Pyrethrum farming in Kenya has been an essential agricultural activity for many years. Pyrethrum, also known as the “African daisy,” is a flowering plant that is primarily grown for its natural insecticidal properties. The active compounds in pyrethrum, called pyrethrins, are widely used in the production of environmentally-friendly insecticides.

Pyrethrum Farming In Kenya; A Growers Manual

Pyrethrum Farming In Kenya

Pyrethrum was introduced in Kenya in 1928 and until 1998, Kenya used to produce between 10,000 to 15,000 metric tonnes annually on 100,000 acres; this constituted about 70% of the world’s supply (the global supply was about 20,000 MT, with 85% of this bought by USA, Canada, South America, UK, EU, Australia, and other African countries). At independence in 1963, pyrethrum was one of four major cash crops after coffee, tea, and maize, and this was reflected in Kenya’s national coat of arms.

The advent of cheaper synthetic pyrethroids in the early 1990s to cater to the increased pyrethrin demand among other factors led to the decline of the pyrethrum subsector’s production to 300 MT (i.e., 2% of global pyrethrum demand) on 3,000 acres valued at KES 1.06 billion (10.6 million USD).

Kenya is said to have ideal climatic conditions for optimal pyrethrin yield and has been a preferred supplier by major markets across the globe. In addition, Kenya can produce over 20,000 MT per annum generating 20 – 75 million USD for farmers and 58 million USD in foreign exchange earnings from the refined extract alone. With an average size household in Kenya of 4,4 people, one processing company alone can potentially provide livelihoods benefitting more than 880,000 people.

Furthermore, by December 1933 the first commercial crop from the country was sold abroad. Kenya pyrethrum was very high quality. It therefore quickly replaced the Japanese pyrethrum on the world market by around 1941.

The majority of pyrethrum growers today are small scale growers with less than 5 acres of land.
In most cases, the area occupied by pyrethrum averages a quarter of an acre to three acres.
Pyrethrum is grown in the following counties in Kenya: Nakuru, Uasin Gishu, Elgeyo Marakwet, Nandi, Baringo, Kericho, Bomet, Narok, Laikipia, Trans Nzoia, West Pokot in the highlands of Rift Valley; Kisii and Nyamira in Nyanza; Kiambu, Nyeri and Nyandarua in Central; Meru and Embu in Eastern and Bungoma in Western region.

Kenya enjoyed being the leading producer in the ’80s but recent statistics indicate that the global market is dominated by Botanical Resources Australia at 80% of the market. Other countries that produce pyrethrum include Tanzania, Rwanda, Uganda, Ecuador, Papua New Guinea.

Pyrethrum is used to make natural insecticides. Its demand has continued to rise in the world market because pyrethrum is not harmful to human beings and other warm-blooded animals. It is therefore preferred for use as an insecticide in and around the household. Pyrethrum has advantages over other insecticides in that it has a repellent effect on insects, exhibits rapid “knockdown” and is non-persistent in the environment.

The global demand for Pyrethrum is on an upward trajectory as it is an incredibly effective, broad-based, and natural pesticide with multiple applications in pest control on crops and control of all types of flying insects. Pyrethrum can be transformed into countless value-added products, and its lack of residual effects makes it ideal for safeguarding global ecosystems.

Ecological requirements on Pyrethrum farming in Kenya

Soil requirements

Pyrethrum requires deep soils that are rich in phosphorus; calcium and magnesium with a soil PH of 5.0 – 6.5. The soils should be fertile and well drained with reasonably good texture and structure. A good structure ensures proper water infiltration and controls erosion. Structure and texture of soils frequently damaged by repeated weeding and trampling which cause rapid breakdown of the soil.

Such soils require rehabilitation by addition of humus in the form of the farmyard manure or compost manure (coffee husks, cereals trash, etc).

In newly cleared forest areas where the vegetation has greatly enriched the soils, there may be some incidences of root rot. Soil testing for the root rot causing organisms like nematodes is recommended before planting pyrethrum.

Rainfall and water requirement

Pyrethrum requires a minimum of 750mm (30 inches) of rainfall well spread over the season.

