|Non-fumigant Nematicides||Toxicity Categories|
|General Considerations||Fumigant Nematicides||Nematicide Properties and Efficacy|
|Registrations Cancelled||Index of Nematicides||References|
|Exploratory / New Materials||Return to Management Menu|
There are two main categories of chemical nematicides based on their volatility - non-fumigants and fumigants.
Non-fumigant nematicides have low volatility and diffuse through the soil (generally for short distances only) disoolved in the soil solution. Their movement may be enhanced by water movement through irrigation or rainfall. If in granular formulations, there distribution may be enhanced by physical incorporation into the soil.
Two main groups of chemicals, carbamates and organophosphates, and some alternative materials.
|Dasanit (Considered not profitable to re-register in California)||Manufacturer: Bayer|
|(phenamiphos, fenamiphos)||Introduced: 1969.|
Paraphrased from Associated Press (Sacramento Bee,
Dec 17, 2000):
A pesticide that Sonoma County officials believe killed some 400 birds last month has been banned from farms and vineyards.
The Sonoma County agricultural commissioner is refusing new applications to use Nemacur after birds were found dead near a Geyserville vineyard.
.............there may have been a leaking pipe when the chemical was applied in a vineyard....birds drank from contaminated water.
County agricultural officials said there probably won't be any widespread impact because the season when it is usually used in vineyards has passed.
Nemacur has been linked to bird kills in the past according to the US EPA.
Phenamiphos is reported to become less
effective when applied repeatedly to soils, possibly due to selection for
organisms that degrade it more rapidly (Davis, et al., 1993; Johnson,
In consideration of the cost of obtaining additional safety data requested
by the USEPA, Bayer Crop Sciences elected to voluntarily withdraw the
registration of Nemacur in the USA effective May 31, 2007.
Revised labels have been submitted to USEPA to implement risk mitigation measures.
Registrations are altered as follows:
As of May 31, 2007, all sale and distribution by Bayer, the sole registrant, of existing stocks (manufacturing-use and end-use products), shall be prohibited in the USA. Persons other than the registrant may sell and distribute such products until May 31, 2008. Use of stocks in the channels of trade may continue until depleted, except where prohibited by the label. Any distribution, sale, or use of existing stocks after the effective date of the cancellation order that the Agency intends to issue that is not consistent with the terms of that order will be considered a violation of section 2(a)(2)(K) and/or 12(a)(1)(A) of FIFRA.
Manufacture, sale, distribution and usage of Nemacur continues in the rest of the world.
|ClandoSan (Pending??)||Manufacturer: I-gene|
From the company's annual report:
ClandoSan(R) is the Company's registered trademark
biological control agent by stimulating the growth of
degrade chitin present in the cuticles and eggs of plant-pathogenic nematodes. ClandoSan(R) does not have a direct adverse
suppress nematode populations in soils.
|DiTera||Manufacturer: Abbott Labs.
Now by Valent Biosciences
|(fungal metabolite)||Introduced: 1996??|
Fumigant nematicides are generally chemicals with high volatility. They move most rapidly through the air speces between soil particles. Therefore, their movement may be restricted if soil pore spaces or pore necks are filled with water. Aklso, since nematodes are resident in soil water films, Henry's constant (kH), the propensity to partition between the soil water and soil air phases, may be important. Also, volatility will be affected by soil temperature: lower in cool soils, high in warm soils.
Two main groups of chemicals, halogenated hydrocarbons and liberators of methyl isothiocyanate or other volatile chemicals.
|Chlor-O-Pic||Manufacturer: Great Lakes, Arvesta, others|
|(96.5% - 99% chloropicrin) (CCl3NO2).||Introduced: 1908|
First tested as a preplant soil fumigant in 1920. Chloropicrin (molecular
weight 164.4) is a small, single-carbon molecule that diffuses rapidly
through soil. It is a clear, colorless, nonflammable liquid with a
moderate vapor pressure (18.3 mmHg at 68oF) and boiling point
(234oF). Chloropicrin is a strong lacrimator and therefore an
irritant if it escapes from the soil. Chloropicrin is injected as a
liquid 6-10 inches below the soil surface, 14 days or more before
Released to the atmosphere it photodegrades (half-life 20 days) to phosgene and nitrosyl chloride.
|Meth-O-Gas||Manufacturer: Great Lakes|
|(100% methyl bromide)||Introduced: 1932|
|Brom-O-Gas||Manufacturer: Great Lakes|
|(98.6% methyl bromide, 1.4% chloropicrin)||Introduced:|
Tarped strawberry fields, Santa Barbara County, 2002
|Terr-O-Gas||Manufacturer: Great Lakes|
|(33-100% methyl bromide, 67-0% chloropicrin)||Introduced:|
Phase-out of Methyl Bromide
The Montreal Protocol required a 25% decrease in use of methyl bromide between 1991 and 1999. That goal was met by 1998 in California but there was a slight increase in 1999. In 2001, usage is required to drop to 50% of 1991 levels. The price of methyl bromide more than doubled between 1997 and 2000.
