A review of research results with metam sodium from Ontario and other locations
Cheryl Trueman, M.Sc., College Professor, Ridgetown Campus, University of Guelph; Janice LeBoeuf, Vegetable Crop Specialist, OMAFRA-Ridgetown; Anne Verhallen, Soil Management Specialist – Horticulture, OMAFRA-Ridgetown
Last week we discussed what fumigants are and how they work. We also presented a summary of recent research that evaluated the effect of metam sodium on tomato yield. Our conclusion from that research was that metam sodium is not an effective tool for improving yield associated with root rot and vine decline under field conditions. In this article, we’ll review research results from older research in Ontario, as well as peer-reviewed research from locations outside Ontario.
Previous Ontario research results
The late Dr. Ron Pitblado, who worked as a College Professor at the Ridgetown College of Agricultural Technology and later Ridgetown Campus of the University of Guelph, conducted research on metam sodium in processing tomato fields from 1989 to 1991. We dusted off Dr. Pitblado’s industry research reports from that time and summarized the results in Table 1. Metam sodium was applied using standard industry practices at the time, which are quite similar to the practices in use today. The target pests were root lesion nematodes and the fungal pathogen Verticillium dahliae. Dr. Pitblado also found results with metam sodium to be inconsistent. For example, in 1990, all 5 sites that had pest levels above the treatment threshold responded with a yield increase following fumigation. However, of the three test sites evaluated in 1991, none produced a yield response to fumigation, even though all three were above threshold for both target pests.
Table 1. Summary of results of research conducted by Dr. Pitblado on processing tomatoes in Essex Co., Ontario, 1989-1991.
| Year Number of Sites | Target Pest | Effect on Pest | Effect on Yield |
| Year: 1989 6 sites | Root lesion nematode | Reduction | Not measured |
| Year: 1990 5 sites at pest threshold(s) | Root lesion nematode, Verticillium dahliae | Not measured | Increase at all 5 sites |
| Year: 1990 5 sites below pest threshold(s) | Root lesion nematode, Verticillium dahliae | Not measured | No effect at 4 of 5 sites |
| Year: 1990 31 sites (10 at pest threshold levels) | Root lesion nematode, Verticillium dahliae | Reduction with pooled data, but not at all individual sites | Not measured |
| Year: 1991 3 sites (all at pest threshold levels for both pathogens) | Root lesion nematode, Verticillium dahliae | Not analyzed | No effect at any site, possibly because of poor Verticillium control |
Research results from other locations in North America
Research results from other locations in North America are also inconsistent. Table 2 summarizes results where metam sodium was applied using soil injection methods, whereas Table 3 summarizes results using other applications methods.
Table 2. Summary of research results on the effectiveness of soil injection-applied metam sodium at reducing soil pest populations or increasing tomato yield at various locations in North America.
| Location (Source) Target Pest | Application method |
Reduced disease?* |
Increased yield?* |
| Florida (McGovern et al., 1998) Fusarium oxysporum f. sp. radicis-lycopersici | Injection chisel, 6 per bed, 4-in chisel spacing, 8-9 inch depth |
0 of 2 sites |
0 of 2 sites |
| Florida (Csinos et al., 2002) Rhizoctonia solani, Pythium spp., Fusarium spp., Aspergillus spp., Penicillium spp. and others | Injection chisel, 6 per bed, 12-inch spacing, 8-inch depth + sealed with polyethylene film |
Reduction in pathogen populations in soil at 3 of 3 sites |
Not measured |
| California (Hartz et al., 2005) Verticillium dahliae, Fusarium spp. | Injection shanks, 4 per bed |
1 of 1 sites with V. dahliae |
0 of 2 sites |
*Disease reduction or yield increase as compared to nontreated control, unless otherwise noted.
Table 3. Summary of research results on the effectiveness of various metam sodium application methods at reducing soil pest populations or increasing tomato yield at various locations in North America.
| Location (Source) Target Pest | Application method | Reduced disease? | Increased yield? |
| Florida (McGovern et al., 1998) Fusarium spp. | Drip chemigation | 0 of 2 sites except in one case where high rate reduced severity but not incidence | 0 of 2 sites |
| Pre-bed spray | 1 of 1 sites reduction in incidence but not severity | 0 of 1 sites | |
| Florida (Csinos et al., 2002) Rhizoctonia solani, Pythium spp., Fusarium spp., Aspergillus spp., Penicillium spp. and others | Spray-till + plastic mulch | 3 of 3 sites reduced pathogen population in soil, depending on days of film cover | Not measured |
| Florida (Gilreath et al., 2004)Fusarium oxysporum f. sp. radicis-lycopersici, various root-galling nematode species | Spray-till + plastic mulch | 1 of 2 sites for F oxysporum; 2 of 2 sites for nematodes | 2 of 2 sites |
| Florida (Csinos et al., 2000)Rhizoctonia solani, Pythium spp., Fusarium spp., Aspergillus spp., Penicillium spp. and others + ring, root-knot, stubby-root, and spiral nematode | Spray-till + plastic mulch | 2 of 2 sites reduced pathogen populations in soil; 0 of 1 sites reduced root-knot nematode population but not damage; 1 of 1 sites reduced root-knot nematode damage | Not measured |
| North Carolina (Sydorovych et al., 2008) Verticillium dahliae | Drip chemigation | Increase in financial returns compared to fumigation with MeBr (6-year study) | |
| Spray-till | Financial returns equivalent to use of MeBr (6-year study) | ||
| Florida (Locascio et al., 1997) Rhizoctonia solani, Macrophomina phaseolina, Fusarium spp., root-knot nematode | Drip chemigation | 2 of 3 sites for fungal pathogens; 1 of 2 sites for root-knot nematode damage | 2 of 3 sites |
| Spray-till + plastic | 1 of 3 sites for fungal pathogens; 0 of 2 sites for root-knot nematode damage | 0 of 3 sites | |
So, why the inconsistency? We will discuss factors that can contribute to inconsistent results with fumigation in Part III of this series, which will appear on ONvegetables.com later this week.
References:
Csinos, A.S. et al. 2000. Methyl bromide alternatives in tobacco, tomato and pepper transplant production. Crop Protection. 19:39-49.
Csinos, A.S. et al. 2002. Application and crop safety parameters for soil fumigants. Crop Protection. 21:973-982.
Gilreath, J.P. et al. 2004. Soil fumigant evaluations for soilborne pest and Cyperus rotundus control in fresh market tomato. Crop Protection. 23:889-893.
Hartz, T.K. et al. 2005. Mustard cover crops are ineffective in suppressing soilborne diseases or improving processing tomato yield. HortScience. 40:2016-2019.
Locascio et al., 1997. Fumigant alternatives to methyl bromide for polyethylene-mulched tomato. HortScience. 32:1208-1211.
McGovern, R. J. et al. 1998. Evaluation of application methods of metam sodium for management of Fusarium crown and root rot in tomato in southwest Florida. Plant Dis. 82:919-923.
Sydorovych, O. et al. 2008. Economic evaluations of methyl bromide alternatives for the production of tomatoes in North Carolina. HortTechnology. 18:705-713.
0 comments on “Soil fumigants and tomato production, Part II”