ABSTRACT

This chapter presents absorption of the imidazolinones by roots and shoots and the subsequent translocation to the meristems. It reviews the morphology and physiology of the transport system. Herbicides present in the soil solution are available for absorption by plant roots. The first stage of absorption is penetration of the epidermis, which leads to the root cortex. Although herbicide reaching the soil may be available for root uptake, postemergence-applied herbicides are primarily absorbed by the foliage. Plant leaves are complex organs composed of several different layers of photosynthetic cells lying beneath a layer of epidermal tissue. Differences in translocation of imazaquin may be related to differences in susceptibility among species. Imazethapyr is often more active than imazaquin when applied postemergence to weeds. The high degree of lipophilicity of imazamethabenz-methyl enhances its foliar uptake while the lack of a dissociable acid group limits its phloem mobility. Translocation of the imidazolinones can be affected by the activity of other herbicides.