Field Validation of the Effect of Soil Fumigation of Ethanedinitrile (EDN) on the Mortality of Meloidogyne hapla and Carrot Yield Parameters
Round 1
Reviewer 1 Report
Minor changes
The paper is well-prepared and important for agro-practice, while the Meloidogyne species are the most dangerous pathogens for vegetable crops worldwide. EDN is new and very promising eco-safe fumigant.
Some notes to improve the text understanding.
Lines 83-84
A pressurized vessel containing 83 EDN was placed on the mulch layer, and EDN was applied to the soil at a depth of 20 cm. The towing speed and EDN flow were adjusted to reach desired concentrations of 30 g/m2 and 50 g/m2.
=Please explain more understandable: how you may regulate the final EDN concentration? What are dimensions of the gas vessel? Whether it is a part of the Rain-Flo 2600 (Dubois) standard equipment, or it was hand-made or produced, if the latter case please give info about the producer and name of ware.
Lines 112-114
For analysis, 120 carrot plants were randomly picked from each 112 experimental variant, and the following parameters were assessed: fresh root weight, fresh leaf weight, largest root diameter, root length and number of root galls.
= Please indicate here and in tables, whether the values of parameters were given per plant or per area unit (m2).
Lines 161-162
Previously, [18] and [19] reported that EDN showed equal or even better nematicidal activity 160 than methyl bromide in tests performed under in vitro conditions on Steinernema carpocapsae
= Please indicate in the Discussion, that the Steinernema carpocapsae is the insect biocontrol agent which highly useful to increase the yield, thus the control of that species is not the vegetable protection but even increase the chance of insect attacks on carrot plants.
You cite the crop losses values: “ annual monetary losses equal to 157 billion USD (line 28 )”
=Please add in the Discussion part some rough estimations of the economic effect of the EDN application for carrot growers. The application procedure has to be done by the licensed services and possibly it will be useful only for the large agrofirms; what field size will be the economic limit to use EDN fumigation?
Author Response
Please see my answers in bold:
Lines 83-84
A pressurized vessel containing 83 EDN was placed on the mulch layer, and EDN was applied to the soil at a depth of 20 cm. The towing speed and EDN flow were adjusted to reach desired concentrations of 30 g/m2 and 50 g/m2.
=Please explain more understandable: how you may regulate the final EDN concentration? What are dimensions of the gas vessel? Whether it is a part of the Rain-Flo 2600 (Dubois) standard equipment or it was hand-made or produced, if the latter case please give info about the producer and name of ware.
Accepted, more details on technique of EDN application added into Material and Methods.
Lines 112-114
For analysis, 120 carrot plants were randomly picked from each 112 experimental variant, and the following parameters were assessed: fresh root weight, fresh leaf weight, largest root diameter, root length and number of root galls.
= Please indicate here and in tables, whether the values of parameters were given per plant or per area unit (m2).
Per plant, adjusted in the text and tables.
Lines 161-162
Previously, [18] and [19] reported that EDN showed equal or even better nematicidal activity 160 than methyl bromide in tests performed under in vitro conditions on Steinernema carpocapsae
= Please indicate in the Discussion, that the Steinernema carpocapsae is the insect biocontrol agent which highly useful to increase the yield, thus the control of that species is not the vegetable protection but even increase the chance of insect attacks on carrot plants.
Accepted and adjusted
You cite the crop losses values: “annual monetary losses equal to 157 billion USD (line 28 )”
=Please add in the Discussion part some rough estimations of the economic effect of the EDN application for carrot growers. The application procedure has to be done by the licensed services and possibly it will be useful only for the large agrofirms; what field size will be the economic limit to use EDN fumigation?
Accepted, sentence on economic feasibility of EDN treatment added however I would prefer not to describe the precise numbers in the manuscript as prices of root vegetable changes very rapidly and data from the Czech Republic would be of limited relevance for international readers.
Reviewer 2 Report
The problem with MB alternatives in carrot production is important and present study adds new data about practical application of fumigation with C2N2 as a possible alternative nematicide. Some inaccuracy and gaps of presentation of the study have to be amended.
In introduction several basic works on methyl bromide alternative fumigants in carrot production from EU area were not considered (e.g. Fritsch et al. (2014), Curto et al. (2014) and Greco et al. (2019), and etc. ).
EDN was tested against entomopathogenic nematode Steinernema carpocapsae in a primary bioassay (Ren et al., 2002) but it could not be a good example of nematicide target organism as it is interpreted in the text (Line 53).
The main aim of the work postulated as “evaluation of EDN soil application effect on the mortality of Meloidogyne hapla” was incorrect because only level of damage of root knot nematode was evaluated in the study.
Materials and Methods
As a measure of Meloidogyne damage was used direct number of galls per plant instead of Gall Index after Taylor and Sasser (1978) that will made obtained results more comparable with other studies.
