Saturday, 2 June 2012

Strawberry fruits growing ( Rosaceae)

Strawberry plants are perennial low growing fruiting plants, which produces delicious red fruits. Botanically strawberry plants consist of leaves, a crown, roots, flowers, flower trusses and stolons. The fruits are eaten as desserts or made into jam and may be frozen for latter use. Strawberry roots are found within 7.5-15cm below the ground and can go up to 30cm in light soils such as sandy loamy soils. These plants can be classified according to the photoperiod required to initiate flowering as:-Day neutral plants like Chandler and Douglas with unique ability to flower and fruit under any day length conditions. They are very suitable for growing in tropical regions. Long day plants initiate flowering on availability of light exceeding critical light duration. Short day plants initiate flowering on availability of light equal or less than critical light requirements. Varieties suitable for growing in Kenya include Chandler, Douglas, Tri-Star, Domanil, Rabunda, and Tribute.Warm to temperate climates are required for this crop in addition to well drained loam soils that are  moist throughout .Optimum soil pH is  slightly acidic to neutral i.e. 6.5-7.Plants grown in highly acidic soils tend to exhibit iron deficiency. Salinity should be low both in soil and irrigation water as strawberry plants are sensitive to salts and therefore should not be grown in saline soils.Soil analysis is recommended before planting

High salt levels cause stunting, marginal leaf scorch and severe yield reduction. Enough water should be applied to ensure that salts are leached below the root zone. Availability of suitable varieties and clean sowing materials is essential for success of strawberry fruits cultivation. In preparation of strawberry cultivation it is important for the grower to undertake soil analysis to determine soil acidity/alkalinity, the level of plants nutrients and also soil born diseases such as verticilium wilt. Field preparation involves making beds 1m wide and raised to a height 20-30cm.A path of 50cm separates the beds to allow carrying out of operations. Alternatively sowing can be done into the field at a spacing of 50 cm from row to row and 30cm from hole to hole. Well decomposed manure is incorporated into the bed to a depth of at least 30cm. DAP or other compound fertilizers are applied at the rate of 200kg per ha and incorporated 15cm along the rows. Apply topdressing CAN fertilizer after 4 weeks at a rate of 10g around the crown compound fertilizers after 2 months. Subsequent application is necessary every 3 months. Application of foliar feed can supplement but to a lesser extent. Well rotted manure or compost should also be applied. For nematodes infested soils appropriate nematicides should be applied according to instructions of experts. Strawberry fruits are propagated through vegetative methods. This is accomplished using runners or splits of the crown. Growing strawberry is preceded by thorough bed watering, followed by sowing the crown with the root zone just below the soil surface. Shallow sowing leaves the roots inadequately covered and likely to dry.

Too deep sowing leads to rotting of the stem. Unpack plants and soak in water for 10 minutes, then sow as soon as possible. The roots should be spread out with the crowns at the ground level, and plants firmed up well for good growth. For 1m wide bed 3 rows can be grown at a spacing of 30cm from row to row and 30cm from hole to hole. Cut off runners from plants regularly except those needed for sowing. One or two runners can be rooted from each hole for the next sowing. De-blossom/remove flowers for the first 1-2 months until the strawberry establishes to prevent premature fruits production, poor crop growth, and early crop exhaustion leading to low fruits yield. Renew strawberry fruits plot every 3 years and practice crop rotation for vigorous growth. Keep the plot weed free with shallow light hoeing to avoid damage to the plants roots. Mulching with straw or black polythene is recommended. Strawberry fruits mature 24-40 days after flower initiation depending on the growth temperature. The fruits bruise easily and should be picked with care and sold the same day. Packing of the strawberry fruits is in punnets. Expected yields per acre of strawberry fruits over 3 years are estimated at:-

  • 1st Year 10,000 kg
  • 2nd Year 7,500 kg
  • 3rd Year 5,000 kg
Chemical disease and pest control in strawberry fruit growing can be minimized by cutting and burning all the leaves from the plants after harvesting for two years. Then apply water and nitrogenous fertilizers. This will control some diseases and result in new clean growth.For more