Amaranthus viridis L.

Code

Growth form

Biological cycle

Habitat

Brazil: In the south-eastern region Amaranthus viridis germinates mainly in spring and summer. The cycle from germination to seed production lasts 80-90 days. Under certain conditions, the plant can produce seeds in 4 weeks, allowing 3 to 4 generations per growing season.
China: Amaranthus viridis flowers from June to August and fruits from August to October.
Mayotte: Amaranthus viridis flowers and fruits all year round.
Morocco: Amaranthus viridis flowers and fruits from May to October.
Nicaragua: Amaranthus viridis flowers and fruits all year round.
West Indies: Amaranthus viridis flowers and fruits almost all year round, but mainly from March to June.

Northern Cameroon: Amaranthus viridis is present throughout the rainy season. In cultivated plot, it is virtually absent at the end of the crop cycle because it is eliminated by weeding. In long days (June-August), the duration of the development cycle, from emergence to seed production, is two months. The plants are then very developed. However, at the end of the rainy season when the days get shorter, the duration of this cycle can be reduced to three weeks. Flowering occurs then in very underdeveloped plants.

Amaranthus viridis is annual a species which reproduces only from seeds. The plant can produce 7,000 up to 10 000 seeds that are dispersed by water or wind. They produce a large amount of seeds that have a long viability.

Key for Amaranthus

Amaranthus viridis is widespread in tropical and subtropical regions and in the rice fields in altitude. It is found on well-drained soils in open areas and cultures, preferably on sandy soil or humus-rich and rather humid. The plant grows best on land where water is not stagnant. It is very common in Java between altitude of 300 and 600 m.

Brazil: Amaranthus viridis can occur in all regions of Brazil, especially in coffee crops or in plots previously cultivated with coffee. It is a common ruderal species in cities and in disturbed environments, especially on ploughed soils provided they are not excessively wet.
Northern Cameroon: A. viridis is primarily a ruderal species that grows on roadsides, near the villages, especially surrounding the livestock-rearing areas and on the discharge areas of household waste. It is a weed of very infrequent cultures. It is very nitrophilous thus its development is more important when the soil is rich in organic matter and nitrogen.
China : A ruderal species and a crop weed.
Comoros: The species grows in cultivated or abandoned land and in the courtyards of houses. It is present at low altitude in all parts of Grande Comore.
French Guiana: Very common plant on the Mana polder and its surroundings, among the ruderal vegetation of the non-flooded environments. It is a nitrophilic weed common in vegetable crops.
Madagascar: A species found mainly at medium altitude on  organic soils rich enough or on semi humid soil of terraces with slopes used in the growing of vegetables.
Mauritius: Common species of cultivated fields, vacant abandoned land, roadsides. It occurs primarily in the humid and dry part of the island.
Mayotte: Species naturalized in degraded environments. As a weed it is frequent in market gardening, mainly in the north of the island but also in the south.
Morocco: Amaranthus viridis is a nitrophilous species that thrives on wasteland, ruderalized areas, rubble, crops and wadi beds.
Nicaragua: An occasional species, in disturbed sites and brackish marshes throughout the country; from 0 to 400 m altitude.
Reunion: The species is found on well-drained soils. The plant has an average water need. It grows best in soil rich in organic matter and nitrogen. It occurs mainly in low and medium altitude, but very little on the east and south coasts of the island. It is much more common in the West.
Seychelles: The species grows well on red soil rich in organic matter of high altitude regions and on very sandy soils.
West Indies: Amaranthus viridis is a common species in all wastelands, stream banks and cultivated fields, especially in irrigated market gardening, from 0 to 200 m (500 m) altitude.

Global Weediness

A weed of minor importance.

Local Weediness

Bangladesh: can cause yield reduction up to 80%.
Kenya: Frequent but not abundant.
India: The slender amaranthus is considered as one of the most harmful weeds which may lead to heavy losses in crop yield. Its weedy status is more important than its culinary value.
Tanzania: Frequent but not abundant.
Uganda: Frequent but not abundant.

Global harmfulness

Amaranthus viridis is a weed of minor importance.
 
Local harmfulness

Burkina Faso: rare and scarce.
Chad: frequent and scarce.
Comoros: A. viridis is a ruderal species and common weed of vegetable crops.
Ivory Coast: frequent and scarce.
Ghana: rare and scarce.
Kenya: common and scarce.
Madagascar: Weed generally infrequent and sparse.
Mali: frequent and scarce.
Mauritius: A weed with a strong harmfulness in vegetables and sugar cane cultivation, when it grows in large numbers.
Mayotte: Amaranthus viridis is more abundant in the north of the island, but also present in the south.
Nigeria: rare and scarce.
Uganda: common and generally abundant.
Reunion: It is a weed that has average ecological amplitude in 23% of the plots. It is uncommon in sugarcane, and found primarily on vegetable crops (Fr> 25%). However, its harmfulness is low, with an overlap of 7 to 15%. Rather it is a ruderal species.
Senegal: frequent and scarce.
Seychelles: Very common species that can be a serious weed in all cultures.
West Indies: Amaranthus viridis is not very present in sugarcane fields. It is particularly widespread in vegetable crops, but has a lesser impact on them.

Food: Young tips eaten as vegetable.
Livestock Feeding: It is also given to the pigs.
Medicinal: The whole plant extracts of Amaranthus viridis have antidiabetic, antihyperlipidemic and antioxidant effects. An infusion of the entire plant is used in Indonesia as a remedy against intestinal cramps, diarrhea and dysentery, and externally as a cooling agent to treat fever. In Malaysia, used against inflammation and fever, and externally to treat wounds. A. viridis is used in local medicine in Taiwan, Often in mixtures with other medicinal plants, to treat hepatitis, tight chest, bronchitis, asthma, and lung troubles, to stop bleeding and as a hair tonic. It is used locally in India against dysentery, as a cholagogue, abortifacient and to treat snake bite, in flamed wounds and boils, and in Thailand and Sri Lanka as galactagogue.

Global control

Cultivation favours emergence of A. viridis, and is a useful mean of killing seedlings before sowing rice.

Biological control: Hypolixus trunculatus whose larve form tunnels and galls in the stems of A. viridis , is known in Pakistan, India and Thailand and feeds on A. viridis. But its suitability as a control agent is hampered by its relatively long life cycle and low reproductive capacity. The caterpillars of Hymenia recurvalis in large number defoliate the weed and, where infestation is severe, practically every plant is infested. But H. recurvalis has a wide host range, is a part of several vegetable crops, which makes it unsuitable for biological control of A. viridis.

Chemical: Pre-emergence application of Buttachlor at 2 to 2.5 kg ha-1 gives excellent control. Post-emergence application of 2 4-D at 500 g/ha.

Management recommandations for annual broad-leaved weeds in rice fields: http://portal.wiktrop.org/document/show/20

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