The Plant Protection Research Institute at the Agriculture Research Council in Pretoria has a very useful website (www.arc.agric.za) and issues very practical newsletters. They've been informing us about Lantana for quite a while "are you listening?"
Lantana (Lantana camara) must be controlled because it is a Category 1 weed that transforms indigenous vegetation into an impenetrable thicket which diminishes natural pasturage, reduces productivity of stock farming, kills cattle, obstructs access to water sources and plantations, suppresses biodiversity, devalues land, and control is required by law.
Summary of Lantana Control Recommendations
Initial Clearing: Cut the weed down to the ground, using loppers or a pruning saw, to remove nutrient reserves. Paint immediately, five times, with a herbicide, using a squeeze-bottle.
imazapyr (Chopper or Hatchet), picloram (Access or Browser) or fluroxypyr/picloram (Plenum).
Dilute the herbicide according to instructions on label. Preferably cut and paint when plants are growing actively, but it may also be done during winter using imazapyr, which has longer persistence.
Follow-up Treatment: This is always absolutely essential. Hand-pull or Spot-spray all weed regrowth when it is 0,5-1,0 m tall, using Access, Browser or Plenum. These herbicides are selective against broadleaved plants, but conserve grasses. Avoid spraying non-target broadleaved plants such as indigenous plants and crops.
Annual Maintenance: Scout for weed regrowth every spring/early summer, and treat as immediately above.
General: Do not rely on biocontrol alone for lantana, because the infestation will become denser and more widespread. Do not disturb the soil, because that creates a seedbed for weeds to germinate in. Do not destroy indigenous plants, because they compete with weeds, and provide various, valuable ecosystem services. If there are big bare areas, rehabilitate them using local indigenous grasses, to impede weeds, restore grazing and prevent erosion.