Striga (Witchweed) Threats to Cereal Crops Production and Its Management: A Review

Abstract

Striga (witchweed) is one of the most successful parasitic weeds of cereal crops in Africa. It is ‘a poor farmer’s problem’ as there is a near perfect ecological overlap between areas of Striga infestation and where hunger prevails. It is originated in Semien hills of Ethiopia and the Nubian hills of Sudan and later expanded in about 42 African countries. Striga hermonthica, Striga asiatica, Striga gesnerioides, and Striga aspera constitute the greatest economic threat to cereal crops’ yield losses. They are obligate root parasites causing growth inhibition and yield losses of 20-100% in maize, rice, sorghum, pearl millet, finger millet, sugar cane and cowpea. Cultural practices such as long-term rotational cultivation of cereal crops with legume crops unaffected by the parasite is effective in managing the weed. Besides, biological control by use of parasitic fungi (Fusarium oxysporum and Vesicular arbuscular mycorrhiza) play a role in managing the weed. In addition, chemical control with imidazolinone herbicide, ethylene gas, dicamba and 2,4-D are effective in managing striga in cereal crops in extreme cases. Integrated use of striga resistant crop varieties with water conservation practices, soil fertility amendment and use of parasitic fungi (Fusarium oxysporum and Vesicular arbuscular mycorrhiza) is effective in control, economically safe, socially acceptable and environmentally friendly than a single control measure. Therefore, the promising integrated striga management practices should be highly promoted. Moreover, host and Striga species specific integrated Striga management should be designed.

Keywords: Haustoria; Obligate parasite; Root parasite; Strigolactones; Witchweed

DOI: 10.7176/ALST/88-02

Publication date:July 31^st 2021