1. Is it reasonable to expect that commercialization of plants with the transgenic resistance trait will have more substantial adverse effects on nontarget organisms than current pest control5 has on these organisms?

    1. Yes or More data needed to make a determination—subject to nontarget considerations.

    2. No—exempt from nontarget considerations.

Hybridization with Wild or Weedy Relatives: Guiding Principles

The following guiding principles regarding hybridization with wild or weedy relatives are suggested for reviewing transgenic pest-protected plants. These guidelines are designed for annual crop plants and may require modification in order to address perennials. EPA's categorical exemptions of transgenic plants that have sexually compatible, nontoxic, and viral coat proteins are not in agreement with these principles in some cases. USDA analyzes these concerns according to risks posed to agriculture, so weedy relatives with agricultural effects are of concern; its methods are similar to the following questions, although original data are not always used. FDA does not provide oversight for ecological concerns.

  1. Does the cultivated plant occur in feral populations or hybridize with related species in the United States?6

    1. Yes or More data needed—go to 2.

    2. No—exempt from weedy-relative considerations.

  2. Have feral populations or wild relatives been reported as weedy or invasive in the United States or have a reasonable potential to become weedy?7

    1. Yes or More data needed—go to 3.

    2. No—exempt from weedy-relative considerations.


Current pest control methods could include both the use of chemical insecticides or other non-chemically based methods.


Hybridization refers to any naturally occurring gene flow that results in permanent introgression of genes from cultivated plants into noncultivated populations. Annual crops that persist for 1 or 2 years as volunteers are not considered to be feral populations.


Applies to plants in both managed and unmanaged habitats. A species does not have to be included on the Federal Noxious Weed List to qualify as weedy or invasive, but it should be mentioned in peer-reviewed journals or other professional publications.

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