Using broad-spectrum weed killers on weeds that are competing with crops for sunlight, water, and nutrients presents a difficulty: how to keep the crop from being killed along with the weeds  For at least some food crops, specially treated seed that produces plants resistant to weed killers is under development  This resistance wears off as the plants mature
Ttherefore, the special seed treatment will be especially useful for plants that
provide, as they approach maturity, shade dense enough to keep weeds from growing