Now’s the time to act on Lippia

January 18, 2010
By: Mark Kesby, Projects Officer

Anyone that lives on the floodplain should be aware what a scourge Lippia really is. It takes over productive pastures and makes them virtually worthless, smothers native vegetation along rivers and wetlands and can increase bank slump and erosion.

Lippia infests a staggering 5.3 million hectares in the Murray-Darling Basin and is estimated to cost the grazing industry alone $38 million per annum! Landholder surveys conducted by New England consultant Judi Earl conclude that the average reduction in stocking rate is around 55%, but in some situations 100% destocking has been necessary.

Lippia Distribution

In some areas, Lippia was introduced in an attempt to stabilise banks. Unfortunately, it actually has the opposite effect. Because of the massive tap root, lippia has the ability to dry the soil out to several metres, causing the bank to slump and collapse.

Lippia is spread both by seed and plant fragments. It would appear that seed is the major form of spread. It is a prolific seeder and those seeds stay viable for at least 10 years. The seeds need to be covered by free water for a period of time to germinate. Hence, there will be a massive germination of lippia now underway as the floodwaters recede down the valley.

There is good evidence that lippia seed is also spread by vehicles, machinery and animals. For example, it survives through the sheep rumen, and germinates in the dung. However, floods are the major source of spread.

Control of lippia is not easy. Once established, its prolific seeding means that it will never be eradicated. Our only option is to learn to control and manage it. It does have some weaknesses that can be exploited to aid our efforts.

Firstly, there are two chemicals that will give pretty good control in pastures (Lantana DP600 and 2,4-D Amine). Be sure to read and follow the label!

If the infestation is scattered than spot-spraying can is an option. For thicker lippia populations, boom spraying is required. I have been using DP600 for several years to spot-spray my infestations with encouraging results.

Research has shown that one spray will give moderate control but a follow up spray later in the same season will potentially give 100% control if conditions are favourable.

Hard experience of poor results has shown that the only time to spray is when the plant is flowering and not under stress.

This makes now an ideal opportunity! Several years of poor summers has meant that there have been few opportunities so this one should not be missed.

Environmentally sensitive areas can be difficult or impossible to spray. Luckily there are other options. Despite its reputation, lippia is not a good competitor. Overgrazing and floods give it the niche to dominate. If there is good groundcover, conditions are generally unfavourable for seedlings to survive. A good vigorous perennial pasture and sensible rotational grazing will help keep lippia under control.

A case study near Dalby clearly demonstrates the importance of controlling grazing in sensitive areas. A nature reserve had been grazed under lease for an extended period. In 1999, there was dieback in the trees, gully erosion and the groundcover was dominated by lippia. Five years after the removal of livestock many native grasses have regenerated. Lippia will always be present but the balance has been shifted back to native groundcover.

Photograph of Lippia flowering.

Much of the information for this article has come from the excellent Lippia Management Guide put out by the National Lippia Working Group. It contains much more information than I’ve covered here. I’d recommend that anyone with lippia issues on their property get hold of a copy. It is available from our office or any Namoi CMA office.

LPLM 6741 8375
www.lplmc.com.au
A healthy catchment for a productive future