Screening And Safety Evaluation Of Herbicides Against Mikania Micrantha Kunth

American rope,Mikania micrantha Kunth,is a quarantine invasive weed.It spread rapidly and widely in South China,which could cover the ground and the original vegetation entirely in a short time.Due to its serious threatens to biological diversity,it has been reported to cause serious impact and great loss to agriculture and forestry in South China.Chemical control could be considered as one of the most important control strategies in the comprehensive control system against M.micrantha.In the meanwhile,it is urgent and indispensable to develop novel and efficient product to provide green control.Due to urgent situation to control such invasive weed,lack of the efficient and optimal chemical product,low extent to be able to apply comprehensively,week research foundation,the aim of this study is to developing and screening efficient and safe chemical product by evaluating nine kinds of compounds in the field,developing two kinds of mixed reagents,examined the safety to the non-target plants and animals to provide optimal and candidate products and technology,which could be able to popularize in the future.Moreover,in our study,the toxicity of the principle active compound in M.micrantha against rat was also examined.1.Evaluated the field control effects of 9 kinds of herbicides to control of M.micrantha.The results indicated that 20%fluroxypyr EC,24%picloram AS,30%Clopyralid AS could reach to a high level of efficient control in a short timem which could fully control the M.micrantha within one month and the duration of persistence could reach to two months.For the perspective of efficiency and persistence to control leaf and stem of M.micrantha,10%sulfometuron WP works best in the efficiency and persistence,but had the potential toxic effect against non-target plants;25%fomesafen AS seemed to have comparable effects to10%sulfometuron WP to control M.micrantha,while have poor persistence,10%bensulfuron have the poorest performance in persistence.30%glyphosate AS,70%2,4-D dimethyl amine salt AS and 13%MCPA-Na have the acceptable persistence,but the control effect is poor.Collectively,combined with the persistence,control effect and innovation,fluroxypyr,fomesafen mixed with proper reagent could have satisfied effects in the practical application.2.In our study,two kinds of mixed reagents were developed and the control effects in the field were also evaluated.Fomesafen and 2,4-D dimethyl amine salt were mixed together in proper ratio and developed into 25%compound 2 AS,while fluroxypryr and 2,4-D dimethyl amine salt were mixed together in proper ration and developed into 25%compound3 AS.The coverage effects of compound 2 at different concentrations?100,200,400ml/667m²?could be reached to 95%-100%after 15-90 d treatment,the fresh weight control effects could be reached to 94%-100%at 60 and 90 d post treatment,and the coverage control effect could remain at 75%-92%after 180 d.The coverage control effects of compound 3 at different concentrations?50,100,200 ml/667m²?could reach to 90%-99%after 15 to 90 day of treatment,while the fresh weight control effects could reach to 89%-99%after 30-90 d of treatment.Moreover the control effect on the stem could reach to 72%to91%,but the coverage control effect of compound 3 started to decline after treatment for 180d.The persistence of compound 2 and compound 3 could be comparable to the commercialized product(10%sulfometuron-Methyl and 24%Dichloropyridine dichloride AS,as well as the coverage control effect,fresh weight control effect and stem control effect.In the meanwhile,the persistence of two mixed reagents was significantly longer than the control pesticide.3.The safety of two mixed reagents to four kinds of representative fruit trees in Southern China,including carambola,citrus,mango and lychee,was evaluated.Carambola is sensitive to both of the reagents.Citrus trees exert certain tolerance to the compound 2 and 3.Mango and litchi equipped the ability of tolerance to the compound 2 and 3.Based on those results,the compounds 3 and 2 should be banned from the carambola,citrus or liychee orchards or the nearby area.The compound 2 exert better performance in the safety to different trees,but both of the compound 2 and compound 3 should avoid to be spraying directly to all fruit trees.4.The safety of Compound 2 and 3 was evaluated on 9 garden plants.From the results,Brachychiton acerifolius,Podocarpus macrophyllus,Sterculia lanceolata and Acacia auriculiformis were extremely sensitive or sensitive to the tested ingredients,so it is recommended that Compound 2 and 3 are forbidden in the control of M.micrantha where there those plants are around.For Ficus microcarpais,it was extremely sensitive to Compound 3 but not to Compound 2,so the use of Compound 2 should be warned near F.microcarpais.Besides,Ficus benjamina,Callistemon viminalis and Chrysalidocarpus lutescens were also sensitive to Compound 2.As a result,it is highly suggested not to apply Compound 2 in the surrounding area.In addition,only Bauhinia plants was insensitive to Compound 2.Therefore,the use of Compound 2 and 3 should avoid the direct contact with the as-mentioned garden plants.5.Acute toxicity to zebrafish was evaluated by using Compound 2 and 3.By treating with the extremely high concentration of Compound 3 at 1000 mL/L,the lethal rate of zebrafish was 0 in 96 h.By treating with Compound 2 at 100 and 1000 mL/L,10%of zebrafish was dead after 48 h and 96 h,respectively.According to the classification of pesticide toxicity to aquatic organisms,the toxicity grades of Compound 2 and 3 were both at low toxic or non-toxic levels,which can be used for the management of M.micrantha aside the water area.6.The contents of main components of M.micrantha were determined individually.The water capacity in fresh M.micrantha was 88.87±0.51%.The contents of soluble sugar in roots,stems and leaves of M.micrantha were determined at 0.28±0.01%,4.27±0.33%and5.63±0.15%,respectively.In each part,the protein was measured at 0.14±0.01%,0.10±0.00%and 0.09±0.01%,respectively.As for the content of cellulose,it was at 0.65±0.04%,0.89±0.03%and 0.60±0.04%respectively.In addition,the total phosphorus in each part was0.110±0.001%,0.319±0.007%and 0.222±0.001%.7.The physiological indexes of mice after the feeding of M.micrantha by gavage were evaluated.The results showed that,the acute oral median lethal dose(LD₅₀)of M.micrantha were more than 15000 mg/kg for the female and male mice,therefore,it could be classified as non-toxic compounds.Meanwhile,the weight,water consumption and organ coefficient of mice were investigated,which indicated that the feeding of M.micrantha had no significant influence.The staining by Hematoxylin-eosin also showed that M.micrantha couldn't induce damages to the main organs of mice including heart,liver,spleen,lung and kidney.Taken together,the present results provided an important basis and reference for the comprehensive utilization of invasive M.micrantha,which could expand the functions of its related products,and the guidance of the scientific and reasonable use of drugs.In addition,it is helpful to improve the overall control of M.micrantha,and also provide useful reference and insights for the management of invasive plants.After optimization,the prepared formulation would possess great potential for further utilization and commercialization,which is worthy for the practical application and popularization.