Prior to the 1950s, before herbicides (weed killers) were available, farmers tried all possible means to eradicate poison-leaf (more commonly known as gifblaar). These included piling salt over the leaves or spraying them with paraffin or locust poison. However, the methods were haphazard and led to no definitive results. Leemann (1935), therefore saw the need to scientifically investigate gifblaar eradication. According to Meissner (1964), Leemann was the first researcher to control gilblaar successfully. The methods that he tested were to dig open and uproot the whole plant, or dig the main stem open and treat it with chemicals.