NON-TECHNICAL SUMMARY: Current small grain production systems rely heavily upon herbicides for weed control. Effective control of weeds in small grains requires a systematic approach in which a combination of all the tools available for control are used. Field research is on-going to determine the influence of reduced herbicide rates for wild oat control in spring wheat and barley. The results of this research to date have enabled small grain producers to reduce their wild oat rates an average of 15%, resulting in a savings of $2.7 million in herbicide costs annually.

OBJECTIVES: There are five objectives for this project. The objectives are to evaluate the efficacy, crop injury and carryover potential of new herbicides for weed control in small grains; develop and validate a wild oat predictive model using wild oat growth and development and evaluating the effectiveness of reduced herbicide input for wild oat management in hard red spring wheat and barley; continue to develop, adapt and validate a predictive model for green and yellow foxtail management in hard red spring wheat; evaluate the impact on herbicide resistance hard red spring wheat on weed management systems and to determine the implications of spatially variable weed emergence and growth in weed management decision making.

APPROACH: Current small grain production systems rely heavily upon herbicides for weed control. In a grower survey conducted by the Minnesota Department of Agriculture in 1990, 89% of spring wheat and 85% of barley fields received at least one herbicide application per year, at a cost of $10 to $30 per acre. Research will be conducted to determine herbicide efficacy and the potential for crop injury and carryover to rotational crops to help them determine if they should adopt the use of these new herbicides. Concurrently, growers are looking for effective ways of reducing their herbicide inputs Effective control of wild oat requires a systematic approach in which a combination of all the tools available for control are used. Extensive research has been conducted on the economical importance, geographic distribution, seedling dormancy and germination, population dynamics (competition) and wild oat response to herbicides. However, limited research has be conducted on the biological aspect of wild oat growth and development. Research will be conducted to determine the differences in growth and development characteristics and environmental affects on wild oat growth and development are key pieces of information need for optimum and consistent control. Understanding the spatial and temporal dynamics of weed emergence, growth, and development across variable landscapes is critical in the design and implementation of site-specific management strategies that optimize integration, timing, and placement of various control strategies. Our preliminary research (Schneider et al 2001) has shown dramatic differences in annual weed emergence and growth rates between geographic locations within a field landscape. This information can be used to help farmers and other agricultural professionals site-specifically target knowledge-based integrated management strategies that are based on an understanding of weed emergence, growth, and development as a function of landscape position. This information can be used to help farmers and other agricultural professionals site-specifically target knowledge-based integrated management strategies that are based on an understanding of weed emergence, growth, and development as a function of landscape position. Moreover, it is critical that we understand the processes or drivers that give rise to differences in crop and weed growth across variable landscapes.

KEYWORDS: spring wheat; barley; wild oats; setaria glauca; setaria viridis; spatial distribution; weeds; plant population; herbicide resistance; herbicide resistant plants; weed control; small grains; crop production; production systems; crop damage; efficacy; carryover; herbicides; validation; predictive models; herbicide effectiveness; seedling emergence; decision making; herbicide application; application rate

PROGRESS: 2006/01 TO 2006/12
Small grain production systems rely heavily upon herbicides for weed control, however growers continue to search for methods to reduce herbicide inputs. Field experiments were conducted to evaluate the efficacy of reduced herbicide rates, crop rotations, cultural methods and tillage on weed control in small grains. Data from these trials were made available to the public in the MN Extension Service Publication "Cultural and Chemical Weed Control in Field Crops". Wild oat remains the number one weed control problem in small grains in Minnesota. Timely and more accurate control of wild oat may be developed if there is a better understanding of wild oat emergence patterns. The objectives of this research were to evaluate the emergence pattern of wild oat, and determine if emergence can be predicted using soil growing degree days (GDD) and/or hydrothermal time (HTT). Research plots were established in the Red River Valley of Minnesota and North Dakota from 2002 to 2006. Wild oat emergence was significantly correlated with GDD and HTT but not calendar days. A Weibull function was fitted to cumulative wild oat emergence and GDD and HTT. The GDD and HTT models closely fit observed wild oat emergence patterns. The later model is the first to use HTT to predict wild oat emergence under field conditions. These models will aid in the future study of wild oat emergence and assist growers and agricultural professionals with planning timely and more accurate wild oat control.

IMPACT: 2006/01 TO 2006/12
Field research is on-going to determine the influence of reduced herbicide rates, growing degree days, and wild oat emergence for wild oat control in spring wheat and barley. This research will be used to develop a wild oat control predictive model for use by agricultural crop consultants. The results of this research to date have enabled small grain producers to reduce this wild oat herbicide rates an average of 10%. These models will aid in the future study of wild oat emergence and assist growers and agricultural professionals with planning timely and more accurate wild oat control.

PUBLICATIONS (not previously reported): 2006/01 TO 2006/12
1. Martinson, K.B., Durgan, B.R., Gunsolus, J.L., and Sothern, R.B. 2006. Time of day of application effect on glyphosate and glufosinate efficacy. Online. Crop Management doi:10.1094/CM-2005-0718-02-RS.
2. Martinson, K.B., Durgan B.R., Wiersma, J., and Forcella, F. 2006. Modeling weed emergence. 2006 NCWSS Research Report: 61:30.

PROJECT CONTACT:
Name: Durgan, B. R.
Phone: 612-625-7262
Fax: 612-6250-1260
Email: bdurgan@umn.edu