Project Details:

Non-Xtend Soybean Response to Simulated Dicamba Drift

Parent Project: This is the first year of this project.
Checkoff Organization:Kansas Soybean Commission
Categories:Weed control
Organization Project Code:1856
Project Year:2018
Lead Principal Investigator:Dallas Peterson (Kansas State University)
Co-Principal Investigators:

Contributing Organizations

Funding Institutions

Information and Results

Comprehensive project details are posted online for three-years only, and final reports indefinitely. For more information on this project please contact this state soybean organization.

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Final Project Results

Updated May 28, 2019:

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Field experiments were conducted at Manhattan Kansas to evaluate: 1) non-Xtend soybean injury and yield loss from dicamba exposure at different growth stages, rates, and multiple exposures, and 2) injury and yield loss from dicamba exposure on different non-Xtend soybean varieties and traits.
Engenia herbicide was applied at 1/100, 1/500 and 1/1000X of the standard use rate of 12.8 oz/a (0.5 lb ae/a) to soybeans at the V3 stage on June 12, R1 stage on July 2, and R3 stage on July 16. Dicamba injury symptoms were evident within 1 week after treatment at each timing and were visually evaluated at weekly intervals until late in the season. Dicamba symptomology on the non-Xtend soybeans was maximized about 3 to 4 weeks after treatment. Soybeans treated with dicamba at the V3 stage expressed early season leaf cupping, but seemed to have recovered fairly well by 8 weeks after treatment, regardless of the application rate (1/100, 1/500, and 1/1000 X). Injury from dicamba applications at the R1 and R3 stages included leaf cupping, stunting, epinasty, and abnormal growing point and pod development. Symptoms from the R1 and R3 applications were more persistent and evident through the remainder of the growing season than applications at the V3 stage of soybean growth. The most severe soybean injury occurred with the multiple application timings and at the highest rates.
Soybean harvest was delayed and complicated due to unusually wet conditions in the fall. Soybean yield reduction from dicamba injury was not as great as visual injury ratings. Soybean yield loss was minimal from exposure during the V3 stage, regardless of exposure rate, or from the 1/1000X exposure rate, regardless of exposure stage or with multiple exposure timings. The greatest yield loss was from multiple exposure events and at the highest exposure rate of 1/100X dicamba. Soybean yield was reduced 68% from exposure to dicamba at the 1/100X rate at all three timings of V3/R1/R3, and 53% from the 1/100X rate at the R1 and R3 timings. Soybean yield was reduced 25% from a single exposure of 1/100X rate at the R1 stage and 18% from the 1/100X rate at the R3 growth stage.
Visual soybean injury varied among varieties and timings. Visual injury from dicamba tended to be highest on the Stine 40BA02 variety and lowest on the Credenz 4746 LL variety. Lower injury on the Credenz 4746 variety may have been partially due to the longer maturity, but application on the same dates.
Despite differences in dicamba injury among varieties, soybean yield effects were not different among varieties. Soybean yield was not reduced from dicamba exposure at the V3 timing and was actually slightly higher than the untreated check. Soybean yields from dicamba exposure at the R1 stage was reduced 23% compared to the untreated check, similar to the results from the other experiment.

Project Years