Screening And Control Effect Of Stem And Leaf Herbicide In Direct Seeded Rice Field Of Xiangyin,Hunan Province

In this study,from 2019 to 2021,the resistance test of barngrass to commonly used herbicides in Xiangyin County was carried out.Local conventional agents,new herbicide single agent and compound agent were selected to carry out comparative field control experiments,in order to provide reference for weed resistance management in Xiangyin County,and evaluate the control effect,safety and economic benefits of the "only kill but not block" control strategy adopted by some farmers to explore its feasibility,the main content and results of the study as follows:1.The resistance test results of barnyardgrass in Xiangyin area to commonly used herbicides show that barnyardgrass in Xiangyin area has produced moderate level resistance to cyhalofop-butyl,penoxsulam and bispyribac-sodium.The resistance index(RI)of cyhalofop-butyl was 36.29 times,the resistance index(RI)of penoxsulam was 31.55 times,and the resistance index(RI)of bispyribac-sodium was21.14 times.2.The field test results of the commonly used sealing agents,stem-leaf treatment agents and traditional sealing agents and stem-leaf treatment agents in Xiangyin area show that the combination of sealing agents and stem-and-leaf treatment agents is used in the herbicidal program,the control effect was significantly higher than that of using only pre-emergence blocking treatment without stem and leaf treatment herbicide and only for stem and leaf treatment,in which the second investigation of blocking agents and The combination of stem and leaf treatment agents has a plant control effect of more than 85% and a fresh weight control effect of more than 88%.It has a good control effect on three types of weeds,especially for grass weeds.The fresh weight control effect is over 90%.The yield increase rate of the combined chemical treatment plot of the closed treatment and the stem and leaf treatment is also the highest,among them,the yield increase rate of the best agent combination is9.69%,and the yield increase effect is the best;only used alone the control effect of blocking herbicides is not as good as that of stem-leaf treatment alone,and the combination of blocking treatment and stem-leaf treatment is obviously better than the previous two control strategies.3.The test results of using new type of herbicide(single dose)that are not commonly used for stem and leaf treatment in Xiangyin area show that: among the tested agents,the best control effects in the second investigation are 10%pyribenzoxim OD,15% oxaziclomefone OD,25g/L penoxsulam OD and 10%metamifop EC,the total control effects were 54.6%,54.5%,53.3% and 47.2%,respectively.The control efficiency of fresh weight was 53.25%,47.26%,62.82% and52.5%,respectively.Among them,25g/L penoxsulam had the highest OD yield increase rate of 8.19%.There is a gap between the two control effects and yield increase rates compared with the "one-two-kill" chemical combination,so even if the new or uncommonly used stem and leaf treatments that do not produce high levels of resistance are used alone,no pre-emergence sealing treatment is added.,and can not achieve the ideal weed control effect.4.The experimental results of using new and uncommon stem and leaf treatment herbicide(compound)in Xiangyin area showed that: In the second survey,the better control effects were 12% metamifop · penoxsulam OD,60g/L penoxsulam · cyhalofop-butyl OD,6% penoxsulam · pyribenzoxim OD,29%penoxsulam·fluroxypyr-meptyl OD and 20% pyrime·cyfluoxyl acid EC.The total control effects of grass plants were 87.2%,86.0%,82.9% and 81.0%,respectively.The control effects of fresh weight were 90.8%,89.3%,86.1%,86.7% and83.3%,respectively.The yield increase rate of 60g/L penoxsulam·cyhalofop-butyl OD was 11.10%,and that of 12% metamifop · penoxsulam OD was 10.86%.In conclusion,the control effect and rice yield yield of stem and leaf herbicide treatment on weeds in direct-seeding rice field are similar to that of traditional closed and stem and leaf herbicide treatment,but less time and cost.5.The herbicides involved in the test are used at the highest dosage recommended by the manufacturer,and are generally safe.Even if they cause minor phytotoxicity,most of them can be recovered within 7-15 days;However,when 15%oxaziclomefone can disperse oil suspension agent is sprayed or the amount of rice is large,the stump phenomenon will occur and the heart leaves will die,need to pay attention to the dosage.