ABOUT US
Information
Membership Info
Officers
Members
Perspective

RESEARCH &
EDUCATION
Research
Education
Facilities
Cooperators

PLANT
MANAGEMENT
BMP Manual
Plant Pests
Management Options
Economics
Pesticides
Professional Help

INFORMATION
News
Calendar
Publications
Links

Cody J. Gray, J.D. Madsen, R.M. Wersal and K.D. Getsinger

Two invasive weed species, Eurasian watermilfoil (Myriophyllum spicatum L.) and parrotfeather [Myriophyllum aquaticum (Vell.) Verdc.], were grown in outdoor mesocosms to determine the efficacy of carfentrazone-ethyl (a,2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorobenzenepropanoic acid, ethyl ester), alone and in combination with 2,4-D, a herbicide routinely used for watermilfoil control. Eurasian watermilfoil control was ≥ 98% when carfentrazone rates were applied alone at ≥ 150 μg ai L-1.
Carfentrazone alone initially controlled parrotfeather; however, tissue viability 3 weeks after treatment suggested plant recovery was likely. Both Eurasian watermilfoil and parrotfeather control was 100% when 2,4-D was applied at 1000 μg ae. L-1; however, when 2,4-D rate was reduced to 100 μg ae L-1 control declined to <50%. Herbicide applications containing carfentrazone with low rates of 2,4-D resulted in 100% death of both plant species. These results indicate that Eurasian watermilfoil control can be obtained using carfentrazone alone; but the addition of low levels of 2,4-D may be needed to achieve desired parrotfeather control.