Pyrethrum (Chrysanthemum cinerariaefolium) was introduced in Kenya in 1928 and grown in highland areas above 1,800m in Rift Valley, Central, Nyanza and Eastern regions in over 24 counties on 100,000ha.
Rift Valley is the highest pyrethrum producer in Kenya accounting for 80% of the production. This crop is grown mainly in Nakuru, Nyandarua, Uasin
Gishu, Kericho, Kisii, Kiambu and Narok counties and provides livelihoods to about 8,000 farmers. The crop provides employment directly and indirectly to more than 1million people.
Pyrethrum is grown for its natural pyrethrins which are used in formulating insecticides. The pyrethrins attack the nervous systems of all insects. The use of Pyrethrum as an insecticide is advantageous over other insecticides in that it has a repellent effect on insects, exhibits rapid “knockdown”, and is non-persistent in the environment since they break down on exposure to light or oxygen.
Pyrethrum farming in Kenya dropped in yields during the mid—1990s was due to increasing production costs, disease damage, and delayed the payment by the Pyrethrum Board of Kenya (PBK). The growing demand for “organic” and “natural” pesticides has increased international demand for pyrethrum, despite the existence of synthetic chemical substitutes.
Pyrethrum is an important foreign exchange earner and a significant contributor to the economy. Kenya is the leading producer of pyrethrum extract.
Climatic condition suitable for growing pyrethrum is found in four major regions in Kenya-Lake Victoria, North Rift Valley, South Rift Valley and the Mt. Kenya region. Any shortfall in production in one region due to bad weather can be supplemented by higher production in other regions
Diversification of growing regions as well as flexible seed programmes ensures availability of pyrethrum flowers at all times. Thus, investment in the production of flowers and seeds, in addition to the processing of pyrethrin are assured of the ready local, regional and international market.
The growing demand for organic and natural pesticides has increased international demand for pyrethrin.
Pyrethrum Farming in Kenya – Pyrethrum Growing Areas
Nyanza Region
The pyrethrum growing region is mainly the highlands of Kisii, Gucha and
Nyamira counties in south Nyanza. The climate is mainly wet with continuous rainfall. The area is situated at the centre of the convergence zone of the lake winds and easterlies. Pyrethrum flower production occurs throughout the year.
Rift Valley
The pyrethrum growing counties are Uasin Gishu, Keiyo Marakwet, Trans-Nzoia and Nandi in the North rift and Nakuru, Bomet, Kericho, Baringo, Narok and Laikipia in South rift. Rainfall in the North rift is 1000-1250 mm with clear peaks in April-August and OctoberDecember. Low temperatures and adequate rainfall make the region ideal for pyrethrum roduction.
South rift is the highest pyrethrum producing area and receives 1000-1500 mm of rainfall withpeaks in April-May and October and November. The general climate is cold and wet with a mean temperature of 10-15 o C characterised by a very long cropping season.
Central
The central regions include Nyandarua, Nyeri, Kiambu and Meru which receive 1,000-1500 mm annual rainfall with high peaks between April-May and October-November. The rainfall is bimodal and areas have long cropping season.
Pyrethrum Farming in Kenya – Ideal conditions
Rainfall – Pyrethrum requires a minimum of 750mm of rainfall well spread over the season.
Altitude – an altitude of 2,000 meters above sea level is required.
Temperature – changes in temperature affect the content of pyrethrin.
Land preparation – The land should be well tilled to allow easy penetration by roots. All weeds should be removed and Ploughing should be done during dry months to help destroy stubborn weeds.
Seed selection – Farmers should select seeds based on their agro-ecological zone.
Planting – pyrethrum should be spaced 2 feet inter-row (from row to row) and 1 feet intra-row ( from plant to plant). A tablespoon of Triple Super phosphate fertilizer should be used per plant and mixed thoroughly with soil to avoid scorching.
