Important Weeds in Maize

In South Africa and the rest of southern Africa maize is the most important field crop as the most important source of carbohydrates. South Africa is the main maize producer in the Southern African Development Community (SADC). More than 9,000 commercial maize producers are responsible for the major part of the South African crop, while the rest is produced by thousands of small-scale producers. Maize is produced mainly in North West province, the Free State, the Mpumalanga Highveld and the KwaZulu-Natal Midlands. Approximately 10-12 million tons of maize is produced in South Africa annually on more-or-less 2.7 million hectares of land. Currently almost half of the production consists of white maize, for human food consumption (Source: Grain SA, 2014)

Successful cultivation of maize depends largely on the efficacy of weed control. Weed control during the first six to eight weeks after planting is crucial, because weeds compete vigorously with the crop for nutrients and water during this period. Annual yield losses occur as a result of weed infestations in cultivated crops. Crop yield losses that are attributable to weeds vary with type of weed, type of crop, and the environmental conditions involved. Generally, depending on the level of weed control practiced yield losses can vary from 10 to 100 %. Rarely does one experience zero yield loss due to weeds.

Yield losses occur as a result of weed interference with the crop's growth and development. Interference encompasses two natural phenomena, competition and allelopathy. Competition occurs for nutrients, water and light, whereas allelopathy is interference through phytotoxic chemicals (allelochemicals) which plants release into the environment. This explains why effective weed control is imperative. In order to do effective control the first critical requirement is correct weed identification.

This page highlights certain weeds that are known to seriously interfere with maize in South Africa.