1020 N Street
||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.
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.
U.S. EPA REG. NO.
|Chevron Chemical Company
||Ortho Garden Weed Preventer 239-2456-AA
||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 (firstname.lastname@example.org)
or by telephone at (916) 324-3931.
original signed by Barry Cortez
March 24, 1998
|Barry Cortez, Chief
Pesticide Registration Branch
James W. Wells