Coexistence in Agriculture Minimising Pollen Traffic

The goal is simple: Agriculture with and without genetic engineering must coexist side by side. The right measures need to be taken so that GM pollen won't drift into other fields and fertilise conventional cultivars.

Male flower: When July comes around the pollen starts to fly. Female flower: Sticky silk catches airborne pollen as it blows by.

Exactly what measures need to be taken for coexistence depends mostly on the reproductive biology of that specific crop. An example: Maize In midsummer, maize produces its male flowers (tassels) and releases pollen into the air. The pollen reaches the female flowers (the ears) primarily by wind. Even though bees visit the tassels to collect pollen, they have no interest in the female flowers, and therefore do not play a role in pollination. With maize, as is the case with many plants, cross-pollination is preferred. Cross-pollination is when pollen from one plant pollinates flowers on a different plant. Each maize plant tends to release its pollen a few days before its own silk becomes receptive, thereby preventing its own self-pollination. Since maize has no sexually compatible wild relatives in Europe, the only plants that maize could possibly pollinate would be other maize plants.

If GM maize is grown, it is to be expected that cross-pollination with plants in nearby fields will occur. Several research projects have worked on finding out how far maize pollen flies, and how often it fertilises conventional maize in other fields. The test plantings of GM maize conducted in Germany in 2004 looked into these questions. Based on the data from these studies, a set of guidelines was written up that was designed to ensure that coexistence with maize can be achieved.

Codes of practise: Avoiding mixing and crossing

Farmers who grow GM crops need to abide by certain rules and precautions to minimise cross-pollination with neighbouring conventional plants. Appropriate measures include:

• Allowing for sufficient space between fields
• Buffer strips of traditional crops surrounding GM plantings
• Careful cleaning of harvesting equipment
• Arranging plantings and selecting cultivars so that conventional maize can be harvested first
   

The effectiveness of these measures depends on several factors, like for example, field sizes, prevailing winds, and other climatic and geographic conditions. The biology of the cultivar being planted also plays a major role in forming management strategies.

At this point, there are no standardised or enforced codes of practice for GM crops. In the future, regulations could make codes of practice legally binding. It is also possible that seed companies come up with their own guidelines and provide them for their customers’ use.

See also on GMO-Compass:

• Freedom of choice: Selecting the deliberately applied system