To implement the 5% embedded option in isolated large field situations, 5% of the field tshould be planted to a non-B.t. variety and the remainder in B.t. For very large fields (length and/or width greater than one mile), place the refuge in more than one location in the field.

Field Unit - Definition

Any group of fields that are contained within a one-mile-squared (one mile by one mile) area.

To implement the 5% embedded option for smaller fields or fields that are closely associated, fields can be grouped into “field units” so that one of the smaller fields, or a portion of one of the fields, serves as the “embedded” non-B.t. refuge. Any fields contained within a one-mile-squared area can be considered a “field unit.” Likewise, this embedded refuge can be treated with the same insecticide (except foliar B.t.k. products) at the same time that ALL of the associated B.t. fields within the same field unit are sprayed, but cannot be treated with insecticides (listed on previous page) active on tobacco budworms, cotton bollworms or pink bollworms independently of the associated B.t. fields. The embedded refuge within a field or field unit must average at least 150 feet wide, but preferably 300 feet wide.

For areas in California, Arizona and New Mexico, where pink bollworm is the only pest of concern (such as in central Arizona), growers are allowed to mix individual rows of non-B.t. with B.t. rows to embed their refuge. Plant the refuge cotton as at least one single non-B.t.-cotton row for every six to 10 rows of B.t. cotton. The refuge may be treated with sterile insects, any insecticide (excluding foliar B.t.k. products), or pheromones labeled for the control of pink bollworm whenever the entire field is treated. The in-field refuge rows may not be treated independently of the surrounding B.t. cotton field in which it is embedded. The refuge must be managed (fertilizer, weed control, etc.) identically to the B.t. cotton fields. One way this “embedded” option could be planted is by putting a non-B.t. variety in one seed hopper and B.t. seed in the remaining seed hoppers. This will result in interspersed rows of a non-B.t. variety across a B.t. field. Growers should be cautioned to confirm the appropriateness of interspersing different varieties within a field with their respective seed companies and crop advisers. The field unit concept for embedded refuge is not allowed in California, Arizona and New Mexico, where pink bollworm is the only pest of concern. Interspersing rows is not allowed for cotton grown in any states other than California, Arizona and New Mexico.

To avoid mixing seed in the planting process, be sure to clean all seed out of hoppers when switching from non-B.t. seed to B.t. seed, or vice versa. In cases where placement of the refuge within one mile of the B.t. cotton would be in conflict with state seed production regulations, the grower must plant the refuge as close to the B.t. cotton as allowed.