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  A Publication of UVM Extension's Vermont Vegetable and Berry Program

Transgenic Crop Production in Vermont: Strategies for Co-Existence

by Vern Grubinger and Gary Deziel
University of Vermont Extension

Across the nation, plantings of genetically-engineered, or transgenic, crops have increased rapidly in recent years, primarily in soybean, cotton and corn.  While many farmers see the use of such crops as beneficial for controlling pests, other farmers, particularly organic farmers and farmers with markets for non-GMO products, are concerned about transgenic crops because of the potential for contamination of their crops. In addition, concern about genetically-modified organisms (GMOs) is present in Vermont communities, as indicated by the nearly 70 Vermont towns that have considered and passed resolutions regarding their use.  Pro, con, or neutral, Vermonters are quite aware of this controversial issue. The University of Vermont’s Center for Rural Studies 2002 Vermonter Poll found that 82 percent of respondents had heard of GMOs.

Although the US Food and Drug Administration has determined transgenic crops to be "substantially equivalent" to non-GMO foods, the issue will be debated for some time to come and ultimately be decided by consumers in the marketplace, federal and state regulators, and perhaps, the courts.

Meanwhile, there are no regulations or official recommendations in place to guide farmers on how to strike a balance between the right to farm as they see fit and the desire to avoid conflict with their neighbors. So, in the Vermont spirit of tolerance, accommodation and protection of individual rights we offer the following strategies as a common-sense, pro-active approach to keeping transgenic seeds, plants and pollen where they are wanted -- and preventing them from going where they are not.  There’s room in Vermont for a wide spectrum of farmers.  But, as a farmer, you have a responsibility to maintain open communication with neighbors, especially if you plan to plant transgenic crops this spring or if you are an organic producer who faces significant crop devaluation through contamination with GMOs.

In Vermont, transgenic field corn is of particular concern because it cross pollinates and has pollen that can be airborne for some distance. Although soybeans are primarily self-pollinating, they also warrant attention because pollen can go where not intended due to bees and other insects. Soon, transgenic varieties of alfalfa and other crops may be available, so the need for careful planning and good communication will only increase.

Talk to Your Neighbors

Producers who plan on planting transgenic crops are encouraged to speak to their farm neighbors about their plans.  In addition, organic producers, or those who have concerns about transgenic crop plantings adjacent to their farm properties, are encouraged to talk to their farm neighbors about their need to meet organic standards. To start with, good communication can determine if there is any reason for concern – maybe no transgenic crops are being planted, or maybe there are no neighbor concerns.  If there are concerns, efforts can be made to prevent contamination by selecting fields away from neighboring farms for planting of transgenic crops and/or for planting of organic crops at risk of contamination, and/or by planting of ‘buffer strips on one or both neighboring farms.

Know What You Plant

Farmers that do not want to plant transgenic crops should take care to order the appropriate varieties. Transgenic seed orders usually require a signed contract, but farmers should still inspect the seed bag labels before planting to make sure they did not accidentally get a transgenic variety. If unsure of what you are about to plant, contact your seed salesperson.

Shared Equipment Can Move Seed

Trucks, bins, planters, combines, etc. can have residual seeds in them. If you share equipment with other farms, be aware that you may get some of their seed onto your farm. While some equipment can be pretty thoroughly cleaned out, some cannot. Combines in particular are almost impossible to get absolutely clean.

Use Rotation Plans to Separate Crops

If farmer A is organic and farmer B is planting transgenic corn, but both grow mixed alfalfa hay, the 2 farms could co-ordinate their rotation to minimize the threat of transgenic corn pollen drift. In other words, when farmer A’s organic hay is by their shared border, farmer B’s transgenic corn could be grown on the other side of B’s farm, and when organic corn is by the border, conventional hay could be on the other side. This will work at least until we have to deal with transgenic alfalfa.

Use Crop Maturity Dates to Avoid Cross Pollination

If a farmer is growing long-season transgenic field corn, a neighboring organic sweet corn grower could try to avoid cross-pollination by planting short-season varieties.

Use Physical Distance to Separate Crops

The crops to be grown in adjacent fields are of highest concern for cross contamination. While the majority of corn pollen falls very near the edge of a cornfield it’s the small amount that remains airborne that we have to be concerned about, particularly when environmental conditions are conducive to the movement of pollen. A localized strong wind during tasseling may carry corn pollen quite far – research has documented corn pollen drift of many miles.

If a transgenic corn crop is to be grown in a field next to an organic field corn crop, for instance, implementing adequate isolation distances or using an appropriate number of border rows should be considered.  While there’s no absolute guarantee that cross contamination will not occur, the likelihood that it will can be greatly reduced by following best-practices hybrid seed corn isolation recommendations. If fields are closer than the minimum isolation distance, then border rows can be used to protect against cross-pollination (see Table below).

We reviewed several crop improvement association isolation recommendations for production of hybrid corn and/or identity preservation. These range from a minimum of 410 feet separation to 610 feet between plantings of different types of corn.

Table 1. Minimum number of border rows of isolation for hybrid corn production. Indiana Crop Improvement Association standards.
                Field size up to 20 acres                                           Field size greater than 20 acres
Min. distance  (ft)          Number of Border                   Min. distanc(ft)              Number of Border
from contaminant           Rows (Minimum)                     from contaminant           Rows (Minimum)
    610                                         0                                     514                                     0
    569                                         1                                     513                                     1
    526                                         2                                     462                                     2
    486                                         3                                     420                                     3
    444                                         4                                     369                                     4
    404                                         5                                     338                                     5
    363                                         6                                     297                                     6
    321                                         7                                     255                                     7
    280                                         8                                     214                                     8
    239                                         9                                     173                                     9
    189                                         10                                   132                                     10
    157                                         12                                     90                                     11
    115                                         14                                     41                                     12
      49                                         16


  • http://www.agry.purdue.edu/ext/corn/news/articles.00/GMO_Issues-000309.html
  • http://www.biotech.iastate.edu/publications/IFAFS/coexistence.html
  • Martens, M-H. What can organic farmers do to reduce contamination from genetically modified crops? Mid-winter 2000 NOFA-NY Newsletter.
  • Robin Palmer.  January 20, 2002.  Vermont Voting on GE Bans & Labeling Across the State, Seeds of discontent: Petition drive aims to make gene-altered crops.  Times Argus, Barre-Montpelier, Vermont.
  • Stein, Jeff, Director of Regulatory Affairs, Syngenta.  From presentation at UVM, 3/28/02.
Published: March 2003
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