In warmer areas, where evaporation is high, 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 short dry spell enhances a higher flower production.

Altitude and temperature

In Kenya, there are clones and varieties suitable for high altitude, above 1980 meters (approximately 6,500 feet) and for low altitudes below 1980 meters (approximately 6,500) down to 1760 meters (approximately 5,770 feet) above sea level. Best flowering is easily achieved at and over 2130 meters (7,000 feet) above sea level.

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In Kenya, the recommended clones and varieties belong either to low, medium and high altitude. A grower is advised to choose the clones and varieties based on the altitude.

The pyrethrins content is affected by changes in temperatures i.e. 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 a reduction in yield due to wilting of tillers. Pyrethrins content is, however, not reduced by mild frost. Under irrigation, frost may have no effect on the crop.

Management Practices On Pyrethrum Farming In Kenya

Land Preparation on Pyrethrum Farming in Kenya

The land should be well tilled to allow easy penetration by roots.

All weeds such as Couch grass, sedge (Watergrass or Nutgrass), Star grass, Kikuyu grass, oxalis, and portulaca should be removed as they are difficult to clear later without damage to the plant. Ploughing the land during dry months helps to destroy stubborn weeds. Pyrethrum should occupy the land for three or at most four years. New planting should not be on land which has grown pyrethrum for the past three to six years. Grass and cereals are good rotation crops with pyrethrum. Steep slopes must be terraced or be avoided altogether.

Ridging and drainage

Pyrethrum cannot tolerate waterlogging. In such a situation, planting should be done on ridges of 2.5 to 3 feet (approximately 0.75 to 0.90 meters) wide. Ridges help to confine trampling to bottom of furrows. This can save young plants from damage during weeding and may lead to higher yields than on the flat field.

Time of Planting

Pyrethrum should be planted as early in the main rains as possible; planting later leads to poor establishment and poor yields in the first year, although subsequent yields are unaffected. An exception to this rule occurs in Kisii and Kericho highlands where there is high rainfall which is so well distributed such that any month, except January, is suitable for planting pyrethrum.

Planting Materials

Pyrethrum plants may be grown from seed or propagated vegetatively by splitting up clonal plants. Planting material derived from the splitting up of one original plant is known as a clone, whilst plants grown from seed are known as a variety. There are three sources of planting material:

  1. Certified clones
  2. Certified seeds
  3. Tissue culture material

Common Varieties of Pyrethrum Grown In Kenya

  • Mombasa Giant: Yield potential of 1,500-2,000 kg/acre, average pyrethrin content of 1.5-2.0%, suitable altitude of 1,500-2,000 m, susceptible to rust and leaf spot.
  • Kenya Giant: Yield potential of 1,500-2,000 kg/acre, average pyrethrin content of 2.0-2.5%, suitable altitude of 1,500-2,000 m, more resistant to rust and leaf spot than Mombasa Giant.
  • Kenya White: Yield potential of 1,200-1,500 kg/acre, average pyrethrin content of 1.0-1.5%, suitable altitude of 1,500-2,000 m, more resistant to drought than Mombasa Giant and Kenya Giant.
  • Pyrethrum Mum: Yield potential of 1,000-1,200 kg/acre, average pyrethrin content of 1.0-1.5%, suitable altitude of 1,500-2,000 m, more resistant to pests and diseases than other varieties.

Where to by pyrethrum seeds in kenya

All the pyrethrum seed material can be obtained from seed merchants. At the moment, these are available at the Pyrethrum Processing Company of Kenya (former PBK).

Growers should never harvest seed from their own plants. Instead, seed should be purchased from seed merchants.

At present, seed is packed in packets of 125g A grower requires to purchase 2 packets which contain enough seeds to plant an acre.

Planting Pyrethrum In Kenya

Planting splits

There should be at least 4-6 inches (100mm-150mm) of moisture in the soil before planting splits. Take good size splits, cut the roots to a length of approximately 4 inches (10cms) with a sharp knife, and remove the old thick woody roots, leaving a young root system on the split. Cut off any young flower shoots, leaving approximately 6 inches (15cms) of green vegetative top on the split.

