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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #228605
Title: Cotton planting date affects the critical period of Bengal dayflower (Commelina benghalensis) control

Author
item Webster, Theodore
item GREY, T - UNIV OF GA
item FLANDERS, J - UNIV OF GA
item CULPEPPER, A - UNIV OF GA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2008
Publication Date: 1/3/2009
Citation: Webster, T.M., Grey, T.L., Flanders, J.T., Culpepper, A.S. 2009. Cotton planting date affects the critical period of Bengal dayflower (Commelina benghalensis) control. Weed Science. 57(1):81-86.

Interpretive Summary: Benghal dayflower (AKA tropical spiderwort) is native to Asia, Africa, and the Pacific islands; but has become a significant weed throughout warm temperate regions of Australia, North America, and South America. In the Southeast US, Benghal dayflower is one of the most troublesome weeds in cotton and peanut, with known occurrences in AL, LA, MS, NC, and SC. Benghal dayflower infests as least 80,000 ha of crop land in GA. Benghal dayflower is a significant pest due to drastic changes in crop production practices, including: elimination of the use of PRE herbicides with soil residual activity, adoption of reduced tillage (and elimination of cultivation as a weed control tactic), and reliance on glyphosate-based systems for weed control. Field studies in 2003, 2004, and 2005 evaluated the relationship between the duration of Benghal dayflower interference and cotton yield. Maximum yield loss in May-planted cotton ranged from 21-30% in 2004 and 2005, while delayed cotton planting until June resulted in maximum yield losses of 40-60%. June-planted cotton had a CPWC of 52 days beginning 16 DAP (days after planting) in 2004 and 59 day-interval beginning 18 DAP in 2005. In contrast, May-planted cotton in 2005 had a narrower CPWC interval of 18 days initiated at 39 DAP. A single weed removal at 44 DAP averted a yield loss greater than 5% in May-planted cotton in 2004. It is recommended that fields infested with Benghal dayflower be planted with cotton early in the growing season in order to minimize weed interference.

Technical Abstract: Benghal dayflower (also known as tropical spiderwort) is one of the most troublesome weeds in Georgia cotton. Field studies were conducted in 2003, 2004, and 2005 to evaluate the relationship between the duration of Benghal dayflower interference and cotton yield in an effort to optimize the timing of weed control efforts. To determine the critical period of weed control (CPWC), Benghal dayflower interference with cotton was allowed or prohibited in 2 wk intervals between 0 to 12 weeks after crop planting. Maximum yield loss in May-planted cotton ranged from 21 to 30% in 2004 and 2005, while delayed cotton planting until June resulted in maximum yield losses of 40 to 60%. June-planted cotton had a CPWC of 190 to 800 GDD (growing degree days) in 2004 [52 d interval beginning at 16 DAP (days after planting)] and 190 to 910 GDD in 2005 (59 d interval beginning at 18 DAP). In contrast, May-planted cotton had a narrower CPWC interval of 396 to 587 GDD (18 d) that occurred three wks later in the growing season (initiated at 39 DAP). May-planted cotton in 2004 did not have a critical range of weed-free conditions; instead a single weed removal at 490 GDD (44 DAP) averted a yield loss greater than 5%. It is recommended that fields infested with Benghal dayflower be planted with cotton early in the growing season in order to minimize weed interference with the crop.