Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2011
Publication Date: 2/26/2011
Citation: Aulakh, J.S., Price, A.J., Patterson, M.G., Enloe, S.F. 2011. Inversion tillage, high residue covers, and different herbicide regimes for palmer amaranth control in liberty link systems [abstract]. Southern Weed Science Society Annual Meeting. CDROM. Interpretive Summary:
Technical Abstract: Glyphosate-resistant Palmer amaranth is adversely affecting cotton production in the Southeast US. A field experiment was established in fall 2008 at the E.V. Smith Research Center, Field Crops Unit near Shorter, AL, to investigate the role of inversion tillage, high residue cover crops, and different herbicide regimes for Palmer amaranth management in LibertyLink™ cotton. The experimental design contained a split-split-split plot treatment restriction in a randomized complete block design with three replicates. The main plots consisted of tillage (inversion vs no inversion), the subplots were cover crops (winter fallow, crimson clover and cereal rye), and the sub-subplots were herbicide programs (No herbicide, preemergence herbicide (PRE) alone, postemergence (POST) alone and PRE + POST). The herbicide programs included; pendimethalin (0.92 kg a.i/ha) plus fomesafen (0.28 kg a.i/ha) as PRE; single application of glufosinate (0.42 kg a.i/ha) as POST and a combination of these as PRE+POST program. Dixie variety of crimson clover (25 lbs/acre) and Elbon variety of winter rye ( 70 lbs/acre) were planted on November 20th and December A glufosinate- resistant cotton variety FM-1845 was planted on June 3rd and May 29th during 2009 and 2010, respectively. Data were collected on cover biomass, pigweed count and biomass and cotton yield. Palmer amaranth control ratings were taken at weekly interval after herbicide application. Data were analyzed using the GLIMMIX procedure and the LSMEANS PDIFF option to distinguish between treatment means. Inversion tillage without herbicide resulted in = 80% Palmer amaranth control compared to no inversion and resulted in one and half time higher cotton yield. Results reveal that cover crop biomass differed between years; cover biomass was less during 2010 due to extremely cool weather. Surprisingly, clover produced the maximum biomass during both the years compared to rye and winter fallow. Cotton yield was also higher with cotton following clover cover. Among herbicide programs, significant interactions of inversion by herbicide and cover by herbicide programs were revealed. While PRE and PRE + POST treatments gave more than 95% control of Palmer amaranth, single POST application of glufosinate under no inversion did not control (20%) this weed compared to inversion tillage (95%). Among cover crops, again the PRE and PRE + POST herbicide programs gave similar control in all the cover crops; clover was more effective in Palmer amaranth suppression than rye and winter fallow when no herbicide was used. Averaging over the tillage system, the highest cotton yield was recorded with PRE + POST herbicide program followed by PRE and POST alone. Our research indicates that though soil inversion helps reduce Palmer amaranth density but a LibertyLink™ , no inversion tillage, PRE + POST herbicide program will likely achieve = 95 % control of Palmer amaranth while protecting conservation tillage.