​A weed is any plant that grows in an undesirable place. Any plant can thus be a weed, for instance a maize plant growing in a wheat field is also considered a weed.

Plants that become weeds are usually vigorous growers, making them compete against the crop for water, light, space and nutrients. Some weeds may interfere with the harvesting process and when they occur during the off-season they withdraw moisture from the soil and, when mature, set seed which grows and causes problems in the next crop.

 

 

Ryegrass

Lolium spp.

 

Ryegrass originated in Europe and in South Africa occurs in Gauteng, North West Province, Free State and Kwazulu-Natal.  It is usually found along roadsides and in other disturbed areas.  In some areas ryegrass is planted as a fodder crop.

It is also a well-known weed in the coastal regions of the southern Cape and is considered to be the most important grass weed in winter cereals in the Western Cape occurring in both the Swartland and Rûens regions.  Because of its propensity to rapidly evolve herbicide resistance, ryegrass is widely considered the most problematic weed in South Africa.  Where ryegrass has become resistant to the herbicides used to control it, an intergrated control approch within a crop rotation system is most succesful in dealing with the problem.   

Ryegrass also occurs as a weed in deciduous fruit orchards as well as in vineyards. All Lolium species hybridize freely with one another and therefore no distinction is made between different ryegrass species.

 Ryegrass in a wheat field

 

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Wild Radish

Raphanus raphanistrum


​Wild radish also originates from Europe and is widespread in South Africa. It is a very strong competitor for both  water and nutrients, competing easily with small grain crops for these resources.

 It is also a common weed in gardens and disturbed areas. Wild radish is considered to be the most important broadleaf weed in winter cereals in the Western Cape. It also occurs quite frequently in wheat fields in the eastern Free State and sometimes in the North West Province. 

 

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Wild Oats

Avena fatua

 

Wild oats originates from Europe and Asia.

It is a common weed in the southern Cape Province and the grain producing areas of the Free State. It also occurs less frequently in other parts of the country. Wild oats is commonly found along roadsides and in cultivated fields, especially in wheat fields. It is also a winter weed and has become a major problem in the irrigation areas of the Northern Cape.

 

 

 

Wild Buckwheat

Polygonum convolvulus

 

​Wild buckwheat originates from Europe and is widespread in southern Africa. This weed climbs up against other crops to reach the sunlight and competes with the crop to such extent that the crop may die. It is especially troublesome in winter wheat in the eastern Free State.

 

 

White Goosefoot

Chenopodium album

 

​White goosefoot originates from Europe and Asia and is widespread in southern Africa. It is a severe competitor with several crops. White goosefoot is an important weed in various crops like wheat and maize and is also a problem in gardens.

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