ABSTRACT
2,4-Dichlorophenoxyacetic acid (2,4-D) is a member of a class of herbicides with activity against many dicotyledonous weeds. Monocotyledonous plants are considerably less sensitive to phenoxyacetic herbicides and hence these herbicides are of particular use for broadleaf weed control in monocot crops such as cereals and sugarcane. 2,4-D is an important auxin in the tissue culture of cereals and is an active growth regulator for these species. Weed control remains an important component of cotton production, primarily because of the noncompetitive nature of cotton seedlings. 2,4-D is used on about one third of the cotton farms from ground rigs at any time after defoliation through to sowing the next season, but its popularity is reduced by fears of damage that could result from residues in the soil. Transgenic tobacco plants were produced by Agrobacterium infection of leaf pieces using relatively standard protocols with selection on toxic levels of kanamycin sulfate.
