Amaranthus spinosus L.

Code

AMASP

broadleaf

Biological cycle

annual

Habitat

terrestrial

China: Amaranthus spinosus flowers and fruits from July to November.
Morocco: Amaranthus spinosus flowers and fruits from July to November.
Nicaragua: Amaranthus spinosus flowers and fruits all year round.
West Indies:  Amaranthus spinosus flowers and fruits all year raound.

 Northern Cameroon: Amaranthus spinosus is present throughout the rainy season and crop cycle. 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 then occurs in poorly developed plants.

Amaranthus spinosus is an annual species. It reproduces only by seeds. Seed production can be very high; some ecotypes are known to produce up to 235,000 seeds per plant. These have a long viability. They are spread by water and wind. Their level of dormancy varies.

 Keys for Amaranthus

Amaranthus spinosus is a widely spread tropical species. It looks for aerated areas and appreciates deep soils of good quality and rich in nitrogen.

Brazil: Amaranthus spinosus occurs in all regions of Brazil. It is the predominant species in the northern and north-eastern regions.
Northern Cameroon: Amaranthus spinosus is a ruderal species that grows on roadsides, near the villages, especially on the edge of livestock-rearing areas, or in the discharge areas of household waste. It is also a weed of crops. It is very neutrophil, thus its development is more important when the soil is rich in organic matter and nitrogen. It is very common in sheltered fields around the villages and receiving household waste.
China: A ruderal species that thrives in waste places and gardens.
Madagascar: Ruderal species very common around villages, in the sheltered crops.
Mauritius: Common in abandoned land and along roadsides.
Morocco: Amaranthus spinosus is a nitrophilous species found on wasteland and in damp crops, and is fairly rare in Morocco.
Nicaragua: Common in disturbed areas, in all parts of the country, less abundant in the Atlantic zone; from 0 to 1400 m altitude.
Reunion: Species present mainly on the coast or on average altitude in abandoned places, open cultures and along roadsides.
Seychelles: absent.
West Indies: It is a pioneer species that occupies most of the anthropic environments (roadsides, cultivated areas...) of low altitude zones between 0 and 200 m. In Martinique, it is more frequent and sometimes abundant on the poorly developed soils on ash in the North Caribbean region. It is a very nitrophilic species that appreciates fertile cultivated soils.

Local Weediness

Tanzania: Frequent but not abundant.

Local harmfulness

Benin: Amaranthus spinosus is rare, but abundant when present in paddy fields.
Northern Cameroon: In cultivated plot, A. spinosus is less common (4%) in the Sudano-Sahelian regions. However, in the Sudanese region where annual rainfall exceeds 1200 mm, it is present in 15% of the plots. It prefers well-drained loamy soils as excess water slows its growth. In northern Cameroon, with the exception of compound fields with high organic manure, this species is never abundant. It is even sometimes kept in the plots, because its leaves are used for consumption.
Madagascar: A. spinosus is a weed relatively infrequent (perhaps due to the deterioration of the fertility of cultivated soil) and scanty but sometimes troublesome for cultures of vegetable.
Mauritius: A weed occasionally present in the sugar cane fields with very low harmfulness.
Reunion: A weed very infrequent in Reunion, was found in only   two sugarcane plots, but its coverage can be very consequent, to the extent of 85% in very rich soils.
Seychelles: absent.
West Indies: Amaranthus spinosus is a typical species for vegetable and food crops in lowland areas. Although it is sensitive to herbicides, it has a high germination capacity that allows it to colonise bare soil that has been chemically weeded. It is sometimes associated with orchards, but integrated weed management and the absence of ploughing strongly limit its development.

A.spinosus is an alternative host for the nematode Meloidogyne incognita (Kofoid & White) Chitwood and for the mosaic virus disease of tobacco and groundnut rosette.

Uses

Food: In North Cameroon, Amaranthus spinosus is sometimes grown in the plots, because its leaves are used for human consumption.

Global control

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

Local control

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