By 2003, methyl bromide production/import must drop to 30% of the 1991 baseline. The pesticide is to be completely phased out by 2005.
The phase-out of methyl bromide is based on purported damage to the earth's ozone layer by bromine and chlorine interacting with elevated temperature.
About 93% of methyl bromide use in California is for preplant soil fumigation:
Critical Use Exemptions (CUEs) may be granted where the case is made that there are no viable alternatives and significant economic damage may result from lack of availability of methyl bromide.
|Methyl Iodide (Iodomethane), Midas||Manufacturer: Arysta Life Science Corp, Tokyo|
|Withdrawn from US market March 2012|
|Telone II||Manufacturer: Dow|
Cabbage plants grown in plot fumigated with Telone (right), unfumigated (left).
Other Formulations of Telone:
|Telone EC||Emulsifiable concentrate form of Telone II for drip irrigation application through surface or buried drip tape. Area must be tarped for 14 days after application (see news release below and product label).|
|InLine||Drip irrigation formulation of Telone C35. Application is through surface or buried drip tape. Area must be tarped for 14 days after application (see news release below and product label).|
|Curfew||Liquid formulation for application in turf. Becomes a fumigant in contact with Nitrogen.|
Telone Usage in California, 1999:
|Commodity||Percent Usage||lbs., 1999||acres, 1999|
|perennial trees and vines||30%||896,196||3,148|
|annual fruits and vegetables||66%||1,985,398||21,999|
News Release from Jim Mueller (DowAgrosciences), May 2001
Township Restrictions on Use of Telone in California
Curfew Soil Fumigant
Active ingredient: 1,3- Dichloropropene
Registered for applications in established turf in: Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas on golf course putting greens, fairways and tees, and also on athletic fields.
Must be custom applied by authorized operators.
Soil should be moist and have a nitrogen application prior to treatment.
Curfew is shank-injected as a liquid and converts to a gas which moves rapidly through soil. Kills nematodes and soil insects on contact.
According to the manufacture, turf recovers after application as follows:
Some dead leaves and runners from mechanical damage at injection slits seen 1 to 2 days after treatment.
Limited chemical burn in immediate area of injection slits seen 2 to 7 days after treatment:
Injection slits remain visible but begin to disappear 7 to 14 days after treatment.
Injury associated with application no longer visible; darker-green turf in area of injection slits 14 to 21 days after treatment.
Above-and below-ground improvement in turf growth and development; darker-green turf associated with injection slits may coalesce, resulting in more uniform appearance 21 days and beyond after treatment.
Left: Treated with Curfew; Right: Untreated. (Photograph from Dow AgroSciences)
Turf roots after application of Curfew (left); Nemacur (center) and untreated control (right).
(Photograph from Dow AgroSciences)
Effects of Telone (1,3-D) and Other Soil Fumigants on Soil Fertility
Under some soil conditions, especially in cold, wet soils, 1,3-D can delay nitrification of ammoniacal and urea nitrogen, by temporarily suppressing the activity of Nitrosomonas and Nitrobacter. These bacteria convert ammonium N to nitrite and nitrate. The effect can be an advantage, because the positively charged ammonia nitrogen is less prone to leaching than the negatively charged nitrite and nitrate ions. However, if too much ammonium nitrogen accumulates in the root zone, it can injure roots. Consequently, most 1,3-D labels have wording similar to:
"Fertility Interactions: Fumigation may temporarily raise the level of ammonia nitrogen and soluble salts in the soil. This is most likely to occur when heavy rates of fertilizer and fumigant are applied to soils that are either cold, wet, acid, or high in organic matter. To avoid injury to certain crops including red beets, carrots, corn, radishes, cole crops, legumes (beans), lettuce, onions, and sugar beets, fertilize as indicated by soil tests made after fumigation. To avoid ammonia injury or nitrate starvation (or both) to crops grown on high organic soils, fertilizers containing ammonium salts are not recommended."
