Lantana camara

Lantana camara, known as Lantana, is a species of flowering shrub belonging to the verbena family Verbenaceae, that is native to Mexico, Central America, the Greater Antilles, The Bahamas, Colombia, and Venezuela. It has been introduced to many other parts of the world as an ornamental plant where in many cases is has become an invasive species in particular in tropical and sub-tropical areas.

Lantana camara

Lantana camara is poisonous to livestock and children have been known to die after eating unripe berries. 

 

Ecological impact  

Lantana camara is a thicket forming shrubs which were introduced into South Africa as ornamental plants but which have become a serious invasive weed.  

Lantana is one of the worst weeds in the world which is still widening its range. It is probably the most widespread invasive plant in Africa. One of the reasons that lantana camara is able to colonise areas easily is because it releases chemicals into the soil that can prevent the germination and growth of other plant species.  

  

Lantana camara has been declared a Category 1 invasive weed in South Africa.  

In terms of the Conservation of Agricultural Resources Act (No 43 of 1983) land occupiers and owners are legally obliged to control Lantana camara. Lantana camara comprises a complex of vigorous, prolific, man-made hybrids, bred in Europe from unrecorded parents from Central and South America, and spread all over the world as a hardy, ornamental shrub, with multi-coloured flowers. Dispersed by fruit-eating birds, it establishes along fence lines and under trees, where it out-competes indigenous plants and forms impenetrable, prickly thickets that reduce biodiversity and land values.   

 

Control of Lantana 

The best form of weed control is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing. 

 

Biological Control 

Conventional control measures for lantana are expensive and ineffective and it has therefore been targeted since 1961 for biological control. A total of 9 lantana biocontrol agents and 3 associated insects were established on lantana in South Africa before 1997, however most agents persist at low densities and only occasionally impact plant populations. The damage is caused by the developing larva or nymph. Some of these agents undergo sporadic, localized outbreaks that defoliate whole stands of lantana, but the plant recovers completely, and continues to densify and spread. Current South African research into biological control of lantana focuses on developing new, host-specific, biocontrol agents to supplement the activity of the agents established earlier. The lantana biocontrol agents established in South Africa are generally widespread but very sparse, reaching only about 10% of maximum abundance. The introduction of the lantana herringbone leaf miner, Ophiomyia camarae has significantly improved biocontrol of lantana along the hot and humid coast of KwaZulu-Natal, but it is sparse inland, and cannot over winter on the highveld. 

 

The lantana biocontrol agents currently established are simply unable to stop the weed spreading. To control lantana, one has to resort to very thorough and persistent mechanical plus chemical treatment. Lantana biocontrol is nevertheless of value, because it reduces the rate of growth and reproduction of the weed, which reduces the frequency and cost of applying other control measures. 

It is extremely difficult to kill lantana, because it comprises a variety of vigorous, prolific, bird-dispersed, polyploid hybrids (with extra sets of genes) that are resistant to drought, frost, fire, insects, pathogens, browsing and herbicides – it dies back, but the parent plant coppices, seeds germinate (better in the sun) and the infestation becomes denser. Quick and easy treatments are a waste of time and money. Getting rid of lantana requires a very thorough and persistent approach. 

 

Initial Clearing: The best form of eradication is to cut the plant down and remove the roots. Where this is not possible cut the lantana plant down to the ground, using a heavy duty brush cutter, bush knife, loppers or a pruning saw, to remove the nutrient reserves. Immediately after cutting paint the surface of the freshly cut stumps with a suitable herbicide, imazapyr (Chopper) is the most cost effective herbicide treatment for initial control dilute according to instructions on the label. Preferably cut and treat when the plants are actively growing during the summer months, but they may also be done during winter when using imazapyr which has longer persistence where breeding birds may be disturbed. Reasonable success can be achieved using a 3 % mixture of Glyphosate and water as well as a 1.5% mixture of triclopyr and diesel 

 

Follow-up Treatment: This is always absolutely essential. Hand-pull or Spot-spray all lantana re-growth as a full cover spray over the leaves when it is 0,5-1,0 m tall, using a herbicide containing the active ingredient glyphosate (Roundup). Avoid spraying non-target plants such as indigenous plants and crops. 

 

Annual Maintenance: Check for re-growth on an annual basis the best time of year being April- May when most birds have finished breeding and when the plants are in flower and are easy to locate. 

 

The many different Lantana camara cultivars found growing in South Africa show a variable response to herbicides. 

 

Michael Hickman 

27.04.12