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California
Environmental
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Agency

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Department of
Pesticide
Regulation

1020 N Street
Sacramento, CA
95814-5624
(916) 445-4300


Branches:

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Registration

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and Safety

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  California Notice 98-2
  POST UNTIL May 1, 1998

NOTICE OF FINAL DECISION CONCERNING REEVALUATION OF PESTICIDE PRODUCTS


The Director of the Department of Pesticide Regulation (DPR), pursuant to Articles 8 and 12 (Title 3) of the California Code of Regulations, files this notice concerning the reevaluation of pesticide products with the Secretary of the Resources Agency for posting. This notice must remain posted for a period of 30 days for public inspection.

REEVALUATION

DPR commenced reevaluation of pesticide products containing chlorthal-dimethyl October 11, 1985. The following currently registered pesticide products contain chlorthal-dimethyl as an active ingredient.

REGISTRANT
BRAND NAME
U.S. EPA REG. NO.

Chevron Chemical Company Ortho Garden Weed Preventer 239-2456-AA
Dexol Industries Dexol Pre-Emergent Weed & Grass Preventer 2 192-206-AA
E.B. Stone & Son, Inc. Prevent Dacthal G-5 Herbicide 50534-3-AA-11204
  Greenall Pre-Emergent Weed Control Plus Lawn Food 802-576-AA-11204
  Master Nursery Master Pro Pre-Emergent Weed Control and Lawn Food 802-576-ZA-11204
ISK Biotech Corporation Dacthal W-75 50534-1-AA
  Dacthal G-5 Herbicide 50534-3-AA
  Dacthal W-75 Turf 50534-20-AA
  90% Dimethyl-T 50534-113-AA
J.R. Simplot Company DCPA 5 Granules 7001-275-AA
Lawn and Garden Products, Inc. Vegetable, Turf & Ornamental Weeder 50534-1-AA-54705

BASIS OF REEVALUATION

DPR placed products containing chlorthal-dimethyl into reevaluation based upon finding residues of the pesticide on crops to which the pesticide had not been applied. DPR found chlorthal-dimethyl residues on crops planted in fields after a legal application of the pesticide was made to the previous crop and on crops adjacent to areas where a legal application of the pesticide was made.

SUMMARY OF REEVALUATION

In the spring of 1987, the Environmental Monitoring and Pest Management Branch of DPR conducted a mass balance study using chlorthal-dimethyl. The study results indicated that drift during application, volatilization after application, and the aerial movement of contaminated soil particles were all sources of chlorthal-dimethyl contamination on nontarget crops.

As a part of the reevaluation, DPR required the basic manufacturer to conduct a field study to identify measures to control the off-site movement of the pesticide. The registrant submitted the results of an off-site movement study in January 1993. The study indicated that the greatest reduction in off-site movement of residues occurred when the product was applied in a band and incorporated into the soil prior to irrigation. In response to the study results, the registrant proposed amendments to the labels of their products, Dacthal W-75 and Dacthal W-75 Turf. DPR determined that the labels of other registered products containing chlorthal-dimethyl did not need to be amended because the products are intended for reformulation or home lawn and garden use.

The registrant amended the label of Dacthal W-75 to provide users with a warning regarding chlorthal-dimethyl's propensity for off-site movement. The warning states that research indicates that banding applications of the preemergent herbicide significantly reduces the potential for off-site movement. In addition, the product label has been amended to require pesticide applications to be banded and incorporated for beans, certain greens, cotton, transplanted cole crops, and new strawberry plantings. The pesticide label requires that chlorthal-dimethyl applications to all other crops on the label be banded. To mitigate off-site movement of residues during turf application, the labels of both Dacthal W-75 and Dacthal W-75 Turf, have been amended to require the pesticide to be watered in within four hours of application with 0.1 to 0.2 inches of water.

FINAL REGULATORY DECISION

The labels of chlorthal-dimethyl products of concern have been amended to mitigate the off-site movement of residues. Therefore, DPR concludes the reevaluation of pesticide products containing chlorthal-dimethyl.

For information regarding this final decision, contact
Ms. Ann Prichard, Senior Environmental Research Scientist,
Pesticide Registration Branch, by E-mail at (aprichard@cdpr.ca.gov)
or by telephone at (916) 324-3931.

original signed by Barry Cortez


March 24, 1998


Barry Cortez, Chief
Pesticide Registration Branch
(916) 445-4377

Date

California State Seal

Pete Wilson
Governor

Peter Rooney

Secretary for
Environmental
Protection



James
W. Wells
Director