Guidelines  |   IRM




U.S. Environmental Protection Agency (EPA) regulations require each grower who plants Herculex XTRA, Herculex XTRA with Roundup Ready2, Herculex I, Herculex I with Roundup Ready2, Roundup Ready2, Agrisure CB and Agrisure GT hybrids to sign and return a Curry Technology Agreement to the Curry office.



A corn borer or corn rootworm refuge is corn that does not control European corn borer or corn rootworm.  If you plant corn that protects you from these two types of insects, you must plant an effective non-corn borer or non-corn rootworm refuge mandated by the EPA.  Only in cotton growing areas may growers plant up to 50% or their corn to BT and/or a combination of BT and RW hybrids. Refuge corn should be planted with a hybrid that is agronomically similar to and managed similar to your corn with a BT or a combination of BT and RW traits.  Please refer to the following for the written requirements of each.




Refuge management requirements state that any grower who plants BT corn must also plant an effective non-corn borer BT refuge of 20% within 1/2 mile of the BT corn fields you plant.  An effective refuge must provide a sufficient quantity of susceptible corn borer moths that are available to mate with moths that could be resistant to BT corn.



Refuge management requirements state that if a grower plants RW (rootworm) corn, the grower has two options for planting refuge. The first option is to plant a block of corn that serves as a refuge for both corn borers and corn rootworms. This is referred to as a common refuge.  The second option available to growers requires planting a separate refuge for corn borers and a separate refuge for corn rootworms.  Growers must plant an effective non-rootworm refuge of 20% within or adjacent to the RW field.  Please see illustrations below for field layouts.


Non-BT Corn Refuge in a BT Corn Field:

        1. Plant a large non-BT block

        2. Split planting to alternative at least four rows   

             (preferably six rows) of non-BT corn.

        3. Plant end rows to a non-BT corn for refuge

             acres. Must be 20% of corn acres to be acceptable.

        4. Plant a block within a pivot.  Pivot corners are not allowed.

        5. Plant non-BT corn in another field that is within 1/2  

            mile of BT field.


Non-RW Corn Refuge in a RW Field:

I. Common Method

       A. Non-RW, non-BT corn must be planted within the same

            field but can be separated by a road. Must be 20% of acres.

       B. Plant non-RW, non-BT corn blocks within a corn rootworm field.

       C. Plant non-RW, non-BT corn within a field by using split planting or

            adjacent multiple rows. Must be at least four rows wide (preferably six rows).

       D. Plant end rows to a non-RW, non-BT corn.


II. Separate Method

       E. 20% corn rootworm refuge remains in the same field.  BT refuge  

            for those acres can be planted separately. Must be at least four rows per strip

            (preferably6 rows).

       F. Plant adjacent field corn rootworm refuge block and corn borer refuge  

            within 1/2 mile of farthest RW field.

       G. Plant BT and RW blocks within the same field.



Note: A neighbor’s field does not qualify as a refuge.

Note: Late planted and/or early harvested sweet corn does not qualify as refuge.

Note: Only if the economic thresholds are reached can the refuge area, BT and/or RW, be treated with proper insecticides for target pests. BT-based microbial insecticide products (e.g., Dipel) must not be used on the refuge area.

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