Herbicide-resistant weed

Chemical, cultural, and mechanical weed control practices have been relatively successful ia reducing yield losses from weeds (448). However, herbicide-resistant weed populations, soil erosion, pesticide persistence ia the environment, and other problems associated with technologies used (ca 1993) to control weeds have raised concerns for the long-term efficacy and sustainability of herbicide-dependent crop production practices (449). These concerns, coupled with ever-increasing demands for food and fiber, contribute to the need for innovative weed management strategies (450). 

The development of herbicide-resistant weeds has also been an influence on the selection of herbicides used on field corn or soybean. Weed resistance now affects nearly every decision a farmer makes about herbicide selection either a farmer is trying to control resistant weeds or is selecting herbicides that may reduce the possibility of weed populations becoming resistant. The adoption of the imidazolinone- and sulfonylurea-tolerant com hybrids mentioned above was in part a response to the presence of atrazine-tolerant pigweeds or kochia in many fields. However, a recent decrease in die use of imidazolinone and sulfonylurea herbicides can also be attributed to the development of populations of weeds that have become resistant to these herbicides. 

Pfister, K. and C.J. Amtzen (1979). The mode of action of photosystem II-specific inhibitors in herbicide-resistant weed biotypes. Z. Naturforsch. Sect. C Biosci., 34 996-1009. 

Heap, I.M. (2006). International Survey of Herbicide Resistant Weeds. Available at www.weedscience.org/... 

Holt, J.S. and H.M. LeBaron (1990). Significance and distribution of herbicide resistance. Weed Technol., 4 141-149. 

LeBaron, H.M. (1991). Distribution and seriousness of herbicide-resistant weed infestations worldwide, pp. 27 4-3. In Caseley, J.C., G.W. Cussans, and R.K. Atkin, eds., Herbicide Resistance in Weeds and Crops. Oxford, UK Butterworth-Heinemann. 

A major limitation of global surveys and confirmations of herbicide-resistant weeds has been the variability in the methods used in identifying resistance. Unless the cases of resistance have been confirmed by laboratory or greenhouse studies and include information on the degree of resistance, the reports of resistance should not be recognized as being confirmed. Van Oorschot (1991) Truelove and Hensley (1982) and others have conducted and reported on extensive research on the best methods for confirming triazine-resistant weeds. 

As had been predicted by many weed scientists who understood the biological cause and nature of herbicide-resistant weeds, resistance to the ALS inhibitors and other newer herbicides developed more rapidly than resistance to the triazine herbicides. 

Excellent progress has been made in the understanding of the cause, nature, genetics, mechanism and solutions of herbicide-resistant weeds since the first triazine-resistant common groundsel was reported more than 35 years ago. Resistance management programs have been extremely successful in controlling most weeds that have developed resistance to the triazine herbicides. However, research is critical to better understand the rapid increase and spread of many new weed biotypes resistant to several classes of herbicides. 

Bandeen, J.D., G.R. Stephenson, and E.R. Cowett (1982). Discovery and distribution of herbicide-resistant weeds in North America. In H.M. LeBaron and J. Gressel, eds., Herbicide Resistance in Plants. NY, NY John Wiley Sons, pp. 9-30. 

Gasquez, J. (1988). Herbicide resistance in France. In Herbicide-Resistant Weeds and Alternative Control Methods. Commission of the European Communities. Proceedings of a Meeting of the EC Experts Group. Tollose, Denmark. 

Heap, I.M. (1997). The occurrence of herbicide-resistant weeds worldwide. Pestic. Sci., 51 235-243. 

Moss, S.R. and B. Rubin (1993). Herbicide-resistant weeds A worldwide perspective. J. Agric. Sci., 120 141-148. 

Putwain, P.D. and A.M. Mortimer (1995). Evolution and spread of herbicide resistant weeds The role of selection pressure. In Proceedings of the International Symposium on Weed and Crop Resistance to Herbicides. Cordoba, Spain, April 3-6, 1995, p. 114. 

Rubin, B. (1996). Herbicide-resistant weeds The inevitable phenomenon Mechanisms, distribution and significance. Z. Pfl. Krankh, Pfl. Schutz, Sonderh., XV 17-32. 

Global Status and Importance of Herbicide Resistance Distribution of Herbicide-Resistant Weeds... 

Weeds are rapidly becoming resistant to some of the newer herbicides, and it is important to realize the consequences. For example, in Missouri, Bader et al. (1995) conducted a study on corn-soybean rotations in which they used only ALS-inhibitor herbicides, that is, imazethapyr in soybean and primisulfuron-methyl in corn. Within 4 years, a common waterhemp biotype resistant to 5-fold higher rates of ALS inhibitors was flourishing. Greenhouse tests confirmed that ALS-resistant common waterhemp biotypes were present in several plots in the experiment. Within the same state, Bader et al. (1994) reported one case of atrazine-resistant common waterhemp, which developed where a farmer grew continuous com and used only atrazine for more than 10 years. Table 11.1 shows trends in the numbers of herbicide-resistant weeds. 

Table 11.3 The number of herbicide-resistant weed biotypes in each of 52 countries in 2006...

Bader, B.M., M.S. DeFelice, J.S. Dilbeck, and C.S. Holman (1994). Herbicide resistant weed populations discovered in Missouri. Proc. North Cent. Weed Sci. Soc., 49 89-90. 

Heap, I.M. (1999). International survey of herbicide-resistant weeds. Annual report. WSSA, E-mail IanHeap WeedSmart.com website http //www.weedscience.com... 

Kotoula-Syka, E., C. Afentouli, and I. Georgoulas (2004). Herbicide-resistant weeds in cereal crops in Greece. 4th International Weed Science Congress, p. 50, S15MT08P00. 

Powles, S.B. and P.D. Howat (1990). Herbicide-resistant weeds in Australia. Weed Technol., 4 178-185. 

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