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Ministry of Agriculture, Food and Rural Affairs


Trade Names: Lorox

Registration status: This herbicide is registered for use on established trees in tender fruit orchards.

When to suspect injury: Injury may occur from drift up into trees from under-tree applications, or from neighbouring fields under windy conditions. Linuron should not be applied on soils with less than 2% organic matter or absorption through roots may occur. If unusually heavy rains follow application, severe injury may occur.  If you notice symptoms of leaf yellowing, wilting or necrosis, look carefully at neighbouring fields, and at weeds in the treated area.

Herbicide Information:  Knowing how the herbicide works will help to determine the likelihood of injury from either direct application or drift.  Consider how the herbicide works in plants, behaves in soils and what symptoms are common in other plants.  

Chemical Family: Substituted urea

Site of Action/WSSA Group: Inhibitors of photosynthesis at photosystem II, Site B (alternate binding site)– Group 7

General Symptoms in Plants

  • Interveinal chlorosis
  • Yellow leaf margins
  • Leaves eventually wilt, and die
  • Older leaves are more damaged than young leaves

Symptoms in Fruit Trees

  • Leaves have yellow margins and interveinal chlorosis from root uptake
  • If rates are high enough, leaves will turn brown and die
  • Symptoms will be worse on older leaves
  • Leaves with drift droplets will have yellowing, chlorosis and eventually die

Uptake and Translocation

  • Readily absorbed through the roots
  • Little absorption through the foliage
  • Translocation upward in the xylem with little or no downward movement in phloem


  • Seldom poses a problem for subsequent crops
  • Moderately persistent in soils
  • Half-life in field: 230 days

If you suspect herbicide injury, laboratory analyses of herbicide levels in plant tissue are necessary to confirm the presence of herbicides, although symptoms may be helpful in diagnosing which herbicides caused the problem.

Both damaged and healthy plant tissues should be analyzed, because comparison levels are not readily available for many herbicides. Contact your lab for instructions on which plant parts should be sampled, how to handle and ship the sample, and what costs are involved to ensure an accurate and timely diagnosis.

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