Evaluation of the herbicidal activity and safety of tembotrione to maize
To explore the application procedures and potential of tembotrione in maize fields in China,the herbicidal spectrum of tembotrione and its weed control activity against common weeds,as well as its safety on different maize varieties,were determined using the greenhouse pot experiment method.Field efficacy trials were conducted to verify its effects.The results showed that when post-emergence herbicides(POST)was applied at the recommended field rate(RFR)of 100 g(a.i.)/hm2,tembotrione could effectively control common grasses,sedges,and broad-leaved weeds in maize fields.It exhibited high activity against Amaranthus retroflexus and Eclipta prostrata,with a fresh weight inhibition rate reaching over 90％.The tembotrione rates resulting in a 50％growth reduction for six common weeds from maize fields,including Echinochloa crus-galli,Digitaria sanguinalis,Ipomoea purpurea,A.retro-flexus,Cyperus iria,and Celosia argentea,were 8.44,17.16,9.37,8.68,9.40,and 32.51 g(a.i.)/hm2,re-spectively,with the herbicidal activity of tembotrione higher than the control herbicide mesotrione when applied at the tested rates.Under the RFR,tembotrione was relatively safe for all 11 maize variet-ies except for Heinuo 301.When the RFR was increased two-fold,growth inhibition in different maize varieties was enhanced.Tembotrione showed good selectivity between four maize varieties,Zhengdan 958,Zhenzhunuo 8,Suketian 1506,and Zhongnuo 2,as well as six weeds,including E.crus-galli,D.sanguinalis,I.purpurea,A.retroflexus,C.iria,and C.argentea,with a selectivity index ranging from 10.40 to 29.14.Field efficacy trials indicated that at 28 d after POST treatment with 126 g(a.i.)/hm2 of tembotrione,the total plant control efficacy against weeds such as E.crus-galli,D.sanguinalis,Setar-ia viridis,Cyperus rotundus,I.purpurea,and Alternanthera philoxeroides in maize fields was 86.51％,and the fresh weight control efficacy was 87.81％,while it was safe for the tested maize variety Caitian-nuo 102.
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