This chapter addresses the complexity of managing cover crops in selected growing regions of the world. It focuses on the contributions that cover crops can make to weed management and the trade-offs that may be required between achieving weed management, crop production, and environmental benefits. Since cover crops can play a significant role in mitigating environmental impacts worldwide, interactions between weed management and management to enhance environmental protection are emphasized.
This chapter describes the three main techniques of mechanical weed management, i.e. (1) the use of tillage, (2) cutting weeds, and (3) pulling weeds. The economics of mechanical weed management is discussed.
Herbicidal activities of clove oil and its primary constituent eugenol on broccoli, common lambsquarters, and redroot pigweed and the role of crystalline leaf epicuticular wax (LEW) in susceptibility and retention of these essential oils were studied. Clove oil (2.5%) and eugenol (1.5%) were applied to leaves of greenhouse-grown broccoli, common lambsquarters, and redroot pigweed seedlings and effects on seedling growth and leaf cell membrane integrity were studied. Compared with eugenol, clove oil caused greater inhibition of seedling growth in all species. Both eugenol and clove oil caused greater loss of membrane integrity and inhibition of seedling growth in redroot pigweed, which has no crystalline LEW, compared with common lambsquarters, which has a thick layer of crystalline LEW. In broccoli seedlings with LEW, clove oil caused greater inhibition of growth than eugenol. Both clove oil and eugenol caused greater electrolyte leakage from broccoli leaves without LEW than in the leaves with LEW. Removal of LEW increased electrolyte leakage, an indicator of cell membrane damage, by 97% in eugenol-treated and 26% in clove oil–treated broccoli leaves. Susceptibility of broccoli seedlings and possibly some weed species may, therefore, be affected by factors (e.g., genetic, environmental) that influence the amount of LEW. Although the presence of LEW greatly reduced the retention of the essential oil solutions, there was no significant difference between the retention of clove oil and eugenol solutions, indicating that differences in their phytotoxicity to broccoli leaves was not due to differential foliar retention.
This chapter describes various options that use energy to cause thermal injury to plants for weed control. These include the use of fire, flaming, infrared radiation, hot water, steam, electrical energy, microwave radiation, ultraviolet radiation, lasers and freezing temperatures. Some of these options, e.g. flame weeding, are commercially viable, but some are impractical at present, and others need further research and development before they can be used under field conditions. Thermal weed control methods have shown environmental benefits in terms of impacts on soil and water, but negative impacts on air quality and energy usage, compared with mechanical and chemical methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.