Chemical Methods of Nematode Management

Rev 10/10/07

Contents

 Non-fumigant Nematicides Toxicity Categories
General Considerations Fumigant Nematicides Nematicide Properties and Efficacy
Registrations Cancelled Return to Management Menu References
Exploratory / New Materials    


Important Considerations:

There are two main categories of chemical nematicides based on their volatility - non-fumigants and fumigants.

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Non-fumigant Nematicides

Two main groups of chemicals, carbamates and organophosphates, and some alternative materials.

1.  Carbamates:

Examples:          

Temik  Manufacturer:  Rhone-Poulenc
(aldicarb) Introduced: 1965
  • contact and systemic nematicide, insecticide, acaricide
  • granular formulation 
  • Category I pesticide
  • under EPA review - groundwater contamination

 

Furadan Manufacturer:  Mobay
(carbofuran) Introduced: 1969
  • contact and systemic nematicide, insecticide
  • granular and liquid formulations 
  • Category I pesticide
  • under EPA review - bird toxicity
  • EPA Administrative Review, August 2006.

 

Vydate Manufacturer:  Dupont
(oxamyl) Introduced: 1972

 

Standak Manufacturer:  Rhone-Poulenc
(aldoxycarb) Introduced: 1976


2. Organophosphates: 

 

Dasanit (Considered not profitable to re-register in California) Manufacturer:  Mobay
 (fensulfothion) Introduced: 1957

 

Mocap  Manufacturer:  Rhone-Poulenc
(ethoprop) Introduced: 1963

 

Nemacur Manufacturer:  Bayer
(phenamiphos, fenamiphos) Introduced: 1969. 
  • contact and systemic nematicide, insecticide
  • granular (10G and 15G) and liquid (Nemacur 3) formulations.  The Nemacur 3 formulation is used in tree and vine plantings in California. 
  • Category I pesticide
  • Active ingredient (35%): Ethyl 3-methyl-4-(methylthio)phenyl-(1-methylethyl)phosphoramidate
 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, 1998).

 
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:

  • all use and prohibited on vulnerable soils after May 31, 2005;
  • production capped at 500,000 pounds in the United States for the year ending May 31, 2003; and
  • production capped for each subsequent year at 20% of the previous year's production during the 5-year phase out period.

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.

 

 

3. Others:

ClandoSan  (Pending??) Manufacturer:  I-gene
(chitin+urea) Introduced: 1985??
  • enhances chitinolytic fungi
  • granular formulation 

 

DiTera  Manufacturer:  Abbott Labs.

Now by Valent Biosciences

 
(fungal metabolite) Introduced: 1996??
  • antibiotic
  • liquid formulation 
  • DiTera ES is a liquid formulation.
  • DiTera G and DiTera WDG are granular formulations.
  • Good mammalian and non-target toxicity characteristics.
  • DiTera WDG is listed by the Organic Materials Review Institute (OMRI) for use in organic production
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Fumigant Nematicides

Two main groups of chemicals,  halogenated hydrocarbons and methyl isothiocyanate liberators.

1.  Halogenated hydrocarbons:

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 crop planting.
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:

Commodity Percent Usage lbs., 1999 acres, 1999
strawberries 33% 5,650,000 26,937
annual fruits and vegetables 19% 2,307,548 13,657
grapes 12% 1,602,363 4,738
fruit and nut trees 19% 2,334,960 9,362
nursery crops 12% 1,582,686 5,243
cut flowers 4% 407,251 1,501

 

 

Methyl Iodide (Iodomethane), Midas Manufacturer: Arysta Life Science Corp, Tokyo
 


Telone II Manufacturer:  Dow
(1,3-dichloropropene) Introduced: 1956
  • soil fumigant
  • liquid formulation
  • phytotoxic 
  • Category I pesticide
  • application restrictions in California, limited amounts per region
  • Telone EC is the drip irrigation formulation of Telone II.

