Evaluation of Industrial Hemp Seed Treatments for Management of Damping-Off for Enhanced Stand Establishment

Round 1

Reviewer 1 Report

The authors present a descriptive and comparative study of the effect of different fungicide treatments on seeds including commercial products used in chemical, biochemical and biological treatments. The effectiveness on the vigor and growth of hemp seedlings is compared under field cultivation conditions in different geographical areas and at different seasons. They conclude that, contrary to the biological product, the products containing copper (biochemical products) show an interesting efficacy comparable to that of chemical treatments both under laboratory conditions and in field trials. This work is interesting and original because it seeks to evaluate the impact of treatments on seeds. This strategy is promising because less active ingredient is needed for the treatment, and the presence of these products at the start of the crop is essential to ensure good yields.

The comparison on different cultivation sites gives a good view of the variability to be taken into account. The conclusions of the articles are in line with the results presented. However, there are some editorial improvements to consider to make the article more understandable:

• Line 40 "will have potential a lucrative high value crop when grown for..." The sentence is not understandable and needs to be rephrased.
• Line 60 The sentence "Significant advances have been made in recent decades ..." needs references.
• The active molecules of the commercial products are described in Table 1, but it would be preferable to recall the names of the commercial products when describing their effects in the result part. This is the case, for example, in the description of table 2 concerning "chemical seed treatments" on line 237.
• The notations A, B, C which are presented in the tables and figures must be explained in the legends.
• In Figures 4 and 5  : describe in the legende titel that it is trial 1 and 2 because we need to read all befor understanding that it is 2 different trials..
• The histograms of the Figures 2 to 7 could be presented in one and the same figure, which would make it possible to better compare the different experimental sites and to better identify the trends in the efficacy of the products.

The part of the 'pathogen diagnosis' results presented in tables 5 and 6 is not very convincing and rather suggests that the disease pressure presents a variability in the field which makes the analyzes difficult to interpret. not much to the message of the article and is moreover little or not discussed.The mastery of as many pathosystems on a species can be worked on is quite ambitious.

In the discussion part, the positive effect of copper on growth and vigour, must however be weighted given the observed variability highlighted by the statistical analysis.

 

Author Response

Reviewer 1 

The authors present a descriptive and comparative study of the effect of different fungicide treatments on seeds including commercial products used in chemical, biochemical and biological treatments. The effectiveness on the vigor and growth of hemp seedlings is compared under field cultivation conditions in different geographical areas and at different seasons. They conclude that, contrary to the biological product, the products containing copper (biochemical products) show an interesting efficacy comparable to that of chemical treatments both under laboratory conditions and in field trials. This work is interesting and original because it seeks to evaluate the impact of treatments on seeds. This strategy is promising because less active ingredient is needed for the treatment, and the presence of these products at the start of the crop is essential to ensure good yields. The comparison on different cultivation sites gives a good view of the variability to be taken into account. The conclusions of the articles are in line with the results presented. However, there are some editorial improvements to consider to make the article more understandable:

Response to reviewer #1: We would like to thank the Reviewer #1 for careful and detailed reading of our manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of our manuscript. Our response (in red) follows:

Point 1: Line 40 "will have potential a lucrative high value crop when grown for..." The sentence is not understandable and needs to be rephrased.

Response 1: Agree and sentence is outside the scope of this study and deleted.

Point 2: Line 60 The sentence "Significant advances have been made in recent decades ..." needs references.

Response 2: The following reference added (Line 474):

[19] Harman, G. Biological Seed Treatments. Preprints 2021, 2021030303 doi: 10.20944/preprints202103.0303.v1

Point 3: The active molecules of the commercial products are described in Table 1, but it would be preferable to recall the names of the commercial products when describing their effects in the result part. This is the case, for example, in the description of table 2 concerning "chemical seed treatments" on line 237.

Response 3: Line 242-246 edited as follow:

 

and chemical seed treatments (#9-12, Table 1, 4 and 5) when compared to the non-treated control (Table 4). Results from the soil bioassay showed that only Ultim, an organic copper treatment and chemical seed treatments (Apron XL + Maxim 4FS and in combination with Mertect 340 F [rates presented in Table 1, 4 and 5]) reduced damping off compared to the non-treated control and other treatments after 7 and 10 days.

Treatments number added as a column to Table 4 for clarification of Treatments # and descriptions.

Point 4: The notations A, B, C which are presented in the tables and figures must be explained in the legends.

Response 4:

Table 4: The following statement was added to the footnote of Table 4 (Lines 252-253):

Mean values with different letters are statistically different. **Significant at 0.01

Table 5: The following statement added to the footnote of Table 5 (Lines 296-297):

*, **, *** Significant at 0.10, 0.05, and 0.01. NS - Not significant at 0.05. Mean values with different letters are statistically different. Final Count Days After Planting: w = 24 days, x = 27 days, y = 35 days, and z = 20 days.

Point 5: In Figures 4 and 5 : describe in the legende titel that it is trial 1 and 2 because we need to read all before understanding that it is 2 different trials.

Response 5: Data in Figures 2-7 presented as Table 5 (Please see Response 6).

Point 6: The histograms of the Figures 2 to 7 could be presented in one and the same figure, which would make it possible to better compare the different experimental sites and to better identify the trends in the efficacy of the products.

