Long-Term Benefits of Protecting Table Grape Vineyards against Trunk Diseases in the California Desert
Round 1
Reviewer 1 Report
Dear Editor,
Manuscript “agronomy-971570” reports data from a 6-year long experiment conducted in order to assess the effects of protecting grapevine pruning wounds with thiophanate methyl on the incidence of grapevine trunk diseases (GTD) and the yield of grapes. Moreover, data on the economic net benefits of the treatment obtained through simulation are reported.
The novelty of the paper as explained in Lines 270-272 is the prophylactic use of fungicide on healthy plants that have not previously developed GTD. This clearly led to a reduced incidence of GTD with time. This should be clearly highlighted in the abstract in order to quickly grab the attention of readers (a recommendation).
On another note, the study was conducted using young plants (less than 10-year-old). It remained unknown whether the treatment could prevent foliar symptom emergence which is clearly associated with grape losses. This limitation of the study could also be discussed with one or two sentences.
Line 41: “during the winter months” – I could not understand why irrigation is performed during winter.
Lines 58-59: Armillaria root disease is not a GTD. Please, check again.
Line 110: It is important to describe the types of symptoms observed in the wood and if possible to associate the symptoms with black foot, esca, eutypa dieback, botryosphaeria cancer or petri disease.
Lines 140-144: Data in figures 4-6 point to the use of Wilcox test for pairwise comparisons as related to count of replants, disease incidence, and grape yield. It is not clear why the Poisson regression test was conducted.
Line 198: All the supplementary tables and figures (except for supplementary Table 1) are date generated from the study. Please strongly consider moving these tables and figures to the main body of the manuscript.
Supplementary Figures: The meaning for treatment 1 and treatment 2 should be provided.
Author Response
The goal of this study is highlighted in the second sentence of the abstract (L17-19).
L113-114: We clarified the point that we only measured disease incidence based on wood symptoms and not foliar symptoms.
L41: Overhead sprinkler irrigation is performed in the winter the mild winter months to not provide enough chilling units to the crop (see L38-42).
L58-59: I respectfully disagree. GTDs are characterized by the fact that they affect the vasculature of grapevine and the causal agent of Armillaria root rot affects the vascular system mostly of the plant root just like other soilborne pathogens such as the causal agents of black foot that are now widely accepted as part of the GTD complex. In my opinion Armillaria should be viewed as a member of the trunk disease complex.
L110: We chose not to separate the pathogens based on wood symptoms because the vines used in this study were young and thus wood symptoms were not so severe and ‘typical’ of a disease. Often just a wood discoloration or black streaking. See Figure 3.
L140-144: No, we used Poisson regression for statistical analysis in Figs 4-6 as described in the Materials and Methods (L144-148). Poisson regression is commonly used for count data. However, we changed the language in the Figs 4-6 figure legends to clarify.
L198: We feel that it is more appropriate that these tables and figures remain in the supplemental files.
Supplemental Figures. The meaning for treatments 1 and 2 was added.
Reviewer 2 Report
The manuscript contains the results of a very specific experimentation. The results of the application of a single fungicide (thiophanate-methyl) after pruning are described to evaluate its incidence on wood fungi and the yield in a California vineyard with a variety of vine. The objectives set out in this manuscript are not achieved with the proposed experimentation plan.
Author Response
We respectfully disagree with these comments and we would appreciate if the reviewer could provide evidence to support this statement. Thank you.
Reviewer 3 Report
It is great to see a long-term study that asks the hard questions about economic benefits of a disease management program in a perennial fruit crop.
Some points to consider:
Although the authors indicate that Thiophanate Methyl is an industry standard in the grape industry, my search of fungicide registration data and product labels indicate that fungincides such as Topsin-M are not registered for GTD, but for a range of other diseases in grapes (Botrytis bunch rot, black rot, powdery mildew and phomposis cane and leaf spot). I do concede that Baumgartner et al. 2019 refer to work indicating the efficiacy of this fungicide against GTD, however, it woud be helpful if the authors were clearer about this point. Interestingly, my brief searching of the literature does not indicate a wealth of knowledge about the efficacy or use of Thiophanate methyl (a Group1 fungicide) against various Botryo' fungi, however other fungicides such as Pyraclostrobin (G11), Fluazinam (G29) and Folicur (G3) do show good activity. It may be helpful to broaden this report by considering this issue.
Can the authors also clarify why data was not presented on the frequency (and treatment differences) of occurrence of the various fungal species isolated from infected grapevine wood. Providing a list of species names without qualification sells short the value of the work done here.
Presumably, hand-directed application of fungicides to the vines post-pruning would improve the levels of disease control (compared to other studies). Is there potential here for artificial intelligence directed smart sprayers?
Author Response
Topsin M (thiophanate methyl) has been used for years for GTD management and is very common in California (see references in our manuscript #6, 20, 21, 23). The product label does name foliar diseases but some growers also use it for GTD management of grapevine as long as they overall input per year for all diseases combined does not go over 4.5 kg per ha (4 lbs. per acre: see p3 https://gcrec.ifas.ufl.edu/static/docs/pdf/strawberry-pathology/Fung-label/2009/topsin-M-70WP.pdf).
We clarified disease incidence (number of samples that were positive for pathogens) in the narrative (L220-225).
