Herbicide Application

Herbicide Application

1. Foliar

   • Contact
   • Translocated
   • selective
     • broad leaf
     • grass
   • non selective
   • Retention
     • keeping droplet on leaf
     • leaf properties
       • overcome waxy cuticle
         • wetters and stickers
           • reduce surface tension
             • need to get in plant quickly
     • environmental factors
       • evaporation
       • wax quantity
         • glasshouse plants have thinner waxy cuticle
         • water stressed = more wax
       • humidity
         • 100% efficacy @ 95% RH 30% efficacy @ 40% RH
           • Anderson et al 1993
       • temperature
       • light
         • can be necessary for efficacy
         • causes activity
           • active plants absorb active product quicker
             • wont survive as long
       • rainfall
         • some plants need a longer period after rain than others
           • water loving or water hating

2. Soil

   • pre emergence
   • post emergence
   • don't know how long will last on soil
     • affected by water and OM
   • selectivity
     • broad leaf taken up through roots
     • grass weeds through shoots as emerge

3. All

   • some herbicides will not control some weeds
   • bigger plants are better at breaking down herbicides
     • hence need more to kill
   • translocated herbicides should be applied to actively growing plants
   • active plants are more reactive
   • if soil temp below 5C will not grow
     • if temp drops after taking up herbicide then effect slows accordingly