Territory Stories

Northern Territory weed management handbook



Northern Territory weed management handbook

Other title

Weed management handbook


E-Publications; E-Books; PublicationNT




Made available via the Publications (Legal Deposit) Act 2004 (NT).; This manual has been developed to provide detailed information about weed control in the Northern Territory.


Date:2012; Includes: Weeds in the N.T. -- Legislative responsibilities -- Strategic & planned approaches to weed management -- Prevention -- Weed control methods -- Integrated weed control -- Using herbicides correctly -- Herbicide toxicity -- Modes of action -- Herbicide resistance -- Herbicide control techniques -- Using adjuvants, surfactants & oils with herbicides -- Factors affecting adjuvant use -- Records of use -- Disposal of excess chemicals & used chemical containers -- Chemical handling training -- Weed control option tables -- Publications -- Websites.




Weeds -- Control; Weeds -- Northern Territory -- Identification

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Northern Territory Government

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53 p., : ill. (chiefly col.) ; 30 cm.

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10 NORTHERN TERRITORY WEED MANAGEMENT HANDBOOK 2012 Re-entry Intervals Once applied, herbicides can remain on sprayed plants in the form of foliar aerosol particles. These residues can readily be dislodged and absorbed through the skin. The re-entry interval is the time that must lapse between applying the herbicide and re-entry into the sprayed area in order to avoid post application exposure. Re-entry intervals appear on the labels of products that have been subject to a technical review by the APVMA. If a re-entry period is not specifi ed on the label, the general rule is to wait 24 hours after application or until the plants are dry, whichever is the longer. Re-entry in the prescribed timeframe should always be avoided if possible, and if re-entry is necessary, personal protective equipment should be worn. Sprayed areas should never be re-entered when the plants are wet i.e. from dew or light rain, irrespective of the time elapsed, unless appropriate personal protective equipment is worn. Withholding Periods The withholding period is the minimum mandated interval that should elapse between the last application of herbicide to any crop, pasture or animal and the harvesting, grazing, cutting, slaughtering or the collection of milk and eggs for human consumption. Observance of the withholding period stated on the registered label is a legal requirement and is part of the direction of use. Modes of Action Modes of action refer to how different groups of herbicides kill plants. Plants are complex organisms with defi ned structures in which many vital processes occur in well ordered sequences. Plants are made up of organs (roots, leaves etc), which consist of tissues (photosynthetic, meristematic and structural tissue etc), that in turn are made up of cells. Within these cells metabolic processes such as photosynthesis, protein synthesis and respiration occur. Other processes include cell growth and differentiation, seed formation, translocation of molecules and transpiration. Herbicides are designed so that they disrupt one or more of these processes and kill the plant. In simple terms, the following describe the various modes of action: growth regulators; amino acid synthesis inhibitors; lipid synthesis inhibitors; seedling growth inhibitors; photosynthetic inhibitors; cell membrane disrupters; and pigment inhibitors. For further information see Appendix E. Herbicide Resistance Herbicide resistance is the ability of a plant to survive, grow and reproduce after exposure to a dose of a particular herbicide that would normally be lethal. In certain plant populations herbicide resistance may occur naturally or may be a result of genetic engineering. Herbicide resistance may emerge as a problem due to the continual use of a particular herbicide, or group of herbicides with the same mode of action, on a population of plants. When resistant individuals within a population survive and reproduce, the population may become dominated by individuals able to survive the particular herbicide, or group of herbicides with the same mode of action. The development of herbicide resistance can be reduced by minimising use of high resistance risk herbicides (e.g. group A and B herbicides), see Appendix E, and ensuring that herbicides with the same mode of action are not used repeatedly on the same population of weeds.

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