Pyrethrum is a cash crop grown for its natural pyrethrins which are used in formulating insecticides. The flowers are pulverized and the active components, called pyrethrins, contained in the seed cases, are extracted and sold in the form of an oleoresin. Pyrethrins attack the nervous systems of all insects . Pyrethrum has advantages over other insecticides in that it has repellent effect on insects, exhibits rapid “knockdown”, and is non-persistent in the environment and hence recommended by the World Health Organization ( WHO) for export horticulture and fruit production due to its low Minimum Residue Levels (MRLs). It is considered to be amongst the safest insecticides for use around food. It is one of the most commonly used allowed non-synthetic insecticides in certified organic agriculture. Pyrethrins are gradually replacing organophosphates and organochlorides as the pesticide of first choice. They are not persistent, being biodegradable, and break down on exposure to light or oxygen.
Pyrethrum was first introduced in Kenya in 1928 from Europe and by December, 1933 the first commercial crop from the country was sold abroad. Kenyan pyrethrum was of very high quality. It therefore quickly replaced the Japanese pyrethrum on the world market by around 1941. The majority o f Pyrethrum growers today are small scale farmers with less than 5 acres of land. The counties with potential to grow pyrethrum in Kenya include: Nakuru, Uasin Gishu, Keiyo, Marakwet, Nandi, Baringo,Koibatek, Kericho, Bomet, Narok, Laikipia, Trans Nzoia, West Pokot , Kisii, Nyamira , Kiambu, Nyeri , Nyandarua , Meru, Nyambene and Embu .
Pyrethrum is well adapted to the Kenyan conditions and usually does not require a lot chemical inputs. Although Kenya produces the best quality pyrethrum in the world, the sector has been bedeviled by many problems that have contributed to the downfall of Kenya’s share in the world market from a high of 70% to the current 2%.
It’s with great hope that the entry of HighChem Agriculture into the pyrethrum industry will significantly contribute to current efforts in the country to turn around the fortunes of this sub sector to reclaim its place as the industrial crop of choice for Kenyas small holder farmers.
Pyrethrum Growing Recommendations
Rainfall : Pyrethrum requires a minimum of 750mm (30 inches) of rainfall well spread over the season. In warmer areas, where evaporation is high, a precipitation of 1000 to 1125mm (40 to 45 inches) well distributed per season is preferable. When there is adequate rainfall at the beginning of the season, there is an immediate flower flush. Excessive rains may encourage root rot and bud diseases which drastically reduce yields. A persistent drought of four months and above will greatly reduce yields while a short dry spell gives a wintering effect resulting into higher flower production.
Altitude and temperature: In Kenya, there are clones and varieties suitable for high altitude, above 1980 metres (approximately 6,500 feet) down to 1760 metres (approximately 5,770 feet) above sea level. Best flowering is easily achieved at and over 2130 metres (7,000 feet) above sea level. The Pyrethrins content is affected by changes in temperatures i.e. as the mean temperature falls, the content rises. Flower initiation also increases as the temperature falls during the onset of rains. The flower initiation is reduced by high temperatures which prevail in low altitudes while heavy frost, which can occur at high altitudes, causes reduction in yield due to wilting of tillers. Pyrethrins content is however, not reduced by mild frost. Under irrigation, frost may have no affect on the crop.
Land preparation : The land should be well tilled to allow easy penetration by roots. All weeds should be removed . Farmers can use Highstop herbicide which removes unwanted weeds. Ploughing should be done during dry months to help destroy stubborn weeds.
Seed selection: A farmer needs to select the seed based on agro- ecological zone. HighChem and Pyrethrum and other industrial crops directorate have maintained diverse clones and seed material suitable for various zones.
Seed Sourcing :HighChem Agriculture maintains nurseries that are able to provide farmers in Kenya and the region with all the planting materials i.e. high quality clones (K 223 splits) and high quality seeds (P.4) variety. Seeds are packaged in 250 grams satchels which is enough for half an acre.
· Pyrethrum is a perennial crop and occupies land for three – four years and hence a farmer should have this in mind before planting.
· Ideally,an acre should have 22,000 plants and produces approximately 400kgs of dried pyrethrum flowers annually.
- Spacing : 2 feet ( 60cm) inter- row and 1 feet ( 30cm) from plant to plant ( intra-row)
· Use a table spoon of Triple Super phosphate ( TSP ) for every plant when planting. 50kgs of TSP is sufficient for one acre. The fertilizer should be mixed thoroughly with soil in the hole before planting, to avoid scorching the plant roots by fertilizer. Compost manure can also used instead of TSP at the rate of 200 grams per hole.
Crop Management: The crop should be kept clean and free from weeds for sustained productivity for 3- 4 years. Pyrethrum does not tolerate water logging and hence should be planted on hilly and well drained areas.
Pests and diseases: Pyrethrum is affected by nematodes and several pests including thrips, aphids, red spider mites which affect the production of quality. Nematodes are managed by crop rotation and use of Nemakil. It’s recommended to spray Albaz, Hycarb or Hable to control pests.
Crop Rotation: Pyrethrum clones should remain in the ground for three to four years after which they should be uprooted and transplanted in a new field. Under very good management, transplanting to a new field can be deferred up to the fourth year. Pyrethrum plants raised from varieties should not be replanted at the end of the rotation period. These should be discarded and new seed used to plant the next field. If pyrethrum is left in the same field for more than three years, flower yield declines to un uneconomical level in subsequent years due to accumulated effect of pathogens, pests and nutrient depletion.
To restore soil structure and reduce soil pests and diseases of pyrethrum, the land should be rested under grass or bush fallow. A clean-up crop, for example, cereals such as maize, wheat, oats or barley or grasses such as weeping love grass, guinea grass, Guatemala grass may be used for rotation.
Topdressing: For flower production, top dressing is NOT recommended as the plant has the tendency to produce a lot of vegetative material and not buds which is required for flower production. It is recommended that farmers spray Boomflower two weeks before onset of flower and there after in intervals of two months for profuse flowering.
Harvesting: Flower picking can be done every two or three weeks. It is advisable that flowers are picked when the ray florets have opened to horizontal position and approximately 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 still contain appreciable amounts of pyrethrins. Young flowers contain little pyrethrins and if picked in large quantities will lower the pyrethrins content. Flowers picked with excessive moisture are liable to ferment resulting in losses of pyrethrins. It is recommended, therefore, that growers allow dew and rain water to fall off before picking.
Avoid picking flowers with flower stalks because stalks have little pyrethrins and therefore cause reduction in pyrethrins content of the flowers. The best picking is achieved by holding the flower between the first and the second finger and jerking the flower head with the thumb.
Drying: The ideal method of drying flowers, where small scale production is concerned is by sun drying. It is less costly and entails no significant loss of pyrethrins. However, in cloudy weather or when large quantities of flowers need to be dried fast, artificial drying may be employed.
Artificial methods of flower drying however 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 500C to avoid excessive loss of pyrethrins through overheating.
To speed up drying, HighChem Agriculture in collaboration with Afgen are coming up with artificial solar dryers which will be attached to pyrethrum collection centers and cooperatives.
Highchem Agriculture - Dry Flower Purchase Procedures:
· The pyrethrum flower must be clean with no foreign matter
· Must be dry flower with moisture content of less than 11%
- Collected from designated centers as agreed with farmer cooperatives
· Payment on the basis of weight and pyrethrin content.