Study On The Synergism Of Adjuvants To Mesosulfuron-methyl And Pyroxsulam In Controlling Tausch’s Goatgrass (Aegilops Tauschii Coss.)

Tausch’s goatgrass (Aegilops tauschii Coss.), an annual or biennial grass weed, is classified asAegilop. In recent years, tausch’s goatgrass has infested in winter wheat fields in Hebei, Shandong,Henan, Shanxi and Shaanxi provinces. Morphology and growth habits of tausch’s goatgrass are similarto winter wheat because it is the D genome donor to common wheat. Furthermore, lack of adequategrass weed herbicide makes it difficult to control in wheat field.Indoor experiments were conducted to study the synergism of adjuvants on mesosulfuron-methyland pyroxsulam in controlling tausch’s goatgrass and synergism mechanism of adjuvants with theherbicides. Field trials were conducted to evaluate the control efficacy of tausch’s goatgrass and safetyto winter wheat of the combination of herbicides and adjuvants. The results were as follows:1. Adjuvants could obviously increase the control efficacy of mesosulfuron-methyl and pyroxsulam ontausch’s goatgrass. The synergism of different adjuvants on mesosulfuron-methyl was different,methylated seed oil (MSO) Mero>organosilicon (OSL) Silwet-806>mineral oil concentrate (MOC)GY-T12>surfactant (SFT) Biopower. While the synergism on pyroxsulam was Silwet-806>Mero>Biopower>GY-T12. In the greenhouse, control efficacy of mesosulfuron-methyl with Mero andpyroxsulam with Silwet-806increased by21.7%~33.2%and24.2%~37.6%, respectively, while in thefiled, control efficacy increased by43.8%~48.9%and10.1%~14.1%, respectively. The addition ofammonium sulfate, ammonium nitrate or urea ammonium nitrate to Mero or Silwet-806made controlefficacy of the two herbicides increase by28.2%~49.9%.2. The interactions among adjuvant, herbicide and leaf stage of tausch’s goatgrass were obvious.Compared with mesosulfuron-methyl or pyroxsulam alone the control efficacy of mesosulfuron-methylwith MSO on goatgrass increased by21.7%and33.2%, respectively, while the efficacy of pyroxsulamwith OSLincreased by34.0%and37.6%when applied at1leaf stage and3~4leaf stages of goatgrass.3. Adjuvants changed the physical characteristics of herbicide solution and increased absorption ofherbicide. OSL, MOC, MSO and SFT evidently reduced surface tension and drying time, augment leafretention of herbicide solution. With the adjuvants, the absorption of the herbicide increased by190.9%,154.5%,233.3%and106.1%, respectively, compared with the herbicide alone.4. Mesosulfuron-methyl or pyroxsulam with adjuvnts did not effect the growth of winter wheat. Theresults showed that there were no significant differences in the SPAD values, Fv/Fm, height and freshweight of winter wheat when mesosulfuron-methyl applied at recommended dosage with or withoutadjuvants in the greenhouse studies. While in the filed trials, there were no significant differences in thetiller, fibril, height, and fresh weight of winter wheat when the herbicides applied with or withoutadjuvants.Results not only provide knowledge and techniques for enhancing the control of tausch’s goatgrass,but also give ideas which help to reduce herbicide dosage, protect environment and increase wheatyield.