However, increased supplies should act to moderate price increases thus,

in turn reducing harvesting and shipping rates. Clearly this type of

simultaneity calls for a model which can take account of supply-demand

conditions and determine equilibrium prices. The preliminary models

developed treat short-run imports, domestic supply and demand endogen-

ously so that market operation may be portrayed realistically.

 The second phase of the analysis then will examine the longer run

supply response of Florida producers and attempt to elicit their re-

actions to expected prices, costs, returns and perceived risk (Just,

Lin, Hammig). Data for Mexican long-run vegetable supply response is

exceptionally weak (Brooker and Pearson, Simmons et al.) with some

indication that planting decisions are made autonomously by the powerful

Mexican growers' association, Union Nacional de Productores Hortalizas

(UNPH) (Meyers). Thus, some aspects of Mexican production will probably

be treated exogenously. A further problem is that climatic factors

cause yields and costs to vary across years so that without time series

data on these variables for Mexican producers certain simplifying assump-

tions will be necessary. In any event, the models created in this phase

will be capable of simulating production levels and projected returns to

parametric changes in domestic demands, tariffs, costs of production,

and import volumes.

Trends in Vegetable Production, Imports and Prices

 Imports comprise a substantial part of non-summer vegetable market-

 ings and there is mounting concern that their share of the winter vegetable

 market will continue to expand (Simmons et al., Meyers). Mexico's rapid

 development of their share of U.S. vegetable market was ostensibly