Reduction of Phenmedipham + Desmedipham + Ethofumesate Herbicides Dosage Based on Application Timing in Sugar Beet

Abstract

An experiment was conducted to study possible reduction of concentration (dose) of phenmedipham + desmedipham + ethofumesate herbicides at different application times to control weeds in sugar beet field. Thus, a factorial experiment based on complete randomized block design with three replications was performed at Sabzevar, Khorasan-e-Razavi in 2013. Factors consisted of herbicide dosages (control, 75% of the recommended dosage, and 125% of recommended dosage and application times at 2-4, 4-8 and 8-12 leaf stages of sugar beet. Herbicide used in the experiment was phenmedipham (9.2%) + desmedipham (7.2%) + ethofumesate (11.3%) (PROGRESS OF BETAMIX) as 877 ga.i ha-1 27.4 EC. The results indicated that the delayed application of herbicide increased weed density by 55.92% and weed dry matter by 33%. Application of herbicide at 4-8 leaf stage produced highest root and sugar yields. Root impurities were not affected by the time of herbicide application. Used of 125% of recommended dosage resulted in lowest weed density and weed dry matter and highest root and sugar yields. Impure sugar percentage and K content was not affected by herbicide dosage. Other root quality characteristics were not statistically significant different between the recommended dose 125% of recommended dosages. Results as a wholes suggested that at early growth stage of sugar beet (2-4 leaf stage) lower herbicide dosage and at later growth stage of sugar beet (8-12 leaf stage) higher herbicide dosage may produce highest root yield of sugar beet.

Keywords

• Herbicides
• Quantitative and qualitative yield
• Reduced dosage
• Sugar beet