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Yield potential is typically the primary characteristic for corn product selection. Protecting yield potential with a combination of cultural practices, pest control traits, and pesticides can be a challenge. Farmers selecting corn products with above- and/or below-ground Bacillus thuringiensis (B.t.) traits must also consider the effort, the cost, and the benefits of establishing a required refuge. With an effective insect resistance management (IRM) plan in place, farmers can benefit from effective and consistent insect protection and the yield potential offered by crops containing B.t. technologies.
First and foremost, the Environmental Protection Agency (EPA) mandates the planting of a refuge wherever B.t. technologies are used. The continued availability of B.t. technologies depends on grower compliance with EPA registration requirements. Refuge acres or individual plants do not contain B.t. insect protection within their genetics.
The main purpose of a refuge is to maintain a population of the specific family of insect pests (examples: European corn borer (ECB) and Southwestern corn borer (SWCB)) that are not exposed to B.t. proteins. This lack of exposure allows susceptible insects emerging from the refuge to mate with any rare B.t.-resistant insects that may emerge from the B.t. corn. Susceptibility to B.t. technology would then be passed on to their offspring, helping to preserve the long-term effectiveness of B.t. technologies.
To help reduce the risk of insects developing resistance, the refuge should be planted with a similar maturity non-B.t. corn product at the same time as the corn crop containing B.t. technologies. As an alternative to structured refuges, many B.t. corn products in the Corn-Growing Area are available for purchase with a blend of B.t. and non-B.t. seed.
Single-bag solutions for refuge management enables farmers in the Corn-Growing Area to simplify planting and help ensure refuge compliance. Farmers who purchase refuge-in-a-bag products can open a bag, plant the seed, and automatically meet EPA requirements. Farmers who have planted refuge-in-a-bag products have attributed a value of about $5/acre for the convenience. Simplified crop planning, inventory management, seed handling, flexibility with planting, and automatic EPA compliance are among the reasons provided for the attributed value.
Depending on the refuge-in-a-bag product, the amount of refuge seed within the unit of seed varies from 5 to 10%. This represents a reduction in the refuge requirement compared to the acreage required for structured refuges.
Genuity® RIB Complete® Corn Blend trait options for the Corn-Growing Area:
Farmers purchasing non-blended B.t. corn products are required to plant an EPA qualifying structured refuge. Structured refuges can be planted in a variety of patterns, from strips within the field to blocks in adjacent fields, but must adhere to IRM guidelines as established by the EPA for the specific B.t. corn product.
A single-pest refuge is a single field (or portion of) that serves solely as a qualified refuge for above-ground pests like ECB, or below-ground pests like CRW, but not both. Each single-trait B.t. product requires its own individual refuge. For stacked B.t. trait corn products, a common refuge is a single field (or portion of) that serves as a qualified refuge for both above- and below-ground pests. Another option for stacked trait corn products requires two fields, one which is adjacent to or within the B.t. field that serves as a qualified refuge for below-ground pests, and a separate field (up to 1/2 mile away) that serves as a qualified refuge for above-ground pests. Various B.t. corn products require from 5 to 20% structured refuges in the Corn-Growing Area and up to 50% in the Cotton-Growing Area.
Several companies offer blend and non-blend corn products with insect protection traits. Regardless of brand, each B.t. protected product should be planted according to its individual refuge requirements. Only Genuity® SmartStax® RIB Complete® Corn Blend offers multiple modes of action for both above- and below-ground insect pests, and seeds that are treated with Acceleron® Seed Treatment Products and Poncho® 500/VOTiVO®. Farmers should carefully evaluate the costs and benefits of each corn product for planting.
Questions farmers should consider include: