University of California
Herbicide Symptoms

Lipid Synthesis Inhibitors

(not ACCase Inhibition)

HRAC Group: N

WSSA Group: 8, 16, 26

Herbicides in this mode of action are most effective on annual grasses and some broadleaf weeds. In general, these herbicides are applied preplanting or preemergence and incorporated into the soil. Most herbicides in this mode of action are volatile and need to be incorporated immediately after application to avoid excessive vapor loss. These herbicides are absorbed through both roots and emerging shoots but are translocated only in the xylem. The primary site of absorption and action is the emerging shoot and growing point. Herbicides in this mode of action belong to four chemistries including benzofuranes, chlorocarbonic acids, phosphorodithioates, and thiocarbamates. The specific mode of action of these herbicides is not well elucidated, but there is strong evidence that they interfere with biosynthesis of fatty acids and lipids in the newly developing shoot, which may account for reported reductions in cuticular wax deposition. In addition, these herbicides cause abnormal cell development or prevent cell division in germinating seedlings. They stop the plant from growing by inhibiting cell division in the shoot and root tips while permitting other cell duplication processes to continue.

Injury Symptoms: Symptoms on grass plants include failure of the shoot to emerge from the coleoptile or whorl of the plant, giving the plant a buggy-whip appearance. Susceptible grass seedlings often fail to emerge from the soil. Injury symptoms on broadleaf plants include enlarged cotyledons, restricted growth of the true leaves, and a dark green color, a symptom sometimes referred to as bud seal. The roots become short, thick, brittle, and club-shaped.

Chemistry Group and Common Names of LS Inhibitors
Used in the United States

ChemistryCommon Name
Benzofurane Ethofumesate
Phosphorodithioate Bensulide
Thiocarbamate Cycloate
  EPTC
  Triallate
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