[Taylor and Sasser (1978) rated root Gall Index on a 0 to 5 scale, in which 0 = no gall on the root, 1 = 1–2 galls, 2 = 3–10, 3 = 11–30, 4 = 31–100, and 5 = more than 100 galls per root.|
In similar studies usually not only root galling is measure of efficacy of treatment but also number of invasive stages in soil before and after application.
Citation: There is incorrect type of citation at several places in the text (e.g. line 160 should be: …Previously, Ren et al. [18] and Waterfordet al. [19] reported that EDN showed equal or even better nematicidal activity….
Curto, G., Dongiovanni C., Sassanelly N., Santori A. & A. Myrta, (2014). Efficacy of Dimethyl Disulfide (DMDS) in the Control of the Root-Knot Nematode Meloidogyne incognita and the Cyst Nematode Heterodera carotae on Carrot in Field Condition in Italy. Acta Hort. 1044, 405-410, DOI: 10.17660/ActaHortic.2014.1044.55
Greco, N., Aranda J.M. López, Saporiti, M., Maccarini, C., de Tommaso, N. and Myrta, A. (2020). Sustainability of European vegetable and strawberry production in relation to fumigation practices in the EU. Acta Hortic. 1270, 203-210
DOI: 10.17660/ActaHortic.2020.1270.24
Fritsch, J., Fargier-Puech, P., Ramponi-Bur, C., Du Fretay, G., Fouillet, T., Charles, P., Descamps S., & Myrta, A. (2014) French Experiences with Dimethyl Disulfide (DMDS) as a Nematicide in Vegetable Crops. Acta horticulturae, 1044, 427-433. doi: 10.17660/ActaHortic.2014.1044.59
Taylor, A.L. and Sasser, J.N. (1978) Biology, Identification and Control of Root-knot Nematodes (Meloidogyne species). North Carolina State University Graphics, Raleigh, North Carolina.
Author Response
Please see my reaction in bold:
The problem with MB alternatives in carrot production is important and present study adds new data about practical application of fumigation with C2N2 as a possible alternative nematicide. Some inaccuracy and gaps of presentation of the study have to be amended.
In introduction several basic works on methyl bromide alternative fumigants in carrot production from EU area were not considered (e.g. Fritsch et al. (2014), Curto et al. (2014) and Greco et al. (2019), and etc. ).
Accepted, citations added.
EDN was tested against entomopathogenic nematode Steinernema carpocapsae in a primary bioassay (Ren et al., 2002) but it could not be a good example of nematicide target organism as it is interpreted in the text (Line 53).
Accepted, remark on limited value of comparison with Steinernema added.
The main aim of the work postulated as “evaluation of EDN soil application effect on the mortality of Meloidogyne hapla” was incorrect because only level of damage of root knot nematode was evaluated in the study.
Accepted, I have changed the aim as “evaluation of EDN soil application effect on the viabilty of Meloidogyne hapla”, as was done by counting of root galls.
Materials and Methods
As a measure of Meloidogyne damage was used direct number of galls per plant instead of Gall Index after Taylor and Sasser (1978) that will made obtained results more comparable with other studies.
[Taylor and Sasser (1978) rated root Gall Index on a 0 to 5 scale, in which 0 = no gall on the root, 1 = 1–2 galls, 2 = 3–10, 3 = 11–30, 4 = 31–100, and 5 = more than 100 galls per root.|
Yes, we are aware of Taylor and Sasser scale however we decide not to use it especially because of extremely low gall incidence in EDN treated variants; according our opinion it is more precise to present absolute gall numbers in this case and high effect of EDN on M. hapla galls is clear from the manuscript even with our type of evaluation.
In similar studies usually not only root galling is measure of efficacy of treatment but also number of invasive stages in soil before and after application.
Yes, J2 numbers are sometimes evaluated as well but in other studies the effect of nematicides is evaluated only using the gall numbers (eg. Aissani, N., Urgeghe, P. P., Oplos, C., Saba, M., Tocco, G., Petretto, G. L., ... & Caboni, P. (2015). Nematicidal activity of the volatilome of Eruca sativa on Meloidogyne incognita. Journal of agricultural and food chemistry, 63(27), 6120-6125.; Kim, T. Y., Jang, J. Y., Yu, N. H., Chi, W. J., Bae, C. H., Yeo, J. H., ... & Kim, J. C. (2018). Nematicidal activity of grammicin produced by Xylaria grammica KCTC 13121BP against Meloidogyne incognita. Pest management science, 74(2), 384-391.).
For our purposes number of root galls is a crucial parameter as we are working with the root vegetable which could easily lost its commercial value completely even with low nematode infestation and therefore we decided to evaluate this parameter only but in bigger detail (precise gall numbers).
Citation: There is incorrect type of citation at several places in the text (e.g. line 160 should be: …Previously, Ren et al. [18] and Waterfordet al. [19] reported that EDN showed equal or even better nematicidal activity….
Adjusted
