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United States Department of Agriculture

Agricultural Research Service

Title: Broadcast applications of acetic acid: Crop injury and onion yields

Authors
item Webber, Charles
item Shrefler, James - OSU, LANE, OK

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: March 3, 2008
Publication Date: May 1, 2008
Citation: Webber III, C.L., Shrefler, J.W. 2008. Broadcast applications of acetic acid: Crop injury and onion yields. In: Proceedings of the 27th Horticultural Industries Show. January 4-5, 2008, Tulsa, Oklahoma. p. 220-225.

Interpretive Summary: Oklahoma producers are interested in organically produced sweet onions (Allium cepa L.) as an alternative crop for farm diversification, but weed control continues to be a primary obstacle. The organic herbicides for onions are limited to non-selective materials, such as corn gluten meal and vinegar. Research in Oklahoma has shown that corn gluten meal can be an affective early season pre-emergence herbicide for onion transplants, but once the residual impact of the corn gluten meal wears off, the resulting weed growth can devastate the onion crop. The post-emergence application of vinegar has the potential to control the weeds emerging after corn gluten meal applications, but the extent of crop injury from broadcast applications of vinegar is unknown. Research was conducted at Lane, OK to determine the impact of a broadcast application of acetic acid on onion crop injury. 'Candy' and 'Cimarron' onions were transplanted on March 13, 2007. The experiment included 6 weed control treatments (2 application volumes, 2 hand weeding levels, plus an untreated weedy-check and an untreated weed-free) with 4 replications. Vinegar (20% acetic acid) was applied as an over-the-top broadcast application at either 50 or 100 gpa on April 21, 2007 using four 8002 nozzles on 20 inch spacing. Within each application volume (50 and 100 gpa) plots were either hand-weeded or the uncontrolled weeds were allowed to grow. Crop injury ratings were collected throughout the growing season. The greatest onion injury was observed at 3 days after treatment (DAT), resulting in 38% onion injury for the 50 gpa rate and 56% for 100 gpa rate. There were no significant differences between onion varieties for injury. The results indicate that the early season crop injury did not significantly impact onion yields.

Technical Abstract: The organic herbicides for sweet onions (Allium cepa L.) are limited to non-selective materials, such as corn gluten meal and vinegar. Research in Oklahoma has shown that corn gluten meal can be an affective early season pre-emergence herbicide for onion transplants, but once the residual impact of the corn gluten meal wears off, the resulting weed growth can devastate the onion crop. The post-emergence application of vinegar has the potential to control the weeds emerging after corn gluten meal applications, but the extent of crop injury from broadcast applications of vinegar is unknown. Research was conducted at Lane, OK to determine the impact of a broadcast application of acetic acid on onion crop injury. 'Candy' and 'Cimarron' onions were transplanted on March 13, 2007. The experiment included 6 treatments (2 application volumes, 2 hand weeding levels, plus an untreated weedy-check and an untreated weed-free) with 4 replications. Vinegar (20% acetic acid) was applied as an over-the-top broadcast application at either 50 or 100 gpa on April 21, 2007 using four 8002 nozzles on 20 inch spacing. Within each application volume (50 and 100 gpa) plots were either handweeded or the uncontrolled weeds were allowed to grow. Crop injury ratings were collected throughout the growing season. The greatest onion injury was observed at 3 days after treatment (DAT), resulting in 38% onion injury for the 50 gpa rate and 56% for 100 gpa rate. There were no significant differences between onion varieties for injury. The results indicate that the early season crop injury did not significantly impact onion yields.

Last Modified: 10/24/2014
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