Stewardship/Management of Transgenic Products Micheal D. K. Owen Iowa State University Ames, IA USA

Introduction Stewardship reflects management decisions that will enhance and preserve a particular crop trait and are economically rewarding Stewardship reflects management decisions that will enhance and preserve a particular crop trait and are economically rewarding Some traits impart selection pressure upon the pest complex for which they are designed (i.e. BT) Some traits impart selection pressure upon the pest complex for which they are designed (i.e. BT) Traits for herbicide resistance in crops are “benign” and do not exert selection pressure – the herbicide exerts the selection pressure Traits for herbicide resistance in crops are “benign” and do not exert selection pressure – the herbicide exerts the selection pressure

Introduction The “stewardship” efforts initiated by the Weed Science group and supported by the Iowa Grain Quality Initiative represent two areas: The “stewardship” efforts initiated by the Weed Science group and supported by the Iowa Grain Quality Initiative represent two areas: Evaluation and monitoring of weeds with variable responses to glyphosateEvaluation and monitoring of weeds with variable responses to glyphosate Development of weed management strategies for specific output traits or specialty traitsDevelopment of weed management strategies for specific output traits or specialty traits

Glyphosate stewardship Clean fields do not necessarily equate to good weed management Clean fields do not necessarily equate to good weed management The objective of weed management is to protect crop yield potentialThe objective of weed management is to protect crop yield potential Diversified weed management tactics provide significant benefits to glyphosate-based systems Diversified weed management tactics provide significant benefits to glyphosate-based systems Residual herbicides applied EPP or PRE are important components of a weed management programResidual herbicides applied EPP or PRE are important components of a weed management program Mechanical weed control tactics should be includedMechanical weed control tactics should be included Timely application of tactics is critical for all weed management programs Timely application of tactics is critical for all weed management programs

Stewardship and Grower Attitudes Considerable effort in providing information about the evolution of herbicide resistance Considerable effort in providing information about the evolution of herbicide resistance These efforts have been marginally effective (e.g. ALS resistance) These efforts have been marginally effective (e.g. ALS resistance) 66% of Indiana growers expressed only a low to moderate concern about glyphosate resistance 66% of Indiana growers expressed only a low to moderate concern about glyphosate resistance Only 38% recognized the role of repeat MOAs on selection pressure Only 38% recognized the role of repeat MOAs on selection pressure Adoption of glyphosate-resistant crops continues to rise Adoption of glyphosate-resistant crops continues to rise

The Glyphosate Decade Source: University & USDA reports 2000: Horseweed in DE, MD, NJ 1998: Rigid ryegrass in CA 2001:Horseweed in TN, KY 2002: Horseweed in IN, OH 2002:“Variably tolerant” waterhemp in IA, IL, MO 2003: Horseweed in AR, MS, NC 2004: Common ragweed in MO 2005: Horseweed in CA 2004: Italian ryegrass in OR 2005: Palmer pigweed suspected in NC 2005: Palmer pigweed in GA and TN 2005: Common waterhemp in MO 2006: Horseweed in NE

Weeds to watch in Iowa Common lambsquarters Common lambsquarters Giant ragweed Giant ragweed Common waterhemp Common waterhemp Asiatic dayflower Asiatic dayflower Marestail Marestail Others? Others?

Even at low population (10 plants/m 2 ) Asiatic dayflower reduces soybean yield (Mishra et al 2002)

Specialty grains/high value crops Several field experiments have been conducted on inbreds, cultivars, and output trait crops Several field experiments have been conducted on inbreds, cultivars, and output trait crops Experiments focus on evaluating the potential for existing and new herbicides to manage weeds in these crops Experiments focus on evaluating the potential for existing and new herbicides to manage weeds in these crops Particular attention is given to the relative tolerance of the crops to the herbicides Particular attention is given to the relative tolerance of the crops to the herbicides Past efforts had included considerable experimentation with popcorn varieties Past efforts had included considerable experimentation with popcorn varieties

2006 efforts Experiments with 8 low lin soybean varieties Experiments with 8 low lin soybean varieties Experiments with 3 white corn varieties, 1 high oil and 1 waxy variety Experiments with 3 white corn varieties, 1 high oil and 1 waxy variety Experiments on 7 sensitive and very sensitive inbreds Experiments on 7 sensitive and very sensitive inbreds

2006 efforts Registered and experimental herbicides were included in the experiments Registered and experimental herbicides were included in the experiments Application timing, herbicide combinations and rates were included Application timing, herbicide combinations and rates were included Results available at Results available at

Questions?