Use 0.5 to 4 ounces of atrazine per gallon of water for most applications

Atrazine mixing rates vary by target weeds and application type. For general pre-emergence or post-emergence control, use 0.5-4 oz per gallon (1-4 lbs per acre). Always follow label instructions for crop-specific rates, as corn, sorghum, and non-crop areas require different concentrations. Water volume typically ranges from 10-40 gallons per acre for even coverage.

Standard Atrazine Mixing Rates by Use Case

  • Pre-emergence (soil-applied): 1-2 oz/gallon (2-4 qt/acre). Targets annual grasses/broadleaf weeds before germination.
  • Post-emergence (early weed growth): 0.5-1 oz/gallon (1-2 qt/acre). Combine with a non-ionic surfactant for better absorption.
  • Non-crop areas (e.g., industrial sites): Up to 4 oz/gallon (4 lbs/acre). Higher rates for persistent weeds like pigweed or ragweed.
  • Tank mixes: Reduce to 0.25-0.75 oz/gallon when combined with other herbicides (e.g., glyphosate or 2,4-D).

Atrazine Mixing Guide: Rates vs. Water Volume

Application Type Atrazine per Gallon Total Water Volume (per acre) Target Weeds Notes
Pre-emergence (field crops) 1-2 oz 20-30 gallons Crabgrass, foxtail, lambsquarters Apply before weed seeds germinate. Incorporate lightly into soil.
Post-emergence (corn/sorghum) 0.5-1 oz 10-20 gallons Pigweed, ragweed, cocklebur Add 0.25% surfactant. Avoid spraying in temperatures above 85°F.
Non-crop/industrial 2-4 oz 30-40 gallons Perennial broadleaves, tough grasses Higher rates may require split applications. Check local regulations.

Key Factors Affecting Atrazine Rates

  • Soil type: Sandy soils may need lower rates (0.5-1 oz/gallon); clay soils can handle up to 2 oz/gallon.
  • Weed size: Post-emergence applications require higher rates for weeds over 4 inches tall.
  • Crop tolerance: Corn tolerates up to 2.5 lbs/acre; sorghum maxes at 2 lbs/acre. Avoid drift to sensitive plants.
  • Rainfall: Apply pre-emergence atrazine before rain (within 7 days) to activate it. Post-emergence needs 6-8 hours of dry weather.

Safety and Handling Tips

  1. PPE required: Wear chemical-resistant gloves, goggles, and long sleeves during mixing/spraying.
  2. Mixing order: Fill spray tank halfway with water, add atrazine, then agitate before adding other herbicides.
  3. Storage: Keep in original containers at 40-90°F. Avoid freezing or direct sunlight.
  4. Disposal: Triple-rinse empty containers. Dispose of wastewater at an approved facility.

Common Mistakes to Avoid

  • Using metal containers for mixing (corrosion risk). Use plastic or stainless steel.
  • Applying atrazine to wet leaves (reduces absorption). Spray in early morning or late afternoon.
  • Exceeding 4 lbs/acre annually (can lead to crop injury or environmental harm).
  • Skipping a jar test when tank-mixing with other herbicides (may cause precipitation).