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: | John Linville |
| County of Site: | Champaign |
| Nearest Town: | Woodstock |
| Major Soil Type: | Brookston Silty Clay Loam |
| Drainage (List Type): | N/A |
| Irrigation: | No |
| Tillage: | None |
| Previous Crop: | Corn |
| Soil Test: | pH N/A P N/A K N/A |
| Fertilizer Applied: | N/A |
| Herbicide Program: | Listed in table |
| Plant Population: | 200,000 seeds per acre |
| Plant Population @Harvest: | N/A |
| Variety: | Pioneer 9396 (Roundup-Ready) |
| Planting Date: | May 11, 1997 |
| Harvest Date: | October 11, 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 23 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 2.0" for 1/4X rate, 3.5" for 1/2X rate, and 6.5" 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. | Vol. Corn | Velvetleaf | |||||
| 1. Canopy (EPP) 1/2X | - 23 | ||||||||
| (POST) 1/4X | < 1 | 40 | 89 | 89 | 94 | 67 | 23.78 | ||
| 2. Canopy (EPP) 1/2X | - 23 | ||||||||
| (POST) 1/2X | < 2 | 47 | 94 | 99 | 99 | 63 | 26.00 | ||
| 3. Canopy (EPP) 1/2X | - 23 | ||||||||
| (POST) 1X | 3-5 | 57 | 100 | 100 | 96 | 66 | 30.44 | ||
| 4. Squadron (EPP) 1/2X | - 23 | ||||||||
| (POST) 1/4X | < 1 | 40 | 86 | 90 | 83 | 69 | 28.72 | ||
| 5. Squadron (EPP) 1/2X | - 23 | ||||||||
| (POST) 1/2X | < 2 | 47 | 97 | 100 | 96 | 67 | 30.94 | ||
| 6. Squadron (EPP) 1/2X | - 23 | ||||||||
| (POST) 1X | 3-5 | 57 | 99 | 100 | 83 | 67 | 35.38 | ||
| 7. Squadron (EPP) 1X | - 23 | 84 | 20 | 83 | 66 | 29.16 | |||
| 8. Roundup (POST) 1X | 3-5 | 51 | 97 | 100 | 99 | 66 | 23.21 | ||
| LSD (0.05%) | 5 | 2 | 10 | NS | |||||
| 1 Abbreviations: Height = broadleaf weed height, DAP = days after planting, An. Gr. = annual grass (giant foxtail, barnyardgrass, and fall panicum), Vol. Corn = volunteer corn, bu/A = bushels per acre, EPP = early pre-plant application, POST = post-emergence application, LSD = least significant difference, NS = no significant difference. | |||||||||
| 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 to moderate. In treatments 4 and 6, some velvetleaf plants were nearly two times taller than were targeted at time of application because the lower control provided by Squadron and Roundup was less effective on these plants. 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.
For additional information, contact:
Jeff Stachler and Dr. Mark Loux
Kottman Hall
The Ohio State University
2021 Coffey Road
Columbus, OH 43210
614-292-1393 or 614-292-9081
stachler.1@osu.edu or loux.1@osu.edu