Herbicide Drift and Trees

It is spring and the weather has been a bit erratic. Farmers, Utility Crews, Tree Services, Landscapers and Homeowners are pushing to get their herbicide applications completed. Unfortunately, sometimes this means herbicides end up “off target” which can cause “damages” to adjacent properties, trees and landscaping. How does this happen?

1. Drift and volatilization
   • This happens when wind speeds and/or direction are not considered or change in the middle of an application. Or when conditions are favorable to volatilization.
2. Misapplication
   • This happens when the wrong chemical, wrong rate or a contaminated  sprayer are used.
3. Run off and leaching
   • This happens when herbicides are soil active and move through the soil due to various environmental reasons.
4. Contaminated soil or mulch
   • This occurs when active herbicides are in mulch or soil and are used around trees or shrubs.
5. Malice
   • This happens when an employee, neighbor, or unruly fan  is ticked off mixes up a tank of herbicides and uses them on a property for a malicious purpose.

When herbicides interact with non-target plants damages can occur. The task for a Consulting Arborist is often to determine

• Are there damages?
• What caused the damages?
  • Is there a biotic cause?
    • Pests
    • Drought or excess water stress
    • Extreme heat or cold     etc?
  • Is there an abiotic cause?
    • Herbicides from an adjacent property?
    • Herbicides but self inflicted?
    • Salt damage from the winter?
    • Other human issues?
• What is the dollar amount of the damages?
• When looking for a Consulting Arborist, look for someone who has experience with herbicides and plant interactions. Often a knee jerk reaction is used and damages are exaggerated. Some damages are temporary with the plant growing out of them, some are temporary but result in replant replacement.
•  Some of the photos below are herbicide related and some are not. Some will have monetary damages, some will not!
• Can you determine which fit into which category?

  Curled oak leaves with necrosis

  

  Biotic  or Abiotic- May need to send to a lab

  Odd circles around a dying tree

  

  What caused this dead ring around the tree?

  Ash with odd galls

  Cupped leaves
  

  Ash dieback
  

  What caused this dead spot?

  Right-of-way application. Damages?