University of Missouri Extension

IPM1007, Revised November 2009

Practical Weed Science for the Field Scout: Corn and Soybean

Photosynthesis inhibitors

Atrazine injury on soybeans appears first at the tips and margins of older leaves.
Atrazine injury on soybeans appears first at the tips and margins of older leaves.Atrazine injury on soybeans appears first at the tips and margins of older leaves.
 

Drift from postemergence applications of atrazine on soybeans or other plants such as ivyleaf morningglory will appear as interveinal chlorosis and necrosis of older leaves first.
Drift from postemergence applications of atrazine on soybeans or other plants such as ivyleaf morningglory will appear as interveinal chlorosis and necrosis of older leaves first.

Metribuzin damage in corn. Note the necrotic leaf edges.Metribuzin damage in corn. Note the necrotic leaf edges.
 

Soybeans injured from a preemergence application of metribuzin. Note the interveinal necrosis that has occurred on the unifoliate leaves. Soybeans injured from a preemergence application of metribuzin. Note the interveinal necrosis that has occurred on the unifoliate leaves.
 

Triazines chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

Injury from metribuzin on corn appears as chlorosis and necrosis along the leaf edges.
Injury from metribuzin on corn appears as chlorosis and necrosis along the leaf edges.Injury from metribuzin on corn appears as chlorosis and necrosis along the leaf edges.
 

Phenylureas chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

Injury from bromoxynil on soybeans and corn. Notice the necrotic tissue, mostly along the edges of the leaf.
Injury from bromoxynil on soybeans and corn. Notice the necrotic tissue, mostly along the edges of the leaf. Injury from bromoxynil on soybeans and corn. Notice the necrotic tissue, mostly along the edges of the leaf. Injury from bromoxynil on soybeans and corn. Notice the necrotic tissue, mostly along the edges of the leaf.
 

Injury from bentazon on soybeans appears as chlorosis, then necrosis of leaf tissue. Injury on corn appears as necrotic spots and streaks across the upper half of the leaf.
Injury from bentazon on soybeans appears as chlorosis, then necrosis of leaf tissue. Injury on corn appears as necrotic spots and streaks across the upper half of the leaf.Injury from bentazon on soybeans appears as chlorosis, then necrosis of leaf tissue. Injury on corn appears as necrotic spots and streaks across the upper half of the leaf.
 

Benzothiadiazoles, benzonitriles and pyradazines chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

 

IPM1007 Practical Weed Science for the Field Scout: Corn and Soybean | University of Missouri Extension

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