Yes, hand application gives better wound coverage and protection than mechanized application (see L291-295). The reviewer has certainly a point with regards to smart sprayers but it was not brought up in our discussion given the lack of literature on the subject.
Reviewer 4 Report
The manuscript entitled "Long-Term Benefits of Protecting Table Grape Vineyards against Trunk Diseases in the California Desert" written by Gispert et al. has been reviewed for its publication in Agronomy, recommending its acceptation wih minor revisions.
The work represents a valuable approach to provide an economic study on the benefits of providing early treatments to protect grapevine prunning wounds, not only for the supplied economic simulation, but also for the long-timming frame in which the experimental data were obtained (up to 6 years), what clearly differences the present study from other similar experimental designs.
Minor corrections and suggestions have been made by hand directly on the manuscript (attached pdf file provided).
Among these observations, it is suggested that a disease scoring method that would have included foliar symptoms, could have better reflect the disease incidence in the experimental vineyard.
Another suggestion for the authors came from the fact of considering (if applicable) nursery production proccesses as one of the responsible factors of the high GTDs pressure in the area studied. Probably a combined action including prunning wound protection and sanitizing initial plant propagation material could yield in more economic net benefits.
Comments for author File: 
Comments.pdf
Author Response
Thank you for your comments and useful feedback. The following changes have been made (see manuscript with track change).
L42-43: Dormex active ingredient was added.
L88-89: We clarified that no data on GTDs incidence and severity were recorded before the start of the experiment.
L104-105: We clarified the criteria that were used for vine removal.
L112-114: We clarified that we rated disease incidence based on wood symptoms only.
L220-225: We added the incidence of each fungal pathogen (number of samples where pathogens were found).
L302-306: We discussed that the GTDs infection levels observed in vines could originate from nurseries.
Round 2
Reviewer 2 Report
The authors include grape weight results, they must describe the material and the methodology used for it.
Author Response
Agreed. Details were added in the Materials and Methods section (see L118-121).
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript contains the results of a very specific experimentation carried out in the field. This describes the results of the application of a single fungicide after pruning to assess its incidence on wood fungi and yield in a California vineyard with a grapevine variety.
The information included in the introduction is very general and not very current. The section on material and methods is incomplete. It is missing to indicate the used doses of fungicides, to describe the equipment used for the applications, conditions of application, equipment used in the fungal identification, ...
The authors have not included the complemental tables and figures.
The authors present results with little scientific rigor.
Reviewer 2 Report
A very interesting and potentially useful study. Overall well done. A few comments below:
L24 - pruning wounds
L37 - 8th largest producer
L50 - add taxonomic names for the pathogens
L55 - ensure
L75 - meters between rows...meters between vines
L76 - two years old
L77 - would be good to mention why stumps are left. I know you say later but the reader is left to wonder for much of the ms why these exist.
L103 - Does this particular symptoms correlate to a specific pathogen?
L106 - diagnosis or diagnostic analysis
L146 - there were no supplemental files to review
L151 - there were no supplemental files to review
L157 - why is Hillis listed here?
L158 - there were no supplemental files to review
L168 - Fuller et al.?
L178 - there were no supplemental files to review
L179 - Baumgartner et al. (20)
Figure 4 -- what do the numbers above the bars represent? This needs more description.
L197 - do you mean except for the last year of the study? The way it is phrased now is awkward
Figure 5 - what do the numbers above the bars represent? This needs more description. Cannot read the y-axis
Figure 6 - what do the numbers above the bars represent? This needs more description.
L216 - there were no supplemental files to review
L219 - there were no supplemental files to review
L223 - there were no supplemental files to review
L244 - do you mean preventative fungicide applications after pruning?
L254 - surgical sounds out of place here. I don't believe that word is necessary
L274 - I think this part about overhead irrigation would have been good to put in the introduction. The reader is left to wonder about the diseases and stumps until now. It shouldn't be sprung on the reader like would be done in a mystery novel.
L301 - and assist with modified decision making (you use help twice in this sentence)
Reviewer 3 Report
This work conducted by Gispert et al. applied fungicide on vine wounds after pruning for six consecutive years, and collected data for replanted vines, Trunk disease incidence, total fruit and marketable fruit for the last year. Based on these data, authors also did an economic analysis to compare the “long-term” benefits between fungicide treated block and control block.
First of all, I was attractive by the title of this manuscript. But, after reading through the whole paper, even though I appreciated that authors did an integrated economic analysis from the perspective among industry stakeholders. I was a bit disappointed by that the authors did not mention anything about the influences of fungicide application on the environments. The benefit for environment should also be evaluated in this paper, e.g. density of fungal pathogens, survival of native insects and microorganisms after fungicide application.
It needed to conducted more lab experiments to check the effects of standard fungicide, in this paper is thiophanate-methyl, on pathogenic fungi which can cause trunk diseases and the plant/soil microbiome.
Even though the treatments were conducted for six consecutive years, but the fact is that the results were only collected for one year. The data collections should be repeated several more times to draw a more robust conclusion out of this paper.
The description about fungicide treatment was too vague, more details were needed.
I was expecting the results from fungal isolation and identification after reading the material and method section, but they were not included by authors in result section. Please keep the consistence between M&M section and Result section, also the order of presenting results.
The y-axis in Figure 5 was not clear.
Some small comments are in the attached pdf.
Comments for author File: Comments.pdf