Make the planting hole 4-6 inches (10-15cms) deep and add a teaspoonful of triple superphosphate and mix with the loose soil in the planting hole. Place the split in the planting hole with roots straight down. NEVER PLANT WITH THE ROOTS OF THE SPLIT BENT SIDEWAYS OR UPWARDS.

The base of the plant, where the roots and stems meet, should be at ground level, with all the roots below the ground level and all leaves above ground.

Fill one third of the hole with soil and press the soil firmly with the fingers. Fill the remainder of the hole with soil and again press firmly, pressing the soil and again press firmly, pressing the soil into the roots from the side, not from the top (the pressing is only applicable when the soil has low moisture). A well planted split should be firm in the soil and should require an appreciable tug to pull it out.

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On a small acreage, plant lines can be laid out by hand. A row of pegs is put in at each end of the terrace, and strings or chains stretched the length of the terrace between them. Along these lines the planting holes are then made by use of a panga.

On a large scale, planting lines can be laid out by tractor-drawn implements (apart from ridgers) or a hand drawn marker. If gaps or blind plants appear, they should be replaced as soon as possible in the first years follows.

Dig the planting hole, then take a sharp spade and cleave at least one third of an adjacent, vigorous plant. Press the soil around the roots against the spade and transfer into the new hole with minimum disturbance of the roots. Fill in and firm down the soil around both plants. The splits can be dipped in a solution containing nematicide and fungicide to control nematodes and fungi.

Planting seeds in seedbeds

Seeds should be evenly sown on beds of finely tilled soil, at ten seeds to the inch in rows half an inch deep and six inches between rows. After sowing, the rows should be covered with grass and well watered. A few days after germination, which takes upwards of 10-14 days, depending on altitude, the grass should be removed, taking care not to uproot the young seedlings.

Seedlings take about three to four months between germination and planting out, and should generally be sown three to four months prior to onset of long rains. Shading of the seed beds is not generally recommended, except in very hot dry conditions, and even then the shade should be removed as soon as possible. Regular watering is essential. Given careful handling, one kilogram of seed should provide sufficient plants for five acres (two hectares).

Transplanting pyrethrum seedlings

Seedlings from seedbeds should also be transplanted when the soil is well moistened. Holes for planting seedlings should be shallower than those for splits because seedlings are smaller. All other planting operations are as for planting splits. Generally seedlings survive better in cases where moisture is low in the soil.

Spacing and plant population

The spacing of 30 cm intra-row (between plants) and 60 cm inter-row (between lines) should be used, but in drier places spacing of 30cm between plants and 90 cm between lines is recommended. The spacing of 30×60 cm would give a population of approximately 22,000 plants per acre (55,000 plants per hectare) and spacing of 30x90cm would give a population of approximately 14,000 plants per acre (36,000 plants per hectare).

Approximately 4,000 mature plants would be required to raise enough splits to plant an acre or 10,000 plants for a hectare. In drier places with spacing of 30×90 cm, only 3,000 plants are required to split into approximately 14,000 splits to plant an acre or 7,000 plants for a hectare. Mechanization in production of pyrethrum is possible in large scale farms.

Fertilizers and manures

Phosphate fertilizers are recommended for use in pyrethrum growing. Triple superphosphate (T.S.P) (46% P) should be applied in each planting hole at the rate of one teaspoonful per hole. This is about 125-150kg/ha (or 2.5-3 bags of 50 kg/ha). The fertilizer should be mixed thoroughly with soil in the hole before planting, to avoid scorching of the plant roots by the fertilizer.

Farm yard manure (FYM) may be used at the rate of 4 tonnes per acre or 10 tonnes per hectare on poor soils. A marked increase in yield is realized after application. The FYM, should be applied three months before planting of the crop. It should be worked into the soil to allow adequate decomposition. If, however, the manure is well decomposed it can be applied at planting time placed in planting holes and mixed up with the soil. Use about 200 grams per hole.

Top dressing with nitrogenous fertilizers on pyrethrum has not proved to be beneficial and is currently not recommended.

