, in the initial 2-leaf stage to the beginning of 4 true leaves for chemical control of weeds in the plots. The grass weeds were removed by hand. Broadleaf weeds were counted separately according to the weed species at before spraying, three and six weeks after spraying and were cut at the soil surface and dried at 70 °C in oven. Then, weed dry weight was measured with a digital scale 0.01 and the percentage reduction in density and dry weight of weeds were calculated. In addition, the amount herbicides used on rapeseed was visually assessed using the EWRS standard table. Then, yield and yield components of rapeseed including number of siliques, seed no. per silique, 1000-seed weight, seed yield, biological yield and harvest index were measured.
Results and Discussion
Results showed that the predominant weed species in the experimental plots included wild clover, queen anne᾿s lace, mallow, Anagalis spp., wild mustard, and field bindweed, which the highest frequency (31.29%) belonged to wild clover and the lowest frequency (1.03%) belonged to field bindweed. The ANOVA results showed that the reduction percentage of density and dry weight of weeds and seed yield were affected by experimental treatments; as the treatments of clopyralid + oxadiazon 100, clopyralid + oxadiazon 175, clopyralid + oxadiargyl 125 in Hyola50 hybrid and clopyralid + oxadiazon 175 in Agamax hybrid reduced the density and dry weight of weeds by 100%. While, the lowest reduction percentage of weed density and dry weight (44.74 and 55.33%, respectively) was observed in Agamax hybrid and clopyralid (1 L ha-1) treatment. Also, the highest and lowest herbicide injury on weeds were observed in clopyralid+oxadiazon 100 (9.67%) and clopyralid alone and combination of clopyralid+oxadiargyl 100 and 150 in Agamax hybrid (0%), respectively. The highest seed yield, biological yield and 1000-seed weight of rapeseed were observed in clopyralid+oxadiazon 200, oxadiargyl 125 and 150 (3377.6 kg ha-1, 11295 kg ha-1, and 3.27 g, respectively), and the lowest was observed in weedy control treatment (2064.2 Kg ha-1, 7458 Kg ha-1 and 2.87 g). 1000-seed weight is less affected by treatments and is a genetic trait. The highest and lowest number of seeds per silique under the influence of herbicide treatment were related to clopyralid+oxadiazone 175 and clopyralid+oxadiargyl 100 (23.33 and 18.17), respectively. An increase in the number of seeds per silique was observed with increasing the dose of herbicide oxadiazone in combination with clopyralid up to 175 ml ha-1. The highest number of siliques per plant was obtained in weeding treatment in Agamax hybrid with 189.33 silique per plant, which was significantly different from weedy control treatment. Also, the lowest number of weed control silique was obtained with Hayola 50 hybrid, which was not significantly different from clopyralid+oxadiazone 100 in Agamax hybrid.
According to the results, mixing herbicides is a solution to eliminate the competition of weeds with rapeseed and increase the yield so that the yield of up to 3.3 tons is obtained, which compared to clopyralide only as a control treatment. In general, the highest yield of rapeseed from plots treated with clopyralid+oxadiazon 200, oxadiargyl 125, and 150 were the best treatment in comparison with the applied treatments. The best treatment is the one in which rapeseed yield has been the highest. In addition, since clopyralid is a selective herbicide in rapeseed, it did not have sufficient efficacy due to poor control of important weeds such as wild mustard. It should also be noted that further testing of the above herbicide mixtures on rapeseed fields throughout the country is necessary in order to obtain the results that are the basis for recommending these mixtures in rapeseed.


Main Subjects

  1. Al- Barrak, K.M. (2006). Irrigation interval and nitrogen level effects on growth and yield of canola (Brassica napus ). Scientific Journal of King Faisal University. Al-Hassa, Saudi Arabia 7(1): 87-102.
