                            In the
 United States Court of Appeals
              For the Seventh Circuit
                        ____________

No. 05-3033
CROPLIFE AMERICA, INC., et al.,
                                            Plaintiffs-Appellants,
                               v.

CITY OF MADISON, et al.,
                                           Defendants-Appellees.
                        ____________
           Appeal from the United States District Court
               for the Western District of Wisconsin.
          No. 04-C-0949-C—Barbara B. Crabb, Chief Judge.
                        ____________
   ARGUED DECEMBER 2, 2005—DECIDED DECEMBER 23, 2005
                        ____________


  Before BAUER, POSNER, and MANION, Circuit Judges.
  POSNER, Circuit Judge. This appeal arises from a suit by
producers and suppliers of “weed and feed” products
against the City of Madison and the county (Dane) in which
Madison is located. Weed and feed products are lawn-care
products each granule of which contains both a herbicide
and a substance, such as phosphorus, that fertilizes. Though
not without its critics, this ingenious combination—“sold by
the chemical industry to homeowners as the magic bullet of
turf care,” Douglas Green, The Everything Lawn Care Book:
From Seed to Soil, Mowing to Fertilizing—Hundreds of Tips for
Growing a Beautiful Lawn 81 (2001)—both “saves time and
2                                                 No. 05-3033

labor” and provides “greater safety since there is less chance
of an incorrect dosage [of pesticide] being applied.” Jack E.
Ingels, Landscaping Principles and Practices 415 (6th ed. 2004);
Ingels, Ornamental Horticulture: Science, Operations, and
Management 93 (3d ed. 2001). However, Madison and Dane
County have enacted ordinances forbidding (with irrelevant
exceptions) the sale or use of fertilizers that include more
than trace amounts of phosphorus, Madison General
Ordinances §§ 7.48(3), (6); Dane County Ordinances §§
80.05, 80.07—as the plaintiffs’ weed and feed products do.
Though an excellent fertilizer, phosphorus is also a pollut-
ant that “contribute[s] to excessive growth of algae and
other undesirable aquatic vegetation in water bodies.” John
Randolph, Environmental Land Use Planning and Management
393 (2003); see also Henry F. Decker & Jane M. Decker, Lawn
Care: A Handbook for Professionals 33-34 (1988). Dane County
contains 102 lakes, of which nine have a surface area
exceeding 2000 acres and one a surface area exceed-
ing 10,000 acres. Wisconsin Department of Natural Re-
sources, “Wisconsin Lakes Directory—Dane County,”
http://www.dnr.state.wi.us/org/water/fhp/lakes/
county/Dane.htm (visited Dec. 12, 2005).
  To comply with the ordinances, the plaintiffs have had
to reconstitute their weed and feed products to eliminate the
phosphorus. Invoking a variety of federal and state legal
theories, their suit seeks a declaration that the ordinances
are invalid. The defendants moved for summary judgment,
which was granted. The only claim pressed in this appeal is
that the ordinances are preempted by a Wisconsin state
statute that, with irrelevant exceptions, forbids a city or
county to “prohibit the use of or otherwise regulate pesti-
cides.” Wis. Stat. § 94.701(3)(a). Ordinarily the district court
would relinquish jurisdiction over supplemental state-law
claims when as in this case all federal claims (diversity of
No. 05-3033                                                 3

citizenship is not alleged) were dismissed before trial. 28
U.S.C. § 1367(c)(3). But relinquishment in such circum-
stances is not mandatory, id., unless the federal claims are
frivolous (frivolous claims do not engage the jurisdiction of
the federal courts, Crowley Cutlery Co. v. United States, 849
F.2d 273, 276-78 (7th Cir. 1988), and cases cited there); and
the plaintiff’s federal claims, based on the commerce clause
and federal pesticide regulation, while weak, were not
frivolous. And both sides want us to decide the state-law
claim rather than protract the litigation.
  The statutory definition of pesticides embraces herbicides,
see Wis. Stat. § 94.67(25), and a regulation defines pesticide
to include “a pesticide-fertilizer mixture.” Wis. Admin.
Code ATCP (Agriculture, Trade, and Consumer Protection)
§ 29.01(28). Therefore, the plaintiffs argue, their weed and
feed products are pesticides, which Madison and Dane
County may not regulate by specifying that the products are
not to contain phosphorus, even though phosphorus is a
fertilizer rather than a pesticide and there is no state
preemption of local regulation of fertilizers.
   Yet the plaintiffs themselves quote the provision of the
Wisconsin statute that defines “fertilizer” to include “mixed
fertilizers,” in turn defined as any combination of “a
fertilizer material and any other substance,” Wis. Stat.
§ 94.64(1)(e), (l). And a regulation, parallel to the one that
defines “pesticide” to include “a pesticide-fertilizer mix-
ture,” defines “combination products containing fertil-
izer” to include “a fertilizer-pesticide combination,” Wis.
Admin. Code ATCP §§ 40.02(3), (8), (11)—and, lest there be
any doubt, adds that “ ’weed and feed’ products are
fertilizer-pesticide combinations.” Wis. Admin. Code ATCP
§ 40.02(11) Note. So it seems that a weed and feed product
is both a pesticide, which only the state can regulate, and a
4                                                  No. 05-3033

