Liberty / glufosinate

WSSA Resistance Group: 10

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: PREPLANT, POST.

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).

Symptoms: 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.

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

Toxicity: 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.