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: | Bob Swetland |
| County of Site: | Morrow |
| Nearest Town: | Sparta |
| Major Soil Type: | Bennington 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: | 223,000 seeds per acre |
| Plant Population @Harvest: | N/A |
| Variety: | Pioneer 9393 |
| Planting Date: | May 13, 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 22 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 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 applied based on broadleaf weed height as listed in the table. Annual grass height was 1.25" for 1/4X rate, 3.0" for 1/2X rate, and 6.0" for 1X rate.
| Treatment and Rate1 | Treatment Timing1 | Weed Control on August 6, 19971 (---- % ----) | Soybean Yield1 (bu/A) | Treatment Cost2 ($/A) | ||
|---|---|---|---|---|---|---|
| Height (inch) | DAP | An. Gr. | An Br. | |||
| 1. Canopy (EPP) 1/2X | - 22 | |||||
| (POST) 1/4X | < 1 | 43 | 99 | 97 | 57 | 23.31 |
| 2. Canopy (EPP) 1/2X | -22 | |||||
| (POST) 1/2X | < 2 | 48 | 100 | 100 | 60 | 31.19 |
| 3. Canopy (EPP) 1/2X | - 22 | |||||
| (POST) 1X | 3-5 | 60 | 99 | 99 | 58 | 46.95 |
| 4. Squadron (EPP) 1/2X | - 22 | |||||
| (POST) 1/4X | < 1 | 37 | 90 | 82 | 57 | 28.25 |
| 5. Squadron (EPP) 1/2X | - 22 | |||||
| (POST) 1/2X | < 2 | 41 | 96 | 92 | 59 | 36.13 |
| 6. Squadron (EPP) 1/2X | - 22 | |||||
| (POST) 1X | 3-5 | 48 | 100 | 93 | 57 | 51.89 |
| 7. Squadron (EPP) 1X | - 22 | 71 | 80 | 55 | 29.16 | |
| 8. Roundup (POST) 1X | 3-5 | 48 | 99 | 95 | 53 | 39.72 |
| LSD (0.05%) | 5.6 | 8 | NS | |||
| 1 Abbreviations: Height = annual broadleaf height, DAP = days after planting, An. Gr. = annual grass (giant foxtail and fall panicum), An. Br. = annual broadleaf weeds (giant ragweed, common ragweed, and velvetleaf), 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 light to moderate. All treatments provided greater than 91% control of weeds except for treatments 4 and 7. Despite this lower control, there was no significant yield reduction. There was great variability in soybean stand caused by Phytophthora root rot, which is why there was no significant yield reduction where weed control was reduced.
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