Remember Your Refuge When Planting Bt Corn

— Written By Carrie Ortel

Remember to plant at least 20% of your corn acres to refuge hybrids (non-Bt varieties). The purpose of the refuge area is to prevent pests from developing resistance to the technology.

Requirements vary based on the exact Bt gene used, this generalizes the requirements to make sure you meet the requirements. All Bt corn products require implementation of an insect resistance management (IRM) program according to the refuge size, guidelines on planting requirements and insecticide usage are described below.

Refuge Planting Requirements:

  1. At least 20% of your corn acres to non-Bt corn. When a single Bt gene is used, 50% of your corn must be a non-Bt refuge
  2. Must be within a 1/2 mile of refuge hybrids
  3. Must be planted in the same field or adjacent to refuge hybrids. This can be done in blocks or strips (as long as strips are at least 4 rows wide within Bt corn field)
  4. Appropriate refuge must be planted on every Bt corn farm

Refuge Insecticide Requirements:

  1. Must be at economic thresholds in order to spray conventional pesticides
  2. Bt-based sprayable insecticides cannot be used on the refuge corn

Remember, the reason for the refuge is to keep a non-resistant population.

Example from Bayer

Example Refuge Field Design from Bayer Crop Science. See complete article in additional links.

Reasons it’s Important:

  1. Without a refuge the resistant populations will thrive and reproduce, leading to complete resistance.
  2. You need to keep non-resistant populations in your field to avoid population selection of resistant genes.
  3. Its a requirement, and you will be held responsible by the seed companies.
Corn Earworm

Corn Earworm Photo: Dr. Dominic Reisig

Links to Additional Information: