Metalaxyl Resistance of Phytophthora palmivora Causing Durian Diseases in Thailand

Round 1

Reviewer 1 Report

Fungicide resistant Phytophthora varieties are general causes of yield and cost loss during durian production and storage. To characterize the fungicide resistant features of prevalent and potential Phytophthora varieties is essential for designing fungicide application and diseases managements.

In the present manuscript, the authors identified major Phytophthora varieties that cause rot diseases in the durian and analyzed the fungicide resistant features against different chemicals. It is found that most of the varieties acquired from the orchard with a heavy application of metalaxyl developed resistance against the specific fungicide. This work provided valuable data on the fungicide management of Phytophthora diseases for durian plants. The data provided may be indications for other plants species to use fungicides as a chemical application for managing rapidly evolving diseases. If the authors address the issues below, the manuscript might meet the high standard for publication.

Main issues:

1. Please indicate the recommended or practical application concentration for each fungicide tested in this manuscript in addition to metalaxyl (azoxystrobin and dimethomorph) to control Phytophthora during disease management.
2. Please indicate the number of clones used for ITS sequencing for each Phytophthora
3. Please indicate how the growth inhibition (%) value of Phytophthora was defined and/or calculated.
4. Please describe the statistical method used for significance analysis.
5. The language of the text needs improvement, even the Abstract and some of the sub-section titles were not well written, there were several mistakes in spelling, phrases, styles, and grammar. For example, in the first paragraph in Results, consider “The sequences of the ITS segments of the 16 isolates have been deposited in DDBJ under the accession numbers LC510501 to LC510515, respectively.” The manuscript needs tremendous improvement and proofreading.
6. It is recommended the authors provide a figure showing the multi-alignment of the ITS sequences from the different varieties with a reference DNA sequence as supplemental data.

Some other issues:

1. Line 20-21, “… with the 50% effective concentration (EC50) higher than 100 mg L⁻¹.”
2. Line 31, “The durian (Durio zibethinus), known as the “king of Thai fruits”, is one of the most…”.
3. Line 51-53, “…, which may significantly reduce their effectiveness. The increase in fungicide-resistant strains in the pathogen populations has been resulting in serious economic problems for farmers [12-14].”
4. Line 64, “; capsici,”
5. Line 231, “…more often during…”.
6. Line 253-255, “The application of Metalaxyl should be well-deigned to combine with alternate fungicides for disease control in orchards where metalaxyl-resistant strains have already appeared or widely distributed.”

Author Response

Dear Reviewer

Thank you very much for your comment.

Best regard,

Pornprapa Kongtragoul

Author Response File: Author Response.docx

Reviewer 2 Report

The paper brings interesting result. The presentation of results is quite clear. But I found some parts that could be improved. Corrections and comments are listed below:

Introduction

1. 2, l. 60-62 – There are so many citation, are they all necessary? Furthermore, in article [16] I think the resistant isolate was from USA and article [29] is not from USA but from Great Britain.

Material and method

1. 2, l. 82-83 – citation is not according to the instructions for authors; the citation is missing in references
2. 2, l. 85 – is word “if” correct or should there be “of”?
3. 3, l. 99-100 - the citation of Ishii et al. is not according to the instructions for authors, are I think, the sentence could be modified to be more clear and then it is not necessary to mention the citation [34] in the end of the sentence l. 104
4. 3, l. 111 - what is the concentration (amount) of DNA in mentioned volume?
5. 4, l. 147 – end of the sentence - citations are not according to the instructions for authors

section 2.3 and 2.5 – were the tests done immediately after the obtaining or were they stored and refreshed before fungicide tests?  

Section 2.5 – was the shape of lesions circular that diameter was selected for calculation

Discussion

1. 6, l. 219-225 – this part seems to be more results than discussion
2. 6, l. 228 - citation is not according to the instructions for authors and then it could be mentioned neither at the end of the sentence and probably nor in line 233.
3. 7, l. 242 – it could be appropriate to mentioned isolates of which pathogen if it is not the same as in first part of the sentence
4. 7, l.250 - the citation of Ramallo et al. is not according to the instructions for authors and is not in the list of references
5. 7, l.252 – the mentioned citation is propably from another article than that citated in references

References

1. 7, l. 282 – the reference no. 2 and 4 are same
2. 8, l. 316 - the reference no. 19 and 32 are same
3. 8, l. 323 – the reference no. 23 and 45 are same

Author Response

Dear Reviewer

Thank you very much for your comments.

Best regards,

Pornprapa Kongtragoul

Author Response File: Author Response.docx