Project Leader and Principal UC
Investigators
D.E. Cosby,
Dept. of Toxicology, UC Davis
J.B.
Bowers
C.J.
Soderquist
William
Draper
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The Rice Research Board funded a UCD project on the environmental fate of
herbicides so as to ensure maximum safety to people and the environment
while controlling rice pests with chemicals. There are three objectives:
- To identify the environmental factors which govern the transport and
chemical transformations of rice pesticides.
- To examine the distribution and dissipation of a pesticide in a rice
field.
- To estimate the importance of environmental factors, to field application
and the significance of pesticide decomposition products.
Previous findings in the UCD Environmental Toxicology Laboratory facilitated
the EPA decision to retain MCPA for control of broadleaved weeds in
California rice fields. Each year one or more chemicals are singled out for
intensive research. Receiving major attention in 1975 was molinate (Ordram).
þ Ordram's environmental fate: about 90% of a post-flood application of Ordram
(molinate) goes into the water, while 10% goes into the top 2 inches of
soil. The soil residue remains unchanged for several months but the Ordram
in the water is half gone in 3 days and 98% gone in 13 days. A final
distribution shows 10% in the soil, where it is probably destroyed by
microorganisms, 1-2% in rice plants and weeds, 4-5% photoxidized by
sunlight, and 80-85% going into the atmosphere as vapor. Volatilization
increases sharply as water temperatures rise.
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A new chemical, bentazon, continues to show remarkable ability to control
broadleaved weeds and cattails. Area free of weeds received 1 lb active
ingredient bentazon after rice emergence. |
READY-REFERENCE LISTING OF CHEMICALS FOR RICE PEST CONTROL:
Table 2 lists the status of the principal chemicals which have been tested
for the control of rice yield-reducing pests. Many of these chemicals are
mentioned in this report. Note that some are not yet registered for use,
some are registered, and some have registrations pending. Consult your local
agricultural commissioner concerning the current status and for use permits
for those you need to use. Be sure you and your applicator follow the
manufacturer's labeled instructions.
Table 2. 1976 status
of chemicals useful in rice pest control* |
HERBICIDES |
Registered |
- Copper sulfate (several mfrs.): algae
- MCPA (several mfrs.): broadleaved weeds
- Ordram® (molinate) (Stauffer Chem. Co.): barnyardgrass
- Silvex (several mfrs.): broadleaved weeds; river bulrush
- 2,4,5-T (several mfrs.): broadleaved weeds
|
Registered for use south of
Sankey Road |
Propanil (several mfrs.): barnyardgrass; broadleaved weeds; sedges |
Registry applied for |
Basagran® (bentazon) (BASF): seedling cattails; sedges; river bulrush,
broadleaved weeds |
Exptl. label for 1000 acres in '76 |
Bolero® (benthiocarb) (Chevron Chem. Co.] barnyardgrass, sprangle. top;
seedling cattails |
Exptl. label received 1975 |
Hydrothol 191® (Pennwalt Corp, American pondweed and some other aquatics |
Not registered for in-crop growing-season use |
Roundup® (glyphosate) (Monsanto Chem.
Co.): rice levee weeds, including mature cattails |
Not registered |
- Destun® (perfluidone) (3M):
grasses and broadleaves; early postflood
- Drepamon® (Hercules Chem. Co.): barnyardgrass; sprangletop
- Simetryn® (CIBA-Giegy): algae; and in combination with other herbicides
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FUNGICIDES |
Registered |
- Captan SP®; Orthocide 50® (captan)
(several mfrs.): seed treatment for seedling diseases
- Difolatan 4F® (folcid) (Chevron Chem.
Co.): seed treatment for seedling diseases
|
Registry applied for |
Du-ter® (triphenyletin
hydroxide) (Thompson-Hayward Chem. Co.): stem rot |
INSECTICIDES |
Registered |
- Copper sulfate (several mfrs.): tadpole shrimp; algae
- Malathion (several mfrs.): rice leaf miner
- Parathion n (several mfrs.): tadpole shrimp; rice leaf
miner; mosquitoes
- Sevin® (carbaryl) (Union Carbide
Chem. Co.): tadpole shrimp; leafhoppers
|
Registered for preflood and
drained-field use |
Bux® (no generic name)
(Chevron Chem. Co.): water weevils |
Registered preflood only |
Furadan® (carbofuran)
(Food Machinery Corp.): water weevils |
Registered for mosquitoes
only |
Lorsban® (Dursban®
- chlorpyrifos) (Dow Chem. Co.): mosquitoes and midge larvae |
Not registered |
Mesurol® (Chemagro
Co.): midge larvae (not effective as seed treatment) |
*Potential uses include some for
which the compound may not currently be registered. See
introductory paragraph to this section. |
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