CORN AND SOYBEAN RESPONSES TO BASAL APPLICATIONS OF VINEGAR

Authors: Coffman, Charles; RADHAKRISHNAN, JAYKUMAR - FORMER SASL POST-DOC; Teasdale, John

Submitted to: Proceedings of Northeastern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2004
Publication Date: 1/3/2005
Citation: Coffman, C.B., Radhakrishnan, J., Teasdale, J.R. 2005. Corn and soybean responses to basal applications of vinegar. Proceedings of Northeastern Weed Science Society. 59:79.

Interpretive Summary:

Technical Abstract: Vinegar applications for in-row weed management in sweet corn (Zea mays) and vegetable soybean (Glycine max) in organic production systems have been investigated for several years at the Beltsville Agricultural Research Center and on an organic farm in Frederick County, Maryland. The effectiveness of 20% acetic acid vinegar for weed control has been reported at several previous conferences. Field studies in 2003 resulted in no visual differences between sweet corn and vegetable soybean plants treated with 20% vinegar and untreated control plants. However, yield of shelled soybean grain was less for vinegar treatments than for untreated controls. The objectives of our investigation in 2004 were to assess the tolerance of sweet corn and vegetable soybean plants to basal applications of 20% vinegar and to characterize weed responses to vinegar applications. Sweet corn was sown in 30 inch rows on 14 May, 2004, in a clean-cultivated field, on the Beltsville Agricultural Research Center, at a rate of 27,000 seeds/A. Weeds between rows were controlled by cultivation. Plots were 20 ft long and 3 rows wide, and were randomly located throughout the field. Plots were divided into 2 groups. Basal applications of vinegar were made to weeds in the center rows of the first group 6 weeks after sowing (WAS), and to the second group 9 WAS. Treatments consisted of 20% vinegar applications to the basal area of the corn plants in the center row to effect complete coverage to runoff of the within-row weeds, plus untreated controls, and were replicated 6 times. Weed flora was dominated by smooth pigweed (Amaranthus hybridus) in both groups. Visual injury ratings were on a scale of 0 to 100, where 0 = no effect of the vinegar and 100 = plant death, and were made 2 weeks after treatment (WAT) for both groups. Vegetable soybean was sown in 36 inch rows in a clean-cultivated field on an organic farm near Buckeystown, MD, on 12 May, 2004, at a rate of 130,000 seeds/A. Weeds between rows were controlled by timely cultivations. Plots 20 ft long and 3 rows wide were randomly located throughout the field. Plots were treated with vinegar 7 WAS. All treatments were replicated 6 times. Treatments were visually rated 6 WAT. Weed flora was dominated by redroot pigweed (Amaranthus retroflexus), giant foxtail (Setaria faberii), and field bindweed (Convolvulus arvensis). Injury scores for sweet corn and vegetable soybean exposed to vinegar treatments ranged from 0 to 5, and did not differ from untreated controls. Corn plants treated 6 WAS produced 3% more biomass than untreated controls, and fresh ear weights were 7% higher. However corn treated 9 WAS produced 16 and 12% less biomass and fresh ear weights, respectively, than the untreated controls. Soybean biomass was the same for treated and untreated plants, but pod counts and pod yields were 1 and 3% higher, respectively, for untreated controls than treated plants. Mean visual weed cover ratings for corn treated with vinegar 6 and 9 WAS were 40 and 61% , respectively, whereas weed cover ratings in the corresponding untreated controls were 90 and 92%, respectively. There were no visual differences in weed cover between vinegar treated and untreated soybean due to timely cultivations and soybean canopy effect on weed growth.