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Title: Corn gluten meal as an alternative weed control option for spring-transplanted onions

Author
item Webber Iii, Charles
item SHREFLER, JAMES - OSU, LANE, OK
item TAYLOR, MERRITT - OSU, LANE, OK

Submitted to: International Journal of Vegetable Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2007
Publication Date: 9/15/2007
Citation: Webber III, C.L., Shrefler, J.W., Taylor, M.J. 2007. Corn gluten meal as an alternative weed control option for spring-transplanted onions. International Journal of Vegetable Science. 13(3):17-33.

Interpretive Summary: Onions (Allium cepa L.) are a potential alternative crop for Oklahoma and northeast Texas. Unfortunately, the onion's slow growth rate, short height, non-branching plant structure, low leaf area, and shallow root system can result in a total loss of marketable yields as a result of weed competition. It is vital to ascertain the efficacy of herbicides, both synthetic and organic, for weed control in onions for this region. Field research was conducted in 2002 and 2003 in southeast Oklahoma (Lane, OK) to determine the weed control efficacy of selected preemergent synthetic herbicides and corn gluten meal (CGM) for use in spring-transplanted onion production (cv. Hybrid Yellow Granex PRR). The research involved 21 treatments [12 synthetic herbicide treatments, 5 CGM applications, a full-season weed-free (hand-weeded) treatment, a full-season weedy-check, a partial-season weed-free (weed-free for the first half of the growing season), and a weedy-check without onions]. The synthetic herbicide treatments included pendimethalin applications at 0.5, 1.0, and 1.5 kg ai/ha **-1, oxyfluorfen at 0.1, 0.2, and 0.3 kg ai/ha **-1, and also tank-mixed at these three levels. In addition, the highest rate of each herbicide—pendimethalin (1.5 kg ai/ha **-1), oxyfluorfen (0.3 kg ai/ha **-1), and the tank mix of pendimethalin (1.5 kg ai/ha **-1) plus oxyfluorfen (0.3 kg ai/ha **-1)-were applied and kept weed-free by hand-weeding. CGM was applied at 4 rates (1000, 2000, 3000, and 4000 kg•ha **-1). A weed-free (hand-weeded) treatment was also combined with the highest CGM rate (4000 kg•ha **-1). Weed cover and weed control ratings were collected at 46 days after planting (DAP) and at harvest. The synthetic herbicide treatments resulted in significantly greater weed control at 46 DAP and harvest compared to all CGM application rates. The highest CGM rate (4000 kg•ha **-1) did maintain fair, 72.1%, total weed control and good, 82.7%, broadleaf weed control until 46 DAP. Among the synthetic herbicides, pendimethalin provided the best early and full season weed control.

Technical Abstract: Successful screening of suitable onion (Allium cepa L.) varieties, viable production areas, and potential marketing options suggest that onions are a potential alternative crop for Oklahoma and northeast Texas. Unfortunately, the onion's slow growth rate, short height, non-branching plant structure, low leaf area, and shallow root system can result in a total loss of marketable yields as a result of weed competition. It is vital to ascertain the efficacy of herbicides, both synthetic and organic, for weed control in onions for this region. Field research was conducted in 2002 and 2003 in southeast Oklahoma (Lane, OK) to determine the weed control efficacy of selected preemergent synthetic herbicides and corn gluten meal (CGM) for use in spring-transplanted onion production (cv. Hybrid Yellow Granex PRR). The research involved 21 treatments [12 synthetic herbicide treatments, 5 CGM applications, a full-season weed-free (hand-weeded) treatment, a full-season weedy-check, a partial-season weed-free (weed-free for the first half of the growing season), and a weedy-check without onions]. The synthetic herbicide treatments included pendimethalin applications at 0.5, 1.0, and 1.5 kg ai/ha **-1, oxyfluorfen at 0.1, 0.2, and 0.3 kg ai/ha **-1, and also tank-mixed at these three levels. In addition, the highest rate of each herbicide-pendimethalin (1.5 kg ai/ha **-1), oxyfluorfen (0.3 kg ai/ha **-1), and the tank mix of pendimethalin (1.5 kg ai/ha **-1) plus oxyfluorfen (0.3 kg ai/ha **-1)-were applied and kept weed-free by hand-weeding. CGM was applied at 4 rates (1000, 2000, 3000, and 4000 kg/ha **-1). A weed-free (hand-weeded) treatment was also combined with the highest CGM rate (4000 kg/ha **-1). Weed cover and weed control ratings were collected at 46 days after planting (DAP) and at harvest. The synthetic herbicide treatments resulted in significantly greater weed control at 46 DAP and harvest compared to all CGM application rates. The highest CGM rate (4000 kg/ha **-1) did maintain fair, 72.1%, total weed control and good, 82.7%, broadleaf weed control until 46 DAP. Among the synthetic herbicides, pendimethalin provided the best early and full season weed control.