Blackjack is susceptible to fungus diseases, which should
be controlled with systemic fungicides. The treatment Further information can be obtained from:
should be done when no flowering is taking place in the Directorate Plant Production
garden. Private Bag X250
PRETORIA 0001
Harvesting methods Tel. 12 319 6072
Fax 12 319 6372
Harvesting is done by hand picking, cutting and uprooting.
Email Thabo.Ramashala@daff.gov.za
Uses
The tender leaves and young shoots are used as a leaf
Blackjack
vegetable. Sundried powdered leaves are preserved to be
used during dry seasons or winter. Old leaves are not suit-
able for consumption because they have a bitter, astringent
taste.
References
BROMILOW. C. 2010. Problem plants of South Africa, Briza.
FABER, M., OELOFSE, A., VAN JAARSVELD, P.J., WENHOLD, F.A.M
& JANSEN VAN RENSBURG, W.S. 2010. African leafy vegetables con-
sumed by households in Limpopo and KwaZulu-Natal. S. Afr. J. Clin. Nutr.
2010:23(1).
ZOBOLO, A.M. & MKABELA, Q.N. 2006. Traditional knowledge transfer
of activities practised by Zulu women to manage medicinal and food plant
gardens. African Journal of Range and Forage Science, 23(1): 77–80.
www.cabi.org/isc/datasheet/9148. Accessed 28/07/2014.
www.database.prota.org/PROTA html/bidens pilosa.En.htm. Accessed
28/07/2014.
2014
Printed and published by: Scientific name: Bidens pilosa L.
Department of Agriculture, Forestry and Fisheries Family: Asteraceae
Obtainable from: Common names: Blackjack, knapsekêrel,
Resource Centre Umhlabangubo, Uqadolo, Mushiji,
Directorate Knowledge and Information Management Mokolonyane, Muchize
Private Bag X388
PRETORIA
agriculture,
0001
forestry & fisheries
Department:
Agriculture, Forestry and Fisheries
REPUBLIC OF SOUTH AFRICA
Origin and distribution
Blackjack is reported to have originated in South America.
It was distributed throughout the tropics in Africa.
Production areas in South Africa
Blackjack is growing naturally in homestead gardens in
KwaZulu-Natal, Limpopo and some parts of Mpumalanga.
Description
It is an erect, slender, branching, annual herb, growing up
to 100 to150 cm in height.
Stem
The stem is erect, ramified, square and hairless and grows
up to 120 cm tall. It has spreading branches, as the season
progresses. The major branches tend to be sprawling and
root at the lower nodes where they touch the ground.
Climate and soil requirements Fertilisation
Leaves Temperature The plants have to be fertilised often and it is recommend-
ed to use manure to enrich the soil at the end of winter.
The leaves are opposite and are divided into 3 to 5 leaflets Blackjack grows well in temperatures ranging from 25 to 38 Fertilise every 20 to 25 days when watering. Use a granular
with toothed margins. The terminal and lateral leaflets are 0C. Temperatures above 45 0C are not favourable and it fertiliser for 3 to 4 months, if the plants are large. In spring,
ovate to lanceolate shaped. Leaf stalks are very slightly also cannot tolerate frost. the use of nitrogen and potassium is recommended to
winged.
favour the development of new growth and flowering.
Rainfall
Flowers
Blackjack thrives with abundant rainfall, but can withstand Irrigation
The flowers are small, white and yellow in colour and are droughts. The optimum rainfall for growth ranges from 500 The plants can be watered from time to time; irrigate the
5 to 15 mm in diameter. They are borne on long, slender to 800 mm. crop with 4 l/m2 every 2 weeks.
stalks at the end of the stems. Each flower head has 4 or
5 short, broad, white petals with numerous, yellow disc Soil
florets. Weed control
Blackjack grows in fertile soil in the wild, planting fields Blackjack often germinates in dense mats. These uniform
Fruit and gardens. It prefers light, medium and heavy soils, but shallow germination stands are relatively easy to control,
thrives in loose soil high in organic matter. It also thrives in especially with post-emergence herbicides. Because of the
The fruit of the blackjack is unpleasant, hairy and able to deep, well-drained soil. It can grow in a soil with a pH rang- large seeds, pre-emergence control can be erratic.
penetrate rapidly through several layers of clothing. It has ing from 4 to 9 and can tolerate saline soil.
a dry, pronged fruitlet with hooks.
Pests and diseases
Cultural practices
Seeds The most common insect attacking blackjack is aphids. At
Propagation the end of winter, the application of insecticides is recom-
Seeds are small, black and slender with little claws on one
Blackjack is propagated by seed. mended to prevent aphid attacks.
end. The seeds are 4 angled, 6 to 12 mm long with 2 or 3
barbed awns (stiff bristles).
