Comparison of Droplet Deposition Control Efficacy on Phytophthora capsica and Aphids in the Processing Pepper Field of the Unmanned Aerial Vehicle and Knapsack Sprayer
, Sifeng Zhao 1, Guoqiang Zhang 1, Wei Fu 2, Guobin Wang 3 and Yubin Lan 4Round 1
Reviewer 1 Report
The paper describes the effects of PPP application using UAV compared to a knapsack sprayer. This is a very important study as the use of UAVs is increasing and it is essential to know about the performance in different applications. The study is very complex as many important application characteristics are involved.
The paper needs improvement. First, the description of the objectives are very general. Detailed aims of the study are missing. Although quite complete, the description of materials and methods should be improved beginning with the general introduction of the application techniques and the treatments and should then go into the details.
Some of the results do not seem to be consistent. For instance, a much higher droplet density (Fig. 5) and bigger droplets (Table 3) were found with EAP but the deposition (Fig. 6) was lower from EAP compared to UAV. On the other hand, the efficacy was better with EAP.
Some detailed comments (for line):
39: High quality and good quality?
42-45: Redundant sentences.
50-51: Readers of this journal should know what aphids are.
89-90: What was the actual spray pressure and flow rate during the tests?
93: What nozzle type/size was used at what pressure and flowrate?
141: Image analysis of the spray deposit is certainly not a good way to determine droplet size, especially in this range of size. It is only possible to determine spot size.
148: I guess n is the number of collection points and X̅ the average?
164-172: This was obviously done with water only. Was there any difference in the standard curve when the liquid contains the chemical applied?
Equ. 6 and 7: Use symbols instead of words in equations!
206: What is meant by “twice spraying”?
207: Are the numbers in brackets the average values from Fig. 4? Explain!
285, Fig. 6: Is this the deposition of spray liquid, chemical or a.i.? If it is not the spray liquid, it does not seem to be reasonable that the deposition with 1/3 dose is higher than with ½ or full dose.
321: This should be Fig. 7.
344: What are possible improvements of the spraying systems? Adjuvants do not always improve deposition!
Author Response
Dear reviewer,
We are so grateful for the excellent suggestions and the detailed revising from you. We have benefited greatly by the revision. Now we explain your questions firstly point by point, and then made modification accordingly.
The paper describes the effects of PPP application using UAV compared to a knapsack sprayer. This is a very important study as the use of UAVs is increasing and it is essential to know about the performance in different applications. The study is very complex as many important application characteristics are involved.
The paper needs improvement. First, the description of the objectives are very general. Detailed aims of the study are missing. Although quite complete, the description of materials and methods should be improved beginning with the general introduction of the application techniques and the treatments and should then go into the details.
Response: This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.
Some of the results do not seem to be consistent. For instance, a much higher droplet density (Fig. 5) and bigger droplets (Table 3) were found with EAP but the deposition (Fig. 6) was lower from EAP compared to UAV. On the other hand, the efficacy was better with EAP.
Response: Many studies showed that the density of droplets increases with spraying volume. In this paper, the spraying volume of EAP was 20 times than that of UAV. Secondly, the deposition amount is related to the pesticide concentration. In this paper, the pesticide concentration sprayed by UAV was 20 times than that of EAP, so the UAV deposition amount was better. However, the uniformity of UAV cannot be compared with EAP, and the control effect is the whole plant.
Some detailed comments (for line): 39: High quality and good quality? Response: Sorry for semantic duplication, we have modified it.
42-45: Redundant sentences.
Response: We have deleted that sentences.
50-51: Readers of this journal should know what aphids are.
Response: The aphids mentioned in this study are cotton aphids, and the Latin name is Aphis gossypii Glover.
89-90: What was the actual spray pressure and flow rate during the tests?
Response: The flow and pressure of UAV are a range of values. The pressure range in actual work is 0.2-0.35 Mpa, and the flow rate is 2.2-2.4 L / min. The working pressure of the double cone nozzle is 0.1-0.2 Mpa, and the flowrate is 1.2-1.4 L / min.
93: What nozzle type/size was used at what pressure and flowrate?