  2. Askari, M., Faraji, A., Dadashi, M.R., & Asgari, M. (2012). Evaluation of some agronomic characteristics and yield of new spring rapeseed hybrids. In: Proceedings of the 1th National Conference on Biology Sciences. Falavarjan. Available in: https://civilica.com/doc/183311/ (visited 11 Desember 2021) (In Persian with English abstract)
  3. Askari, S.A., Saeedipour, S., & Kalantar Hormozi, S. (2016). Evaluation of the effect of application of some herbicides in weed control of rapeseed field in Khuzestan province. In: Proceedings of the 1th National Conference on Modern Research in Agriculture and Animal Sciences. Birjand, p. 1103 (In Persian with English abstract)
  4. Berry, M.P., & Spink, J.H. (2006). A physiological analysis of oilseed rape yield, past and future (review). Journal of Agricultural Science. Cambridge 199: 381-392. https://doi.org/10.1017/S0021859606006423.
  5. Blackshaw, R.E. (2002). Influence of wild radish yield on quality of canola. Weed Science 50(3): 344-349. https://doi.org/10.1614/0043-1745(2002)050[0344:IOWROY]2.0.CO;2.
  6. Dastorani, M., Gholamalipour Alamdari, A., Biabani, A., Avarseji, Z., & Habibi M. (2018). Study the several herbicides effect on weeds control and yield of cumin (Cuminum cyminum). Iranian Journal of Weed Science 14(1): 83-95. (In Persian with English abstract)
  7. Ghosheh, H.Z. (2004). Single herbicide treatments for control of broad-leaved weeds in onion. Crop Protection 23: 539-542. https://doi.org/10.1016/j.cropro.2003.10.010.
  8. Jamal,Q., & Chester, L.F. (2006). Selective weed control in Syrian marjoram (Origanum syriacum L.) with oxadiazon and oxyfluorfen herbicides. Weed Technology 20(3): 670-676. https://doi.org/10.1614/WT-04-129R1.1.
  9. Kudsk, P., & Striebig J.C. (2003). Herbicides – a two-edged sword. Weed Research 43(1): 90–102. https://doi.org/10.1046/j.1365-3180.2003.00328.x.
  10. Mehdinejad, K., Mehdinejad, M., & Shariati Feyzabadi, F. (2011). Toxic effects of different concentrations of oxadiargyl (topstar) herbicide on rice fields on Scenedesmus green algae in water sources. Journal of Biology 5(2): 95-105. (In Persian with English abstract)
  11. Musavi, M.R. (2013). Herbicices: Knowledge and Application. Marze Danesh Press, Iran. 284 pp. (In Persian)
  12. Nasiri, S., Asghari, J., Samizadeh, H., Moradi, P., & Shirzad, F. (2014). Evaluation of oxadiargyl and thiobencarb herbicides efficacy on rice (Oryza sativa) yield and yield components. Cereal Reserch 3(4): 307-319. (In Persian with English abstract)
  13. Naylor, R.E.L., & Lutman, P.J. (2002). What is Weed? Weed Management Handbook, Eds R.E.L. Naylor (2002) Blackwell Science Ltd. pp: 19– 40.
  14. Shimi, P., Poorazar, R., Ghezeli, F., & Sasanfar, H.R. (2014). Efficiency of two commercial forms of clopyralid at different doses in controlling canola weeds. Iranian Journal of Weed Science 10: 145-153. (In Persian with English abstract)
  15. Shimi, P., Saeidi, H., Abtali, Y., Poorazar, R., & Maleki, I. (2008). Testing butisan star in canola. Final on farm research report. Iranian Research Institute of Plant Protection, Plant Protection Organization and Ministry of Agriculture Agronomic Affairs. (In Persian with English abstract)
  16. Tabib, M.H., Ghasemi Nezhad, M., Hassani, M., Shojaee, A., & Beiranvand, H. (2019). The investigation mixing of lontrol with ronstar and topstar for Malva nicaeensis control in rapeseed (Brassica napus) in Behbahan. In: Proceedings of the 8th Iranian Weed Science Congress. Mashhad, p. 891. (In Persian with English abstract)
  17. Yaghoubi, B. 2015. Chemical Control of Pondweed (Potamogeton nodosus) and Barnyardgrass (Echinochloa crus-galli) in paddy fields. Iranian Journal of Weed Science 11: 195-207. (In Persian with English abstract)
  18. Zand, E., Mousavi, S.K., & Heidari, A. (2014). Herbicides and Their Application Methods. Jihad Daneshgahi Press of Mashhad, Iran. 547 pp. (In Persian)