Natural Products for Weed Management in Organic Farming in the USA
Abstract:Weed management was revolutionized in the mid-20th century with the introduction of synthetic herbicides, making weed control less expensive and reducing crop losses due to weed competition. This revolution played a major role in providing and maintaining high crop yields. In the waning years of the 20th century, the introduction of crops containing transgenes conferring resistance to non-selective synthetic herbicides (glyphosate and glufosinate) further reduced the cost of weed management, while simplifying agronomic practices in the few major crops in which this technology is used. The public sentiment toward the use of synthetic herbicides and genetically modified crops has become negative in the developed world. Concomitantly, a series of new regulations, including the 1996 FQPA, have led to the review of the registration of all pesticides used in the USA. This re-evaluation process has eliminated many pesticides, and it is one of the factors that has reduced the number of new products commercialized by the major agrochemical manufacturers. This has had a particularly negative impact on the minor crops producers. In contrast, the popularity of and demand for organic foods has grown throughout the developed world, which has resulted in the conversion of millions of hectares from conventional to organic agriculture. In the US, the surface area dedicated to organic food production more than doubled from 1997 to 2005, yet this increase has not been rapid enough to prevent periodic shortages of some organic products. The increased production of organic foods has been accompanied by a USDA publication 'Report and Recommendations on Organic Farming' in 1980, the enactment of the Federal Organic Foods Production Act in 1990, and the creation of the National Organic Program and release of the USDA Certified Organic label in 2002. Neither synthetic herbicides nor transgenic crops are accepted by organizations that approve products for use in organic farming in the US. This leaves very few commercial options, with organic farmers relying on combinations of mulches, tillage, hand labor, biocontrol, rotation, and cover crops for weed management. These labor intensive methods result in significantly greater cost of weed management, which is one of the major reasons for the greater cost of organic foods. Few studies with commercial products approved for such use in the US are published in peer reviewed journals. The relatively greater number of studies provided on web sites, abstracts or proceedings are not mentioned as the validity of this work cannot be evaluated. Few studies directly compare the efficacy of organic products with synthetic herbicides. These comparisons are admittedly difficult to do because if tests are performed on non-organic land the weed and microbial community may be different than on certified organic land. Nonetheless, such studies have indicated that these products are not very effective and must be used at much higher doses than their synthetic counterparts. Furthermore, few of these studies directly compare the efficacy of these products with synthetic herbicides. This survey points out that the few products available to organic farmers in the US are woefully inadequate compared to the weed management tools available to conventional farmers. Organic farmers have relatively good products for management of insects and plant pathogens, making the development of new and more efficacious weed management tools one of their most critical needs. Additionally, the appeal of 'greener' technologies has begun to impact conventional agriculture. All major agrochemical companies are looking for and developing new environmentally friendlier weed management tools. Therefore, any advances made in the area of organic agriculture may have implications in the larger agricultural community.
Document Type: Research Article
Publication date: 2010-08-01
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