Skip to main content

Permit / halosulfuron

Chemical Structure

Chemical Name:

methyl [[[4,6-dimethoxy-2-pyrimidinyl]amino]carbonylaminosulfonyl]-3-chloro-1-methyl-1-H-pyrazole-4-

Chemical Family:

Sulfonyl ureas.

WSSA Resistance Group:


Crop/non-crop registration:

Field and seed corn, grain sorghum

Sensitive weeds:

Annual BLW (broadleaf weeds): cocklebur, velvetleaf, ragweed, wild mustard, redroot pigweed, Venice mallow, yellow nutsedge.

Application method:

POST- in corn, from spike stage to 10 leaf stage (typically before crop is 50-76 cm tall (20-30").

Absorption & Translocation:

Following foliar absorption, halosulfuron is rapidly absorbed through the leaves and translocated via both xylem and phloem.

Mode of Action:

Inhibition of acetolactate synthase.

Metabolic pathway inhibited:

Inhibits acetolactate synthase (ALS), also called acetohydroxyacid synthase (AHAS), a key enzyme in the biosynthesis of the branched-chain amino acids isoleucine, lecucine, and valine.

Basis of Selectivity:

Metabolized by tolerant species to non-phytotoxic compounds.


Growth of treated plants is inhibited within a few hours after application and susceptible weeds are no longer competitive with the crop;following growth inhibition, meristematic areas gradually become chlorotic and necrotic, followed by a general foliar chlorosis and necrosis with complete control typically occurring within 1-2 wks.


Intermediate (1- 4 months).


Oral LD50 = >1287 mg/kg - slightly toxic.

Additional comments:

When early POST treatments are used in corn, sequential applications may be required to control later weed flushes; following application to foliage, allow 30 days before grazing domestic livestock, harvesting forage, or harvesting silage; halosulfuron can be tank mixed with a number of grass herbicides (atrazine, dicamba, nicosulfuron) to increase the spectrum of control.