Cabbage plants grown in plot fumigated with Telone (right), unfumigated (left).

 

Telone C-17 Manufacturer:  Dow
(73% 1,3-dichloropropene, 17% chloropicrin) Introduced: 1956
  • soil fumigant
  • liquid formulation
  • phytotoxic 
  • Category I pesticide
  • Telone C17 (17% chloropicrin) is still available in some states, but not in CA.
  • When the grower is in a situation that calls for 1,3-D plus chloropicrin in a high value crop, it is generally better to use Telone C-35 which has more chloropicrin than could be delivered with Telone C-17.  However, chloropicrin is an expensive component. There are certain markets where the C-17 formulation is more affordable, for example, pink root control in onions in the Pacific Northwest.

Information from Jim Mueller (2001), Dow AgroSciences

 

Telone C-35 Manufacturer:  Dow
(65% 1,3-dichloropropene, 35% chloropicrin)  
  • soil fumigant
  • liquid formulation
  • phytotoxic 
  • Category I pesticide
  • Telone C-35 contains 35% chloropicrin. The chloropicrin provides a greater level of fungicide activity.
  • This is the product now available in CA.
  • When the grower is in a situation that calls for 1,3-D plus chloropicrin in a high value crop, it is generally better to use more chloropicrin than could be delivered with Telone C-17.  However, chloropicrin is an expensive component. There are certain markets where the C-17 formulation is more affordable, for example, pink root control in onions in the Pacific Northwest.
  • Chloropicrin content is limited to 35% due to product stewardship and reactive chemical concerns. Testing indicates that, at concentrations above about 45% chloropicrin, the mixture becomes shock-sensitive, and under extreme impact situations, could detonate. Custom applicators still have the option of increasing the chloropicrin/1,3-D ratio by using a dual injection system on the field applicator. The mixing then occurs in the soil. Some custom applicators now offer this option.
  • There are application restrictions in California, limited amounts may be applied per region.
  • InLine is the drip irrigation formulation of Telone C-35.

Information from Jim Mueller (2001), DowAgrosciences.

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).
 

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
field crops 2% 57,457 794
nursery/ornamentals 3% 83,095 305

News Release from Jim Mueller (DowAgrosciences), May 2001

Subject Telone EC and InLine registered
Date Fri, 11 May 2001 175840 -0400
 
US-EPA has approved the registrations of Telone EC and InLine Soil Fumigants
for drip irrigation application.
These are the drip application counterparts for the tractor-injected
formulations, Telone II and Telone C35.
 
The Federal labels are attached. Here are some significant details
1. Telone EC and InLine may be applied through surface or buried drip tape.
2. The current labels cover vegetable crops, field crops, strawberries and
pineapples. Other crops will be added, based on the outcome of efficacy
research. In the mean time, its relatively easy to get permits for testing
on other crops.
3. Under the current labels, a plastic tarp seal is mandatory for at least
14 days after all applications of these products. The tarp requirement may
change in the future. Virtually impermeable film (VIF) is not required on
the Federal label.
4. The Federal label specifies a 100 foot buffer zone between the treated
area and occupied structures.
5. CA-specific The labels are being reviewed by CDPR, and we expect
approval in CA soon. The current CA permit conditions require a 300 foot
buffer zone, and the use of VIF. Until the Federal label is approved by CA,
an experimental use permit will continue to allow extensive commercial use
of InLine in CA.
 
Its risky to list names, because some key researchers might be overlooked.
However, the earliest pioneers of this application concept, in the late 80's
and early 90's, were John Radewald, Becky Westerdahl, Mike McKenry, Brent
Sipes and John Darsow. Key contributions were made later by many, including Ole Becker, Tom Trout, Husein Ajwa, John Duniway, Steve Wilhelm, Christopher Winterbottom, Frank Sances and others.
To these scientists, and to all of the others who made this innovation a
reality thanks for the excellent research, and for persevering through the
times of regulatory uncertainty. You should feel a sense of accomplishment,
as you see the results of your work now being implemented by growers
throughout the U.S.

