A new publication from GenØk shows that maize farming by smallholders, for local food production, is particularly vulnerable to the introduction of genetically modified (GM) maize. The reason is that the fields are situated very close to each other (distance often 2-5 m) and that pollen will cross-hybridize at a high rate. In addition, farmers recycle their seeds year after year and share seeds with neighbors and family. Seed sharing may transfer viable seeds up to 100 km.

The study performed fieldwork in Zambia, uses mathematical modelling of pollen spread and interviewed farmers about their seed management practices. Globally, 85 % of all farms are small-scale (< 2ha).

The study concludes that segregation of GM and non-GM maize varieties is likely not an option in these systems. If GM maize is introduced, farmers will contribute to uncontrolled spread of GM maize. One further negative effect is that cross-hybridization of GM (Bt-maize) and non-GM maize may give increased risk of resistance development in pest insects