Herbicide Symptoms - Part 1 (ACIS)

Herbicide Symptom Key

Caroteniod pigment inhibitors - a diverse group of herbicides that prevent the formation of carotenoid (yellow) pigments. Caroteniod pigments protect chlorophyll by dissipating excess light energy or excitation energy. In the absence of carotenoid pigments, this excess light energy leads to the photo-degradation of chlorophyll and the formation of whitened plants.

Symptoms: plants emerge a pale green but tissue rapidly turns chlorotic and white, and eventually necrotic; plants are stunted. Caroteniod pigment inhibitors are absorbed by roots and translocated in the xylem along with water to leaves.

norflurazon – Predict, Solicam, Zorial
clomazone (+ ethafluralin) – Strategy
fluridone - Sonar

Evital (norflurazon) -

Bleached leaves (on corn, Johnson grass, cantaloupe, morningglory, and purslane - top to bottom)

Photo of bleached leaves on corn plants.

Photo of bleached leaves on Johnson grass plants.

Photo of bleached leaves on cantaloupe plants.

Photo of bleached leaves on morningglory plants.

Photo of bleached leaves on purslane plants.

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.


Herbicide Symptom Key Caroteniod pigment inhibitors - a diverse group of herbicides that prevent the formation of carotenoid (yellow) pigments. Caroteniod pigments protect chlorophyll by dissipating excess light energy or excitation energy. In the absence of carotenoid pigments, this excess light energy leads to the photo-degradation of chlorophyll and the formation of whitened plants. Symptoms: plants emerge a pale green but tissue rapidly turns chlorotic and white, and eventually necrotic; plants are stunted. Caroteniod pigment inhibitors are absorbed by roots and translocated in the xylem along with water to leaves. norflurazon – Predict, Solicam, Zorial clomazone (+ ethafluralin) – Strategy fluridone - Sonar Evital (norflurazon) - Bleached leaves (on corn, Johnson grass, cantaloupe, morningglory, and purslane - top to bottom) 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.
Key home page \| Soil Applied \| Foliar Applied Cotton Weed Pubs \| Forage Weed Pubs \| Grain Weed Pubs \| Vegetable Weed Pubs Home \| Weeds Home Page \| Citrus Weeds document located at: http://cals.arizona.edu/crops/weeds/key/partoneD.html Copyright © 2001 University of Arizona, College of Agriculture and Life Sciences webmaster: jsjones@ag.arizona.edu