OBJECTIVES: 1. To better address the risk/benefit analysis of integrated weed managment systems. 2. To discover educational methodologies that will help facilitate the implementation of integrated weed management by Minnesota farmers. 3. To investigate how specific weed biology/managment processes interact with corn and soybean production practices.

APPROACH: 1. Assess the economic stability of herbicide-based weed management systems over several locations, years, and weed spectrums using standard herbicide testing procedures and mean-variance or stochastic dominance analysis techniques. 2. Convene, facilitate, and participate in the development of learning groups which consist of 10 to 15 people from relevant sectors of the farming community who meet over a long-term basis (1-2 years) to focus on a complex system such as integrated weed management. 3. Define and research specific interaction of weed biology and management processes as they influence corn and soybean management processes. Currently evaluating the impact of time of weed emergence on growth at fecundity of several Amaranthus spp., the time of day of herbicide applications influence or efficacy, and the impact of postemergence soybean herbicides on the population dynamics of soybean aphid Aphis glycines.

KEYWORDS: corn; herbicides; amaranthus; soybeans; integrated pest management; integrated control (weeds); economics; weed control; timing; herbicide application; application methods; aphis glycines; crop production; production systems; risk benefit analysis; farmers; plant biology; information dissemination; seedling emergence; insect population; population dynamics; fecundity; plant growth; crop pest models; education programs

PROGRESS: 2006/01 TO 2006/12
The variability inherent in agriculture influences many crop production decisions, including weed management. Farmers perceive variability, or risk, associated with integrated weed management in terms of yield, economic returns, and time and labor management. Biological time constraints such as periodicity of weed emergence, rate of crop and weed growth and development, and critical periods of weed control can influence the outcome and acceptance of integrated weed management systems. A key component to developing successful integrated weed management systems lies in the ability of the crop producer to align individual time and labor management issues with existing biological time constraints. Results were published that assessed a range of different herbicide management practices, in two distinct cropping areas of Minnesota (Waseca and Lamberton), from an economic and agronomic risk management perspective. Economic analysis techniques of: mean-variance and stochastic dominance were used. Results indicate that different herbicide management practices can result in different outcomes for the farmer, depending upon risk attitudes. To illustrate, under a given set of weed species, a risk-averse farmer would choose a lower-cost weed control program that involved just one trip through a field; however, this might not be the best option considering potential changes in weed emergence patterns, application timing concerns, and environmental limitations to field working days.

IMPACT: 2006/01 TO 2006/12
Expected impacts of this research are to assist corn and soybean producers in developing cost-effective integrated weed management programs that will be implemented by producers. Implementation of integrated weed management programs will reduce their exposure to the short-term economic risks that result from poor timing of weed control practices and the longer-term risks that result from weed species shifts such as the development of herbicide resistant weeds.

PUBLICATIONS (not previously reported): 2006/01 TO 2006/12
1. Hoverstad, T.R., Johnson, G.A., Gunsolus, J.L. and King, R.P. 2006. Evaluating the economic risk of herbicide-based weed management systems in corn and soybean using stochastic dominance testing. Weed Technol. 20:422-429.
2. Scursoni, J., Forcella, F., Gunsolus, J., Owen, M., Oliver, R., Smeda, R. and Vidrine, R. 2006. Weed diversity and soybean yield with glyphosate management along a north-south transect in the United States. Weed Sci. 54:713-719.

PROJECT CONTACT:
Name: Gunsolus, J. L.
Phone: 612-625-8130
Fax: 612-624-3288
Email: gunso001@umn.edu