Jim Mueller
 

 

Township Restrictions on Use of Telone in California
On January 28, 2002 the California Department of Pesticide Regulation announced a restructuring of the use management plan for Telone Products.
The refinements will maintain existing protection of public health, while making these key products available to more growers, and will assist growers in their transition away from methyl bromide.
Permit conditions for the use of products containing 1,3-D currently allow the application of a maximum of 90,250 adjusted pounds of 1,3-D per township per year. Adjustments to the applied amount are based on the application method used and the 1,3-D content of the product. For example, when Telone II is applied at a depth of 18 inches and followed by a disk and roller, each gallon applied counts as 1 gallon (10 pounds) toward the township cap.
When InLine or Telone EC are applied through drip irrigation under standard plastic film, each pound of 1,3-D applied counts as 1.16 pounds towards the township cap.
For the next several years, use will be allowed above the cap in townships where use since 1995 has been significantly under the amount allowed by the cap. This increase is limited to 180,500 adjusted pounds of 1,3-D per township per year. Due to the limited use of 1,3-D since 1995, most townships will have access to 180,500 adjusted pounds of 1,3-D per year.
CDPR and Dow AgroSciences both recognize that this refinement is part of a short-term solution to the township cap issue. We will continue to work with CDPR on further refinements, such as regional or area-specific township caps.
I will continue to keep you informed of regulatory progress with Telone Products.
 
 
Jim Mueller



2. Methyl isothiocyanate liberators:

 

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
field crops 5% 883,120 18,980
nursery/ornamentals 2% 334,316 1,376


 

Vorlex Manufacturer:  Nor-Am
(40% 1,3 dichloropropene, 20%  methyl isothiocyanate) Introduced: 1959
  • soil fumigant
  • liquid formulation
  • tarp optional
  • phytotoxic 
  • Category II pesticide
  • not used in California

 

3. Others:

Enzone (GY-81) Manufacturer:  Union Oil?
 sodium tetrathiocarbonate (carbon disulfide liberator) Introduced: 1978
Developmental History:
  • CS2 used as a soil fumigant in 19th century, but explosive
  • 1978 GY-81 formulation developed by UnoCal
  • 1978 greenhouse tests
  • 1980 first field trials
  • 1984 experimental use permit with crop destruction
  • 1987 and 1989 EUP (Experimental Use Permit) without requirement for crop destruction for 4000 acres
  • 1988 groundwater studies completed 
  • 1990 $15 million development costs to date
  • 1995?? California registration


Characteristics (according to manufacturer):

  • no heavy elements
  • no residues
  • short-lived in soil
  • post-plant usage (not phytotoxic)
  • high mobility in soil, not influenced by soil texture
  • low groundwater contamination potential
  • low mammalian toxicity
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______________________________________________________________________________
Toxicity Categories of Pesticides and Signal Indicators:

Category Signal Mammalian Toxicity Oral LD50 (mg/kg) Dermal LD50 (mg/kg) Inhalation LC50 (mg/L)
I
Danger
Poison
Skull
 High 0-50 0-200 0-2000
II Warning Moderate 51-500 201-2,000 2,001-20,000
III Caution Low >500 >2,000 >20,000
______________________________________________
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Nematicide Properties and Efficacy:

1.  For all nematicides, consider properties relative to movement in soil:

  1. water solubility
  2. vapor pressure, volatility, fumigant action
  3. Henry's constant (kH) - affinity for water
  4. method of incorporation or 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.

