Herbicide Symptoms - Part 1 (ACIS)

Auxin type growth regulators - compete with naturally produced auxins. Cause unregulated cell elongation resulting in unequal and abnormal curvature and increase protein and RNA synthesis leading to uncontrolled meristematic growth that disrupts tissues, especially xylem and phloem causing tissue starvation.

Symptoms are twisted deformed growth with death resulting in days to weeks. Selectivity: broadleaves are much more sensitive than grasses. Translocated in the phloem to meristematic regions.

2,4-D and Phenoxy acid herbicides

2,4 – D – Numerous trade names
MCPA - Numerous trade names

Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture, The University of Arizona.

The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Because labels are subject to frequent change, always consult the label attached to the product before using any pesticide. The user must assume responsibility for proper application and for residues on crops as well as for damage or injury caused by pesticides, whether to crop, person or property.

Any products, services, or organizations that are mentioned, shown, or indirectly implied in this web document do not imply endorsement by The University of Arizona.

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.