University of Missouri Extension

IPM1007, Revised November 2009

Practical Weed Science for the Field Scout: Corn and Soybean

Cell membrane disruptors

Paraquat injury symptoms on soybeans will also progress from water-soaked lesions soon after application to necrotic lesions with red rings several days after application.
Paraquat injury symptoms on soybeans will also progress from water-soaked lesions soon after application to necrotic lesions with red rings several days after application.Paraquat injury symptoms on soybeans will also progress from water-soaked lesions soon after application to necrotic lesions with red rings several days after application.
 

Within only a few hours of application, water-soaked lesions can be seen on corn that has been damaged with paraquat.Within only a few hours of application, water-soaked lesions can be seen on corn that has been damaged with paraquat. Within only a few hours of application, water-soaked lesions can be seen on corn that has been damaged with paraquat.
 

Paraquat injury on other plants such as pumpkin, snap beans and squash and is similar in appearance to injury that occurs on soybean plants.
Paraquat injury on other plants such as pumpkin, snap beans and squash and is similar in appearance to injury that occurs on soybean plants.Paraquat injury on other plants such as pumpkin, snap beans and squash and is similar in appearance to injury that occurs on soybean plants. Paraquat injury on other plants such as pumpkin, snap beans and squash and is similar in appearance to injury that occurs on soybean plants.
 

Paraquat drift symptoms on corn will progress as necrotic lesions that will eventually be surrounded by brown or red rings. Paraquat injury will be confined to the foliage that comes in direct contact with the herbicide.
Paraquat drift symptoms on corn will progress as necrotic lesions that will eventually be surrounded by brown or red rings. Paraquat injury will be confined to the foliage that comes in direct contact with the herbicide.
Paraquat drift symptoms on corn will progress as necrotic lesions that will eventually be surrounded by brown or red rings. Paraquat injury will be confined to the foliage that comes in direct contact with the herbicide. Paraquat drift symptoms on corn will progress as necrotic lesions that will eventually be surrounded by brown or red rings. Paraquat injury will be confined to the foliage that comes in direct contact with the herbicide.
 

Bipyridilium chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

Acifluorfen injury will appear as speckling followed by chlorosis then necrosis of tissue contacted by the herbicide.
Acifluorfen injury will appear as speckling followed by chlorosis then necrosis of tissue contacted by the herbicide. Acifluorfen injury will appear as speckling followed by chlorosis then necrosis of tissue contacted by the herbicide. Acifluorfen injury will appear as speckling followed by chlorosis then necrosis of tissue contacted by the herbicide.
 

Fomesafen carryover on corn appears as a clearing of the midvein and veins. This is referred to as veinal chlorosis.
Fomesafen carryover on corn appears as a clearing of the midvein and veins. This is referred to as veinal chlorosis.Fomesafen carryover on corn appears as a clearing of the midvein and veins. This is referred to as veinal chlorosis.
 

Injury from fomesafen can also appear as speckling, chlorosis and necrosis but more often causes leaf crinkling and distortion. New growth is not affected.
Injury from fomesafen can also appear as speckling, chlorosis and necrosis but more often causes leaf crinkling and distortion. New growth is not affected. Injury from fomesafen can also appear as speckling, chlorosis and necrosis but more often causes leaf crinkling and distortion. New growth is not affected.
 

Flumiclorac causes crinkling of leaves that were expanding when treated. Flumiclorac causes crinkling of leaves that were expanding when treated.
 

Flumiclorac injury on corn.Flumiclorac injury on corn.
 

Injury from flumioxazin drift on corn will appear as necrotic lesions and is often confused with paraquat.Injury from flumioxazin drift on corn will appear as necrotic lesions and is often confused with paraquat.
 

N-phenylphthalimides, diphenyl ether and pyrimidinediones chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

Injury from carfentrazone on soybeans will appear as speckling, chlorosis and necrosis of contacted foliage. Note the absence of red rings surrounding the necrotic lesions as with paraquat.
Injury from carfentrazone on soybeans will appear as speckling, chlorosis and necrosis of contacted foliage. Note the absence of red rings surrounding the necrotic lesions as with paraquat.Injury from carfentrazone on soybeans will appear as speckling, chlorosis and necrosis of contacted foliage. Note the absence of red rings surrounding the necrotic lesions as with paraquat.
 

Carfentrazone injury on corn. Carfentrazone injury on corn.
 

Sulfentrazone injury on soybeans. Note the small leaflets, bent cotyledons and purple spots from sulfentrazone Sulfentrazone injury on soybeans. Note the small leaflets, bent cotyledons and purple spots from sulfentrazone "splash"in wet conditions.
 

Sulfentrazone-damaged soybean hypocotyls when cold, wet conditions occurred at emergence. Sulfentrazone-damaged soybean hypocotyls when cold, wet conditions occurred at emergence.
 

Injury from sulfentrazone drift on corn will also appear as necrotic lesions and is often confused with paraquat damage. Injury from sulfentrazone drift on corn will also appear as necrotic lesions and is often confused with paraquat damage.
 

Severe carfentrazone injury on corn as a result of rain washing the herbicide into the whorl. Severe carfentrazone injury on corn as a result of rain washing the herbicide into the whorl.
 

Aryl triazolinones chemical group

Herbicides

Mode of action and characteristics of activity

General symptoms

IPM1007, revised November 2009

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

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