Herbicide Recommendations for Soybeans: Postemergence Broadleaf Herbicides

Table of Contents

1. Basagran Forté
2. Blazer
3. Blazer + Assist
4. Classic + non-ionic surfactant
5. Firstrate + non-ionic surfactant + liquid fertilizer
6. Pinnacle + non-ionic surfactant
7. Reflex + Turbocharge
8. Soybean Herbicide Weed Control Ratings (Table 11-1) (PDF file - 59 kb)
   • Annual Grasses
   • Broadleaf Weeds
   • Perennial Weeds
9. Other Soybean Weed Control Recommendations
   • Pre-Plant Burndown and Residual Control
   • Soil Applied Grass Herbicides
   • Soil Applied Broadleaf Herbicides
   • Soil Applied Grass and Broadleaf Herbicides
   • Soil Applied Tank-mix Options
   • Postemergence Grass Herbicides
   • Postemergence Grass and Broadleaf Herbicides
   • Postemergence Grass and Broadleaf Herbicides - Roundup Ready (glyphosate tolerant) varieties only
   • Postemergence Tank-mix Options
   • Spot Treatment
   • Wick Wiper and Roller Application
   • Preharvest
10. Stages of Soybean Leaf Development
11. Related Links

Precautions

• Apply when soybeans are in unifoliate to 4th trifoliate leaf stage and when weeds are small and actively growing.
• Temporary crop injury may occur under abnormally hot, humid conditions.
• Cool weather or drought may delay control.
• For improved and more consistent control of velvetleaf and lamb's-quarters, 10 L/ha of 28% urea ammonium nitrate (UAN) or 6 L/ha of liquid ammonium sulphate may be added. The addition of either nitrogen source may cause slight leaf burn, but new growth is normal and crop vigour is not reduced.
• Use the higher rate of Basagran Forté when weed pressure is high, weeds are large or conditions for activity are unfavourable.

Precautions

• Apply to emerged weeds up to 10 cm in height (refer to labels for weed heights) when soybeans are in the 1-3 trifoliate leaf stage.
• Do NOT apply before the first trifoliate leaf stage of the soybeans.
• Good spray coverage on the weeds is important for good weed control.
• Soybeans may exhibit speckling, bronzing and/or leaf burn. The trifoliate leaf emerging at the time of application may be distorted. Soybeans usually outgrow these conditions and continue to grow at a normal rate with no adverse effect on vigour, maturity, or crop yield.
• Do NOT apply Blazer to soybeans that have been subjected to stress (see product label).
• Do NOT add oils or surfactants to applications of Blazer at 2.5 L/ha alone.

Precautions

• Apply to emerged redroot pigweed up to and including the 4-leaf stage and to common ragweed up to and including the 8-leaf stage when soybeans are in the 1-3 trifoliate leaf stage.
• Do NOT apply before the first trifoliate leaf stage of the soybeans.
• Good spray coverage on the weeds is important for good weed control.
• Soybeans may exhibit speckling, bronzing and/or leaf burn. The trifoliate leaf emerging at the time of application may be distorted. Soybeans usually outgrow these conditions and continue to grow at a normal rate with no adverse affects on vigour, maturity or crop yield.

Precautions

• Optimal timing for broadleaf control is when the soybeans are in the 1-3 trifoliate stage of growth. Applications may occur prior to the 1st trifoliate leaf stage of soybean if targeted weed species are at the maximum leaf stage for control.
• Do NOT apply before the first trifoliate is fully expanded or after the initiation of flowering.
• Addition of 28% UAN is recommended for improved control of velvetleaf.
• Some rotational cropping restrictions apply (see Table 4-4.).

Precautions

• Apply up to the 8-leaf stage for common ragweed and cocklebur, 6-leaf stage for giant ragweed, and 4-leaf stage for velvetleaf.
• Apply any time prior to flowering stage of soybeans.
• Application prior to full emergence of first trifoliate may cause temporary yellowing of soybeans.

Precautions

• Apply to emerged weeds up to 10 cm in height when soybeans have the first trifoliate leaf fully expanded. Applications may occur prior to the 1st trifoliate leaf stage if targeted weed species are at the maximum leaf stage for control.
• Do NOT apply to soybeans, which have initiated flowering.
• Use the higher rate for lamb's-quarters and velvetleaf.
• The addition of UAN (28-0-0) at 4% v/v will enhance the control of velvetleaf.

Precautions

• Apply early postemergence at 1-2 trifoliate to crop when weeds are small and actively growing (2-4 leaf stage).
• Use 200-350 L/ha (80-140 L/ac) water. Use higher rates of water and pressure for a heavy weed or crop canopy.
• Some bronzing may occur to soybean leaves at the time of application, but plants outgrow these effects without harming maturity or yield.
• Do NOT apply Reflex to any field more often than once every 2 years.
• Do NOT apply to soybeans under stress.
• Some rotational cropping restrictions apply Table 4-4 (PDF - 82K).

Related Links

• Weeds in Ontario
• Soybeans in Ontario
• Problem Weed Control in Field Crops
• Pesticide Application and Safety
• Pesticide Companies and Agents
• OMAFRA Sprayer Calibration Calculator
• Search the PMRA website
• OMAFRA Publication 505: Ontario Weeds
• OMAFRA Publication 75: Guide To Weed Control