Response: The working pressure of the double cone nozzle is 0.1-0.2 Mpa, and the flowrate is 1.2-1.4 L / min.
141: Image analysis of the spray deposit is certainly not a good way to determine droplet size, especially in this range of size. It is only possible to determine spot size.
Response: Zhu et al. had reported the DepositScan could quickly analyzes distributions of spray deposits on collectors such as water sensitive papers or Kromekote® cards, which are widely used for determinations of pesticide spray deposition quality on spray targets. Therefore, many studies obtained droplet spectra from WSP analysis based on measurements of droplets impacts/stains dimension.
Zhu, H.P.; Salyani, M.; Fox, R.D. A portable scanning system for evaluation of spray deposit distribution. Computers and Electronics in Agriculture, 2011, 76, 38–43
Garcerá, C.; Moltó, E.; Chueca, P. Factors influencing the efficacy of two organophosphate insecticides in controlling California red scale, Aonidiella aurantii (Maskell). A basis for reducing spray application volume in Mediterranean conditions. Pest Manag. Sci. 2014; 70: 28–38
Qin, W.C.; Qiu, B.J.; Xue, X.Y.; Chen, C.; Xu, Z.F.,; Zhou, Q.Q. Droplet deposition and control effect of insecticides sprayed with an unmanned aerial vehicle against plant hoppers. Crop Prot. 2017, 85, 79-88.
Wang, G.B.; Lan, Y.B.; Yuan, H.Z.; Qi, X.X.; Chen, P.C.; Ouyang, F.; Han, Y.X. Comparison of Spray Deposition, Control Efficacy on Wheat Aphids and Working Efficiency in the Wheat Field of the Unmanned Aerial Vehicle with Boom Sprayer and Two Conventional Knapsack Sprayers. Appl. Sci. 2019, 9, 218;
Wang, G.B.; Lan, Y.B.; Qi, X.X.; Chen, P.C.; Hewitt, A.J.; Han, Y.X. Field evaluation of an unmanned aerial vehicle (UAV) sprayer: effect of spray volume on deposition and the control of pests and disease in wheat. Pest Manag. Sci. 2019, 9(2), 218
148: I guess n is the number of collection points and X̅ the average?
Response: Sorry, we have modified it.
Equ. 6 and 7: Use symbols instead of words in equations!
Response: Sincerely appreciate your suggestion, we have modified the formula according to your suggestion. we have modified it.
206: What is meant by “twice spraying”?
Response: "Twice spraying" means two spraying on June 26, 2019 and July 18, 2019.
207: Are the numbers in brackets the average values from Fig. 4? Explain!
Response:“ 21.12% VS 1.83% and 18.59% VS 1.43%” These data are from Figure 4.
285, Fig. 6: Is this the deposition of spray liquid, chemical or a.i.? If it is not the spray liquid, it does not seem to be reasonable that the deposition with 1/3 dose is higher than with ½ or full dose.
Response: It was spray liquid.
321: This should be Fig. 7.
Response: Sorry, we have modified it.
Thank you for your suggestions and comments.
Kind regards,
Xiaoqiang Han
2 Jan 2020
Author Response File: 
Author Response.docx
Reviewer 2 Report
In the proposed Manuscript titled “Droplets Deposition Characteristics and Efficient Utilization of Processing Pepper Field Sprayed with Plant Protection Unmanned Aerial Vehicle” the Authors described a comparison – in terms of droplet coverage, droplet density, uniformity of deposition, droplet penetrability and control of Phytophtora Capsici and Aphids on pepper plants – between two different implements for the crop protection, i.e. an electric air-pressure knapstack sprayer and an UAV sprayer.
The study is complete and very interesting, but there are some parts needing improvements.
Specific comments (noted in the manuscript)
Introduction
Lines 36 to 47 please summarize this part.
Line 46: the Authors wrote: “Processing pepper planting and processing has become….” Maybe there is a repetition (“processing”).
Line 63-65: why the use of UAV can reduce pepper production costs? This affirmation requires more discussion and the add of appropriate references.
The references [17] and [18] are not included in the text. Please correct.
