Weed management is one of the most critical and costly aspects for container nursery production. High irrigation and fertilization rates create a favorable environment for weed growth in addition to crop growth. Weeds can quickly out-compete the crop for light and other resources, reducing the rate and amount of crop growth as well as salability (Berchielli-Robertson et al., 1990; Norcini and Stamps, 1992). Weed management in nursery production is most effectively achieved by preventative practices, primarily with the use of pre-emergent herbicides (Gilliam et al., 1990; Gallitano and Skroch, 1993).
However, there are valid reasons for managing weeds using alternatives to synthetic herbicides (Sidebar 1). Ornamental crops encompass a wide array of species, and herbicide products must be tested on each for effective, safe and legal use. Even when a product is labeled for a crop, it may not be sufficiently effective for the weeds present or may induce crop damage under certain circumstances. Finally, use of synthetic herbicides in greenhouses and other enclosed structures is often prohibited on product labels.
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