Figure 3 outlines common results obtained for the relative lobby strength of stakeholders
from table 2 and 3. In the case of seed producers, base state’s lobby strength relative to the
comparator state leads to regulatory congruence. The net negative effect of consumer lobby on
regulatory congruence suggests that its market-consumption effect is more than offset by gains
from protection to the local eco-system. For commodity producers, the net negative effect of
lobbying on regulatory congruence implies that the price-enhancement effect of regulation is
dominated by agronomic-protection gains.
Summary and Conclusions
In this study, we identify large differences in two sets of noxious weed regulations, the Noxious
Weed Seed (NXWS) and the Noxious Weed (NXW) list, among US states. We then investigate
the determinants of such regulations, which can impact interstate trade in plant and plant
products, including interest-groups’ activities. An inter-disciplinary approach, with ecological
and political considerations, is taken to model the supply and demand for noxious weed
regulation. We consider three stakeholders for each state: consumers, seed producers and
nursery growers, and commodity producers. Given the social welfare function, a weighted sum
of net benefits to each interest group, the regulatory choice is derived from a strategic game
between a base state and any other comparator state. The resulting regulatory congruence or
similarity between any two states provides the basis for our empirical analysis.
Regulatory congruence in NXWS and NXW lists across contiguous US states is
estimated using data on ecosystem and agronomic characteristics, and on the rent-seeking
activities. Results from our empirical analysis suggest that ecological dissimilarities, embodied
in temperature and precipitation patterns, give raise to variations and hence, limited regulatory
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