Difficult Weeds

Difficult to Control Weeds in Corn, Soybean and Alfalfa

A number of problem weeds continue to limit row crop production. Shifts or changes in the abundance and types of weeds within agricultural systems are commonplace. These shifts can occur for a number of reasons and may result from cultural, mechanical, or chemical weed management strategies. The right combination of weeds and relying too heavily on any one practice is often the most common cause. The adoption of Roundup Ready soybean has helped managed numerous weeds, but a number of problem annuals and perennials still demand our attention. Some of these weeds discussed in this session will include the annual broadleaves burcucumber, common lambsquarters, and most notable, glyphosate-resistant horseweed or marestail. Burcucumber and common lambsquarters continue to cause problems each year, while glyphosate-resistant horseweed is a new problem weed to watch for. The annual grasses large and smooth crabgrass and yellow foxtail, are increasing in prevalence in some regions. Their later season or prolonged emergence periods make them special problems. Finally, perennials weeds including dandelion, horsenettle, mugwort, yellow nutsedge and wirestem muhly earn some attention. These weeds are either new problems or continue to present a challenge to many grain and forage producers. This presentation will attempt to focus on these weeds and perhaps others that continue to be challenging and will draw attention to specific management opportunities.

Bill Curran Professor of Weed Science
Penn State University
wsc2@psu.edu

Biography: I serve as the extension specialist for programs relating to weed science in agronomic crops. I am responsible for planning and implementing extension education programs that include training county extension staff, conducting workshops, seminars, conferences and other types of training for producers and the agricultural industry of Pennsylvania. I also conduct applied research in Weed Science focusing on current problems, opportunities, and possible solutions. The results of my research along with the results from others here at Penn State and other public institutions provide the foundation for my extension activities. My research program has concentrated in two main areas: identify management opportunities for herbaceous perennial broadleaves and grasses and problem annual species; examine the effect of cover crops on weed emergence and herbicide efficacy. My research agenda over the next several years will continue to concentrate on programs that more effectively manage problem weed species in corn and forages and issues that challenge weed management in conservation tillage systems.