Tuesday, November 6, 2007
170-12

Alternanthera Pungens Control in Bermudagrass.

Ryan Goss and Gabriel Ludwig. Plant and Environmental Sciences, New Mexico State University, New Mexico State University, P.O. Box 30003 MSC 3Q, Las Cruces, NM 88003-8003

Alternanthera pungens is a problematic turfgrass weed, especially in the arid and semi-arid regions of the southern United States and can be found from Georgia to Arizona. Common names for A. pungens include khakiweed, matt chafflower and creeping chaffweed. The prostrate growth habit of A. pungens inhibits aggressively growing bermudagrass (Cynodon dactylon) and other turfgrass species. The perennial plant regenerates from a thick tap root and is a prolific seeder. Few herbicide options have been identified to provide sufficient and long-term control. The objectives of the experiment were to identify herbicide options for A. pungens control and to determine the most effective timing for long-term control. A field experiment was conducted at Las Cruces Country Club in Las Cruces, NM to existing bermudagrass golf course rough that was heavily infested with A. pungens. Applications of various broadleaf herbicides were made in Jun, Jul, Sep and Jun+Jul+Sep of 2006 and 2007. Herbicide combinations of broadleaf herbicides with/without pendimethalin and with/without quinclorac were also made at the same timings. Results indicate that most broadleaf herbicides provide control of A. pungens for up to 45 days after application, regardless of timing. After 60 days after application, most herbicide treatments did not provide sufficient control due to regrowth and/or new weed emergence. However, the addition of pendimethalin improved A. pungens control for most of the herbicide evaluated and shows promise for improved long-term control. Quinclorac did not improve A. pungens control when tank-mixed with broadleaf herbicides investigated. In general, Jun application timing provided greater control than any other single application timing, but application at all three timings provided greater control than any single application timing.