2,4-D
Trade Name: 2,4-D Amine, 2,4-D Ester
Registration status: This herbicide is registered for use in orchards in early spring or post harvest to actively growing weeds.
When to suspect injury: Injury is not expected when 2,4-D is applied with proper equipment and when conditions during application will not cause drift. If applied during warm, humid conditions, vapour drift may occur. If applied during windy conditions, physical drift may occur either up into trees or from neighbouring fields and lawns.
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.
Site of Action/Group:Synthetic auxins, Group 4
General Symptoms in Plants
- Bending, twisting, swelling and elongation of young shoots and petioles
- Young leaves cup, curl and pucker
- Growth inhibition
- Wilting
Symptoms in Fruit Trees
- Leaves turn brown and appear scorched if they have been contacted by a high concentration of herbicide
- Young shoots and trunks of young trees may be swollen, and the bark may split
- If 2,4-D comes in contact with fruit, the fruit may colour and soften prematurely
- Symptoms most frequently observed in early- to mid-summer
- If new growth is affected, symptoms gradually disappear
Uptake and Translocation
- Readily absorbed through leaves or roots
- Translocated primarily in phloem with the sugars but can also move with water in the xylem
- Accumulation is primarily in the young, rapidly growing meristematic regions of roots or shoots
Persistence
- Half life in the soil is usually not longer than 1 or 2 weeks during the growing season due to rapid decomposition by soil micro-organisms
Unique Characteristics
- Amines and esters are the most common formulations of 2,4-D. The esters are the most active, used at lower rates. Since vapour drift is a potential problem with ester formulations, use only the amines on lawns or near susceptible crop areas. Low volatile esters can be used by agriculturalists where risk of damage to sensitive non-target vegetation is low.
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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