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Palmer Amaranth Control in Cotton, 1994-1996

H.R. Hurst


 
ABSTRACT

Cotton (‘DES 119' in 1994 and 1995 or ‘SG 125' in 1996) was planted on a silt loam soil site on May 16, 1994; May 2, 1995; and May 6, 1996. The area was naturally infested with pigweeds. The predominate species was Palmer amaranth (Amaranthus palmeri S. Wats.) with some smooth pigweed (A. hybridus L.). In mid-April 1994, the entire area was disk-harrowed two times at an angle to the row direction, and a finishing harrow was used prior to planting. All treatments in 1995 and 1996 were applied to killed standing wheat stubble previously treated with Gramoxone Extra ® 0.75 lb + Karmex® 0.25 lb in March 1995 and with Roundup D-Pak® 0.75 lb + Goal® 0.2 lb in March 1996. Gramoxone Extra 0.94 lb was applied at planting in 1995 and 1996. Preplant incorporated treatments were soil incorporated with a 4-row tandem disk harrow in the row direction one time in 1995 and two times in 1996 without prior land preparation. Sixteen treatment combinations of preplant incorporated (PPI), preemergence (PRE), and postemergence (over-the-top PO-OT or directed PO-DIR) herbicides were used in a randomized complete block design with 4 replications. Individual plots were four, 40-inch rows 40 feet long. All data were obtained from the two center rows of each plot. Evaluations were made from crop/weed counts, estimated visual weed control/crop injury (0 = no control/injury, 100 = complete control/injury), and seed cotton yield. Weed counts on June 7, 1994 resulted in Palmer amaranth reductions of 12 to 99% below the no-herbicide check. In mid-July 1994, treatments with 90% or greater pigweed control were Treflan® 0.5 lb PPI followed by (fb) Staple® 0.063 lb PO-OT 27 days after planting (DAP) fb Accent® 0.038 lb + Staple 0.032 lb PO-OT 54 DAP (90%), Treflan 0.75 lb PPI fb Staple 0.032 lb PO-OT 27 DAP fb Accent 0.0025 lb + Staple 0.032 lb PO-OT 54 DAP (91%), Prowl® 1.25 lb + Cotoran® 1.25 lb PRE fb Beacon® 0.021 lb PO-DIR 30 DAP (90%), and Bladex® 0.5 lb + Command® 0.75 lb PRE fb Beacon 0.021 lb PO-DIR 30 DAP fb Accent 0.008 lb + Staple 0.032 lb PO-OT 41 DAP (95%). Most of the herbicide treatments were repeated on the same plots in 1995. Treatments with >90% control in late-July were Prowl 1.25 lb + Cotoran 1.25 lb PRE fb Beacon 0.021 lb PO-DIR 43 DAP (91%), Bladex 0.5 lb + Staple 0.063 lb PRE (97%), Prowl 1.0 lb PPI fb Staple 0.047 lb PRE fb Staple 0.063 lb PO-OT 58 DAP (100%), and cultivate + hand hoe weed-free check (100%). All treatments except the no-herbicide checks in 1995 were cultivated as needed, leaving an undisturbed band of 12 inches centered on the row.



Reprinted from Proceedings of the 1997 Beltwide Cotton Conferences pp. 804 - 805
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998