Pyrethrum 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 upto 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.

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If pyrethrum is left in the same field for more than three years, flower yield declines to an 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.

Pyrethrins content and yields

Pyrethrins content and dry flower weight are the most important components of pyrethrum that determine income to a grower. Pyrethrins yield per hectare is made up of dry flower weight multiplied by pyrethrins content of the flowers. Pyrethrins content determines the rate of payment per kilogramme of flowers. Plants of low pyrethrins content should therefore, be avoided. Currently,the Pyrethrum Processing Company of Kenya and National Pyrethrum Research Center, KALRO provides clones and varieties which give high yields and content.

Clones with high pyrethrins content, above 2% and flower yield above 1,000 kgs/ha per year are available. Good cultivation, correct picking and drying, and prompt delivery will maintain high content. Proper planting, correct spacing, elimination of gaps, good field management and regular picking will give high yield.

Note: The yield of dried and undried pyrethrum per acre in Kenya can vary depending on a number of factors, including the variety of pyrethrum grown, the soil quality, the climate, and the management practices used. However, in general, the yield of dried pyrethrum per acre is typically in the range of 200 to 500 kilograms, while the yield of undried pyrethrum per acre is typically in the range of 800 to 1,000 kilograms.

Pests and Diseases affecting pyrethrum farming in Kenya

Pyrethrum farming in Kenya can face various pests and diseases that can significantly impact crop yield and quality. Here are some common pests and diseases, along with control measures:

  1. Pyrethrum Aster Yellows (Disease): Symptoms include yellowing of leaves, stunted growth, and reduced flower production.

Control:

  • Plant disease-resistant pyrethrum varieties.
  • Remove and destroy infected plants to prevent the spread of the disease.
  • Keep the field free of weeds, as some weeds may act as alternative hosts for the disease.
  • Practice crop rotation to break the disease cycle.
  • Apply appropriate fungicides as recommended by agricultural experts.
  1. Pyrethrum Webworm (Pest): Webworm caterpillars feed on pyrethrum leaves, causing extensive defoliation and reduced flower yields.

Control:

  • Introduce natural predators like parasitic wasps and predatory insects to control webworm populations.
  • Use biological insecticides based on Bacillus thuringiensis (Bt) to target webworm caterpillars specifically.
  • Monitor the crop regularly and apply insecticides when the pest population exceeds the economic threshold.
  • Practice good farm hygiene by removing and destroying any crop debris or plant residues that may harbor webworms.
  1. Pyrethrum Leafminer (Pest): The leafminer larvae tunnel through pyrethrum leaves, causing significant damage to the foliage.

Control:

  • Use sticky traps to monitor adult leafminer populations.
  • Apply systemic insecticides early in the season to control the larvae before they cause severe damage.
  • Practice proper sanitation by removing and destroying infested leaves.
  • Encourage natural predators like ladybugs and lacewings to control leafminer populations.
  1. Powdery Mildew (Disease): Powdery mildew appears as white powdery spots on the upper surface of pyrethrum leaves, leading to reduced photosynthesis and plant vigor.

Control:

  • Plant pyrethrum in well-spaced rows to promote air circulation and reduce humidity levels, which discourage mildew growth.
  • Apply fungicides with active ingredients like sulfur or neem oil at the first signs of infection.
  • Avoid overhead irrigation to minimize leaf wetness.
  • Remove and destroy severely affected plant material to prevent the spread of the disease.
  1. Aphids (Pest): Aphids suck sap from pyrethrum plants, causing wilting, deformation, and transmitting viral diseases.

Control:

  • Introduce natural predators like ladybugs and lacewings, which feed on aphids.
  • Use reflective mulches to deter aphids from settling on pyrethrum plants.
  • Apply insecticidal soap or neem oil to control aphid populations.
  • Avoid over-fertilizing, as excessive nitrogen can attract aphids.

Integrated Pest Management (IPM) practices should be implemented to manage pests and diseases sustainably. IPM combines biological, cultural, and chemical control methods to minimize the use of synthetic pesticides and protect the environment while ensuring effective pest and disease management.

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