January 18, 2022
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Effect of Dicamba Formulations and Planting Date on Different Corn Products - 2021
TRIAL OBJECTIVE
Dicamba, a growth regulator herbicide, is an effective broadleaf herbicide in corn. Producers should consider safened dicamba herbicide formulations to help protect yield potential and to help reduce plant stress from factors such as stalk brittleness or greensnap.1
Planting date and corn product selection are some of the major drivers for high yield potential.
The objective of this trial was to evaluate the yield potential impact on twenty different corn products when the products were planted on two different dates and safened and unsafened dicamba formulations were applied at V5 and V9 corn growth stages.
RESEARCH SITE DETAILS
| Location | Gothenburg, NE | ||
| Soil Type | Hord silt loam | ||
| Previous Crop |
Soybean | ||
| Tillage Type |
Strip-tillage |
| Planting Date | 5/5/21, 5/25/21 | ||
| Harvest Date | 11/17/21 | ||
| Potential Yield (bu/acre) |
300 | ||
| Seeding Rate (seeds/acre) |
36,000 |
- Trial was a split-split-plot design with planting date as the whole plot, herbicide as the sub-plot, and corn product as the sub-sub plot with five replications.
- Two corn planting dates of May 5 and May 25 were targeted to provide corn at V9 and V5 growth stages when the dicamba applications were to be applied, respectively.
- Twenty corn products were planted (Tables 1 and 2).
- Residual herbicide program applied on May 22, 2021 to the study area included:
- Balance® flexx Herbicide (Restricted Use Pesticide) (4 oz/acre)
- Harness® herbicide (2 pts/acre)
- Atrazine 4L herbicide (1 qt/acre)
- Roundup PowerMAX® (1 qt/acre) + Ammonium Sulfate (AMS) (17 lb/100 gallon)
- Three herbicide/fungicide treatments were applied on June 23 to the V5 (May 25th - planted) and V9 (May 5th - planted) growth stage plants:
- A non-dicamba treated control:
- Delaro® 325 SC fungicide (0.125 qt/acre) + Roundup PowerMAX® herbicide (1 qt/acre) + AMS (17 lb/100 gallon)
- An unsafened dicamba formulation (Bold):
- Sterling Blue® herbicide (0.5 qt/acre) + Delaro® 325 SC fungicide (0.125 qt/acre) + Roundup PowerMAX® herbicide (1 qt/acre) + AMS (17 lb/100 gallon)
- A safened dicamba formulation (Bold):
- DiFlexx® Herbicide (0.5 qt/acre) + Delaro® 325 SC fungicide (0.125 qt/acre) + Roundup PowerMAX® herbicide (1 qt/acre) + AMS (17 lb/100 gallon)
- A non-dicamba treated control:
- Trial was sprinkler irrigated.
- Fertility program applied through strip-tillage before planting included 60 lb/acre phosphorus, 25 lb/acre sulfur, and 0.25 lb/acre zinc. Nitrogen was applied on 05/10/2021 using a stream bar at 100 lb/acre and side-dressed on 06/21/2021 with 60 lb/acre using 360 Y-DROP®.
UNDERSTANDING THE RESULTS
Figure 1. Average yield by different dicamba herbicide formulations and corn growth stage across corn products.
Early planted corn (May 5) did not have a difference in grain yield between the safened dicamba formulation and the control treatment (Figure 1).
Corn products with the safened dicamba formulation produced an average 9.7 and 6.8 bu/acre greater yield than the unsafened dicamba formulation treatment when corn was planted on May 5 and May 25, respectively (Figure 1).
Greater average yields were observed when corn was planted early (May 5) compared to late (May 25) (Figure 1 and Table 1).
Although planting corn late (May 25) reduced average grain yield significantly, it is important to consider that the safened dicamba formulation had significantly higher average yields than the unsafened dicamba formulation when applied to the May 5 corn at the V9 growth stage with a similar trend observed on the corn planted on May 25 at the V5 growth stage (Figure 1).
Table 1. Average grain yield of corn products according to planting date and averaged across dicamba treatments. Bayer Water Utilization Learning Center, Gothenburg, NE. (2021)
- All corn products reached significantly higher average yields with the May 5 planting date compared to the May 25 planting date (Table 1).
- Greater average yield variability was observed with May 5 planting date with five products over 290.0 bu/acre and a low average yield of 246.8 bu/acre.
- Average yields were less variable across the corn products with the May 25 planting date (Table 1).
Table 2. Average grain yield of corn products according to dicamba herbicide formulation treatments across planting dates. Bayer Water Utilization Learning Center, Gothenburg, NE (2021)
- Eight out of 20 corn products reached significantly higher yields (more than 10 bu/acre) when treated with the safened versus the unsafened dicamba formulation (Table 2). No corn product reached significantly higher yields when treated with the unsafened compared to the safened dicamba formulation (Table 2).
KEY LEARNINGS
- In this study, the safened dicamba formulation treatment with DiFlexx® Herbicide produced a greater average yield than the unsafened dicamba formulation.
