Glyphosate and sulfosate are foliar applied while the others are mainly soil applied but do have foliar activity. These herbicides inhibit enzymes critical to the production of certain amino acids.
Amino acids are important building blocks in the production of proteins.
Proteins are important structural components, constituents of cell membranes and as enzymes are regulators of metabolic processes. When amino acid production stops, plant growth decreases and finally is stopped. The corn plant on the left had been treated with a foliar application of imazethapyr ten days earlier. Note the stunting and purple color of the stem. The bean plant on the left is stunted with chlorotic leaves from treatment with glyphosate 14 days earlier.