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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #186605
Title: TROPICAL SPIDERWORT (COMMELINA BENGHALENSIS) CONTROL AND EMERGENCE PATTERNS IN PREEMERGENCE HERBICIDE SYSTEMS

Author
item Webster, Theodore
item BURTON, M - NC STATE UNIVERSITY
item CULPEPPER, A - UNIVERSITY OF GEORGIA
item FLANDERS, J - UNIVERSITY OF GEORGIA
item GREY, T - UNIVERSITY OF GEORGIA

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2006
Publication Date: 5/12/2006
Citation: Webster, T.M., Burton, M.G., Culpepper, A.S., Flanders, J.T., Grey, T.L., York, A.C. 2006. Tropical spiderwort (Commelina benghalensis) control and emergence patterns in preemergence herbicide systems. Journal of Cotton Science. 10:68-75.

Interpretive Summary: An exotic invasive weed, tropical spiderwort has recently become the most troublesome cotton weed in Georgia and Florida. Tropical spiderwort is tolerant to many of the commonly used herbicides and thrives in reduced tillage cropping systems. Glyphosate-tolerant cotton varieties have dominated our cotton cropping systems, which rely primarily on glyphosate for weed management, abandoning many of the herbicides with soil residual activity that may assist in suppressing tropical spiderwort. Due to the continuous emergence pattern of tropical spiderwort, successful management will require a multi-component approach, with inclusion of an effective herbicide with soil residual activity. Field studies were conducted in Georgia and North Carolina to evaluate the effectiveness of several preemergence herbicides in suppressing tropical spiderwort emergence. The most effective (>80% control) herbicides in 2002 at six weeks after treatment (6 WAT) were clomazone, fluometuron, and s-metholachlor. In 2003 and 2004, only s-metolachlor controlled tropical spiderwort >80%. Linear relationships existed between tropical spiderwort emergence and time. Rates of tropical spiderwort emergence for most treatments were similar to the nontreated control (1.61% per day). Flumioxazin (1.22% per day) and s-metolachlor (0.50 to 0.73 per day) had lower rates of emergence than the nontreated control. Herbicides with soil residual activity will be crucial for management of tropical spiderwort.

Technical Abstract: Tropical spiderwort is the most troublesome cotton weed in Georgia and Florida. Due to the continuous emergence pattern of tropical spiderwort, successful management will require a multi-component approach, with inclusion of an effective herbicide with soil residual activity. Field studies were conducted in Georgia and North Carolina to evaluate the effectiveness of several preemergence herbicides in suppressing tropical spiderwort emergence. The most effective (>80% control) herbicides in 2002 at six weeks after treatment (6 WAT) were clomazone at 0.42 and 1.05 kg ai/ha, fluometuron at 1.68 kg ai/ha, and s-metholachlor at 1.07 and 1.60 kg ai/ha. In 2003 and 2004, only s-metolachlor at 1.60 kg/ha controlled tropical spiderwort >80%. Linear relationships existed between tropical spiderwort emergence and time. Rates of tropical spiderwort emergence for most treatments were similar to the nontreated control (1.61% per day). Flumioxazin at 0.035 kg/ha (1.22% per day) and s-metolachlor at 1.07 and 1.60 kg/ha (0.73 and 0.50% per day, respectively) had lower rates of emergence than the nontreated control. The time at which 40% of the total season’s emergence in the nontreated control occurred was termed the E40. S-metolachlor at 1.07 kg/ha delayed E40 by 21 days relative to the nontreated control, while s-metolachlor at 1.60 kg/ha suppressed emergence below the E40 until cotton canopy closure. Herbicides with soil residual activity will be crucial for management of tropical spiderwort.