2.3. Use Rates
The label use rates per application of Clipper Herbicide are:
· Surface treatment at a rate of 6 to 12 ounces of formulated product per acre (0.375 to 0.75
lbs a.i./acre). The product should be applied in sufficient water volume to achieve
adequate coverage of target vegetation.
· Subsurface application rates that produce 100 to 400 ppb of active ingredient in the water
column. The product label provides information on the amount of product required per
surface acre and water depth to achieve a desired water concentration. Application rates
in waters greater than 7 ft deep should not exceed 14.8 lbs of product per surface acre.
The label specifies a minimum retreatment interval is 28 days for a given section of a
water body. In water bodies with a higher pH, efficacy of the herbicide is maximized by
applications done early in the morning because lower pH values tend to occur at that time
of the day.
2.4. Target Species
Clipper Herbicide is capable of controlling various submerged, floating, and emerged weed
species. Floating and emerged weeds listed on the label include alligator weed, frog’s bit, water
fern, water lettuce, water pennywort, and filamentous algae species. Submerged/floating weeds
listed on the label include coontail, duckweed, fanwort, hydrilla, naiad, pondweed (curley,
Illinois, sago, variable-leaf), water fern, water meal, and water milfoil (Eurasian, variable-leaf).
A complete list of weeds controlled can be found on the product label (Valent Corp., 2012).
2. Human Health Effects of Other Ingredients
Both active and inert ingredients undergo scientific evaluation before approval by the USEPA.
The agency must have sufficient data to make a safety determination regarding human health and
the environment. For those inert ingredients applied to food, a tolerance or tolerance exemption
is required. All food-use inert ingredients are also permitted for nonfood uses such as for
ornamental plants, rights-of-way, aquatic use, structural use, etc.
MDAR/MassDEP 4 June 2013
Based on the information available on the US EPA website for pesticide inert ingredients1, the
inert ingredients in Clipper Herbicide are approved for both nonfood and food uses.
The chemical-by-chemical approach in risk assessment does not address mixture toxicity and
thereby adds uncertainty. EPA’s approach with toxicity assessment of mixtures is based on
grouping of chemicals that exhibit their effects through a common mechanism. However, this is
only applied to the cumulative risk assessments of active ingredients.
Adjuvants are generally broadly defined as any substance separately added to a pesticide product
(typically as part of a spray tank mixture) that will improve the performance of the pesticide
product. Since pesticide adjuvant products don’t make pesticidal claims, they are not required to
be registered. Where a product label directs the user to add a particular adjuvant before use, EPA
will treat that adjuvant as an “other ingredient” in making the registration decision, and will
assure that any necessary tolerances or exemptions from the requirement of a tolerance are
established. However, it should be noted that residues of pesticide adjuvants in or on food
commodities are subject to the requirements of the Federal Food, Drug and Cosmetic Act, which
means that a food additive regulation or exemption from the requirement of a tolerance is needed
for any substance used as a pesticide adjuvant that is applied to food crops. Adjuvant products
used by aquatic vegetation management professionals in MA are recommended for aquatic use
2.3. Use Rates