High tunnels have been used for many years worldwide, but in the United States, the utilization of high tunnel technology for the production of horticultural crops is a relatively recent phenomenon. Single and multibay high tunnels are used throughout the world to extend the production season. One big advantage of high tunnels in the temperate and tropical regions of the world is the exclusion of rain, thus reducing the amount of disease pressure and crop loss while improving crop quality and shelf life. In temperate regions of the world, high tunnels are used to increase temperatures for crop production in spring, fall, and sometimes winter seasons. The use of high tunnels in their many forms continues to increase worldwide, and many different kinds of vegetables, small fruit, tree fruit, and flowers are being cultivated. One impediment in determining high tunnel usage worldwide is the failure of many authors and agricultural census takers to distinguish between high tunnels and plastic-covered greenhou ses. In many instances, they are presented together under the heading ''protected cultivation.
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