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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #278377
Title: Role of herbicide treatments and application times in cogongrass eradication under open field infestation scenario

Author
item AULAKH, JATINDER - Auburn University
item ENLOE, S - Auburn University
item Price, Andrew

Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2012
Publication Date: 2/28/2012
Citation: Aulakh, J.S., Enloe, S.F., Price, A.J. 2012. Role of herbicide treatments and application times in cogongrass eradication under open field infestation scenario. Proceedings of Southern Weed Science Society. CDROM.

Interpretive Summary:

Technical Abstract: A Cogongrass eradication project was conducted from spring 2008 through fall 2011 on natural, open-field Cogongrass infestations at two locations near Tilman's Corner and Bayou La Batre in southwestern Alabama. Treatments consisted of glyphosate alone (4 lb/acre), imazapyr alone (0.75 lb/acre) and a combination of both at three different application times (May, August and October). Time of herbicide application did not affect any response variable. However, application time by herbicide interaction was significant for rhizome dry weight only. Rhizome dry weight, %TNC content and alive- rhizome depth decreased as the eradication process advanced. Imazapyr alone and combination of glyphosate plus imazapyr were equally effective regardless of the application timing. Further, the glyphosate applied twice in May and October was as effective as imazapyr alone and combination of glyphosate plus imazapyr 12 MAT onwards at Bayou La Batre and 24 MAT onwards at Tilman’s corner site. At Bayou La Batre, complete rhizome kill was achieved by 24 MAT with combination of glyphosate plus imazapyr and glyphosate applied twice in May and October and by 36 MAT with imazapyr alone. However, at Tilman’s corner, same treatments reached complete rhizome kill by 36 MAT. Single glyphosate application either in July or October resulted in complete rhizome kill at Bayou La Batre site by 36 MAT but did never reach complete rhizome kill at Tilman’s corner site. Both the maximum alive-rhizome depth and % TNC content pursued very much the same decreasing trend as the rhizome dry weight under different locations, herbicides, MAT and their interactions. Deeper rhizomes were killed first likely due to higher sink activity of the younger rhizomes concentrated in deeper layers. Additionally, the effective herbicide treatments exercised double adverse impact on Cogongrass through direct rhizome kill and depletion of reserves that eventually lead to the eradication.