Pendimethalin - Registration of a Major Change in Labeling for Prowl 3.3 EC 8/95
August 8, 1995
Ms. Michaeleen E. Linahan
State Registration Manager
U.S. Plant State Regulatory Affairs
American Cyanamid Company
P.O. Box 400
Princeton, NJ 08543-0400
Dear Ms. Linahan:
Re: Registration of a Major Change in Labelling for Prowl 3.3 EC
Herbicide (EPA Reg. No. 241-337)
The New York State Department of Environmental Conservation has accepted
your application to register the pesticide product Prowl 3.3 EC
Herbicide (EPA Reg. No. 241-337) in New York State for use on garlic,
dry bulb shallots, and direct-seeded and transplanted onions. Prowl 3.3
EC contains the active ingredient pendimethalin, which is currently
registered in New York State for use on corn, sorghum, soybeans,
potatoes, sunflowers, beans, forage legumes, nonbearing fruit and nut
crops, and vineyards.
The major change in label is the addition of use on garlic, dry bulb
shallots, and direct-seeded and transplanted onions. The labelled
application rate (range from 1.96 60 3.96 lbs Active Ingredient/Acre per
application up to a seasonal maximum of 11.88 lbs AI/A) on onions in
muck soil exceeds the application rates for other labelled food crops.
The data package was submitted for review to the Department's Division
of Water (DOW), the Division of Fish and Wildlife (DF&W), and the New
York State Department of Health (NYSDOH).
The DOW has concluded that labelled use of Prowl 3.3 EC Herbicide should
not have a significant impact on groundwater in New York State.
Although labelled usage rates are high for a preemergence herbicide,
pendimethalin is very strongly absorbed to both mineral and organic soil
constituents and is unlikely to exhibit significant mobility in soils.
The long-term field study demonstrated that residues did not accumulate
in the top nine inches of soil.
The Bureau of Environmental Protection (DF&W) stated in their review
that they have no objection to registration of the major change in
label. A Section 18 Emergency Exemption was granted for use of
pendimethalin on muck soil dry bulb onions for the 1989 through 1993
growing seasons with no adverse effects observed on the onion crop or
The primary fate of pendimethalin is photolysis with a half-life on land
30 days and 21 days in water. Pendimethalin is biodegraded both
aerobically and anaerobically, by both microorganisms and soil fungi.
While biodegradation is slow, Pendimethalin is not likely to be acutely
or chronicly toxic to birds or mammals as the highest predicted
pendime[halin residue is 248 ppm in food (which is half the lowest
chronic toxicity no-observed-effect-level or NOEL of 500ppm for
Pendimethalin is very toxic to fish and aquatic invertebrates; however,
due to its high partitioning coefficients, pendimethalin will not likely
be mobile in soil. The projected contamination from runoff is very low.
If used as labelled, pendimethalin should not pose a hazard to fish and
The NYSDOH stated in their review that adherence to labelled application
rates and preharvest intervals should not result in detectable residues
on the new target crops or exposure from their consumption. The
physiochemical properties of pendimethalin indicate that it is not
likely to leach from treated areas to pose a risk of groundwater
contamination. There are no chemical specific federal or state drinking
water standards for pendimethalin. Based on its chemical structure,
pendimethalin falls under the five micrograms per liter New York
drinking water standard for a "principal organic contaminant" (10 NYCRR
Part 5-Public Water Systems).
The use of Prowl 3.3 EC on garlic, shallots, and onions is not likely to
significantly increase exposure or risks to the general public from
pendimethalin and NYSDOH does not object to the addition of these crops
to the Prowl 3.3 EC label in New York State.
Enclosed, for your files, is a stamped-accepted label for the referenced
If you have any questions on this matter, please contact Maureen
Serafini, Supervisor of our Pesticide Product Registration Section, at
Norman H. Nosenchuck, P.E.
Division of Hazardous Substances Regulation