3 ACTIVE INGREDIENTS: Chlorthal-dimethyl 750 g/kg.
4 CHEMICAL GROUP: D.
Benzoic acid. (Chorthiamid)
5 RELATED HERBICIDES:
Dichlobenil.
6 GENERAL DESCRIPTION:
A pre emergent herbicide used mainly in vegetables, ornamentals and lawns.
7 APPLICATION METHODS AND TIPS:
Apply before seeds germinate.
Cultivate soil, plant crop, apply Dacthal then water in.
Mechanically incorporate herbicide to 25 mm deep or less if rain or irrigation is not available within 3 days of spraying.
Don't apply more than 3 days after cultivation because some weeds may have germinated.
Does not control emerged weeds.
Higher rates are required for heavy soils or where extended weed control is required.
Cultivation or disturbance after spraying reduces the effectiveness and residual life of the herbicide.
Apply in 450 L/ha of water or more.
Mix powder to a cream with a small quantity of water and add slowly to spray tank while it is filling and agitating.
Keep spray solution agitated.
10 WATER QUALITY:
Hard water
Colloids
pH
14 HERBICIDE RESISTANCE:
18 PROTECTIVE CLOTHING:
20 MODE OF ACTION:
Inhibits tubulin formation.
Chlorthal is converted to dichlobenil in the soil, then it is absorbed by the roots. It is less volatile and has a greater water solubility, which makes it easier to apply effectively.
It is a powerful sprout and growth inhibiting compound and active on germinating seeds, rhizomes and young seedlings.
Metabolites of chlorthiamid inhibit oxidative phosphorylation and have similar action to bromoxynil.
Uptake and translocation:
Absorbed by germinating seeds.
Mainly root absorbed and moves upwards in the transpiration stream (xylem). Dichlobenil is lost from the plant through the leaves as it evaporates in the transpiration stream.
Very limited movement of chlorthiamid or dichlobenil in a downward direction and little movement for leaves to buds or fruit.
Physiological effects:
Residual Life and Breakdown:
Selectivity:
Does not control established plants.
Selectivity is based on the different rates of metabolism in different plants. Tolerant plants actively degrade the herbicide.
Chlorthiamid affects nearly all plants and selectivity is also based differences in exposure to the herbicide. Deep seeded slow growing plants are generally more tolerant than small seeded fast growing plants.
23 PLANT SYMPTOMS:
Failure to establish.
Toxic to germinating seeds and actively dividing meristems.
Tissue swelling.
Blackened and dead growing points.
Yellowing of leaf margins.
Brittle stems, roots or shoots.
May cause collar necrosis in trees or shrubs.
SECONDARY EFFECTS:
Inhibits soil nitrification and the proliferation of nitrifiers in the soil.
24 TOXICITY:
Summary:
Details:
Mammalian toxicity -
Acute oral LD50 - mg/kg (rats), [For comparison table salt is 3000 mg/kg]
Acute dermal LD50 - > mg/kg (rabbit).
Skin -
Eye -
Vapour inhalation - LC50 - > mg/L air (rat).
Chronic oral toxicity NOEL - ppm for two years.
Not mutagenic or teratogenic (i.e. does not cause cancer or reproductive problems).
Other Species -
Birds - toxicity.
Fish - toxicity LC50 > ppm.
Invertebrates - toxicity.
Bees - toxicity.
25 TOXICITY SYMPTOMS:
26 FIRST AID:
27 ENVIRONMENTAL FATE:
It mainly degraded by soil microbes with some chemical degradation also.
It has a half life in soil of weeks to months. Half life in soil of chlorthiamid is short but dichlobenil the herbicidally active breakdown product is from a few weeks to many months. The variation is due to differing rates of volatile losses in different soils. Surface sprays, high temperatures, wind and low organic matter levels result in short half lives.
It has an EPA classification for soil mobility that ranges from
Ground water contamination
Replanting intervals
Accumulation in milk and tissues. Rapidly degraded in animals and excreted mainly in the urine.
31 PROPERTIES:
Stable in sunlight, acid and hot conditions.
Hydrolyses to dichlobenil in aqueous alkaline conditions.
Water solubility at 25 C. - ppm at pH ;
Oil solubility -
Octanol:Water ratio at 25 C. - at pH 5;
Vapour Pressure at 25 C. -
Dissociation constant - pKa
Melting point - C.
Molecular weight -
Half life in water - days at pH5 and 35 C.
33 REFERENCES:
Ashton, F.M. and Crafts, A.S. (1981) Mode of Action of Herbicides. (Wiley-Interscience publication). P262.
Kearney, P.C. and Kaufman, D.D. (1976). Herbicides. Chemistry, degradation and mode of action. Vol 2. p571-581.
Acknowledgments:
Collated by HerbiGuide. For more information see www.herbiguide.com.au or phone 08 98444064.