Topology – pyrethrum should be planted on hilly and well drained areas since it does not tolerate water logging.
Transplanting – Pyrethrum should remain in the ground for three to four years after which it should be uprooted and transplanted in a new field.
Pest and Diseases – Nematodes and several other pests such as thrips, aphids, red spider mites attack pyrethrum thus affecting the production.
Pyrethrum Farming in Kenya – Weed control
Pyrethrum fields must always be kept clean, particularly when plants are young. The major weeds in pyrethrum growing areas are Brassicas and Oxalis. In the Molo region Sheep sorrel (Rumex acetosella L.) is also becoming a weed of concern as is favoured by acidic and impoverished soils. Other weeds of concern are rhizomatous weeds such as couch grass, Sedge and Kikuyu grass.
Pyrethrum Farming in Kenya – Fertilizer Application
Phosphate fertilizers are recommended for use in pyrethrum growing. Triple superphosphate (T.S.P) (46% P205) should be applied in each planting hole at the rate of 125 – 150 kg/ha or 2.5 – 3 bags of 50kg/ha. To avoid seedling scorching, the fertilizer should be thoroughly mixed with soil
in the hole before planting.
Farm yard Manure (FYM) may be used at the rate of 4 tonnes per acre or 10 tonnes per hectare on poor soils. The FYM should be applied three months before planting of the crop. It should be worked in the soil to allow adequate decomposition. If, however, the manure is well decomposed it can be applied at planting time.
Hand Weeding
Hand weeding should be carried out frequently (every 4 weeks) using small forked jembes to avoid root damage. If the roots are damaged, they may result in die-back of the plants. The soil should be drawn around the base of plants. Large scale farmers CAN USE a Ridger for cultivating between rows to be followed with fork jembes to cultivate in the intra-row spaces.
Chemical weed control
Large scale farmers have an option of using carefully selected herbicides to control weeds. Herbicides such as Sencor (Metribuzin), Venzar (Lenacil), Ronstar and Illoxan (Dicoflop methyl) can be used alone or in mixture to control grass and broad leaf weeds. Users of such herbicides should carefully read the labels to get information on rates of application and the necessary precautionary measures.
Cutting back
Pyrethrum plants should be cut back once a year, normally towards the end of the dry season, after picking the flowers. A sickle, not a panga, should be used to remove all the stalks, but not the leaves. Removed stalks should be burnt otherwise they will act as hide outs for pests and diseases. They can also be troublesome during weeding.
Pyrethrum Farming in Kenya – Harvesting
Pyrethrum is grown for its flowers which contain pyrethrins. Studies show that pyrethrins content, dry weight and total pyrethrins gradually increase from the bud stage and reach a maximum when the ray florets are horizontal and 3-4 lines of the outer disc florets are open. During the optimal stage the pyrethrins content may reach 1.8 – 2.0% w/w in improved clones.
Farmers are small-scale and cultivate pyrethrum on land units of between 0.25 and 1.0 ha. Pyrethrum farmers are paid according to the pyrethrins concentration of their flowers. Indiscriminate harvesting of flowers results in large number of immature flowers which decrease the pyrethrins yield of the harvested produce. It has been noted that farmers do not pick flowers at their optimal stage but tend to pick all flowers indiscriminately resulting in reduction of pyrethrins content.
Manual picking of pyrethrum flowers
The pyrethrum plant is cultivated for the production of pyrethrins. Although other parts of pyrethrum contain pyrethrins the highest concentration is in the flowers which contain about 92% of all pyrethrins. The amount of pyrethrin concentration in the flower is determined by the
genotype and environment (altitude, temperature).
Farmers can maximize pyrethrins production through picking flowers at the right time. The recommended picking interval of pyrethrum flowers is 2-3 weeks. At this interval most of the flowers will have attained maximum pyrethrins content.
