In many agricultural seed products—such as oilseed crops, grains and legumes, and seeds harvested specifically for planting—premature release of seeds prior to harvest results in serious losses. Swathing and other methods for minimizing harvest loses add to overall production costs. In addition, regardless of cost factors, the need for positive control of seed release may in future years become a desirable capability when genetically modified organism (GMO) crops become widespread, in order to assure satisfactory containment.