Impact of Reducing Synthetic Chemical Inputs on Pest and Disease Management in Commercial Onion Production Systems
Round 1
Reviewer 1 Report
Overall, this manuscript would be a useful contribution to the integrated pest management of onion against Thrips tabaci and bulb rot disease. However, since similar issues have been studied previously in the same region (see Leach et al. Agric. Ecosyst. Environ. 2017 250, 89-101; Leach et al. Crop Prot. 2020 133, 105123), the novelty of this work should be clearly underlined by the Authors. Although the manuscript is well written and appropriate research methods are used, it does require some corrections as shown below.
Introduction
R: In the Introduction part, it should be explained why research on the effect of the intensity of fertilization of plants and the frequency of insecticide application on T. tabaci and the bacterial bulb rot disease was undertaken (especially in the context of already published information from the region).
Line 70: „Reducing nitrogen levels have reduced incidence of bacterial bulb rots.”
R: Add information where/ in what case/under what circumstances (soil type), because in the next sentence you write about the lack of this effect in New York muck soils.
Materials and Methods
Part 2.3 fertilizer applications
Soil testing and fertilizer application dates should be added.
Results
Line 270: Are 1.2 and 0.6 larvae per leaf the average of the three years of study? Please clarify.
In Figure 2, there is an error in the number of treatments in 2021. It should be 3-9 in the "Threshold" column and 7-11 in the "Weekly" column instead of "3-7" and "7-10"
Discussion
In the discussion, it should be emphasized how the research presented in the manuscript broadened the knowledge in this field (although similar experiments were already carried out on this type of soil and in this area, this time their scope was greater, more varieties were tested, etc.).
Lines 330-331 - Remove “(Fig.2)” from the text
Lines 331-333: “The greatest reduction occurred in one field in 2019 where five fewer sprays were made 331 using the action-threshold program compared with the weekly program (three sprays versus eight sprays).”
R: This text is relevant to Results, not Discussion.
Supplementary materials
Figure S1
R: I propose to remove the NS symbols from all figures as they relate to a different analysis than that illustrated in Figure S1. The NS symbols relate to the comparison of individual nutrient contents between the 3 fertilization combinations and this information is summarized in Table S5. They are not needed on Fig S1 because they are misleading.
Author Response
Please see responses to comments in the attached document.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Manuscript ID agronomy-1689329
The manuscript indicates that reducing fertilizer application and following an insecticide threshold-based application has no impact on onion production. The manuscript presents a worthy methodology and results supporting the main conclusions reached. However, the authors must insert an economic context in the manuscript to validate their findings. We do not know how significantly these reductions reflect economic ways to the growers (e.g., fertilizers and insecticides cost reduction). This message might be hidden in the results but should be brought to the front to provide a shred of solid evidence to the authors’ claims. Thus, my recommendation is a significant review before publication.
#Comments
L 37: Here and elsewhere, I suggest changing larvae by immatures. Because thrips nomenclature regarding its development is still under debate, readers may assume that larvae mean holometabolous. Thus, immature seems more appropriate.
L 132-140: In the illustration, may the authors consider including the name experimental unit to differ from plots (Are they the same?). Plus, what is the block? The text is unclear what they refer to, and the illustration would be helpful on it.
L 160-161: Was it similar to lines 215-217 (25 plants per experimental unit)?
L 178-181: I suggest the authors move the insecticides applied from the supplementary material to here because they are the central part of the methods in the study.
L 158: A reference is necessary to support the statement.
L 197-210: This section may be moved to results since it is part of the authors’ discussion in section 4.3.
Table 1: I would recommend keeping only one mention of the degrees of freedom from the residuals (at the end of each year). The current presentation may lead to misinterpretation like pseudoreplicates in the model.
Figure 2: A temporal graph provides a better picture of the study. The mean is enough to show the primary outcome, but not for this type of data presentation. Plus, may the authors consider pointing out an analysis to compare the number of applications between treatments to reinforce one of the central claims in the manuscript – insecticide application can be reduced without compromising onion yield (e.g., L 24).
L 329-330: Does it differ economically and statistically? I believe it is necessary to look at this argument in those ways because the EIL threshold is based on the cost of the application and products (insecticides). Besides, the author’s claims suggest that such analysis is necessary as they argue in lines 341-342 ‘considerable savings in insecticides costs’.
L 331-333: It does not agree with the results in figure 2A, where the number of thrips was higher in the threshold plots and almost close to the EIL.
Author Response
Please see attached file for comments that were addressed.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Manuscript ID agronomy-1689329
The author’s response clarified some aspects that were unclear to me, especially regarding the economic analysis that I mentioned in the previous review.
I would recommend the manuscript for publication in its current form.
Best regards.
