Control of annual broadleaf weeds by combinations of herbicides in sugar beet

Abstract

Sugar beet is a poor competitor to weeds. Weeds are a major constraintto sugar beet productivity. Field experiments were conducted atInstitute of Agriculture, Lithuanian Research Centre for Agriculture andForestry (55 degrees 23'N, 23 degrees 51'E) during the period 2010-2012on a loamy Endocalcari-Epihypogleyic Cambisol (CAlg-p-w-can) todetermine the influence of tank-mixed herbicides phenmedipham +desmedipham + ethofumesate (136.5 + 106.5 + 168 g ha(-1) a.i.) withchloridazon (624 g ha(-1) a.i.), metamitron (700 g ha(-1) a.i.) andtriflusulfuron (3.75 g he a.i.) on broad leaf weeds. Phenmedipham +desmedipham + ethofumesate was applied at three doses, 1/1, 2/3 and 1/2of the recommended dose. Metamitron was applied at two doses, 1/1 and1/2 of the recommended dose. All herbicide combinations acted similarlyin reducing these weed species: Chenopodium album, Thlaspi arvense,Tripleurospermum perforatm, Polygonum aviculare, Viola arvensis,Veronica arvensis, Lamium purpureum, Capsella bursa-pastoris andEuphorbia helioscopia. The efficacy of phenm puedipham + desmedipham +ethofumesate at full (1/1) dose was similar to that applied in a tankmix with chloridazon, metamitron and triflusulfuron at full dose. Therewere no significant differences in weed weight. Having reduced the doseof phenmedipham + desmedipham + ethofumesate by 33% and 50% in a tankmix, the dry weight of C. album, T perforatum and P aviculare increasednot significantly. The addition of chloridazon, metamitron andtriflusulfuron at full dose had a similar impact on weeds. The action oftriflusulfuron was longer because the weight of dominant weeds (C. albumand T perforatum) decreased (6-37%) during all crop growing period.Reducing the dose of metamitron from 525 to 350 g ha(-1) a.i. (33%) ina tank mix with phenmedipfam + desmedipham + ethofumesate at 1/2 dose,the dry weight of C. album, T perforatum, P aviculare, V arvensis and C.bursa-pastoris increased not significantly. By reducing the dose ofherbicides in a tank mix, the number of active ingredients (a.i.) shouldbe increased.