|Vapam / Soilprep/Metam-Sodium||Manufacturer: Stauffer|
|(sodium methyl dithiocarbamate)||Introduced: 1954|
|Metam-Sodium Usage in California, 1999:|
|Commodity||Percent Usage||lbs., 1999||acres, 1999|
|perennial trees and vines||0.5%||65,367||354|
|annual fruits and vegetables||92.5%||15,794,398||160,987|
|(40% 1,3 dichloropropene, 20% methyl isothiocyanate)||Introduced: 1959|
|Enzone (GY-81)||Manufacturer: Arysta Life Sciences North America|
|sodium tetrathiocarbonate (carbon disulfide liberator)||Introduced: 1978|
Materials that can be applied to the aboveground parts of plants and that are systemically translocated throughout the plant, or to specific parts of the plant (leaves, roots, etc.).
|Manufacturer: Bayer CropScience|
|(lipid biosynthesis inhibitor based on the Tetramic acids)||2008|
|spirotetramat: cis-3-(2,5-dimethlyphenyl)-8-methoxy-2-oxo-1-azaspiro[4.5]dec-3-en-4-yl-ethyl carbonate|
|Manufacturer: Poulenger USA, Inc. Lakeland, Florida|
|(sesame seed oil containing aldehyde, ketones and linolenic acids)||?2002|
For light to moderate nematode
infestations, 2.5 to 3 gpa
Furfural - Crop Guard; Multiguard Protect (in USA)
|2-furfuraldehyde, a derivative of pentose sugars||?2001|
|Registered in US for nematode control on golf courses and turf farms.|
|Category||Signal||Mammalian Toxicity||Oral LD50 (mg/kg)||Dermal LD50 (mg/kg)||Inhalation LC50 (mg/L)|
1. For all nematicides, consider properties relative to movement in soil:
2. Nematicides in soil are in dynamic equilibrium among the three soil phases: 1) solids (adsorbed to clay and OM), 2) soil solution, and 3) soil air.
|Nemagon, DBCP||Manufacturers: Shell, Dow, Occidental Petroleum|
Billboard along California Hwy 99, 1970s
Until 1977, DBCP was used as a soil fumigant and nematicide on over 40 different crops in the United States.
A high incidence of male sterility was reported among workers at the Occidental Petroleum plant in Lathrop, CA, where DBCP was manufactured, in early 1977. Additional, and presumably confirmatory, studies were conducted at DBCP-manufacturing plants of Dow and/or Shell in Texas. From 1977 to 1979, EPA suspended registration for all DBCP-containing products except for use on pineapples in Hawaii. In 1985, EPA issued an intent to cancel all registrations for DBCP, including use on pineapples. Subsequently, the use of existing stocks of DBCP was prohibited.
Acute (short-term) exposure to DBCP in humans results in moderate depression of the central nervous system (CNS) and pulmonary congestion from inhalation, and gastrointestinal distress and pulmonary edema from oral exposure. Chronic (long-term) exposure to DBCP in humans causes male reproductive effects, such as decreased sperm counts. Available human data on DBCP and cancer are inadequate. High incidences of tumors of the nasal tract, tongue, adrenal cortex, and lungs of rodents were reported in a National Toxicology Program (NTP) inhalation study. EPA has classified DBCP as a Group B2, probable human carcinogen.
Source: USEPA Air Toxics Website
|(Ethylene dibromide), 1,2-dibromoethane||Introduced: 1945|
|(D-D Mixture), 1,3-dichloropropene, 1,2-dichloropropane||Introduced: 1943|
California Department of Pesticide Regulation
Davis, R.F., A.W. Johnson and R.D. Wauchope. 1993. Accelerated degradation of fenamiphos and its metabolites in soil previously treated with fenamiphos. Journal of Nematology 25:479-485.
Johnson, A.W. 1998. Degradation of fenamiphos in agricultural production soil. Journal of Nematology 30:40-44.
McKenry and Thomason
Rodriguez-Kabana, R. Nematicidal and herbicidal properties of furfural-based biofumigants. Department of Entomology and Plant Pathology, Auburn University,
Thomason, I. J. 1987. Challenges facing Nematology: environmental risks with nematicides and the need for new approaches. In J.A. Veech and D.W. Dickson (eds) Vistas on Nematology.
Trout, Tom. 2001. Fumigant use in California. USDA-ARS, Fresno, California.