Determine if reduced rates of herbicides can provide adequate weed control and show no yield loss in no-tillage soybean utilizing pre-emergence and post-emergence herbicide applications.
| Cooperator: | Jim Patton |
| County of Site: | Logan |
| Nearest Town: | Belle Center |
| Major Soil Type: | Paulding Clay |
| Drainage (List Type): | N/A |
| Irrigation: | No |
| Tillage: | None |
| Previous Crop: | Soybean |
| Soil Test: | pH N/A P N/A K N/A |
| Fertilizer Applied: | N/A |
| Herbicide Program: | Listed in table |
| Plant Population: | 210,000 seeds per acre |
| Plant Population @Harvest: | N/A |
| Variety: | Asgrow 3301 (Roundup-Ready) |
| Planting Date: | May 14, 1997 |
| Harvest Date: | October 15, 1997 |
The plot size for this study was 20 feet wide and 300 feet in length. Each treatment was replicated three times. 2,4-D ester at 1.0 pt/A plus Prime Oil (COC) was added to treatments 1-7 and applied alone to treatment 8 to control existing weeds 29 days prior to planting. The 1X Canopy rate was 6.0 oz/A and 1X Squadron rate was 3.0 pt/A. The post-emergence application of Roundup Ultra at 1X rate was 1.5 pt/A and applied based upon the broadleaf weed height listed in the table. Annual grass height was 1.25" for 1/4X rate, 3.5" for 1/2X rate, and 7.0" for 1X rate.
| Treatment and Rate1 | Treatment Timing1 | Weed Control on August 4, 19971 (--- % ---) | Soybean Yield1 (bu/A) | Treatment Cost2 ($/A) | |||
|---|---|---|---|---|---|---|---|
| Height (inch) | DAP | An. Gr. | C. Rag. | ||||
| 1. Canopy (EPP) 1/2X | - 29 | ||||||
| (POST) 1/4X | < 1 | 33 | 87 | 100 | 53 | 23.78 | |
| 2. Canopy (EPP) 1/2X | - 29 | ||||||
| (POST) 1/2X | < 2 | 40 | 98 | 100 | 52 | 26.00 | |
| 3. Canopy (EPP) 1/2X | - 29 | ||||||
| (POST) 1X | 3-5 | 49 | 100 | 100 | 53 | 30.44 | |
| 4. Squadron (EPP) 1/2X | - 29 | ||||||
| (POST) 1/4X | < 1 | 33 | 85 | 92 | 53 | 28.72 | |
| 5. Squadron (EPP) 1/2X | - 29 | ||||||
| (POST) 1/2X | < 2 | 40 | 97 | 96 | 53 | 30.94 | |
| 6. Squadron (EPP) 1/2X | - 29 | ||||||
| (POST) 1X | 3-5 | 49 | 98 | 99 | 53 | 35.38 | |
| 7. Squadron (EPP) 1X | - 29 | 77 | 55 | 52 | 29.16 | ||
| 8. Roundup (POST) 1X | 3-5 | 42 | 98 | 100 | 52 | 23.21 | |
| LSD (0.05%) | 6.5 | 7 | NS | ||||
| 1 Abbreviations: Height = broadleaf weed height, DAP = days after planting, An. Gr. = annual grass (giant foxtail, yellow foxtail, and fall panicum), C. Rag. = common ragweed, bu/A = bushels per acre, EPP = early pre-plant application, POST = post-emergence | |||||||
| 2 Treatment cost = cost of all herbicides and additives (including burndown), application cost at $2.00/A/application, and Roundup-Ready technology fee of $7.50/A. | |||||||
The weed pressure in this study was light. The reduced annual grass control in treatments 1 and 4 is due to the lack of rapid soybean canopy closure after application, because the soybeans were only at the second trifoliate at application. Despite the lower weed control in treatments 1, 4, and 7, there was no significant reduction in yield.
For additional information, contact:
Jeff Stachler and Dr. Mark Loux