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WC 94


The success of weed management programs, more specifically herbicide programs, varied considerably during 2012 reflecting the importance of environmental conditions on herbicide performance. Variability of success was seen not only in the postemergence herbicide applications that continue to dominate herbicide use but also in the soil-applied residual herbicides; all herbicide applications were strongly influenced by tillage system, crop planting date, timing and amount of rainfall, and resulting weed emergence timing. While more soil-applied herbicides were used in Iowa during 2012, there are still too many acres of corn and soybean that are treated only with glyphosate. Importantly, the trend of no new herbicide sites of action continues and while new herbicides will be available in 2013, they have old sites of action, many of which have existing resistant weed populations. The new products and changes in herbicides will be described in this paper. The implications of the 2012 drought on herbicide degradation and the potential for herbicide carryover will be addressed. Furthermore, an update on the development of new herbicide resistant crops and the anticipated implications of these technologies when deregulated and available commercially will be discussed.

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Iowa State University Extension and Outreach


Ames, IA


Agronomy, Weed Science


Agricultural Science | Agriculture | Agronomy and Crop Sciences | Weed Science


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2013 Herbicide Guide for Iowa Corn and Soybean Production