Study On The Screening Of Control Agents For Bromus Tectorum In Spring Wheat Field And The Synergism Effect Of Adjuvants

Bromus tectorum L is mainly distributed in Qinghai,Xinjiang,Ningxia,Gansu,Sichuan,Yunnan,Tibet and other regions in China.Due to the biological characteristics of pubescence of Bromus tectorum plants and the unique climatic conditions in Qinghai,there is still a lack of herbicides that are effective for Bromus tectorum and safe for wheat.Therefore,Bromus tectorum has risen to become one of the dominant weeds in farmland in some parts of Qinghai.In this paper,Bromus tectorum was taken as the research object,and the herbicides with high efficiency against the target were screened through indoor bioassay.On this basis,the additives that could increase the herbicide effect and be safe to wheat were further screened,and the optimal application period was determined.The main research results are as follows:1.The indoor biological activity of herbicides on Bromus tectorum showed that:Among the 7 herbicides tested for stem and leaf treatments,flucarbazone-sodium,pyroxsulam,diflufenican were effective against drought at the recommended doses in the field.The fresh weight control effect of brome is 80.91%,78.20%,70.21%;clodinafop-propargyl,pinoxaden,metsulfuron-methyl and fenoxaprop-P-ethyl on the fresh weight of bromegrass at the highest dose The control effects were 57.24%,58.91%,60.38%,61.87%,respectively,and the control effect on dry brome was poor.The three soil treatment herbicides tested have a fresh weight control effect of more than 90%on Bromus tectorum at the recommended dosage in the field.2.With the addition of 0.1%of Jiexiaoli,the control effect of pyroxsulam alone on Bromus tectorum increased by 33.98%to 85.65%;after adding 0.1%Jiexiaoli,flucarbazone-sodium increased the control effect by 33.98%and reached 85.65%.Compared with flucarbazone-sodium alone,the control effect of bromegrass increased by 23.65%,reaching 80.03%.3.The sensitivity of different leaf ages of Bromus tectorum to pyroxsulam and flucarbazone-sodium showed a certain difference.When the dosage of pyroxsulam is15 g ai/hm~2,it is better for Bromus tectorum of 1 to 4 leaf age.The fresh-weight control effect is more than 80%,while the fresh-weight control effect of 5-6 leaf-aged Bromus tectorum is 68.42%;when the dosage of flucarbazone-sodium is 31.5 g ai/hm~2,the control effect of 1～2.5 leaf-age The fresh weight control effect of Bromus tectorum is more than 81%,and the fresh weight control effect of 5-6 leaf-age Bromus tectorum is 62.07%.4.At the recommended dose,Pyroxasulfone is safe to plateau wheat 448;flufenacet is poor in safety to the tested wheat varieties.After adding the adjuvant Jiexiaoli,pyroxsulam showed slight phytotoxicity to Ningchun 4 wheat under all treatments.The specific manifestation was that the recovery speed of chlorophyll content and ALS activity was slow after application.However,the plants of Qingchun38 and Gaoyuan 448 grew normally under each treatment.