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Practical Weed Science for the Field Scout: Corn and Soybean

Lipid synthesis inhibitors

Low doses of ACCase inhibitors such as sethoxydim and clethodim as drift or tank contamination can cause corn to whiten leaves in the whorl.
 

Postemergence lipid synthesis-inhibiting herbicide like sethoxydim, clethodim and quizalofop causes chlorosis and purpling of corn leaves and will cause the meristem of the newest leaf to rot.
 

Injury from post-selective grass herbicide. Notice the dead, necrotic meristem of the plant when the whorl is removed.
 

Quizalofop can cause chlorosis near leaf veins of soybeans. This injury will eventually progress into necrosis.
 

Aryloxyphenoxypropionates and cyclohexanediones chemical group

Herbicides

• Fluazifop (Fusilade, in Fusion)
• Quizalofop (Assure)
• Fenoxaprop (Whip, in Fusion)
• Diclopfop (Hoelon)
• Sethoxydim (Poast, Poast Plus)
• Clethodim (Select Max)

Mode of action and characteristics of activity

• Inhibition of acetyl CoA carboxylase (ACCase) enzyme
• Postemergence control of annual and perennial grasses, foliar activity, translocates upward in xylem and to growing points and roots in phloem
• Very short soil residual
• No activity on broadleaf weeds

General symptoms

• Reddening of leaves and stems, necrotic at nodes
• Injury is seen in grasses only
• Newer leaf tissue will be chlorotic or necrotic and the leaves in the whorl can be easily separated from the rest of the plant
• Symptoms appear 3 to 7 days after application

IPM1007, revised November 2009

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