Influencing Factors And Controlling Methods For Spraying Control Of Cladosporium Fulvum With Hexaconazole

In the north of China,tomatoes is mainly based on the greenhouse environment.Tomato leaf mold is one of the important diseases which affecting tomato production.Tomatoes are susceptible to pathogene of Cladosporium fulvum in the environment which have airtight,high temperature,high humidity and serried planting.The irregular mildew layer is formed on the back of the leaf when the disease occurs,which affects the deposition and retention of the fungicides at the target leaves.At present,the control of C.fulvum in greenhouse is mainly spraying by using the Knapsack electric sprayer.It was found that the deposition of pesticide on the target plants was about 35%by using conventional spraying.And less than 0.1%pesticide reached the target pest.The influence factors of spraying effect include the physicochemical characteristics of active ingredient,equipment,technology?period,dose and water volume?and the structure characteristics of target plants,mainly.Therefore,this study established the relationship between the deposition and the control efficacy in different disease stage,and confirmed the application period and dose.A set of application system which have the optimal deposition was established by integrating the factors of equipment,method,water volume and adjuvants.In this way,the deposition of fungicides at the target plants can be increased,and the control efficacy can be increased.The main results are summarized as follows:1.Establishment of the relationship between the deposition and control efficacy in different pathogenesis stages:The logarithm of the deposition was in a linear relationship with the control efficacy.According to the linear regression equation of different pathogenesis stages,the deposition and control effect can be calculated.The linear regression equation were y=69.29 x-17.30?without disease?,y=57.02 x-16.24?in the early stage?and y=59.83x-27.22?in the middle and late stage?.According to the linear regression equation:The deposition in the middle and late stage of the disease was 1/2 of that in the early stage of the disease and 2/3 of that in the early stage of the disease.To achieve the same control efficacy,the dose of fungicides in the middle and late stage of the disease is 5-6 times that in the early stage of the disease,and 2-3 times that in the early stage of the disease.The pesticide utilization of hexaconazole applied in different disease stage was 74.38%,65.59%,and 41.07%,respectively.Therefore,it is recommended to use hexaconazole in the stage of without disease or early and the dose is 90-180 g a.i.ha^-1.And with the delay of the application time,the dose increases correspondingly.2.Determination of the application method and water volume for conventional spraying:When the water volume was 800 L ha^-1,the deposition of z-shaped spraying method and flat-shaped spraying method were 9.67 and 9.52 mg kg^-11 in the whole plants,respectively,which higher than concave-convex spraying method.The deposition of z-shaped spraying method in upper,middle and lower canopy were 10.26,10.21 and 8.54 mg kg^-1,respectively.The deposition of flat shaped spraying method were 12.15,9.62 and 6.79 mg kg^-1,respectively.The distribution of deposition for z-shaped spraying method in the canopy was more uniform,so it was recommended to use z-shaped spraying method in the field.The deposition is the largest when the water volume is 800 L ha^-1.When the water volume is 400-800 L ha^-1,the deposition increases with the increase of the water consumption;when the water volume is 800-1600 L ha^-1,the deposition decreases with the increase of the water consumption.It is recommended to use 800 L ha^-1 as the reference standard for field water volume.3.Determination of spraying water volume and droplet evenness when applied mist sprayer:The deposition gradually rose until spray volume reached to 75 L ha^-1.when the spray volume reached 75 L ha^-1,the deposition approach saturation point.There was no significant relationship between spray volume and canopy.The medium diameter of the droplet volume was 110-136 um,which can improve the uniformity of fog drips on the blade.The density of fog drips is 247-305 drop cm^-2,which is conducive to improve deposition on the blade.4.Determination the related parameters of adjuvants which influence the deposition:The CMC of S618,AEO-5,OP-10 and Gemini-31511 were 100 mg L^-1,100 mg L^-1,200mg L^-1 and 200 mg L^-1,respectively.And the concentrations of S618,AEO-5,OP-10 and Gemini-31511 reaching the maximum retention were 0.05%,0.1%,0.2%and 0.2%,respectively.The four adjuvants reduced the contact angle of the drops on the tomato blade.The S618can significantly decreasing the contact angle which determine that it has strongest ability to improve the wettability of the dilution on the target plants.Adjuvants increased the deposition of dilution on target plants more obviously when applied mist sprayer.Added adjuvants which like S618?0.05%?,AEO-5?0.1%?,OP-10?0.2%?and Gemini-31511?0.2%?,the deposition increased by 3.90,1.24,0.24 and 2.06 mg kg^-11 when spraying with conventional sprayer,respectively.The deposition increased by 5.28,1.50,0.38and 2.66 mg kg^-1 when spraying with mist sprayer,respectively.And the S618?0.05%?has the most significant effect on increasing deposition.5.In summary,the mist machine application has obvious advantages over the conventional application.The water volume,deposition and time of using mist sprayer is about 1/10,1.37 times,and1/32 of conventional application,respectively.