Herbicide Injury Symptomology: Pigment Inhibitor Injury

Isoxazolidones, Isoxazoles, Pyridazinone

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Isoxazolidones

smIsoxazolidones1 (6436 bytes) smIsoxazolidones2 (9559 bytes)

Trade Name and Uses:

  • Command (Clomazone)
    -soybeans

Mode of Action: Inhibition of an enzyme in the isoprenoid pathway.

Injury Symptoms: Plants turn white, after becoming translucent at the leaf tips. In corn, if more than 75% of the plant is white it will likely die.

Isoxazoles

smIsoxazoles3 (10718 bytes) smIsoxazoles1 (7105 bytes) smIsoxazoles2 (9606 bytes)

Trade Name and Uses:

  • Balance (Isoxaflutole)
    -corn

Mode of Action: Specific Site Unknown

Injury Symptomology: Plants emerge, turn white, become necrotic and die. Emerged plants will take up more herbicide and show symptoms and sometimes die after a rain.

Pyridazinone

Trade Name and Uses:

  • Zorial (Norflurazon)smZorialc (5613 bytes)
    -alfalfa

Mode of Action: Inhibition of phytoene desaturase and subsequent blocking of carotenoid biosynthesis.

Injury Symptomology: Interveinal whitening of leaf and stem tissue becomes apparent as susceptable seedlings emerge from soil. Tissue eventually becomes necrotic and dies.


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