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 Shawhan |
| County of Site: | Greene |
| Nearest Town: | Selma |
| Major Soil Type: | Celina Silt 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: | 240,000 seeds per acre |
| Plant Population @Harvest: | N/A |
| Variety: | Settlemyre 3795 |
| Planting Date: April 26, 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 four days prior to planting. The 1X Canopy rate was 6.0 oz/A and 1X Squadron rate was 3.0 pt/A. For treatments 1 and 4, only Select + Prime Oil (COC) at 2.0 oz/A + 1.0%v/v was applied as no broadleaf weeds were present. The post-emergence application of Basagran + Flexstar + Select + Priority MSO + 28% Nitrogen at the 1X rate was 1.0 pt/A + 1.0 pt/A + 8.0 floz/A + 1.0%v/v + 2.5%v/v and was applied at the listed rate to treatments 2, 3, 5, 6, and 8.
| Treatment and Rate1 | Treatment Timing1 | Weed Control on July 24, 19971 (----- % -----) | Soybean Yield1 (bu/A) | Treatment Cost2 ($/A) | ||
|---|---|---|---|---|---|---|
| Height (inch) | DAP | An. Gr. | H. Milk. | |||
| 1. Canopy (EPP) 1/2X | - 4 | |||||
| (POST) 1/4X | < 1 | 32 | 64 | 0 | 64 | 17.86 |
| 2. Canopy (EPP) 1/2X | - 4 | |||||
| (POST) 1/2X | < 2 | 55 | 78 | 27 | 63 | 31.19 |
| 3. Canopy (EPP) 1/2X | - 4 | |||||
| (POST) 1X | 3-5 | 72 | 98 | 77 | 62 | 46.95 |
| 4. Squadron (EPP) 1/2X | - 4 | |||||
| (POST) 1/4X | < 1 | 32 | 75 | 0 | 64 | 22.80 |
| 5. Squadron (EPP) 1/2X | - 4 | |||||
| (POST) 1/2X | < 2 | 55 | 77 | 23 | 66 | 36.13 |
| 6. Squadron (EPP) 1/2X | - 4 | |||||
| (POST) 1X | 3-5 | 72 | 96 | 67 | 62 | 51.89 |
| 7. Squadron (EPP) 1X | - 4 | 76 | 0 | 63 | 29.16 | |
| 8. Roundup (POST) 1X | 3-5 | 59 | 83 | 29 | 62 | 39.72 |
| LSD (0.05%) | 10 | 15 | NS | |||
| 1 Abbreviations: Height = annual grass height, DAP = days after planting, An. Gr. = annual grass (giant foxtail), H. Milk. = honeyvine milkweed, 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) and application cost at $2.00/A/application. | ||||||
The annual grass pressure was moderate to heavy and the annual broadleaf
pressure was nearly non-existent. Only treatments 3, 6, and 8 provided
greater than 82% annual grass control on July 24, but all treatments
except treatment 1 provided greater than 82% annual grass control on
September 29 (data not shown). This improvement in control over time was
apparently due to effects of disease on the small grasses, promoted by
large amounts of rain in July and August. This may explain why there was
no significant difference in yield, despite the poor control recorded in
July.
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