Most vegetable crops are characterised by a low plant density, a wide row distance, a slow initial growth and, as a consequence, by a poor competitive ability. Taking into consideration that most vegetables are high-income crops, the threshold weed densities are very low and the critical periods of weed competition are pretty long. Moreover, most vegetables are minor crops, thus the availability of approved herbicides for use is scarce; as a consequence a repeated use of herbicides with similar mode of action may lead to a strong and quick selection of weed flora. Chemical weed control in vegetables shows peculiar environmental and health concerns due to the relatively short growth cycle, to the fresh edible parts of vegetables, and to a coarse soil texture found in the main production areas. An Integrated Management Weed System (IWMS) in vegetables should be based on: 1) weed population management strategies by sound cultural weed control methods (e.g. adequate crop rotations, accurate soil tillage and stale seedbed preparation, competitive cultivars and crop spatial distribution, transplanting instead of sowing, ecc.), that is any aspect of management that favours the crop relative to the weeds, reduces the weed seedbank, regulates weed communities and prevents the build-up of adapted species; 2) an integration of non-chemical (i.e. physical, mechanical and biological) and chemical weed control by adopting methods with a low selection pressure on weed communities, weed economic thresholds (density thresholds and critical period of weed competition), post-emergence control, optimal herbicide doses and herbicide behaviour in the environment. The improving and widespreading of modelling, decision support systems and Site-Specific Weed Management (SSWM) are crucial for developing an IWMS that was environmentally and economically viable. Most important and peculiar aspects of weed flora, weed competition, cultural, physical, mechanical and chemical weed control in IWMS for vegetable crops are reviewed and discussed.
Keywords: IWMS, non-chemical control, chemical control, precision agriculture