The Effect of Pre-Mixed Herbicides of MCPA+ Florasulam on Weed Control of Broadleaf and Wheat (Triticum aestivum) Yield in Fields of Fars Province

Background and objectives: Weeds are one of the most significant limiting factors for the production of crop plants. Weeds primarily cause damage and reduce crop yield through competition. Weed damage in wheat fields has been reported to range from 25% to 30% in Iran. The herbicide application is the most important method for weed control of wheat until now. Also, the application of pre-mixed herbicides is one of the strategies to broaden weed control spectrum. This experiment was conducted to evaluate the efficacy of the pre-mixed herbicide Florasulam+ MCPA in controlling broadleaf weeds in wheat.
Materials and methods: This experiment was conducted in a randomized complete block design with 14 treatments and 4 replications at the Hasanabad Agricultural Research Station of Darab (Fars) during 2022-202. Experimental treatments included the application of Florasulam+ MCPA (42% WP) herbicide at dose rates of 300, 400, 500, 600, 700, 800 g ha-1, Florasulam (Florex@ 10% WP) at a rate of 85 g ha-1, 2,4-D+ MCPA (U46 Combi Fluid@ 67.5% SL) at a rate of 2 L ha-1, Bromoxynil+ 2, 4-D (Buctril Universal@ 56% EC) at a rate of 1.5 L ha-1, Bromoxynil+ MCPA (Bromicid MA@ 40% EC) at a rate of 1.5 L ha-1, Bentazone+ Dichlorprop (Basagran DP@ 56.6% SL) at a rate of 2 L ha-1, Prosulfocarb (Boxer@ 80% EC) at a rate of 4 L ha-1, Pendimethalin (Fist Super@ 45.6% CS) 4 L ha-1, control (weed free). Each plot was divided into two subplots. One subplot was sprayed (treatment) and subplot was unsprayed (weedy check). The herbicides pendimethalin and prosulfocarb were applied as pre-emergence treatments, and other herbicide treatments were applied at the tillering stage of wheat (Zadok’s Stage 25(, according to the 3 to 5 leaf stage of the weeds. The plot had dimensions of 10 × 2 m with a plant density of 400 plants m-2 and 8 planting rows. 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. The measured traits included determining density, dry weight, the percentage of control of weed species, and grain yield and yield components. The means were separated using the LSD test at the 5% level of significance.
Results: The results showed that herbicides that were applied significantly decreased weed density and dry weight of Melilotus officinalis, C. oxyacanthus, S. oleraceus, H. incana, Centaurea iberica, as well as a significant increase in grain per spike, the number of spikes per m2, 1000 grains weight and grain yield. Also, weed control efficiency improved with an increase in the application rate of Florasulam+ MCPA herbicide. The best application rate for the Florasulam+ MCPA herbicide was 800 g ha-1. This treatment decreased the weed biomass of M. officinalis, C. oxyacanthus, S. oleraceus, H. incana, C. iberica 91, 95, 92, 100 and 95%, respectively, and increased the grain yield (7.29-ton ha-1) by 29%.
Conclusion: Based on the results of this experiment, the herbicide efficacy of the pre-mix herbicide florasulam+ MCPA in controlling weeds such as M. officinalis, C. oxyacanthus, S. oleraceus, H. incana and C. iberica was significantly higher than the application of florasulam alone. Furthermore, the efficacy of this herbicide in controlling the mentioned weeds was significantly higher than compared to the soil-applied herbicides pendimethalin and prosulfocarb. Additionally, the efficacy of this herbicide in weeds control was higher compared to the post-emergence herbicides in the experiment. Therefore, considering the broad spectrum of weed control and the increase in grain yield, the application of florasulam+ MCPA herbicide is recommended as a suitable herbicide for controlling broadleaf weeds.