Response 6: Data in Figures 2-7 presented as Table 5:

Table 5. Final stand counts (% emerged seedlings/plants) in two trials of hemp seed treatments across three locations in 2020.

	Location	New York		North Dakota		Virginia
		Trial		Trial		Trial
#	Treatment	1w	2w	1x	2x	1y	2z
1	Non-treated control	33 C	27 BC	37 CD	28 DE	14 CD	16
2	20CU_2697LQ	34 BC	32 ABC	36 CD	32 C-E	17 A-D	9
3	Amplitude	29 C	28 BC	36 CDE	28 DE	15 BCD		13
4	Bioseed	31 C	30 ABC	33 D	34 B-D	12 D	10
5	Varnimo/KaPre Embrella	28 C	21 C	30 D	29 DE	16 BCD	22
6	Phyter	33 BC	24 BC	40 C	26 E	14 CD	17
7	Ultim	42 A	35 AB	49 B	42 A	21 A	28
8	Prudent 44 + Nutrol	41AB	29 BC	38 C	27 DE	21 AB	17
9	Apron XL + Maxim 4FS 1/2 rate	32 C	22 BC	58 A	43 A	20 ABC	17
10	Apron XL + Maxim4FS 1X rate	46 A	33 ABC	58 AB	40 AB	10 D	25
11	Apron XL + Maxim 4FS 2X rate	41 AB	42 A	56 AB	41 A	17 A-D	22
12	Apron XL + Maxim 4FS + Mertect 340F 1X rate	30 C	28 BC	55 AB	36 ABC	15 BCD	20
	P ≤ value	0.0004***	0.09*	0.001***	0.0001***	0.05**	0.12 NS

*, **, *** Significant at 0.10, 0.05, and 0.01. NS - Not significant at 0.05. Mean values with different letters are statistically different. Final Count Days After Planting: w = 24 days, x = 27 days, y = 35 days, and z = 20 days.

Point 7: The part of the 'pathogen diagnosis' results presented in tables 5 and 6 is not very convincing and rather suggests that the disease pressure presents a variability in the field which makes the analyzes difficult to interpret. not much to the message of the article and is moreover little or not discussed. The mastery of as many pathosystems on a species can be worked on is quite ambitious.

Response 7:

The pathogen diagnostic tables report species of plant pathogens identified in the various field trials. The data presented illustrates pathogens found associated with diseased seedlings, and was not an attempt to survey pathogens present in the field soils. We agree disease pressure was variable across locations and does make interpretation of results difficult. Field trials are notorious for variability, to account for this we report on two trials conducted across three very diverse locations. We clearly state our results as broad interpretations of collected data. In general, the biological treatments did not perform as well as the chemical or biochemical treatments. We strongly feel that these conclusions are supported by the data.

Point 8: In the discussion part, the positive effect of copper on growth and vigour, must however be weighted given the observed variability highlighted by the statistical analysis.

Response 8:

We agree there was significant variability in the field data. The laboratory soil bioassay clearly showed that the organic copper treatment was as effective as commercial chemical treatments. We have added a sentence in the discussion regarding the laboratory assays and the broader implications of this research (Lines 404-409). We support our statement that “Collectively, the organic copper seed treatment has potential for both conventional and organic hemp production. Moreover, results from this study provides the foundation for seed treatment research on Cannabis sativa grown for other uses. For example, Ultim, the organic cooper treatment evaluated in this study and other organic copper seed treatments were found to be effective in controlling damping off in the soil bioassay on a CBD (cannabidiol) variety of hemp [50].”

Reviewer 2 Report

The manuscript includes very valuable information on hemp seed treatments against seedling damping off. Appropriate research methods were applied. The results obtained were described sufficiently. However, it would be worth to present the percentages of diseased seedlings in field trials. The discussion is comprehensive.

Author Response

Reviewer 2

The manuscript includes very valuable information on hemp seed treatments against seedling damping off. Appropriate research methods were applied. The results obtained were described sufficiently. However, it would be worth to present the percentages of diseased seedlings in field trials. The discussion is comprehensive.

Response to reviewer #2: Authors of this manuscript appreciate the positive feedback from Reviewer #2 for detailed reading of our manuscript and for the valuable comment. Our response (in red) follows:

Point 1: (x) English language and style are fine/minor spell check required

Response 1: The language and spell check performed.

Point 2: However, it would be worth to present the percentages of diseased seedlings in field trials.

Response 2:

Diseased seedlings perished during early seedling emergence making accurate counts difficult.  The most accurate and important criteria was to measure final plant stands that we reported in Table 5.

Reviewer 3 Report

The paper is well written and documented. It has great practical advantages.

I understand that the molecular techniques described in the methods have been used to identify soil pathogens.

In the descriptions for the charts, I did not find an explanation of the letters A, B etc. used. This should be completed, as well as the meaning of "*" and "**" in the tables.

Author Response

Reviewer 3

I understand that the molecular techniques described in the methods have been used to identify soil pathogens.

Response to reviewer #3: The authors thanks Reviewer #3 for valuable and positive feedback on this manuscript.

Point 1: In the descriptions for the charts, I did not find an explanation of the letters A, B etc. used. This should be completed, as well as the meaning of "*" and "**" in the tables.

Response 1:

The following statement added to the footnote of Table 4 (Lines 252-253):

Mean values with different letters are statistically different. **Significant at 0.01

Figures 2-7 are presented in Table 5 and Table footnote provided.