New Pesticide Preparation And Application For Prevention And Control Of Kiwifruit Bacterial Canker

Kiwifruit bacterial canker is the most destructive disease in kiwifruit production,which incited by Pseudomonas syingae pv.actinidiae.At present,there are some problems in the prevention and control of kiwifruit bacterial canker,such as few varieties of pesticides,short duration of efficacy,and garden destruction caused by untimely prevention and control,which restrict the healthy development of kiwifruit industry.Based on the above issues,this study defined the types of kiwifruit bacterial canker,the main kiwifruit varieties in Hunan,screened the pesticide components with high inhibition to kiwifruit bacterial canker,prepared growth effect controlled-release microcapsules and water emulsion,and evaluated the quality index of the new preparation and the effect of preventing and controlling kiwifruit bacterial canker.The main conclusions are as follows:The kiwifruit branches with typical symptoms of Kiwifruit bacterial canker were isolated,purified and sequenced by plate scribe separation method.The sequences were compared on the blast of NCIB,and the phylogenetic tree was constructed.It was found that it was similar to Kiwifruit bacterial canker MT463219.1 is highly homologous.It is confirmed that the strain isolated and purified is the Pseudomonas syingae pv.Actinidiae.The measured sequence was uploaded to NCBI and the strain login number MW829404.1.The active components of kasugamycin,copper hydroxide,Iprodione,Kresoxim-methyl,capsaicin,matrine and azoxystrobin were determined by spread plate method.The results showed that kasugamycin,copper hydroxide and Litsea cubeba oil had obvious inhibitory effect on Kiwifruit bacterial canker,while Iprodione,Kresoxim-methyl,capsaicin,matrine and azoxystrobin had no obvious inhibitory effect on Kiwifruit bacterial canker.The toxicity of chunleimycin,copper hydroxide and Litsea cubeba oil was determined.It was found that Litsea cubeba oil had the highest antibacterial ability against Kiwifruit bacterial canker,with EC50 of 0.7757mg/ml,followed by kasugamycin,with EC50 of 0.8188mg/ml.Copper hydroxide had the lowest antibacterial ability against Kiwifruit bacterial canker,with EC50 of 1.8093mg/ml.Finally,Litsea cubeba oil and kasugamycin,two active components with strong antibacterial ability against Kiwifruit bacterial canker,were screened.The 25%Litsea cubeba oil EW was prepared by the phase inversion method,and the optimal formula of the water emulsion was determined:According to the mass ratio,Litsea cubeba oil is 25%,sk-33sc is 4%,yus-d935 is 4%,and pure water makes up to 100%.The water emulsion is excellent in dispersibility and its emulsion stability,thermal storage stability and low temperature stability are all qualified.The 25%Litsea cubeba oil EC was prepared.The formula is:according to the mass ratio,Litsea cubeba oil is 25%,YUS-D935is 4%,SK-33SC is 4%,and sec-Butyl acetate makes up 100%.The appearance of the preparation is transparent oily liquid,The water emulsion is emulsion stability qualified.The kasugamycin microcapsule was prepared by Re-emulsion method with a mass ratio PBS as wall material and yus-fs3000 as emulsifier.The encapsulation rate is 80.41%,and the sample load is 4.97%,and the average volume article size is 5.635μm,and the particle size span is 0.879.After 20 days of release,the cumulative release of the microcapsules The rate reached 90.49%,showing obvious sustained-release performance.The virulence of 25%Litsea cubeba oil EW and 25%Litsea cubeba oil EC to Kiwifruit bacterial canker was determined by growth rate method.The EC₅₀of 25%Litsea cubeba oil EC was 0.9513mg/ml and that of 25%Litsea cubeba oil EW was 0.7267mg/ml.Finally,EW was selected as the dosage form of Litsea cubeba oil.Incubation was conducted to study the preventive effect of 2%kasugamycin microcapsule SC plus film-forming agent on Kiwifruit canker after rain washing.The results show that.The incidence rate of kiwifruit seedlings treated with microcapsules and film forming agent was 0.The other two groups were infected with Kiwifruit bacterial canker 15days,and the incidence rate was 100%.The drug control group and water control group all had disease spots.It is proved that the mixed use of 2%kasugamycin microcapsule SC addition film agent has the ability of preventing rain water scouring.The field test found that the field control effect of 25%Litsea cubeba oil EW investigated in November 2021 was82.69%.The control effect of 25%Litsea cubeba oil EW was 78.92%in March 2022.The results show that 25%Litsea cubeba oil EW can effectively control Kiwi bacterial canker under complex field environmental conditions,and has great application potential.