Weather : mostly fine and sunny, temperatures 20 - 25 degrees celsius.
Scenario at hand : Part of work practical on TAFE campus, car park side border requiring removal of existing grasses and native shrubs, cultivation of soil and preparation for replanting.
Previous weeding on this site : largely unweeded and uncultivated site for several years.
Weeds present : Rope twitch (Agropyron repens), or English couch. Heavy infestation. An erect-growing, perennial rhizomatous plant which can spread in large patches. White Rhizomes can be a considerable length, up to metres long, spreading under barriers like concrete paths. Cultivation of soils can break existing rhizomes,which if left in soil can regrow from nodes and spread quickly.
Treatment Options : Basic hygiene practises such as cleaning clothing, tools and machinery that come into contact with soil carrying rope twitch is very important to avoid spread of rope twitch segments to new areas. Cultural methods suggested by the DPIW include the use of an impervious mulch layer to smother the plant and surrounding soil are, depriving the rope twitch of air, light and gaseous exchange from air to soil - eg. weed matting or black polythene sheeting. The drawback of this technique is that it needs to be laid down for several months to be even reasonably effective and can deprive the soil of beneficial organisms. A mulch layer of woodchip or bark alone is not sufficient usually to control rope twitch as it tends to grow in the mulch layer, but this makes manual weeding somewhat easier, although rhizomes will remain in the soil. Manual control includes freezing but Tasmania usually doesn't get sufficient frosts.
Chemical control can be achieved by the use of round-up or fusilade, but this will also target other monocotyledons such as iris and lillies.
Treatment Techniques chosen : In the end we decided to manually weed what rope twitch we could using a square mouth shovel to first break up the soil and then a garden fork to bring the rhizomes to the surface for removal.
OH&S issues : correct technique for manual weeding to avoid back strain, clothing and broad-brimmed hat to avoid sun exposure and exposure to insects/allergens, wearing high visibility vests because of nearby traffic.
Environmental Work Practises : cleaning of all tools after use, disposal of rope twitch by leaving it in isolation in the compost area exposed to full sun - the best technique is by solarization.
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