Striga asiatica (L.) Kuntze

Code

STRLU

Growth form

parasitic

Biological cycle

Annual

Habitat

terrestrial

After a period of dormancy, Striga asiatica seeds go through a pre-conditioning phase (rehydration) before germination, which is triggered upon receipt of a signal transmitted by the roots of host plants (and other strigol compounds). In the absence of this signal, the seeds become dormant again and can remain viable for over 15 years in the soil. After germination, the striga develops a tenuous organ that will quickly fix on the roots of host and penetrate them to plug into their vascular system. It is thus an exclusive parasite (holoparasite), developing entirely at the expense of the parasitic plant throughout the underground phase, which lasts around fifty days. It is then in the form of whitish ramifications on pinkish roots. After emergence, the leaves grow and become chlorophylous and the plant becomes hemi-parasite, able to support 25% of its needs.
 

 For more information , see the site AccessAgriculture :

a video on the biology of striga produced by ICRISAT

Striga asiatica is an annual hemi parasitic plant, fixed to the roots of wild or cultivated grasses such as corn and sugar cane. It reproduces by seed, transported by water, wind, farm equipment and animals. A plant can produce 50 000-500 000 seeds.

Distinctive characters of some species of Striga spp.
 

Habit	Height	Bract	Calyx	Flower color	Corolla tube	Species
Candelstick with few leaves	10-30 cm	3-5 mm long, linear	5 nervs	pale pink white cream	bent upper than the calyx edge	Striga gesnerioides
Candelstick with well developped leaves	7-30 cm	8 mm long, linear	10 nervs	red yellow white	bent upper than the calyx edge	Striga asiatica
Candelstick with well developped leaves	15-50 cm	longer than the calyx, lanceolate	5 nervs	pink	bent at the calyx edge	Striga hermonthica
Candelstick with well developped leaves	15-45 cm	3 mm long, linear	10 nervs	pink white	bent upper than the calyx edge	Striga aspera
Candelstick with well developped leaves	30-40 cm	30 mm long	10 nervs	yellowish white cream	curve inflated	Striga passargei

 

Striga asiatica is a good indicator species of degraded soils with low fertility.
 
Comoros: This species grows on clayey and stony soils. It is present in the three islands,at low altitude areas especially in meadows of grasses.
Madagascar: Parasitic weed quite widespread in savanna areas (sub humid and semi arid: Middle-West, West, Northwest and Southwest).
Mauritius: Parasitic plant little known, it is found occasionally in sugar cane fields.
Mayotte: Striga asiatica is a native species, parasitic on grasses, discrete but quite common in lawns, padza, crops, pastures and degraded areas.
Reunion: Striga asiatica is a savannah plant that grows in sandy to clayey soil. In Reunion it is present mainly on the east and southeast of the island, up to Saint Pierre.
Seychelles: Present in cultivated areas and abandoned places.

 

 

Global control

From its particular development mode Striga asiatica is very difficult to control by conventional methods. Contamination by seeds cannot be avoided (Production million seeds easily transported). Mechanical work of the soil before cultivation is ineffective, striga does not germinate before the crop began to grow. Conventional herbicides also have almost no effect, striga having cause very high damage even before its emergence. Soil fumigation, very expensive and difficult to implement is also of limited effectiveness.
 
Local control

Madagascar: Striga asiatica is quickly and very well controlled by systems through direct seeding mulch-growing plants that combine traps that trigger the germination of Striga but are not parasitized, creating unfavorable conditions for germination (down soil temperature), enriching the soil with organic matter and nitrogen from cover crops and creating conditions (humidity, temperature, food) favor the development of parasitic striga (insects, fungi).
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cf. The control of striga by DMC systems (direct seeding on permanent Plant Cover). Olivier Husson, Michellon Roger, Hubert Charpentier, Célestin Razanamparany, Narcissus Moussa, Naudin Krishna, Hubert Razafintsalama, Christian Rakotoarinivo, Alain-Paul Andrianaivo, Rakotondramanana Lucien Seguy. Practical Handbook of direct seeding in Madagascar. Volume I. Chapter 3. § 3.1. 2008 (download)
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An information video on Striga management in rice cultivation in Madagascar Highlands has been produced by the Africa Rice Center (AfricaRice) and its partners in the project funded by the African Development Bank 'Support to Agricultural Research for Development of Strategic Crops in Africa "(SARD-SC).
The video explains the agronomic principles that help rice farmers to reduce the impact of Striga in their culture. This 21-minute video explains the four principles that contribute to a reduction in Striga infestation: rotating crops or associated crops including legumes; direct seeding into crop residue without soil tillage; mineral and organic fertilizers; using rice variety resistant to striga.
The first three practices also contribute significantly to the conservation and soil fertility. Farmers describe in their own words their experiences with these practices and explain why and how they do.
The video is the product of close collaboration between AfricaRice, CIRAD (Centre for International Cooperation in Research for Development), the National Agricultural Extension Programme in Madagascar (FOFIFA) and Direct Selection Association in Madagascar (GSDM). The video is available in five languages, English, French, Malagasy, Swahili and Portuguese on the site AfricaRice YouTube.

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