Comparative Study of Phosphorous-Acid-Containing Products for Managing Phytophthora Blight of Bell Pepper
Round 1
Reviewer 1 Report
Dear Authors,
The manuscript agronomy-1702371 “Comparative Study of Phosphorous Acid-containing Products 2 for Managing Phytophthora Blight of Bell Pepper” presents interesting data on the application of 5 phosphorous acid-containing products (e.g., ProPhyt, K-Phite, Lexx-A-Phos, Agri-Fos and Nutri-Phite) in controlling Phytophthora capsici, the aetiological agent of bell pepper.
If I correctly read the paper, the efficacy of five products containing phosphorous acid (ProPhyt, K-Phite, Lexx-A-Phos, Agri-Fos and Nutri-Phite) was evaluated in the laboratory and greenhouse studies in comparation with Mefenoxam (Ridomil Gold 480 EC) as chemical against Phytophthora capsici. Acibenzolar-S-methyl (Actigard) was also tested as an inducer of systemic resistance.
- capsici strains PPC1 (A1 mating type) and PPC6 (A2 mating type) were used in the test on mycelial growth, sporangium formation and zoospore germination. Compared with Mefenoxam, the five products containing phosphorous acid were less effective in inhibiting mycelial growth and sporangium formation, but more effective against zoospore germination. Greenhouse experiments were performed in a plastic tube (4 cm diameter, 20.5 cm long) with bell pepper variety Camelot in PPC1 infested growing media drench-treated with phosphorous acid-containing products at 0.25% and 0.10% (w/w). Sterile distilled water and V8-broth-vermiculite-distilled-water were used as untreated infested and non-infested controls, respectively. Disease incidence was recorded every five days for one month using the 0-5 disease severity rating scale described by Candole et al. [25]. Plant height, fresh and dry weight of shoot and root were measured after the last disease evaluation. Nutri-Phite at 0.25% and 0.1% Ridomil Gold (applied as control) were the most effective in disease incidence reduction.
The ability of phosphorous acid-containing products to induce systemic resistance against P. capsici was studied on bell pepper variety Camelot seedlings in 10 cm diameter plastic pots under greenhouse conditions. Phosphorous acid products were applied at two concentrations (0.10% and 0.25%) as a drench (25 mL per pot) 5 days before the first fully expanded leaf of each tested seedling inoculation with 50 μl per pot of strain PPC1 zoospore suspension (4×104 mL-1). The incidence of Phytophthora blight was determined three days after inoculation based on a 0-5 disease severity rating scale [25].
The percentage of disease index was calculated at the end of the tests. Plant height and shoot and root weights were also determined to evaluate the effect of treatment on plant growth. Actigard (0.004%) was used as a positive control for plant activators of systemic resistance. ProPhyt, K-Phite and Nutri-Phite at 0.1 and 0.25 % and 0.25% Agri-Fos reduced Phytophthora blight incidence in comparison with the non-treated plants, while were not significantly different with Acibenzolar-S-methyl.
My general impression of this study is positive, but its presentation in the form of a manuscript requires some adjustments.
I think that the abstract is a very important part of the manuscript, after reading the manuscript I suggest to rewrite it.
Line 10: What does “chemical resistance” mean in this sentence?
Line 13: Indicate the phosphorus acid equivalent used.
Line 14: put “-1” as an apex.
Line 14: use “two P. capsici strains“ instead of “P. capsici”.
Line 20: “suppress” or “reduce” or “displayed lower disease occurrence and delay Phytophthora blight of bell pepper”
Line 20: insert “without phytotoxic effects” between “pepper” and “.”
Verify the correct use of the International System of Units.
Use the correct Author’s name for Phytophthora capsici: Phytophthora capsici Leonian (see: http://www.indexfungorum.org/names/Names.asp). In non-taxonomic papers is facultative to indicate the Authors associated to Latin names of plants and fungi. Indicate the Author for Capsicum annuum or delete all the Authors name.
