Herbicide Injury Symptoms on Corn and Soybeans Department of Botany and Plant Pathology Purdue University West Lafayette, IN 47907 Page 3

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This web page address is:
http://www.btny.purdue.edu/Extension/Weeds/HerbInj2/InjuryMOA3.html

Classified by Mode of Action

This section displays herbicide injury symptoms based on the mode of action of the herbicide, e.g. 2,4-D is in the Growth Regulator family.

Classified by Herbicide Active Ingredient

Select the "Classified by Herbicide Active Ingredient" link to view the section on herbicide injury symptoms based on the common name (active ingredient) of the herbicide. Most herbicide products will list the common name under the active ingredient section of the label. A cross reference list of trade names and common names can also be found in Weed Control Guidelines for Indiana WS-16.

Mode of Action Index:

Photosynthetic Inhibitor

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	CORN Mode: Photosynthetic Inhibitor Herbicide: Cyanazine Injury: Lower leaves display burning of tip to base of leaf and outer edges toward center of leaf Condition: Herbicide applied to sandy soils and/or soils with high pH; stressed conditions (warm, sunny weather following prolonged cool, wet weather)
	SOYBEAN Mode: Photosynthetic Inhibitor Herbicide: Atrazine, Metribuzin Injury: Lower leaves display interveinal chlorosis with necrotic margins Condition: Carryover of atrazine or high rate of metribuzin
	SOYBEAN Mode: Photosynthetic Inhibitor Herbicide: Atrazine, Metribuzin Injury: Lower leaves go from chlorotic to necrotic, fall off of stem, and in severe cases, complete death of plant Condition: Carryover of atrazine or high rate of metribuzin; both herbicides are influenced by high soil pH making the herbicides more available to cause injury; eroded knolls in field are likely areas where injury may occur

Cell Membrane Disruptor

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	CORN Mode: Cell Membrane Disruptor Herbicide: Paraquat Injury: Necrotic spots Condition: Herbicide drift from nearby field, most likely a no-till field where a burndown treatment of paraquat was applied
	SOYBEAN Mode: Cell Membrane Distruptor Herbicide: Acifluorfen, Fomesafen, Lactofen Injury: Bronzing, speckling of leaves Condition: Herbicide applied postemergence on days with high temperatures and humidity; misapplication

Pigment Inhibitor

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CORN Mode: Pigment Inhibitor Herbicide: Clomazone Injury: Young corn plant may be entirely white; lower leaves bleached-white with these white areas sometimes highlighted with pink Condition: Carryover of herbicide due mostly to lack of moisture for breakdown; misapplication; drift

Index