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Lorox / linuron

Chemical Structure

Chemical Name:


Chemical Family:

Substituted ureas.

WSSA Resistance Group:


Crop/non-crop registration:

Corn, soybeans, wheat, oats, barley, potatoes, carrots

Sensitive weeds:

Many annual grasses and BLW (broadleaf weeds); seedlings of dandelion, plantain and perennial sow-thistle.

Application method:


Absorption & Translocation:

Readily (most) absorbed by roots via xylem, some uptake also by foliage;translocated to top of plant accumulating at growing points and leaf margins (i.e. acropetal movement); uptake and translocation rates increase with transpiration rates.

Mode of Action:

Inhibition of photosynthesis and ATP formation by blocking electron transport.

Metabolic pathway inhibited:

Inhibition of photosynthesis by binding to the QB-binding niche on the D1 protein of the photosystem II complex in chloroplast thylakoid membranes, thus blocking electron transport from QA to QB; this stops CO2 fixation and production of ATP and NADPH2 which are required for plant growth; however, plant death often results from other factors (e.g. lipid peroxidation).

Basis of Selectivity:

Differential metabolism, uptake and translocation in tolerant species.


Symptoms first observed in older leaves (foliar veinal chlorosis (yellowing) and leaf-tip dieback) develop within several days of application; later on, have water-soaked wilted appearance which eventually lead to stem collapse, necrosis (brown in BLW, white in grasses) and plant death.


Intermediate (1- 4 months).


Oral LD50 = 1254 mg/kg - moderately toxic.

Additional comments:

Do not use on sandy or coarse-textured soils having less than 2% organic matter; if unusually heavy rains follow application, severe injury may occur to corn, soybeans, carrots and potatoes.