- In addition, the safened dicamba formulation showed greater average yield in 40% of the products tested when compared to the unsafened dicamba formulation.
- Farmers should be encouraged to use DiFlexx® herbicide as an option for early weed control in corn to help lower the risk for potential crop damage and decreased yield that can be observed when using unsafened dicamba herbicide products.
- Preference should be given to planting corn early such as the May 5 planting date as it increased yield 33.9 bu/acre, on average, for all corn products tested compared to the May 25 planting date.
Reference
1Bayer Water Utilization Learning Center Research Book. 2020. Dicamba Formulation Impact on Corn. Gothenburg, NE.
Dicamba Formulation Impact on Corn - 2020
TRIAL OBJECTIVE
Dicamba, a growth regulator, is an effective herbicide for early weed control in corn. However, using a dicamba formulation that doesn’t contain a safener can cause brace root abnormalities (fusing) and increased stalk brittleness.1 These injuries can lead to an increase in greensnap, root lodging, and a subsequent decrease in corn yield.
The objective of this study was to determine the effect of safened versus unsafened dicamba products on plant health and yield of corn.
RESEARCH SITE DETAILS
| Location | Gothenburg, NE | ||
| Soil Type | Hord silt loam | ||
| Previous Crop |
Corn | ||
| Tillage Type |
Strip till |
| Planting Date | 4/30/20 | ||
| Harvest Date | 10/31/20 | ||
| Potential Yield (bu/acre) |
250 | ||
| Seeding Rate (seeds/acre) |
36,000 |
- The study was setup as a split-plot design with herbicide treatments as the whole plot and corn products as the sub-plot with four replications.
- The three herbicide treatments were a non-dicamba treated check, an unsafened dicamba product application, and a safened dicamba product application.
- The unsafened dicamba formulation was Sterling Blue® herbicide at a rate of 0.5 qt/acre.
- The safened dicamba formulation was DiFlexx® herbicide at a rate of 0.5 qt/acre.
- All dicamba treatments, including the non-dicamba check, were applied on 6/24/20 in combination with Delaro® 325 SC fungicide (0.125 qt/acre), Roundup PowerMAX® herbicide (1 qt/acre), and AMS (17 lb/100 gallon) at the V6 growth stage of corn.
- Five corn products were used in this study.
- 104 relative maturity (RM) and 107-RM corn products with growth regulator herbicide injury ratings of CAUTION.
- 105-RM, 109-RM and 113-RM corn products with growth regulator herbicide injury ratings of ACCEPTABLE.
- All treatments received herbicide applications of Roundup PowerMAX herbicide (32 oz/acre), Harness® herbicide (2 pt/acre), Balance® Flexx herbicide (3 pt/acre), and Atrazine 4L herbicide (32 oz/acre) on 5/1/20.
- Corn was sprinkler irrigated and fertilized with 70 lb phosphorus/acre, 15 lb sulfur (S)/acre, and 27.5 lb nitrogen (N)/acre via strip till on 4/26/20; 100 lb N/acre applied 4/28/20 using Stream Bars; and 15 lb S/acre and 90 lb N/acre applied sidedress on 6/26/20 with 360 Y-DROP® applicators.
Shelled corn weight, moisture, and test weight were collected to calculate average yield. Corn greensnap counts were taken to determine the percent greensnap.
Figure 1. Corn product on August 17, 2020 with the safened dicamba formulation treatment of DiFlexx® herbicide.
UNDERSTANDING THE RESULTS
Figure 2. Average corn yield with unsafened and safened dicamba herbicide products.
Figure 3. Greensnap percentage impact from unsafened and safened dicamba herbicide products averaged across corn products.
Table 1. Average greensnap percentage and yield for each corn product under different dicamba herbicide formulation treatments.
For this trial, the safened dicamba formulation treatment of DiFlexx® herbicide produced an average corn yield that was significantly greater than the unsafened dicamba formulation herbicide treatment (Figure 2).
Corn greensnap percentage was significantly higher for the unsafened dicamba formulation treatment compared to the safened DiFlexx herbicide treatment and the non-treated check (Figure 3).
The greater percentage of greensnap in the unsafened dicamba formulation treatment was likely a result of stalk brittleness that directly reduced corn yield.
There was little difference in percent greensnap between corn products with CAUTION and ACCEPTABLE growth regulator herbicide injury ratings (Table 1).
KEY LEARNINGS
Unsafened dicamba formulation products can have the potential to cause corn to greensnap at a higher rate than corn treated with safened dicamba formulation products.
Farmers are encouraged to use safened dicamba formulation products like DiFlexx® herbicide as an option for early weed control in corn to help lower the risk of crop damage and decreased yield potential that can be observed when using unsafened dicamba herbicide products.
Source:
1Clay, S. 2016. Chapter 42: Herbicide injury to corn. In Clay, D., Carlson, C., Clay, S., and Byamukama, E. (eds). iGrow Corn: Best Management Practices. South Dakota State University. https://extension.sdstate.edu.
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