Study On Herbicidal Activity And Application Technology Of N-(4-fluorobenzyl)-6-methylpicolinamide

Phytoene dehydrogenase（PDS）andζ-carotene dehydrogenase（ZDS）are two key enzymes in the biosynthetic pathway of carotenoid.Inhibition of their activities result in the block of carotenoid biosynthesis,bleaching effect in plant tissue,and eventually death.N-（4-fluorobenzyl）-6-methylpicolinamide（No.ZI-22）is a member of patent compound6-methylpicolinamides,a new type of herbicides discovered in our lab by using random synthesis strategy.Preliminary investigation on mode of action of ZI-22 revealed that it targets both PDS and ZDS.It exhibits good herbicidal activity against a panel of weeds and has the potential for commercialization.In this paper,the herbicidal activity in laboratory and synergistic effect of ZI-22,as well as the mixture of ZI-22 with amicarbazone,was evaluated by pot experiments.Their efficacies of controlling weeds in corn fields,the residue degradation dynamics in soil and the resistance risk evaluation were also investigated in this study.The results provides valuable theoretical basis for its commercial development and application technology.The herbicidal activity in laboratory and synergistic effect of ZI-22.Post-emergence herbicidal of ZI-22 against Portulaca oleracea,Eleusine indica,Digitaria sanguinalis,Abutilon theophrasti,Echinochloa crusgalli,Setaria viridis were evaluated by pot experiments in glass house.ZI-22 showed better activity against broadleaf weeds than that of grass weeds,and the most sensitive spicies was P.oleracea,and its ED₅₀ value was 59.50 g a.i./hm²;The mixture of ZI-22 and amicarbazone at the ratio of 1:9 showed obvious synergistic effect in the controlling of poaceae weed E.crusgalli,S.viridis,E.indica,D.sanguinalis,and good safety to maize.Post-emergence controlling efficacy on weeds of the mixture ZI-22 and amicarbazone were evaluated in maize field.The results showed that the mixture had synergistic effect and could control most weeds in corn fields.At the application rate of 150 g a.i./hm²,the fresh weight control effect of the mixture on weeds was 85.59%after 30 days,which could be used as the recommended dosage.The soil leaching test and residue dynamics of ZI-22 and amicarbazone in corn field soil.The soil leaching test of ZI-22 and amicarbazone was carried out with central Shaanxi loess as the tested material.The results showed that ZI-22 was difficult to move in loess,its half-life was 6.51 days in the field,and it was easy to degrade in the field,so it was safe for the environment and the succeeding crops.Amicarbazone was easy to move in loess,but its half-life under field conditions was 3.12 days,so it was easy to degrade and was relatively safe for the environment and succeeding crops.Assessment of risk resistance of ZI-22.Using Chlamydomonas reinhardtii as the experimental material,ZI-22 and the PDS inhibitor diflufenican were used to domesticate C.reinhardtii,and the resistant C.reinhardtii was finally obtained after repeated generations.The results showed that after 48 generations of culture,the resistance multiples of C.reinhardtii to diflufenican and ZI-22 were 3873 times and 34.83 times,respectively,which indicated that the resistance risk of ZI-22 was extremely low.The cross-resistance assay of C.reinhardtii against ZI-22 and diflufenican showed that ZI-22-resistant C.reinhardtii was also had a high resistance to diflufenican,and the resistance of diflufenican-resistant C.reinhardtii to ZI-22 was 4.5 times of that,which indicated that ZI-22 had certain cross-resistance with PDS inhibitors.According to the research in this paper,the application technology of ZI-22 has the following characteristics:the recommended dosage of the mixture of ZI-22 and amicarbazone in the 3-5 leaf stage of corn is 150 g a.i./hm²;The residue period of the mixture in field soil is short,so it can be applied twice,and it will not cause harm to the succeeding crops.ZI-22 has low risk of resistance and can be used frequently,but it has certain cross-resistance with PDS herbicide,so it should be avoided using alternately with PDS herbicide for a long time.