Overview

My professional career as a weed scientist began as a Research Associate on the brush control project in the Department of Range Science at the Texas A&M University Research and Extension Center at Lubbock, Texas in 1969. I joined the Integrated Field Crop and Soil extension team at Cornell as an Extension Associate in 1974 and was subsequently promoted to Sr. Extension Associate and Associate Professor. As an extension specialist, my mission has been to evaluate weed management strategies for agronomic crops in New York State, to incorporate these research results into management guidelines, and to conduct educational programs on the implementation of these guidelines. Stakeholders include extension field staff, crop advisors, ag business dealers, pesticide applicators, and field crop producers. Research is focused on chemical and cultural weed management practices including herbicide evaluation for control of problem weeds such as triazine-resistant annualweeds, control/management of perennial broadleaf weeds such as hedge bindweed and dandelion,use of perennial forage grasses to suppress weeds in alfalfa, evaluation of buckwheat as a nurse crop during establishment of perennial forages and as a cover crop for weed suppression between crops, and development of weed control programs for conventional and genetically modified corn and soybeans. Objectives are to continue researching strategies to support weed management guidelines and extension education programs on herbicide resistance management, to enhance the weed management sections of the field crop guide website, and to enhance the training module for the Certified Crop Advisor exam preparation course.

Research Focus

Research focus is on weed management strategies for field crops. Troublesome annual broadleaf weeds such as common ragweed and triazine-resistant biotypes of common lambsquarters receive special attention along with perennial weeds like hedge bindweed and dandelion. Renewed interest in integrated weed management has led to expanded efforts with total postemergence weed control programs with conventional and herbicide-resistant crop cultivars.

Outreach and Extension Focus

Extension efforts emphasize the development and delivery of educational programs on weed management in field crops. A key element in these programs is the annual update of the weed management sections of the Cornell Guide for Integrated Field Crop Management based on results of field research conducted at Musgrave Research Farm, Valatie Research Farm, Caldwell Field, and in grower fields. Target audiences include extension field staff, dealers, applicators, Northeast Region Certified Crop Advisers (NRCCA), and field crop producers in New York and New England. I serve on the College's IPM Operating Committee as Chair of the Livestock/Field Crops IPM Committee. In addition, as part of the responsibilities of being Department Extension Leader, I served as editor of the What's Cropping Up? Newsletter thru 6/30/07.

Additional Links

• Cornell Guide for Integrated Field Crop Management
• Crop and Soil Sciences Extension
• Link to CALS Research portal
• Link to CALS Impact statements

Selected Publications

• Hahn, R.R. and Shields, E.J. 2006. Glyphosate-resistant horseweed - should we be concerned? What`s Cropping Up? 16(3):6-7.
• Hahn, R.R. and Stachowski, P.J. 2006. Role of residual herbicides in Roundup Ready corn programs. What`s Cropping Up? 16(6):6-7.
• Hahn, R.R. and Stachowski, P.J. 2006. Knapweeds controlled in pastures and hayfields with new herbicide. What`s Cropping Up? 16(5):1-3.
• Hahn, R.R. and Stachowski, P.J. 2006. KIH-485 for large crabgrass and giant foxtail control in corn. Proc. Northeastern Weed Sci. Soc. 60:82.
• Hahn, R.R. and Stachowski, P.J. 2006. Role of residual herbicides in Roundup Ready corn programs. In Field Crop Dealer Meetings. Dept. of Crop and Soil Sciences Extension Series No. E06-4:11-14.
• Hahn, R.R. and Stachowski, P. J. 2007. Distinct and Status bring new features to dicamba herbicide. What's Cropping Up? 17(4):9-11.
• Hahn, R.R. and Stachowski, P.J. 2007. Size of common lambsquarters is critical for control with glyphosate. What's Cropping Up? 17(3):10-11.
• Hahn, R.R. and Stachowski, P.J. 2007. Impact herbicide registered for corn in NY State. What's Cropping Up? 17(2):5.
• Hahn, R.R. and Stachowski, P.J. 2007. Hedge bindweed control one year after postemergence herbicide applications in field corn. What's Cropping Up? 17(1):5.
• Hahn, R.R. 2007. Russ's Weed Alert ? Lambsquarters control issues with glyphosate. In NYS IPM Weekly Field Crop Pest Report. Vol. 6, No. 8.
• Dennis, J.S. and R.R. Hahn. 2007. Russ's Weed Alert ? Impact Herbicide. In NYS IPM Weekly Field Crop Pest Report. Vol. 6, No. 6.
• Hahn, R.R. Ed. 2007 Cornell Guide for Integrated Field Crop Management
• Hahn, R.R. and Shields, E.J. 2006. Glyphosate-resistant horseweed - should we be concerned? What`s Cropping Up? 16(3):6-7.
• Hahn,R.R. and Stachowski, P.J. 2006. Hedge bindweed control in field corn. Proc. Northeastern Weed Sci. Soc. 60:81.
• Hahn, R.R. 2006. Total postemergence field corn weed control - a good choice before rotating to perennial forages. What`s Cropping Up? 16(1):2-3.
• Hahn, R.R. 2006. Tillage systems affect types of weeds in summer annual crops. What`s Cropping Up? 16(4):4.
• Hahn, R.R. and Stachowski, P.J. 2006. Weed management research update. In Field Crop Dealer Meetings. Dept. of Crop and Soil Sciences Extension Series No. E06-4:23-25.
• Cox,W.J., Hahn,R.R., and Stachowski,P.J. 2006. Time of weed removal with glyphosate affects corn growth and yield components. Agron. J.98:349-353.

[top]