Striga hermonthica (Del.) Benth.

Code

STRHE

Growth form

Parasite

Biological cycle

Annual

Habitat

Terrestrial

Northern Cameroon: In rainfed crops sawn in May-June, germination of Striga hermonthica starts in early July. The underground development phase lasts 4 to 5 weeks. The first emergences begin at the beginning of August and can occur until mid-October. Flowering begins in September, 5-7 weeks after emergence and lasts until November. Fruiting and seed dispersal takes place in October and November. The complete cycle lasts 90 to 120 days. In the case of irrigated or off-season crops, the development cycle of S. hermonthica increases with decreasing temperature.

Striga hermonthica is an annual species, parasite of Poaceae (wild sorghum, maize, millet, rainfed rice, sugar cane and wild Poaceae). It multiplies by seeds. A plant can produce 10,000 to 50,000 seeds. It is an allogamous species, whose fertilization is ensured by insects, especially butterflies. The viability of seeds in the soil can reach 10 to 15 years. Dissemination is mainly by wind and runoff. When they are dispersed, the seeds are dormant. Germination is triggered by substances (strigol) contained in the root exudates of the host plants, then the radicle attaches to the host root by the haustorium. S. hermonthica then develops into a parasite by feeding on the raw sap of the host. Once emerged, it develops roots and becomes hemiparasitic.

Striga hermonthica can be confused with Striga aspera (Willdenow) Bentham, whose vegetative structure is similar, although smaller. The tube of the corolla of S. aspera is bent 4 to 5 mm above the top of the calyx and has glandular hairs; the bract is 1-2 mm wide. S. aspera parasitizes mainly rainfed rice and wild Poaceae, occasionally sorghum, maize and sugar cane.

Distinctive characters of some species of Striga spp.
 

Northern Cameroon: Sriga hermonthica occurs preferentially in poor soils with a degraded structure with a sandy surface horizon, a clay level (2-5%) and a very low organic matter (less than 0.7%), such as degraded ferruginous soils. Several factors favor infestations: a low rainfall (between 500 and 1000 mm), plots exploited for many years and sensitive crops (millet, sorghum, maize) returning very frequently in the rotation. It prefers strong sunstroke and is more abundant in plots with low density. Conversely, grain crops associated with a legume, such as groundnuts and more particularly creeping cowpeas that cover the soil, are less infested.

Worldwide distribution

Striga hermonthica is an African species. It is widespread in the semi-arid zone of sub-Saharan tropical Africa between 5 and 20 degrees north latitude. It is present throughout Eastern Africa, from Ethiopia to Mozambique and also in Madagascar and the Arabian Peninsula.

Local harmfulness

Northern Cameroon: Uncommon in the wild or in long-term fallow, Striga hermonthica appears in plots cultivated for 3 or 4 years, to become very abundant after 7 or 8 years of cultivation, especially when cereals predominate in the rotation. It is a major regional weed for most sub-Sahelian countries (Mali, Burkina Faso, Benin, Cameroon ...). Two-thirds of the 73 million hectares devoted to cereal production in Africa are located in ecological zones where Striga is present. In North Cameroon, yield losses due to S. hermonthica attacks are estimated at between 30 and 100%. Half of the districts have all of their contaminated cereal plots.

For more information on Striga asiatica please consult AccessAgriculture, and videos on striga management,
published by ICRISAT

• Integrated approach against striga
• Composting to beat striga
• Joining hands against striga
• Grow row by row
• Animals and trees for a better crop
• Reviving soils with mucuna
• Storing cowpea seeds
• Succeed with seeds

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Striga%2520hermonthica