Dicamba
Trade Names: Banvel II, Hawkeye Power, Oracle, Vanquish, VMD 480
Registration status: This herbicide is not registered for use in tender fruit orchards.
When to suspect injury: When dicamba 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. At higher rates, dicamba can be toxic to trees and shrubs having roots under the treated areas.
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: Benzoic acid/phenoxy
Site of Action/ Group: Synthetic auxins (WSSA Group 4)
General Symptoms in Plants
- Bending, twisting, swelling and elongation of stems
- Leaf cupping and curling
- Chlorosis developing later at the growing points
- Growth inhibition
- Wilting in later stages
- 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
- Readily absorbed by roots, stems or leaves
- Translocated to other plant parts
Persistence
- Half-life in soil: 30 days
Residue carryover into the next season is not a problem when applied at rates recommended for crop situations
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.