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Herbicides
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• Safety - page 25 • First aid - page 33 • Resistance management - page 41
2,4-D (cont’d)
periods of high temperatures (> 27ºC) when crops may be under stress as damage to the crop may occur. Do not spray
during periods of high winds when spray is likely to drift. Coarse sprays are less likely to drift.
How it Works
Systemic, non-selective herbicide. 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. It inhibits pigments, including chlorophyll, leading to death.
Expected Results
Susceptible plants become malformed before they die.
Restrictions
Effect of Rainfall:
2,4-D amine:
A rain-free period of 4 hrs is needed after application.
2,4-D ester:
A rain-free period of 2 hrs is needed after application.
Grazing:
Do not permit lactating dairy animals to graze fields within 7 days after application. Do not graze
or cut treated crops for forage until 30 days after application. Withdraw meat animals from treated fields at least
3 days before slaughter.
Re-cropping:
No restrictions the year after treatment.
Restricted-entry Interval:
Do not enter treated area within 12 hrs after application.
Environmental Precautions
Toxic to small mammals, birds, aquatic organisms and non-target terrestrial plants.
Leaching:
The use of this
chemical may result in contamination of groundwater, particularly in areas where soils are permeable (e.g. sandy
soil) and/or the depth to the water table is shallow. Runoff: To reduce runoff from treated areas into aquatic habitats,
avoid application to areas with moderate to steep slope, bare soil, compacted soil, or clay.
Toxicity
Moderate acute mammalian toxicity. Acute oral LD
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(rats) = technical 300 - 1200 mg/kg. 2,4-D formulations are
toxic to small mammals, birds, aquatic organisms and non-target terrestrial plants.
Storage
2,4-D amine requires heated storage. 2,4-D ester may be frozen.