Project Details:

Title:
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:
Keywords:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Procedures:
Objective 1: Field experiments will be conducted at the KSU Ag Research fields near Manhattan and Hays, Kansas. Liberty Link soybeans will be planted in 30 inch rows following standard agronomic practices. Authority Elite will be applied preemergence and Liberty postemergence to the entire plot area, along with hand weeding to maintain the plot area weed free. Engenia herbicide will be applied at 1/100, 1/500 and 1/1000 of the standard use rate of 12.8 oz/a (0.5 lb ae/a) at the V3, R1, R3, V3&R1, V3&R3, R1&R3, and V3&R1&R3 growth stages. Untreated checks will be included for comparisons. The experiment will have a randomized complete block design with factorial arrangement of treatments (4 replications) and 10 by 30 ft plots. Herbicide applications will be applied with a backpack sprayer delivering 15 gpa to the center two rows of each 4 row plot. Applications will be made when environmental conditions are optimal to minimize off-target herbicide movement. To avoid any cross contamination between adjacent treated plots, a nontreated border areas between plots will be maintained. Soybean response will be visually evaluated throughout the season on a scale of 0 to 100, with 0 equal to no response (no injury) and 100 equal to plant mortality. Soybean canopy height will be recorded at 28 days after applications and at maturity. Soybean yield, and yield components will be measured at maturity. The percent germination and seedlings vigor of soybean progeny seeds will also be assessed. All data will be subjected to analysis of variance and means separated using Fisher’s Protected LSD test at P <0.05.


Objective 2. Field experiments will be conducted at the KSU Ag Research fields near Manhattan and Hays, Kansas. Liberty Link, Roundup Ready 2, Balance GT, and Enlist (if commercially available) soybeans will be planted in 30 inch rows following standard agronomic practices. Authority Elite will be applied preemergence to the entire plot area, along with hand weeding throughout the season to maintain the plot area weed free. Engenia herbicide will be applied at 1/100 of the standard use rate of 12.8 oz/a (0.5 lb ae/a) at the V3 and R1 growth stages to each of the soybean herbicide traits. Untreated checks will be included for comparisons. The experiment will have a randomized complete block design in a split plot arrangement with soybean trait as the main plot and herbicide treatment as the subplot. The experiment will have 4 replications and 10 by 30 ft plots. Herbicide applications will be made with a backpack sprayer delivering 15 gpa to the center two rows of each 4 row plot. Applications will be made when environmental conditions are optimal to minimize off-target herbicide movement. Soybean response will be visually evaluated throughout the season on a scale of 0 to 100, with 0 equal to no response and 100 equal to plant mortality. Soybean canopy height will be recorded at 28 days after applications and at maturity. Soybean yield, and yield components will be measured at maturity. The percent germination and seedlings vigor of soybean progeny seeds will also be assessed. All data will be subjected to analysis of variance and means separated using Fisher’s Protected LSD test at P <0.05.

Project Objectives

1. Determine non-Xtend soybean injury and yield loss from dicamba exposure at different growth stages, rates, and multiple exposures.

2. Determine injury and yield loss from dicamba exposure on different non-Xtend soybeans traits.

Project Deliverables

This research should provide additional data on the susceptibility of non-Xtend soybeans to different dicamba rates, timings, number of exposures, soybean trait, and environmental conditions. Information generated from this research will be communicated to soybean growers through news releases, newsletters, Extension meetings and field days, and in research publications.

Progress of Work

Updated June 22, 2018:
Tyler Meyeres was recruited as a graduate student to work on this project for her M.S. thesis research. Soybean experiments were planted on May 22, 2018 at Manhattan, KS, and on May 25 at Hays, KS. A good stand of soybeans was established at Manhattan, but a marginal stand of soybeans was established at Hays due to heavy rains and soil crusting following planting. The first application of dicamba at the simulated drift rates was applied to soybeans at the V3 stage of growth on June 12 at Manhattan and on June 22 at Hays. Dicamba injury symptoms were evident and visually evaluated 1 week after treatment at the Manhattan site. Simulated dicamba rates will be applied at the appropriate times for the R1 and R3 applications during the coming weeks. Soybeans will be visually evaluated for dicamba injury throughout the season and yield and yield components determined at soybean maturity.

Updated September 10, 2018:
All dicamba applications were made to both experimental sites and experiments at the planned growth stages. The experiments at the Manhattan site have turned out extremely well and should produce good yield data unless the weather doesn't cooperate. The plots have excellent definition with no apparent cross herbicide contamination from within or outside the experimental area. Visual injury symptoms were evaluated on a regular basis through the growing 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 evident through the remainder of the growing season and correlated to exposure rate. The most severe soybean injury occurred with the multiple application timings and at the highest rates. Soybean response to dicamba varied among varieties, but did not appear to be trait dependent. Canopy measurements were assessed using the Canopeo app as untreated soybeans were nearing canopy closure. Video and NIR imaging was completed with a UAS on September 10. Soybean yield components and yields will be determined for the Manhattan site as the soybeans mature. Unfortunately, the experiments at Hays were abandoned as a result of poor stand establishment and herbicide drift onto the experiment from outside the plot area.

Updated December 7, 2018:
Samples were collected from each plot to determine soybean biomass and yield components. Soybeans were harvested with a plot combine in late October and yields determined. 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. Data and samples from the experiments will be processed and summarized in the coming months.

Updated April 17, 2019:
Soybean variety/trait response to dicamba applied at the V3 and R1 stages at the 100X dicamba rate indicated there was no significant interaction between the varieties/trait and dicamba treatments. Late season visual injury to soybeans was greater from dicamba application at the R1 than at the V3 stage of exposure. Soybean yields varied among varieties, with the later maturity variety yielding higher than the other 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. Soybean yield response to dicamba exposure at the same rate (1/100X) and stages (V3 and R1) in the variety/trait comparison experiment were similar to responses in the rate by timing experiment. Grain harvested from both experiments had extremely poor quality due to early season drought stress and delayed harvest as a result of excess moisture in the fall at harvest time. Consequently, seed viability was very low, highly variable, and not different among treatments. The experiments will be repeated in 2019 at Manhattan and Ottawa, KS. The second field site has been relocated from Hays to Ottawa due to ongoing concerns with dicamba drift from outside the experimental area at Hays.

Updated May 28, 2019:

View uploaded report PDF file

Final Project Results

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.

Benefit to Soybean Farmers

We believe this research will help provide new information and a better understanding of the factors affecting dicamba injury to non-Xtend soybeans to help guide management decisions in the future.

Performance Metrics

Project Years