| Microcapsule suspension seed coatings with neonicotinoid insecticides as the core are currently less researched and applied.The main reason is that this type of insecticide has low solubility in conventional solvents;(2)The mechanism of microcapsule formation is still in the exploratory stage;(3)The related encapsulation technology is not yet mature.However,because the microcapsule formulation can achieve the excellent characteristics of slow release and sustained effect of pesticide original drug,it represents the direction of research and development of seed coating agents.Aiming at the phenomenon that the neonicotinoid insecticide clothianidin lacks a relatively high content of microcapsule suspension seed coating agents,this study first obtained the wetting of 40%clothianidin SC through the screening of wetting agents and dispersants and the optimization of the formula.Types of dispersant and dispersant,by further determining the flow point value of the test wetting agent and dispersant,as well as the prepared 40%clothianidin SC particle size,viscosity value,standing at room temperature for 30 d and thermal storage for 14 d,stability and other indicators,Determine the type,matching ratio and addition amount of formula wetting agent and dispersant,and finally determine the formula of 40%clothianidin suspension.On the basis of the preparation of 40%clothianidin SC,the encapsulation system of clothianidin technical was constructed by the in-situ polymerization method through screening of cyst wall materials and acidifying reagents.Through a series of indoor and field experiments,the safety of 20%clothianidin CF on crop emergence and seedlings,as well as the field sustainability study oncrop aphids,and the selection of the best dosage have been established to clarify the effectiveness of 20%clothianidin CF.Field application technology;and by studying the digestion dynamics of 18%clothianidin FS and 20%clothianidin CF in wheat plants and soil,it is analyzed that 20%clothianidin CF can achieve slow release and sustained effect control mechanism.The specific research results are as follows:40%clothianidin SC was prepared by flow point method,ratio method,and viscosity value method.Based on this,the optimal acidity value,curing temperature,antifreeze,and thickener of the encapsulation were screened.The process of 20%clothianidin CF was finally determined.The results are as follows:Wetting agent and dispersant SP-SC29:2851=1:9,the added mass fraction is 4%,the encapsulating material is melamine resin,the end point acidification value is pH=5,the acidification time is 0.5 h,and the stirring rate is 200 rpm/min,curing temperature 35℃,curing time 1 h,antifreeze ethylene glycol 4%,thickener xanthan gum 0.18%,magnesium aluminum silicate 0.5%,white carbon black addition amount 0.5%,deionized water Make up 100%.The 20%clothianidin CF processed in the laboratory meets the industry standards of product quality indicators and physical and chemical properties.The paper bed method was used to clarify the safety of 20%clothianidin CF on three wheat varieties,Jimai 22,Shiluan,and Lunxuan 145.The field dressing treatment clarified the effect of reducing the amount of spring wheat and winter wheat aphids.There were no significant differences in germination vigor and germination rate of the three wheat varieties under the feed-dose seed dressing treatment and the blank control.In the peak period of wheat aphid occurrence in the spring wheat area of Tangshan,20%clothianidin CF1.40 g/kg seed,0.70 g/kg seed and 18%clothianidin FS2.10 g/kg seed dressing treatment can control the aphid control of wheat aphid.There was no significant difference in the control effect.Compared with the dosage of the control agent,the effective ingredients of the test agent were reduced by 33%and 67%,respectively.The author carried out a field evaluation of the control effect of 20%clothianidin CF on winter wheat aphids from 2019 to 2020.When 20%clothianidin CF2.10 g/kg,18%clothianidin FS4.20 g/kg and 70%imidacloprid ZF4.20 g/kg seed dressing treatment,the three pesticides did not show obvious control of wheat aphid difference.The results of wheat aphid control during the peak period in the two regions show that 20%clothianidin CF can achieve the effect of reducing the dose and increasing the efficiency.However,from the perspective of the damage degree of the wheat aphid in the two regions,the aphid damage in Baoding area is more serious,and the amount of pesticide application is slightly higher.The paper bed method/field experiment was used to clarify the safety of 20%clothianidin CF on cotton germination and seedling growth,and the continuous control effect of field dressing on cotton seedling aphids population.The results of the study showed that the effective ingredient dosage of the tested agents such as 20%clothianidin CF and 70%imidacloprid ZF was 4.20 g/kg seed treatment for 7 days,and the inhibition rate of cottonseed germination was 2.08%-8.34%,with no significant difference.The chemical treatments in the field did not significantly affect the emergence of cotton seedlings 14 days after sowing.The results of field chemical seed dressing to prevent and control cotton aphids showed that the five chemical treatments showed good control effects on the seedling aphids in the early stage of the emergence of seedling aphids and the initial peak period(18 d～25 d after cotton sowing).By 32 days after sowing,20%clothianidin CF and 50%pymetrozine WG had the highest control effects,but only 55.52%and 59.43%.When the control effect of 600 g/L clothianidin FS with the same effective ingredient dosage in the late stage of cotton seedling aphid is significantly reduced,20%clothianidin CF still has a better sustained control effect on aphids,and prolongs the duration of the effective ingredients compared with other agents.The active ingredient dosage of 20%clothianidin CF and the control agent 18%clothianidin FS was determined by high performance liquid chromatography-mass spectrometry.The active ingredient dosage of 4.20 g/kg clothianidin in wheat plants and rhizosphere soil was determined after seed dressing.Residual dynamics.The results showed that the content of clothianidin in wheat plants gradually decreased with the growth of the plant,and the degradation rate of clothianidin in the plant during the period from booting stage to filling stage showed an almost horizontal trend.There are significant differences in the degradation rate of clothianidin seed dressing treatments in wheat plants.The control agent 18%clothianidin FS has the fastest degradation rate in the seedling stage(before winter),and 20%clothianidin CF is from the seedling stage to the The degradation rate is higher in the turning green period.After seed dressing treatment with 20%clothianidin CF and 18%clothianidin suspension FS,the average content of clothianidin deposits in the soil reached the peak 20 days after sowing,which were 4.9 and 5.7 mg/kg,respectively.In general,the content of clothianidin in wheat plants was higher than that in the 18%clothianidin FS treatment from 30 days after sowing to the filling stage after 20%clothianidin CF seed dressing,while the content in the soil was always lower than 18%Clothianidin FS. |
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