This plant originates in central South America and is listed as a Category 1b invasive species as part of the NEMBA regulations meaning the plant must be removed and destroyed and it requires control by means of an invasive species management programme.
Threats to food security and human health
This plant causes human and animal health problems such as respiratory and skin allergic reactions. More importantly, it takes over hectares of grazing land, leaving no grasses for cattle and wildlife. As such, it can destroy regional economies based on agriculture or tourism to nature reserves.
It suppresses crop yields and contaminates crop seed. Meat from livestock that has eaten the weed is badly tainted and not fit for consumption. Recent research has implicated famine weed in assisting the spread of malaria mosquitoes, as the mosquitoes are attracted to flowers. Cattle may also be affected and pass the toxic principle into their milk
Famine weed originates from Central America — began invading the province from Swaziland and Mozambique about three years ago. It has spread so fast that it is now found even in southern areas of the province, including Amanzimtoti and Umvumbulu.
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The weed can be successfully managed through a combination of control methods including biological and chemical control, containment strategies, and the utilisation of competitive plants. Ezemvelo KZN Wildlife has compiled a draft strategy to control current famine infestations in their protected areas. Invasion can be curbed by reducing seed introduction and spread, addressing various high-risk activities and following through on appropriate management decisions.
The KZN Department of Agriculture and Environmental Affairs’ Invasive Alien Species Programme offers landowners a herbicide assistance programme for famine weed control. “The South African National Biodiversity Institute’s (SANBI) Invasive Species Programme has a containment project directed at chemical control of parthenium south of Richards Bay. Follow-up herbicide application is required to provide effective suppression.
Famine weed is kept under control by using biocontrol agents and chemical removal, but physical removal of famine weed is not advisable due to the health risks.
Famine weed biological control agents are:
- Zygogramma bicolorata is a leaf-feeding beetle which has been released,
- Puccinia abrupta var. partheniicola is an established winter rust,
- Puccinia xanthii var. parthenii-hysterophorae is a summer rust which has been released and damages the leaves,
- Lystronotus setosipennis is a stem-borer which has been released,
- Epiblema strenuana is a stem-galling moth currently being researched,
- Carmenta nr. ithacae is a root-crown boring moth which has recently been imported and undergoing research,
- Smicronyx lutulentus is a seed-feeding weevil also undergoing pre-release research.