The plant must not be sold, propagated or knowingly distributed by any person other than a person involved in hay or lucerne production. The growth and spread of the plant must be controlled according to the measures specified in a management plan published by the Local Control Authority.
Why Is It Bad?:
Lippia forms a dense mat of growth that can dominate floodplains. The solid taproot can destabilise river banks and increase erosion. It is not considered a major threat to cultivation but can easily invade and dominate grazing areas and native pastures. Lippia tolerates frost, drought, flooding and saline soils. It spreads easily during floods as segments break off and form new infestations.
Lippia is commonly grown as a low-maintenance lawn species, a practice that should be stopped.
Leaves are 1-3cm long and 2-10mm wide, ovate, often covered with minute hairs, and greyish-green.
Flowers are 5-10mm in diameter, occurring in a rounded flowerhead. Petals are lilac or pinkish. Flowering from spring to autumn or when ever moisture conditions are favourable.
Fruit is round, 1-1.5mm in diameter. Split when mature, contain 2 flat, brown, oval seeds.
A central taproot can grow to 80cm in depth with fibrous secondary roots. Roots can also form at the nodes along stems.
Manual removal or ploughing Lippia into soil can achieve short term control, however this is not recommended for riparian situations where erosion risk is high.
Multiple herbicide applications within a season can provide effective control; late spring or early summer application followed by a late summer application. Selection of herbicide can be difficult as care must be taken not to pollute waterways or kill non-target species.
Slashing & Cutting:
Biological control agents are being investigated by CSIRO. Difficulties have arisen due to the unknown origin of the 2nd Phyla species in Australia, P. nodiflora.
Grazing is not generally used as Lippia is not very palatable to stock. As a ground hugging species, stock are more likely to eat other species present first, decreasing competition for Lippia.
Cultivation & Scalping:
Cultivation and cropping over several years can provide effective control of Lippia. Cultivation of dry soil in hot weather has been found to prevent transplants. When the cropping cycle moves into pasture phase, care must be taken to prevent re-establishment.
Competitive and productive pastures prevent rapid re-invasions and are an essential part of long term Lippia control.
Successful treatment programs rely on ongoing monitoring of sites. Regrowth can easily become larger infestations if follow-up treatments are not part of the management program.