This article needs attention from an expert on the subject.July 2009)(
Despite the potential for some crop weeds to be used as a food source, many can also prove harmful to crops, both directly and indirectly. Crop weeds can inhibit the growth of crops, contaminate harvested crops and often spread rapidly. They can also host crop pests such as aphids, fungal rots and viruses. Cost increases and yield losses occur as a result. Striga, one of the main cereal crop weeds in Sub-Saharan Africa, commonly causes yield losses of 40–100% and accounts for around $7 billion in losses annually. Around 100 million hectares of land in Sub-Saharan Africa are affected by striga. Barnyard grass has been identified as a culprit in global rice yield losses and certain species have been known to mimic rice.
- Robert L. Zimdahl (12 March 2004). Weed-crop competition: a review. Wiley-Blackwell. ISBN 978-0-8138-0279-4. Retrieved 31 July 2010.
- "The African Witchweed menace". Global Food Security. December 2009. Retrieved 7 October 2015.
- Labrada, R. (July 2002). The need for improved weed management in rice. Proceedings of the 20th Session of the International Rice Commission. Bangkok, Thailand. Retrieved 7 October 2015.
- THC Cartridge
- "MSU Extension Publication Archive" (PDF). Michigan State University Library. Retrieved 5 July 2012.[permanent dead link]