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Environmental management for weeds (invasive plants)
Environmental management aims to alter the conditions required by a particular weeds (called invasive plants in the Biosecurity Act 2014), and to destroy them without using herbicides.
Some weeds are fire-sensitive (fire will either destroy or suppress them). However, the susceptibility of plants to fire varies greatly. In some cases fire is used to destroy the weed, in other cases it is used to get access to the weed.
Be aware that some weeds actually benefit from fire. Using fire at times when seeds are developing or ripening can help to prevent the release of seeds, but here the timing of the burn is critical. This approach is most effective with annual weeds that depend on each season's seed crop.
The use of fire as a control method requires detailed planning, such as installing fire breaks, and organising personnel and equipment. In all cases, permits and approvals must be obtained.
Moisture and nutrient control
Some weeds require certain moisture and nutrient levels, and by altering these levels the plant becomes disadvantaged. Some infestations occur due to water run-off, where extra nutrients from gardens, paddocks or drains are carried in the water. If this nutrient supply is cut off, weeds are less likely to thrive.
Overlaying weeds with mulch, newspaper or black plastic (solarisation) are other ways of altering the growing environment for the plant, and will usually prevent plants from germinating. Commercial weed mats are also available.
Over-planting with native species is a long-term control strategy. The objective is to establish a canopy that will 'shade out' and out-compete weeds. This method is usually combined with other control measures.