 

Nematicides with Registrations Cancelled or No Longer Manufactured

 

Nemagon, DBCP Manufacturers:  Shell, Dow, Occidental Petroleum
(1,2-Dibromo-3-
chloropropane)		 Introduced: 1954
  • soil fumigant
  • liquid formulation
  • moved with water in soil
  • non-phytotoxic 
  •  
  • groundwater contamination
  • male sterility
  • registration cancelled 1977

Billboard along California Hwy 99, 1970s

 
  • The chemical formula for DBCP is C3H5Br2Cl, and the molecular weight is 236.36 g/mol.
  • DBCP occurs as a colorless liquid when pure, and commercial grades as a dark-amber to dark-brown liquid that is slightly soluble in water.
  • DBCP has a pungent odor with an odor threshold of 0.3 mg/m3.
  • The vapor pressure for DBCP is 0.8 mm Hg at 21 °C, and its log octanol/water partition coefficient (log Kow) is 2.43.
    •

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

 

EDB Manufacturer:  
(Ethylene dibromide), 1,2-dibromoethane Introduced: 1945
  • soil fumigant
  • liquid formulation
  • phytotoxic 
  • carcinogen
  • registration cancelled 1970s
  • Category I pesticide

 

D-D Manufacturer:  Shell
(D-D Mixture), 1,3-dichloropropene, 1,2-dichloropropane Introduced: 1943
  • soil fumigant
  • liquid formulation
  • phytotoxic 
  • reformulated as 1,3-dichloropropene (Telone) which reduced the volume of material tranported and applied
  • Category I pesticide

 

Exploratory / New Materials

 

Dragonfire-CPP

 Manufacturer:  Poulenger USA, Inc.  Lakeland, Florida
(sesame seed oil containing aldehyde, ketones and linolenic acids) ?2002
  • "For use on fine turf, golf courses, sports fields and lawns"
  • Suggested application rates:

For light to moderate nematode infestations, 2.5 to 3 gpa
For moderate to heavy nematode infestations, 3 to 5 gpa

 

 

Furfural

 Manufacturer: 
International Furan Technology,
Durban, South Africa
 

Illovo Sugar Ltd., Durban, South Africa
2-furfuraldehyde, a derivative of pentose sugars ?2001

  1. Properties of Furfural

    • Molecular Weight:

    96.082 g/mole

    • Boiling Point (760 mm Hg):

    161.7 oC

    • Freezing Point: 

    -36.5 oC

    • Specific Gravity d2525:

    1.1610

    • Refractive Index nD20:

    1.52608

    • Viscosity at 25oC:

    1.494 cP

    • Flash Point (closed cup):

    59 oC

    • Ignition Temperature:

    315 oC

    • Solubility in Water at 20 oC:

    8.3 g per 100 ml of water

    • Azeotrope with water at 1 ATM:

    65% by weight of water

    Boiling Point 97.85 oC

    • Toxicity: 

      • LD50 (oral) for a mouse:

      • LD50 (oral) for a rat:

      • LD50 (oral) for a guinea pig:

     

    400 mg/kg

    127 mg/kg

    541 mg/kg

    • Discovered by a German chemist, Döbereiner, 1820; first commercial production in 1922.

    • Registered as a nematicide in Spain and South Africa in 2001

    • An oily liquid that smells of almonds

    • Flammability is similar to diesel.

    • It is a strong solvent

    • It is an aldehyde and chemically reactive.

    • Internationally rated as GRAS (GRAS: Generally Regarded As Safe) when used as a flavor.

    • The very low volatility reduces the toxicity risk.

    • It is metabolized rapidly and excreted in the urine as furoylglycine.

    • Furfural is formed from pentosan, a five-carbon cellulose which occurs in corncobs, bagasse, wood chips and other organic material.  The organic source is heated to 100°C, the pentosan is hydrolysed to the soluble sugar pentose (xylose) and dissolves in the available water.

       

      Pentosan + n.Water             n.Pentose.

                                                                                                  

      Dehydration of pentose to furfural is by acid catalysis.

       

                                                        Acid

      Pentose  -  3 (Water)        + 3 Water

                                                      Heat         Furfural

       

    Reference:

    International Furan Technology website

     

     

 

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References:

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.

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