Pyrethrum is an industrial crop that provides an insecticide, pyrethrin. Pyrethrum (Tanacetum cineraria folium) belongs to the genus Tanacetum in the family Compositae. White settlers introduced Pyrethrum farming in Kenya on an experimental basis. In 1941, pyrethrum was commercialized by Africans and white settlers.
In the 1990s, Kenya controlled over 90% of the world’s pyrethrum production. However, this has changed after the reduction of acreage under pyrethrum. Nationally the crop was the 3rd leading export after tea and coffee. Due to its demand and profitability, the crop is making its comeback in Kenyan farms. How do you farm this crop? Read on to find out.\
History of Pyrethrum farming
Pyrethrum farming in Kenya dates back to the late 1920s but its commercial production started in 1941. Since its arrival in Kenya, “pyrethrum schooled generations” before its decline in profitability.
Growing areas in Kenya.
Pyrethrum is a hardy crop that continuously produces flowers for 10 months annually. From seedling planting to the first picking of the flowers, it takes 3-6 months.
The crop grows well in cool temperatures and high rainfall areas which occur in high attitude areas ranging from 1500–3000m. Fertile and well-drained soils of moderate organic matter are also ideal for vigorous pyrethrum flower production. In Kenya 18 counties have favorable conditions for growing pyrethrum.
Rift Valley Region accounts for the highest pyrethrum production. In North Rift Uasin Gishu, Keiyo Marakwet, Trans-Nzoia, and Nandi counties grow pyrethrum. Additionally, in South Rift Nakuru, Bomet, Kericho, Baringo, Narok, and Laikipia counties grow pyrethrum.
In the Nyanza region, Kisii and Nyamira are pyrethrum farming counties while in Central Region Kiambu, Nyandarua, Nyeri, Embu, and Meru grow this crop.
How to plant Pyrethrum
Planting starts by propagating cultivars in nursery beds. However, It is advisable for a farmer to get pyrethrum seedlings from approved nurseries. Transplanting from the nursery is after three to four years.
Additionally, there are various pyrethrum clones for each growing area. For instance, P4 clone grows well at an altitude of above 2000 meters while K235 grows well at an altitude of 1500 meters. Each clone produces differently from the others. Selecting the right clone gives high flower yields with high pyrethrin content.
Once the seedlings are acquired, they should be spaced 2 feet inter-row (from row to row) and 1-foot intra-row ( from plant to plant). A tablespoon of Triple Superphosphate fertilizer should be used per plant and mixed thoroughly with soil to avoid scorching.
Weed control in a pyrethrum farm
To have better yields and quality, pyrethrum farms should be kept free from weeds. Hand weeding is the most preferred weeding method in Kenya. Brassicas and Oxalis are the most common weeds in pyrethrum farms. However, Sheep sorrel (Rumex acetosella L.) is also becoming a weed of concern in Molo. Other weeds of concern are rhizomatous weeds such as couch grass, Sedge, and Kikuyu grass.
Pest and Disease Control
Just like any crop, pyrethrum has various pests and diseases that affect its quality and yields. The most common 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.
Fungal diseases also attack the pyrethrum. Root rot is the most common disease, caused by Fusarium spp.
The first picking of mature flowers occurs 3-4 months after planting. Thereafter, pick the flowers between two to three weeks intervals. It is important to note that young flowers contain little pyrethrin. It is therefore advisable to pick flowers that have florets that have opened to a horizontal position and approximately three rows of the disc florets open.
Hand-picking is the most common method of harvesting. Pick the flower between the first and second fingers and then jerk the flower head with the thumb. Harvesting should not be done during a rainy season as it results in flower fermentation. Once picked, the flowers are dried. Sun-drying is the ideal condition as other methods result in the loss of pyrethrin.