The purpose of the study (lines 71-73) is too generic. I suggest the Authors to better define the focus of their study, considering the title of the manuscript.
Materials and Methods
The strict division of this paragraph on the one hand makes it clear the followed methodology, on the other hand it appears very difficult for the reader to understand how the experiment has been carried out. In particular, to begin the paragraph with the list of experimental reagent used without providing the main information about the experimental design, in my opinion is not appropriate for a logical reading of the manuscript. I suggest the Authors to introduce a general description of the experimental design with the followed methodology and after to deepen the various materials considered.
Lines 77-82: what is the utility of the cited reagents in the experiment? Please define it in the general description required above.
Lines 84-94: the Authors have described the two implements. About the UAV I suggest adding its payload, the volume of the tank and the number of rotors. About the knapsack sprayer please insert the tank volume.
Lines 99-103: what is the utility in the present study of the balance, of the swirl meter, of the handheld weather station ecc? This because these instruments are described, but in the manuscript I did not find their contribution to the results.
Line 133: what is the ground clearance of the kromekote card and filter fixed on the various plants? This is important to define the heights of the layers discussed in the “Results” paragraph.
Equation 2: please define what is “n”
Line 158: the droplet deposition is indicate as “Dd” and not as “Ds”. Please correct.
Results
Figure 4 and Figure 5: Please write directly on the figures what are the charts related to UAV and those related to EAP.
Droplet coverage sub-paragraph (line 204). I have one doubt related to the results of droplet coverage obtained using UAV: I expected that the turbulence caused by the UAV’ rotors would have increased the droplet coverage in the middle layer and lower layer, this because the movement of the upper layer would showed the underlying layers, by exposing them to the agro-chemical treatment. Please clarify this aspect.
This fact must be discussed also for the uniformity of deposition described in the dedicated sub paragraph (Line 262).
Line 321: “Figure 7” and not “Figure 6” in the caption. Please correct.
Author Response
Dear reviewer,
We are so grateful for the excellent suggestions and the detailed revising from you. We have benefited greatly by the revision. Now we explain your questions firstly point by point, and then made modification accordingly.
In the proposed Manuscript titled “Droplets Deposition Characteristics and Efficient Utilization of Processing Pepper Field Sprayed with Plant Protection Unmanned Aerial Vehicle” the Authors described a comparison – in terms of droplet coverage, droplet density, uniformity of deposition, droplet penetrability and control of Phytophtora Capsici and Aphids on pepper plants – between two different implements for the crop protection, i.e. an electric air-pressure knapstack sprayer and an UAV sprayer.
The study is complete and very interesting, but there are some parts needing improvements.
Specific comments (noted in the manuscript)
Introduction
Lines 36 to 47 please summarize this part.
Response: This part mainly introduces the planting situation of processing pepper in Xinjiang.
Line 46: the Authors wrote: “Processing pepper planting and processing has become….” Maybe there is a repetition (“processing”).
Response: Sorry for semantic duplication, we have modified it.
The references [17] and [18] are not included in the text. Please correct.
Response: We confirm that references [17] and [18] are in the text, in line 73.
The purpose of the study (lines 71-73) is too generic. I suggest the Authors to better define the focus of their study, considering the title of the manuscript.
Response: This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.
Materials and Methods
The strict division of this paragraph on the one hand makes it clear the followed methodology, on the other hand it appears very difficult for the reader to understand how the experiment has been carried out. In particular, to begin the paragraph with the list of experimental reagent used without providing the main information about the experimental design, in my opinion is not appropriate for a logical reading of the manuscript. I suggest the Authors to introduce a general description of the experimental design with the followed methodology and after to deepen the various materials considered.
Response: Thanks for the excellent suggestion on our manuscript. We had added more details in all sections.
Lines 77-82: what is the utility of the cited reagents in the experiment? Please define it in the general description required above.
Response: We have defined the use of the drug in the material.
Lines 84-94: the Authors have described the two implements. About the UAV I suggest adding its payload, the volume of the tank and the number of rotors. About the knapsack sprayer please insert the tank volume.
