GM Glyphosate-tolerant Maize in Europe Can Help Alleviate the Global Food Shortage
In Europe, one of the main factors limiting the yield potential of maize is weeds. Maize is very susceptible to competition from weeds in the early stages of growth. The crop does not grow fast enough to compete with the local flora, and is particularly sensitive to competition for resources such as water, nutrients and light up until the 8-leaf stage (first 6–8 weeks), after which it can grow higher than the weeds, if they are controlled early. Best economic return from their control is achieved by spraying herbicides before or at the 4-leaf stage of maize. There is a wide range of important weeds that infest maize fields. These weed species are present throughout Europe, and the combination of dicots and monocots, both annual and perennial in habit, presents a significant challenge to any weed control programme in this crop, especially as current control methods rely almost exclusively on herbicides. Little, if any, cultural or mechanical control is practised, and that only on organic farms, or the poorer parts of Europe. The choice of herbicides, applied alone or in tank mixes, is driven by the need to cope with the wide spectrum of weeds present. The broad-spectrum persistent residual herbicide, atrazine, was one of the most commonly used herbicides for pre- and post-emergence control until 2003, when it was banned across the EU due to its perceived unfavourable environmental profile, especially in relation to its leaching to groundwater. This was a political decision, which was not universally accepted by all countries concerned. Following the atrazine ban farmers were forced to use an alternative assortment of pre- and post-emergence herbicides, none of which is as effective and the cost of weed control has increased as a result. However, the number of active ingredients available is likely to decrease further following yet another review of the safety of both new and older pesticides within the EU. Currently, of 981 existing and 136 new active ingredients (all types of pesticides for all crops) being considered under the revision of article 8 of Directive 91/414/EEC, only 14.7% are approved, 54.5% are not approved (including atrazine), and 30.8% are awaiting a decision. This makes it even more imperative that alternative strategies are developed as soon as possible. One solution to the reduction in number of herbicide Als is to develop new, more-environmentally-friendly ones. However, effective herbicides that are safe to the target crop, and which meet the increasingly stringent regulatory guidelines, are difficult and expensive to find. As a result, there are far fewer companies actively searching for and developing new herbicides. Another alternative is already available and being used in many other countries of the world – genetically modified herbicide-tolerant (GMHT) hybrids used with their respective herbicides. There are several very effective options, which could be important components of weed control programmes. The lack of cultivation approvals for these technologies is restricted among others, by the European Parliament, and is a policy certainly not based on scientific scrutiny, but on political expedience. This article reviews the strengths of GMHT crops and the advantages that they bestow on the grower and society and also emphasises the safety of this approach to cost-effective weed control in European maize.
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Document Type: Research Article
Publication date: 01 April 2010
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