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Ministry of Agriculture, Food and Rural Affairs


Trade Names: Lontrel 360

Registration status: This herbicide is not registered for use in tender fruit orchards.

When to suspect injury:  When clopryralid is applied during hot or humid conditions, the product may volatilize and move onto sensitive crops Injury may also occur from drift from neighbouring fields under windy conditions. If you notice symptoms of bending, twisting or leaf curling, 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:  Pyridine

Site of Action/Group:  Synthetic auxins (WSSA Group 4)

General Symptoms in Plants
At first symptoms include

  • Bending, twisting, swelling and elongation of stems
  • Leaf cupping and curling

Followed by

  • Chlorosis at the growing points
  • Growth inhibition
  • Wilting
  • Necrosis, and death of susceptible plants within 3- 5 weeks
  • Low concentration may cause young leaves to look puckered
Symptoms in Fruit Trees

  • As above, most likely bending, twisting and chlorosis of the growing point

Uptake and Translocation

  • Rapidly absorbed by foliage
  • Translocated readily throughout the plant via both xylem and phloem systems
  • Clopyralid is distributed throughout the plant to the meristem


  • Half life in field: less than 30 days
  • Residues may injure certain crops (such as tomatoes and peppers) planted 1 year after application

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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