Stewardship/Management of Transgenic Products

1. Stewardship/Management of Transgenic Products Micheal D. K. Owen Iowa State UniversityAmes, IA 50011 USA mdowen@iastate.edu www.weeds.iastate.edu

2. Introduction • 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) • Traits for herbicide resistance in crops are “benign” and do not exert selection pressure – the herbicide exerts the selection pressure

3. Introduction • 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 glyphosate • Development of weed management strategies for specific output traits or specialty traits

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

5. Stewardship and Grower Attitudes • Considerable effort in providing information about the evolution of herbicide 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 • Only 38% recognized the role of repeat MOAs on selection pressure • Adoption of glyphosate-resistant crops continues to rise

6. 1998: Rigid ryegrass in CA 2000: Horseweed in DE, MD, NJ 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 2004: Italian ryegrass in OR 2005: Palmer pigweed suspected in NC 2005: Horseweed in CA 2005: Palmer pigweed in GA and TN 2005: Common waterhemp in MO The Glyphosate Decade 2006: Horseweed in NE Source: University & USDA reports

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

8. Even at low population (10 plants/m2) Asiatic dayflower reduces soybean yield (Mishra et al 2002)

10. Specialty grains/high value 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 • Particular attention is given to the relative tolerance of the crops to the herbicides • Past efforts had included considerable experimentation with popcorn varieties

11. 2006 efforts • Experiments with 8 low lin soybean varieties • Experiments with 3 white corn varieties, 1 high oil and 1 waxy variety • Experiments on 7 sensitive and very sensitive inbreds

12. 2006 efforts • Registered and experimental herbicides were included in the experiments • Application timing, herbicide combinations and rates were included • Results available at www.weeds.iastate.edu

13. Questions?