Response: The UAV has six rotors, the volume of the tank is 16 L, and the payload is 15 kg. We have inserted tank volume about the knapsack sprayer.
Lines 99-103: what is the utility in the present study of the balance, of the swirl meter, of the handheld weather station ecc? This because these instruments are described, but in the manuscript I did not find their contribution to the results.
Response: The balance was used to weigh medicines, and a handheld weather station was used to record weather including (temperature, humidity, wind speed), but these meteorological data were not used in the results discussion. We had deleted the swirl meter.
Line 133: what is the ground clearance of the kromekote card and filter fixed on the various plants? This is important to define the heights of the layers discussed in the “Results” paragraph.
Response: On June 26, 2019, the kromekote card and filter were placed at a height of 0, 5, 30, and 45 cm from the ground; on July 18, 2019, the paper and filter paper were 0, 10, 55, and 80 cm from the ground.
Equation 2: please define what is “n”
Response: Sorry, n is the number of collection points and X̅ the average.
Line 158: the droplet deposition is indicate as “Dd” and not as “Ds”. Please correct.
Response: Sorry, we have modified it.
Results
Figure 4 and Figure 5: Please write directly on the figures what are the charts related to UAV and those related to EAP.
Response: Thanks for the excellent suggestion on our manuscript. We had added more details in all sections.
Droplet coverage sub-paragraph (line 204). I have one doubt related to the results of droplet coverage obtained using UAV: I expected that the turbulence caused by the UAV’ rotors would have increased the droplet coverage in the middle layer and lower layer, this because the movement of the upper layer would showed the underlying layers, by exposing them to the agro-chemical treatment. Please clarify this aspect.
Response: Thanks for the excellent suggestion on our manuscript. This test was divided into two tests. On the test on June 26, 2019, the average height of the plant was 49 cm, the coverage of the upper layer was about 3.3%, the middle layer was 2.1%, and the lower layer was 1.2%. This is a good result. On July 18, 2019, the average plant height was 88 cm. The coverage of the lower and middle layers decreased significantly.
This fact must be discussed also for the uniformity of deposition described in the dedicated sub paragraph (Line 262).
Line 321: “Figure 7” and not “Figure 6” in the caption. Please correct.
Response: Sorry, we have modified it.
Thank you for your suggestions and comments.
Kind regards,
Xiaoqiang Han
2 Jan 2020
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The comments made on the original version were dealt with, at least in the reply letter. The replies are not for my personal information though, it would be helpful to include the conclusions for all replies in the manuscript.
Author Response
Dear reviewer,
We are so grateful for the excellent suggestions and the detailed revising from you. We have benefited greatly by the revision. Now we explain your questions firstly point by point, and then made modification accordingly.
The comments made on the original version were dealt with, at least in the reply letter. The replies are not for my personal information though, it would be helpful to include the conclusions for all replies in the manuscript.
Response: Thanks for the excellent suggestion on our manuscript.
The last sentence of the second paragraph of the Introduction had been replaced by “In this study, we compared the spraying effect of EAP sprayer and UAV sprayer, the droplet distribution and control efficacy were studied. This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.”
We had added a brief description of the experimental methodology at the beginning of the chapter “Materials and Methods”
We had added a discussion in the 3.1.1 paragraph.
Thank you for your suggestions and comments.
Kind regards,
Xiaoqiang Han
22 Jan 2020
Author Response File: Author Response.docx
Reviewer 2 Report
In the proposed Manuscript titled “Droplets Deposition Characteristics and Efficient Utilization of Processing Pepper Field Sprayed with Plant Protection Unmanned Aerial Vehicle” the Authors described a comparison – in terms of droplet coverage, droplet density, uniformity of deposition, droplet penetrability and control of Phytophtora Capsici and Aphids on pepper plants – between two different implements for the crop protection, i.e. an electric air-pressure knapstack sprayer and an UAV sprayer.
The study is very interesting, but still requires improvements.