Lines 38-39, 48-49: Please insert state manufacturer, city, and country for each cited compound (e.g., Ridomil, Ridomil Gold, Agri-Fos, 48 K-Phite, Lexx-A-Phos, Nutri-Phite, and ProPhyt) or insert the reference to Table 1.
Table 1:
Lines 74-75: delete “against Phytophthora capsici and Phytophthora blight of pepper”
Table header: Use “Commercial name” instead of “Chemical”
Use “AU” instead of “Australia”
Line 76-77: insert a space between “spp.” and “2”: use “resistance inductor” instead of “induced resistance.”
Line 86: Insert information on EC50 determination.
Lines 99-100: What does “the percentage of the total number of zoospores examined for each treatment” mean?
The results section (table 2) reports data on EC50. Insert information on EC50 determination in Materials and Methods.
Line 107: Insert information on EC50 determination.
Line 113: Is Camelot a variety or a cultivar?
Line 120: use “CaCO3 1 g L-1” or “1 g L-1 CaCO3” instead of “1 g CaCO3 L-1”
Line 132: insert information on Disease incidence determination. See lines 146-152.
Line 142: delete “zoospore” between “4” and “ml”
In the section “2. Materials and Methods” insert information on “phytotoxic effect”
The “Results” section is difficult to read.
Table 2, Figure 1, Figure 2 and Table 3: if I correctly interpret, the data are the average of different repetitions (12 plants), then standard deviation is necessary to measure the dataset dispersion relative to the means.
Table 2
Lines 177-178: delete “Range of”. Insert “Phytophthora capsici” between “for” and “mycelial”. Delete “ of P. capsici”
Align “Fungicides” with “EC50 (μg mL-1)”
Are “Ridomil Gold EC” and “Ridomil Gold 480 EC” the same product? Please uniform the name.
Figure 1 reports two controls, Ridomil gold and 5 phosphorous acid-containing products.
I suggest the legend:
Figure 1. Phytophthora blight incidence on bell pepper variety Camelot under different treatments. Data are the mean of ?? replicates ± standard deviation. Values accompanied by the same letters are not significantly different according to Fisher’s least significant difference test (P = 0.05).
Figure 2.
I suggest the legend:
Figure 2. Incidence of Phytophthora blight of pepper (cv., Camelot) plants under different treatments. Data are the mean of ?? replicates ± standard deviation. Values accompanied by the same letters are not significantly different according to Fisher’s least significant difference test (P = 0.05).
Line 204: How was phytotoxicity assessed? Please insert it in the material and methods section.
Lines 202-209:
The section “3.4. Effect of phosphorous acid-containing products on plant growth” is not related to the material and methods section.
Are data in section 3.4 referred to section 2.3.1, 2.3.2 or their combination?
To correctly understand data on plant growth parameters, I suggest comparing: healthy control, non-treated control, inoculated and not inoculated plants treated with the five phosphorous acid-containing products and Ridomil Gold.
Line 216: Is Ridomil gold a fungicide? Ridomil Gold provides systemic control of soilborne diseases of root and stem diseases caused by Pythium and Phytophthora spp. and improves plant health and vigour. Pythium and Phytophthora are not in the Fungi Kingdom.
Revise the “Reference” section following the Agronomy instructions for Authors.
Author Response
Dear reviewer,
Thank you for the comments and suggestions on our manuscript. Please see the attached file for our responses to your comments.
Best,
Emran Ali
Author Response File: 
Author Response.pdf
Reviewer 2 Report
strenght: IN this interesting paper effectiveness of chemicals currently in use against P. capsici the agent causing Phytophthora blight of pepper is uncertain due to the development of chemical resistance by this pathogen, so the efficacy of alternative chemicals such as phosphorous acid-containing products was evaluated in laboratory and greenhouse studies. Similar concentrations ProPhyt, K-Phite, Lexx-A-Phos, Agri-Fos and Nutri-Phite were less effective in inhibition of mycelial growth (EC50 = 50.5 to 246.4 μ g mL-1) and sporangium formation of P. capsici, but more effective against zoospore germination compared with Mefenoxam. Nutri-Phite was most effective at EC50 = 50.5 and 94.5 μ g mL-1 in inhibiting mycelial growth of two P. capsici isolates. The use of Nutri-Phite, Agri-Fos, ProPhyt, and K-Phite could induce systemic resistance against foliar blight when applied to the root and potting mix. The results indicated that some phosphorous acid-containing products have the potential to suppress Phytophthora blight of bell pepper. The utility of the systemic protection induced by these products is promising in Phytophthora blight management.