fertilizer, which local government can regulate. (For further
confirmation that weed and feed products are both pesti-
cides and fertilizers, see Wis. Admin. Code ATCP §
40.02(29).) How can this be?
  The answer is that the dual definition is necessary to
avoid creating a regulatory loophole. If “pesticide” were not
defined to include a mixed pesticide-fertilizer product, then
a manufacturer of a pesticide might be able to get out from
under regulation by mixing his pesticide with a fertilizer.
And if “fertilizer” were not defined to include a mixed
pesticide-fertilizer product, then a manufacturer of fertilizer
might be able to get out from under regulation by mix-
ing his fertilizer with a pesticide. The definition of both
“pesticide” and “fertilizer” as including a mixture of the
two preserves both state regulation of pesticides and
local regulation of fertilizers. The state regulates the pesti-
cide components of the mixed products, local government
the fertilizer components.
  Suppose a weed and feed product sold in Wisconsin
contained atrazine, a herbicide, as well as phosphorus, a
fertilizer. And suppose the state wanted to ban atrazine and
Madison wanted to ban phosphorus. The definition
of “pesticide” as including a pesticide mixed with a fertil-
izer would empower the state to ban atrazine in the prod-
uct, and the definition of “fertilizer” as including a fertilizer
mixed with a pesticide would empower Madison to ban
phosphorus in the product because there is no state preemp-
tion of local fertilizer regulation. If “pesticide” were defined
to exclude mixtures, the state would be helpless to deal with
atrazine in a weed and feed product, while if “fertilizer”
were defined to exclude mixtures, the city could not deal
with the phosphorus in the product because (assuming
“pesticide” was defined to include mixtures) the product
No. 05-3033                                                    5

would just be a pesticide, and not also a fertilizer, and so the
city and county would be preempted.
  The plaintiffs complain that unless local regulation is
preempted, they cannot sell a weed and feed product in
Dane County without reconstituting the product to replace
phosphorus with some other fertilizer. They have presented
no evidence, however, that such reconstitution is infeasible,
or even that it is costly. Indeed, they are selling the reconsti-
tuted product in Dane County. No doubt they prefer
phosphorus to whatever they have substituted for it in the
reconstituted product, or else they would have made the
substitution voluntarily. But if phosphorus is indeed a
pollutant with serious consequences for lakes (which the
plaintiffs have made no effort to confute, although they
have made some effort to downplay the polluting effect of
their products, as by contending that “the waste from one
adult goose contributes 13.76 ounces of phosphorus runoff
per year or 68 times more than a typical lawn,” though one
might suppose that this would depend on where the goose
spent his year), the plaintiffs will not be heard to complain.
   The defendants point out, without contradiction, that
it makes practical sense to allow local regulation of phos-
phorus because the effects differ from county to county
depending on the number and importance of a county’s
lakes and other bodies of water, not to mention the num-
ber of geese and other contributors to phosphorus pollution.
So our interpretation of the statute, which is the natural
interpretation as a semantic matter and has the further
virtue of closing a regulatory loophole, cannot be rejected on
the ground that it produces absurd or unreasonable results,
which the Wisconsin legislature is unlikely to have in-
tended. Compare Public Citizen v. U.S. Dept. of Justice, 491
U.S. 440, 453-55 (1989); Green v. Bock Laundry Machine Co.,
6                                                  No. 05-3033

490 U.S. 504, 527 (1989) (Scalia, J., concurring). Quite the
contrary, it produces sensible results. See Krzalic v. Republic
Title Co., 314 F.3d 875, 879-80 (7th Cir. 2002); United States v.
Hilario, 218 F.3d 19, 23 (1st Cir. 2000).
                                                     AFFIRMED.

A true Copy:
        Teste:

                            _____________________________
                             Clerk of the United States Court of
                               Appeals for the Seventh Circuit




                     USCA-02-C-0072—12-23-05
