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Ministry of Agriculture, Food and Rural Affairs


Trade Names: Conquest B, Pursuit

Group 2

Site of Action: Inhibitors of acetolactate synthase (ALS) and also called acetohydroxyacid synthase (AHAS)

Grapevines planted into soil containing imazethapyr residues may show severe stunting, often appearing in a patch in the vineyard (the patch correlates to areas of low soil pH).

Following POST emergent application:

  • Within an hour the inhibition of ALS enzyme leads to a rapid cessation of cell division and plant growth
  • Within 1- 2 weeks symptoms become visible
  • Meristematic regions are the first to experience chlorosis and necrosis followed by general foliar chlorosis and necrosis

Uptake and Translocation

  • Absorbed by both roots and foliage
  • Translocation in both xylem and phloem


  • Depends on weather and soil conditions (more persistent under dry conditions)
  • Half-life in field: 60- 90 days
  • For most vegetable crops, a 22 month recropping interval is recommended
  • When soil pH is low (below 6.0), persistance can be many years and residues will only begin to dissipate when lime is applied and pH rises above 6.0.

Diagnostic test for pursuit residue using tomatoes and sugar beets Diagnostic test for pursuit after 6 weeksClick to enlarge.