Comments
1
please check english language
2 why authors have used only one peper ecotype?
3-It would be Good to add field studies nad more statististics
Author Response
Dear Reviewer,
Please see the attached file for our responses to your comments.
Thank you,
Emran Ali
Author Response File: Author Response.pdf
Reviewer 3 Report
In this paper, that is well written and easily readable, authors describe the effects of different phosphorus acid-containing chemicals in the control of Phytophthora Blight of Bell pepper. The topic covered in the paper is in line with one the main objective of Integrated Pest Management protocols, namely the use of alternative products with a low environmental impact and
characterized by a complex mechanism of action, that disadvantage the development of resistance strain of the target pathogen. Results, that was presented in a clear manner using graphical and table means, are supported by appropriate methods and experimental procedures, which are described
with enough detail to allow future researchers to follow-up aspects of the authors’ work. The significance of results obtained was interpreted and discussed with due reference to previously published studies. I really appreciated this work, but I have some concerns, which needs clarification from authors.
Major revisions
Section 2 “Materials and Methods”
Paragraph 2.1 “P. capsici isolates and chemicals”.
- Lines 68-69: “Two P. capsici isolates used in this study were PPC1 (A1 mating type) and PPC6 (A2 mating type).”: do the authors have information (e.g. bibliographic references, genetic analysis results, etc.) that the isolates used belong to the two mating types? If so, I recommend reporting them.
Paragraph 2.2 “In vitro tests”: I suggest describing the mathematical formula used to calculate the EC50, even in a further paragraph.
Paragraph 2.3 “Greenhouse tests”: I suggest describing the two controls (“Healthy control” and “non-treated control”) used in both experiment
Paragraph 2.4 “Statistical analysis”: the authors used a parametric approach both for the analysis of variance and for the comparison between the means. However, did they verify the normality of the data distribution (by means of the Shapiro-Wilk test, for example) and the homogeneity of variances (by means of the Levene test, for example)? Please explain.
Minor revisions
Figure 1 and 2: I suggest inserting the following sentence as a note: “Averages followed by same letter in bar are not significantly different (P > 0.05), based on the Fisher’s least significant difference test”
Table 3: I suggest adding the following sentence to the note: “… based on the Fisher’s least significant difference test”
Lines 221-222: “P. capsici is a heterothallic pathogen with two mating types, designated A1 and A2. Isolates belonging to different mating types are genetically distinct.”: I suggest adding a bibliographic reference, relating to this statement.
Author Response
Dear Reviewer,
Please see the attached file for our responses to your comments.
Thank you,
Emran Ali
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear Authors,
the rewritten version of the manuscript agronomy-1702371 “Comparative Study of Phosphorous Acid-containing Products 2 for Managing Phytophthora Blight of Bell Pepper” was improved respect the first draft.
Some minor suggestions:
Distribute table 1, appropriately on the page.
Table 2: insert “* Data are the mean of ?? replicates ± standard deviation” as a note.
Line 191: insert “*” after “germination”.
Line 203: use “capped” instead of “followed”
Lines 204, 216, and 226: use “p =” instead of “P =”
Table 3: Align “Treatments”, “Concentration (%)” and “Height (cm)” with “Fresh weight”
Author Response
Dear Reviewer,
Please see the attached file for our responses to your comments.
Thank you,
Emran Ali
Author Response File: 
Author Response.docx
Reviewer 3 Report
I thank the authors for responding to my reviews on time. I suggest the authors to insert in paragraph 2.4 "Statistical analysis" the statistical tests used to verify the conditions of normality and homogeneity of the data.
Author Response
Dear reviewer,
Please see the attached file for our responses to your comments.
Best,
Emran Ali
Author Response File: Author Response.docx
