2,4-D
Trade Name: 2,4-D Amine, 2,4-D Ester, Salvo
Group 4
Site of Action: Synthetic auxins
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 soil is usually not longer than 1 or 2 weeks during the growing season due to rapid decomposition by soil micro-organisms.
Symptoms
- Fan-shaped leaves with long “fingers” on the margins
- Downward bending of leaves
- Strap-like leaves with deep sinuses
- Closely-packed thick chlorotic veins
- Leaf puckering
- Zig-zag growth of affected shoots
Young vines are more sensitive to 2,4-D drift than old established vines. 2,4-D is very mobile within the vine and is transported to the growing tips where leaf distortion becomes evident. The cupping and leaf deformation can only occur on growing leaves not on those that are already fully expanded. Conversely a leaf that is deformed while it is growing cannot stop showing symptoms because that is the way it was formed.
Severely affected vines may not recover for 2 years or more.
2,4-D can move either as spray particles in wind or as vapours. With spray particles, the direction is dictated by the wind, which can be predicted. However, vapour movement is more difficult to predict as vapours may move in different directions as air currents change during the many hours after the 2,4-D application.
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