Chapter 13

Weed Management for Organic Crops

(book excerpts)

Weed management continues to be one of the biggest challenges for organic field crop producers. Weeds can be considered a significant problem because they tend to decrease crop yields by increasing competition for water, sunlight, and nutrients while serving as host plants for pests and diseases. Farmers who wish to become organically certified are restricted from using synthetic herbicides for weed control under the Organic Foods Production Act of 1990 and the National Organic Program (NOP), Section 7 of the Code of Federal Regulations (CFR), Part 205, also known as the NOP Final Rule. They meet this challenge by selecting from a wide range of acceptable techniques and strategies, all with the goal of achieving economically acceptable weed control and crop yields. The primary weed control strategies for organic systems are cultural and mechanical, focusing on prevention, crop rotation, crop competition, and cultivation. Organic weed management is a holistic system involving an entirely different approach to managing a farming system. The organic farmer is not interested in eliminating all weeds but wants to keep the weeds at a threshold that is both economical and manageable. A farmer who manages weeds organically must be intimately familiar with the type of weeds and their growth habits to determine which control methods to employ.

Click on the following topics for more information on weed management for organic crops.

Topics Within This Chapter:

  • Introduction to Weed Management for Organic Crops
  • Weed Biology
  • Life Cycle of Weeds
  • Annuals
  • Biennials
  • Perennials
  • Reproduction in Weeds
  • Weed Seed Banks
  • Weed Emergence
  • Weed Monitoring
  • How to Scout for Weeds
  • Unmanned Aerial Vehicles (UAVs) for Monitoring Weeds
  • Maintaining Accurate Weed Records
  • Crops' Minimum Weed-free Periods
  • Cultural Weed Control
  • Managing Weeds with Cover Crops
  • Cover Crops as Living Mulches
  • Allelopathic Cover Crops
  • Role of Crop Rotation in Weed Management
  • Weed Management Practices before Planting
  • Stale (or False) Seedbed Tillage
  • Selecting Varieties that Better Compete with Weeds
  • Altering the Planting Dates to Control Weeds
  • Adjusting Seeding Rate to Control Weeds
  • Mulches for Weed Control
  • Advantages and Disadvantages of Mulching
  • Synthetic Mulches
  • Organic Mulches
  • NOP Guidelines for Using Mulches and Weed Barriers
  • Mechanical Weed Control
  • Tillage
  • Primary Tillage
  • Secondary Tillage
  • Cultivation
  • Tillage and Cultivation Practices in Managing Weeds
  • Annuals
  • Perennials
  • Mowing
  • Rowing/Crimping
  • Controlling Weeds by Cultivation
  • Blind Cultivation
  • Crops Suitable for Blind Cultivation
  • Timing of Blind Cultivation
  • Weeds Susceptible to Blind Cultivation
  • Implements Used for Blind Cultivation
  • Weed Management After Planting
  • In-row Cultivation
  • Between-row Cultivation
  • Weather and Soil Conditions Suitable for Cultivation
  • Flame Weeding
  • Advantages and Disadvantages of Flame Weeding
  • Timing of Flame Weeding
  • Flame Weeding Treatments
  • Non-selective Flame Weeding
  • Selective Flame Weeding
  • Equipment Used for Flame Weeding
  • Soil Solarization for Weed Control
  • Mechanism of Soil Solarization
  • Time of Solarization
  • Methods of Solarization
  • Broadcast Solarization
  • Strip Solarization
  • Solarization Practices for Controlling Weeds
  • Chemical Weed Control
  • NOP Requirements for Using Herbicide Products
  • Application Techniques
  • Types of Herbicides Used for Organic Weed Control
  • Acetic Acid (Vinegar)
  • Corn Gluten Meal
  • Cinnamon Oil
  • Citrus Oils and Extracts
  • Clove Oil
  • Lemongrass Oil
  • Adjuvants Approved for Organic Weed Control
  • References