Dazomet is a common soil
fumigant that acts as a
herbicide
Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
,
fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality ...
,
slimicide
Slimicide (or antislime agent) is a broad-spectrum antimicrobial pesticide used to kill slime-producing microorganisms such as algae, bacteria, fungi, and slime molds. One primary application domain is in the papermaking industry, where it reduc ...
, and
nematicide
A nematicide is a type of chemical pesticide used to kill plant-parasitic nematodes. Nematicides have tended to be broad-spectrum toxicants possessing high volatility or other properties promoting migration through the soil. Aldicarb (Temik), a ca ...
.
Applications
Dazomet is a chemical used to kill pests that inhibit plant growth through gaseous degradation. Dazomet is used as a soil sterilant on a variety of sites such as golf courses, nurseries, turf sites, and potting soils. Dazomet is used for soil sterilization as an alternative to
methyl bromide
Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula C H3 Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozo ...
. Although less effective it is still used to kill pests because of its comparatively lower toxicity. Dazomet is applied to wet soil, which causes dazomet itself to decompose into a gaseous form, which is what actively controls pests. The decomposition of dazomet releases
methyl isothiocyanate
Methyl isothiocyanate is the organosulfur compound with the formula CH3N=C=S. This low melting colorless solid is a powerful lachrymator. As a precursor to a variety of valuable bioactive compounds, it is the most important organic isothiocyanat ...
(MITC) a gas toxic to pests that would prevent or kill plant growth. Dazomet has also been proven to be effective in the prevention of ''
Phellinus noxius
''Phellinus noxius'' is a plant pathogen
Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that ...
'', or brown root rot disease.
Synthesis
Dazomet is synthesized from carbon disulfide (CS
2) and diluted methylamine (CH
3NH
2). After stirring for 1-2 hours, an oily substance is formed, which is the intermediate methyldithiocarbamic acid (HS
2CNHCH
3). Then, formaldehyde (CH
2O) is added to the intermediate to form and precipitate out the dazomet.
Form, color, and smell
Dazomet takes the form of colorless crystals.
Dazomet is described as having a weakly pungent smell.
Toxicology and safety
Dazomet is irritating to the eyes and its degradation product, MITC, is a dermal sensitizer. Dazomet is very toxic to aquatic organisms, and also acutely toxic to mammals. Exposure to dazomet can occur through several means; interaction with unincorporated granules, inhalation of it decomposition product, MITC, and/or water runoff.
Stability and shelf life
Dazomet is stable at temperatures up to 35°C; it is sensitive to temperature >50°C and to moisture.
Dazomet has a shelf life of at least two years when stored below 50°C.
Mass spectrum
The molecular ion peak of dazomet is at 162 m/z. There are two major fragment peaks, one at 89 m/z and one at 42 m/z. The fragment peak at 89 m/z represents the loss of MITC, which is the major, gaseous degrade of dazomet.
Patents
;Patent #US5989597
: Ambrose Rajamannan was the inventor of the novel process of continuously and instantaneously sterilizing soil using a water-activated fumigant. Dazomet is one water-activated fumigant that could be used. This process ensures 100% activation of the fumigant. Therefore, less fumigant would be needed to ensure that the soil would be completely sterilized.
[Rajamannan, A. H. J. Process for sterilizing soil. US Patent 5989597, Nov. 23, 1999.]
;Patent #CN1543787
: See under
References
{{reflist
Herbicides
Insecticides
Nematicides
Dithiocarbamates