Cutting Back
At the end of the growing season the flower stalks which remain on the plant gradually dry up. Dry flower stalks are cut using a sickle to allow for further growth of new shoots at the onset of rains. Dry stalks should be burnt to ease weeding and reduce the risk of harbouring pests and
diseases.
Pyrethrum Farming in Kenya – Pests and Diseases
There are many types of pests and diseases that affect pyrethrum thereby reducing flower yields and quality. The most important pests infesting pyrethrum in Kenya are root knot nematodes (Meloidogyne hapla), thrips (T. tabaci and T. nigropilosus), green aphids Myzus persicae (Sulzer) red spider mites (Tetranychus ludeni), eelworms (Aphelenchoides ritzemabozi), Pratylechus spp., together with the fungal diseases, root rot, a complex of diseases caused by Fusarium spp., Fusarium graminearum, Fusarium oxysporum, Fusarium solani, Sclerotinia minor, Rhizoctonia spp, Aschochyta spp, Pythium spp., Sclerotinia sclerotium, Phoma spp and Diplodia spp (Natrass, 1950; Parlevliet, 1971), and bud disease caused by Ramularia bellunensis (Natrass, 1947).
Pyrethrum Farming in Kenya – Drying of flowers
Picked flowers should be dried at farm level immediately to avoid loss of quality. The ideal method of drying flowers, where small-scale production is concerned is by sun drying. Most farmers in Kenya use sun drying of pyrethrum flowers on top of mat. Sun drying is less costly and entails
no significant loss of pyrethrins.
Artificial methods pose a higher risk of causing losses of pyrethrins and require close attention and great care. Where it is necessary to use mechanical dryer, extreme care should be taken to keep the drying air temperature in the dryer at a maximum of 600 C to avoid excessive loss of
pyrethrins through overheating.
Pyrethrum Farming in Kenya – Production
One hectare accommodates 52,000 plants producing about 1,000kg of dried pyrethrum flowers annually. This quantity yields about 25kg of highly refined extract. Ready flowers are picked at intervals of two weeks with picking continuing for nearly a year from July to April. Although pyrethrum is a perennial crop, a typical plantation lasts for three to four years.
Flower picking should be done every two weeks. The flowers are picked when the ray florets have opened to the horizontal position and about three rows of the disc florets are open. Flowers with all the disc florets open and those at the early overblown stage should also be picked as they also contain appreciable amounts of pyrethrins.
Harvested flower heads are sun-dried under small scale production and artificial drying may be used in large scale production, and in cloudy weather and delivered through rural co-operatives to the centrally located factory of the Pyrethrum Board of Kenya (PBK). Farmers are paid according to the weight and pyrethrin content of their harvests.
Frequently asked Questions About Pyrethrum Farming in Kenya (fAQs)
What is The Spacing Of Pyrethru , Row to Row and Plant to Plant?
The recommended spacing for pyrethrum is 60cm ( 2 feet) row to row and 30 cm ( I foot) plant to plant . This spacing gives a plant population of 22,000 plants per acre (52,000 per hectare).
How Much does a famer gets Per kg of her/his produce?
The prices are based on the prevailing world market prizes. These prizes are communicated routinely through prize lists that are reviewed periodically.
Which pyrethrum variety is suitable for my area?
There are many varieties of pyrethrum recommended for various altitudes. Contact the ministry of agriculture staff in your area or call us for specific information on your area.
How do you propagate pyrethrum?
Start the pyrethrum seeds in a seed-raising tray. Sterilize the tray by soaking it for 15 minutes in a solution of 1 part bleach to 9 parts water. After filling the tray up to 3/4 inch from the top with moist, sterile potting mix, sow the seeds at a depth of 1/4 inch.
How long does pyrethrum take to mature?
Fertile and well- drained soils of moderate organic matter are also ideal for vigorous pyrethrum flower production. Pyrethrum continuously flowers for about 10 months in a year. The first picking of mature flowers occurs 3-4 months after planting. Consequently, the flowers are picked every 14-21 days.