Specific comments (noted in the manuscript)
Introduction
The purpose of the study (lines 73-76) is too generic. I have suggested the Authors - in my first revision - to better define the focus of their study, considering the title of the manuscript. The Authors, in their response to my first revision, wrote:
“This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.” Well, this is the objective of the study, including the comparison between the performances of electric air-pressure knapstack sprayer and an UAV sprayer.
I expect that this suggestion is included in the text.
Materials and Methods
I confirm that the strict division of this paragraph on the one hand makes it clear the followed methodology, on the other hand it appears very difficult for the reader to understand how the experiment has been carried out. In particular, to begin the paragraph with the list of experimental reagent used without providing the main information about the experimental design, in my opinion is not appropriate for a logical reading of the manuscript. I suggest the Authors to introduce a general description of the experimental design with the followed methodology and after to deepen the various materials considered.
I didn’t find this suggestion in the manuscript.
I expect that the Authors include in the text, at the beginning of the chapter “Materials and Methods” a brief description of the experimental methodology. After this brief description, is correct to describe the reagents, the instrumentation etc.
Results
In my first revision, in the Droplet coverage sub-paragraph (line 219), I had one doubt related to the results of droplet coverage obtained using UAV. Indeed, I wrote: “I expected that the turbulence caused by the UAV’ rotors would have increased the droplet coverage in the middle layer and lower layer, this because the movement of the upper layer would showed the underlying layers, by exposing them to the agro-chemical treatment. Please clarify this aspect”.
Thank you for your private response, but I did not find this part in the manuscript. The comment provided in the response to my first revision must be included and discussed in the 3.1.1 paragraph and, eventually, in the 3.1.3 paragraph.
Author Response
Dear reviewer,
We are so grateful for the excellent suggestions and the detailed revising from you. We have benefited greatly by the revision. Now we explain your questions firstly point by point, and then made modification accordingly.
Introduction
The purpose of the study (lines 73-76) is too generic. I have suggested the Authors - in my first revision - to better define the focus of their study, considering the title of the manuscript. The Authors, in their response to my first revision, wrote:
“This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.” Well, this is the objective of the study, including the comparison between the performances of electric air-pressure knapstack sprayer and an UAV sprayer.
I expect that this suggestion is included in the text.
Response: The last sentence of the second paragraph of the Introduction was replaced by “In this study, we compared the spraying effect of EAP sprayer and UAV sprayer, the droplet distribution and control efficacy were studied. This study focused on the feasibility of UAV spraying pesticide in processing pepper field, and further explored the UAV spraying technology to pest control in processing pepper field.”
I confirm that the strict division of this paragraph on the one hand makes it clear the followed methodology, on the other hand it appears very difficult for the reader to understand how the experiment has been carried out. In particular, to begin the paragraph with the list of experimental reagent used without providing the main information about the experimental design, in my opinion is not appropriate for a logical reading of the manuscript. I suggest the Authors to introduce a general description of the experimental design with the followed methodology and after to deepen the various materials considered.
I didn’t find this suggestion in the manuscript.
I expect that the Authors include in the text, at the beginning of the chapter “Materials and Methods” a brief description of the experimental methodology. After this brief description, is correct to describe the reagents, the instrumentation etc.
Response: Thanks for the excellent suggestion on our manuscript. We had added a brief description of the experimental methodology at the beginning of the chapter “Materials and Methods”
Results
In my first revision, in the Droplet coverage sub-paragraph (line 219), I had one doubt related to the results of droplet coverage obtained using UAV. Indeed, I wrote: “I expected that the turbulence caused by the UAV’ rotors would have increased the droplet coverage in the middle layer and lower layer, this because the movement of the upper layer would showed the underlying layers, by exposing them to the agro-chemical treatment. Please clarify this aspect”.
Thank you for your private response, but I did not find this part in the manuscript. The comment provided in the response to my first revision must be included and discussed in the 3.1.1 paragraph and, eventually, in the 3.1.3 paragraph.
Response: Thanks for the excellent suggestion on our manuscript. We had added a discussion in the 3.1.1 paragraph.
Thank you for your suggestions and comments.
Kind regards,
Xiaoqiang Han
22 Jan 2020
Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
I have appreciated the efforts of the Authors and now I am satisfied of this revised version.
