Herbicide Symptoms - Part 1 (ACIS)

Aromatic amino acid synthesis inhibitor (inhibition of 5-enolpyruvylshikimate-3-phosphate synthase, EPSPS) - causes a lack of aromatic amino acids (phenylalanine, tyrosine, and tryptophan) that inhibits synthesis of proteins and secondary plant metabolites. Deregulation of the shikimate pathway and uncontrolled flow of carbon into the shikimate pathway removes building blocks from other metabolic pathways.

Symptoms are yellowing and wilting that progress from the new to the older tissues. Can cause deformed leaves and multiple shoots or whorls of narrow or strapped leaves on regrowth in some plants.

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Erin Taylor, etaylor@cals.arizona.edu Extension Agent, Field & Veg Crops
William B. McCloskey, wmcclosk@ag.arizona.edu Extension Weed Specialist
College of Agriculture, The University of Arizona, Tucson, AZ.
Material written June 2003.