sightly and unsanitary features. The benefits of such enhanced product quality have several forms. Cleaner products can receive a higher price. For example, apple-growers are docked for impurities, and excessively blemished fruits might be salable only for low-value processing uses, such as juice. Processors set limits on impurities, such as insect parts or weeds in fruits and vegetables. They can impose price penalties on violative shipments or reject such shipments altogether. Federal food-purity regulations set limits on impurities in fresh produce; produce found to exceed the limits might not be salable. Federal and state grading standards for fresh fruits and vegetables prescribe lower grades—and thus lower prices—for produce that has more blemishes.
Some have argued that many forms of product quality are purely cosmetic and without a basis in health, nutritional value, or consumer demand (van den Bosch et al. 1975, Pimentel et al. 1991). Federal food-purity standards and grading standards have been especially criticized for that basis. It has been argued that those standards are stricter than necessary and that the stringency of these standards induces farmers to use pesticides more intensively than they otherwise would. Studies of purchases of peaches (Parker and Zilberman 1993), wheat (Ulrich et al. 1987), and other commodities show that consumers are willing to pay more for agricultural products that have fewer blemishes and impurities. Some consumer surveys also indicate unwillingness to purchase produce that has cosmetic defects or insect damage (see, for example, Ott 1990). Studies of pesticide productivity, such as those discussed previously, ignore quality considerations and thus understate benefits of pesticide use. In some cases, aesthetic quality is the primary consideration for pest control, however. Examples include such high-value ornamental crops as flowers, Christmas trees, and woody ornamentals.
Postharvest uses of pesticides include treatment with fungicides or growth regulators to prolong storage life and fumigation to prevent insect contamination. Prolongation of storage life of fresh fruits and vegetables increases consumer and producer welfare by increasing the availability of fresh produce between harvest seasons (Lichtenberg and Zilberman 1997). Prolongation of storage life of grains essentially lowers the cost of producing grain. As noted, insect parts in grain are considered impurities, and buyers might impose dockage or reject shipments; fumigation of grain thus enhances grain quality. Fumigation of fresh fruits and vegetables plays an important role in facilitating trade; many countries require fumigation to prevent inadvertent importation of exotic pest species (Yarkin et al. 1994). Fumigation has been required in interstate commerce in the