Soybeans: Introduction

Introduction

• All treatments should be applied in 150-300 L/ha (60-120 L/ac) water unless otherwise specified.
• Thoroughly clean all equipment used to apply Accent, Accent 1-Pass, Accent Total, Banvel ii, Battalion, Distinct, Lontrel, Marksman, MCPA, Oracle, Peakplus, Shotgun, Summit, Summit Extra, 2,4-D and other related herbicides immidiately after use, as well as before spraying soybeans. See "Cleaning the Sprayer" section.
• Total Weed Control System - Although herbicides themselves may be effective, there is benefit in using all the various weed control methods available to obtain the best weed control possible. Crop rotation, herbicide rotation, early weed control with a rotary hoe, harrowing, cultivating and preventing the spread of weeds as much as possible are all a part of weed management. See the corn section for some details of each of these methods.
• Triazine Residues - When soybeans follow corn treated with triazines such as atrazine or simazine the previous year, and if triazine residues remain they may interact with a number of herbicides used for weed control in soybeans to cause crop injury. Examples of soybean herbicides, which may be involved, include the triazine based herbicide metribuzin (Sencor) or the substituted urea herbicides (Lorox). The potential for injury is greater during adverse weather conditions, in shorter season soybean growing areas and/or in soils with a high pH. Do not confuse herbicide injury symptoms with cold injury symptoms. Also see "Atrazine and Simazine Soil Residues" .
• Resistant Weeds - Biotypes of a number of weeds have been found resistant to Group 5 (triazine) and Group 2 herbicides. Refer to the section "Managing Weed Resistance to Herbicides" for management and control strategies for these weeds.
• Specific Weeds - For information on specific weeds see the Soybean Herbicide Weed Control Ratings Table. Then refer to the appropriate section for details about herbicide treatments.
• Herbicide Application Timings:
  • HerbicideTreatments include:
    • Preplant (PP) - See Chapter 6 Special Methods: Preplant - Site Preparation Prior to Any Crop for details of products, rates and remarks.
    • Preplant Incorporated (PPI) - Two incorporations at right angles operating at a depth of 10 cm using a double disk (7-10 km/hr) or vibrating shank S-tine cultivator (10-13 km/hr) are required unless otherwise stated. Cultivation-type equipment used for herbicide incorporation is known to spread perennial weeds to previously uninfested areas. Ensure machines are clean and/or treat fields with perennial weeds last.
    • Preemergence (PRE) - Rainfall of 15-20 mm within 10 days after application is necessary to activate preemergence treatments. Shallow cultivation, rotary hoeing or harrowing will control weed escapes and improves herbicide activity in the absence of rainfall.
  • Postemergence (POST) - Leaf stage of the weeds is critical for good weed control. Smaller weeds are usually more sensitive to herbicide injury. Apply according to recommended leaf stages. Crop stage is important to optimize crop safety. Adjuvants will frequently improve the weed control when used as directed. Weather or other conditions may influence the optimum rate of adjuvant, see the product label for more details. Always use appropriate drift management technology.

Related Links

• Weeds in Ontario
• Soybeans in Ontario
• Problem Weed Control in Field Crops
• Integrated Pest Management (IPM)
• 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

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