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Liberty / glufosinate

Chemical Structure

Chemical Name:

2-amino-4-(hydroxymethylphosphinyl)butanoic acid.

Chemical Family:

unique (none generally accepted).

WSSA Resistance Group:


Crop/non-crop registration:

Non-selective, (except in LIBERTY-LINK transgenic crops such as canola and corn), also used as a desiccant in dry beans and potatoes, directed applications in nursery stocks, grapes, apples, stone fruits, stale seedbed techniques in asparagus, carrots, lettuce and onions

Sensitive weeds:

Non-selective, affects all actively growing green plants; regrowth of perennial species may occur.

Application method:


Absorption & Translocation:

Absorbed mostly through foliage;little to no glufosinate is absorbed through the roots under field conditions because of rapid microbial breakdown; limited translocation via xylem and phloem.

Mode of Action:

Inhibition of glutamine synthase activity.

Metabolic pathway inhibited:

Inhibits activity of glutamine synthase, the enzyme that converts glutamate plus ammonia to glutamine; accumulation of ammonia in the plant destroys cells and directly inhibits photosystem I and photosystem II reactions.

Basis of Selectivity:

Non-selective in agricultural crops (except LIBERTY-LINK transgenics).


Chlorosis and wilting usually occur within 3-5 days of application, followed by necrosis in 1-2 wks; rate of symptom development is increased by bright sunlight, high humidity, and moist soil; seedlings are not injured before emergence.


None (<1month); there are no cropping or rotational restrictions after application.


Oral LD50 = 2170 mg/kg - moderately toxic.

Additional comments:

Speed of action is influenced by environmental factors; cool temperatures, poor moisture and low humidity reduce speed of action; heavy dew at time of application may reduce control of certain weed species; glufosinate requires a 6 hour rain-free period after application for maximum efficacy.