Sunflower constitutes one of the most important oil crops marketed in Kenya . It is growth habits are either dwarf or tall The tall varieties which are often local and open pollinated grow up to a height of between 1.5 and 2.4 metres. Their yield is also low as compared to the hybrids. Examples of these tall varieties are Kenya Fedha and Hungarian white. Dwarf varieties are hybrids such as H 8998 and grow to a height of 1.2 metres. Their yield is quite high and hence a higher return.
White Sunflower is mainly exported to Europe as bird feed. The black-seeded types are mainly used for edible oil extraction as they have higher oil content.
Ecological requirements Sunflower will grow well where maize and beans are grown. The optimal annual rainfall for a good crop is between 500 and 750 mm though in areas of low rainfall dwarfs are more advisable as they have a shorter maturity period.
Soils should be well ploughed and a firm seed bed established. Prepare land early in mid February for early planting between mid March and April during the long rains and in mid July for planting between Mid August and September.
Planting should be done immediately after the onset of rains for harvesting to occur in
dry weather as wet weather at that time will rot the seed heads.
Plant spacing and Seed rate
With a spacing of 75 x 25 -30cm, the seed rate will range between 3 and 4 kg/acre.
Sunflower needs good fertilization. Use of 60 kg per acre of D.A.P (Diammonium Phosphate) or 3 tonnes per acre of well rotted farmyard manure or compost, applied 2 to 3 weeks before sowing is recommended. The fertilizer should however be mixed properly first with the soil before planting to avoid damaging the seeds, which leads to poor emergence.
Apply CAN at 100 kg/acre around the stems of sunflower when plants are 40cm tall (avoid contact with the plant).
Sunflower is very sensitive to weed competition especially at the early growth stage and they can cause up to 50% yield loss. Weeding can be done either mechanically or chemically. The crop should be kept weed free 4 to 6 weeks after planting. Weed can also be managed by the use of Pre emergence herbicides such as Duol Gold, Pendimethalin (Stomp) and Metalachlor.
Thinning should also be done to one plant per hole around the same period as weeding but when the soil is wet.
Hand harvesting is done when the heads turn deep yellow. Cut the head, spike it upside down on the stalk or thresh and sun-dry.
This prevents rotting and bird damage. Don’t wait until the leaves dry up to reduce bird damage.
Spread the seeds on a clean canvas and leave to dry for 3-5 days or until the seeds become light.
Seeds must be dried to less than 10% moisture content before storage.
Keep dried seed in well aerated stores. Sell seeds to milling merchants to minimize post harvest damage losses (insects and fungal attack).
Under the recommended management practices the farmer can obtain between 3 and 4 tonnes/ha.
Nature of damage: Cut and kill young plants at ground level.
Control: Chemically by use of Thiodan 35% EC 1.51/ha.
Nature of damage: Are caterpillars that eat leaves.
Control: Chemically by use of Permethrin Cypermethrin, Thiodan or Diptrex.
- African bollworms
Nature of damage: Eat leaves and attack the heads.
Control: Chemically by use of Diptrex 95% SP
1.3 Kg/ha or Cypermethrin 11/ha.
Nature of damage: They eat seeds and cause big losses.
- Use bird scaring devices.
- Try and plant Sunflower the same time as other farmers to minimize bird damage.
- Sclerotinia wilt
Nature of damage: Attack roots, stem and head. Infected parts shrink and rot.
- Crop rotation.
- Use certified seeds.
- Burn infected plants.
- Downy Mildew
Nature of damage: Loose white parts on the lower surface of leaves.
- Use crop rotation.
- Use certified seeds.
- Apply Ridomil to young plants.
- Charcoal rot
Nature of damage: Stems appear black at the bottom.
- Crop rotation.
- Use certified seeds
Source : Kenya Seed Company