All about growing passion fruits

I am interested in passion fruit farming and I would like to know more on land preparation, seedlings selection, crop management, disease and pests control all-through to harvesting, please assist.

Karanja

Passion fruit is a perennial climbing vine and a popular crop in the country, with good domestic and export market.

The fruit may be eaten fresh or consumed after extracting the pulp and juice. Juice is used in a variety of products and the pulp may be added to various dishes.

A wide range of cosmetic products and food flavours are derived from the fruit. Passion fruits are rich in vitamins A and C and carotene making it an important food.

Varieties: Both yellow and purple types exist. Purple varieties do better at higher altitudes than yellow types. The yellow types tend to yield higher and are more resistant to diseases.

The purple variety is very acidic, variable in taste and juicy with intense aromatic scent and round in shape. The yellow variety is bigger, with similar taste but possibly less aromatic, more acidic and round in shape.

Both varieties are green before ripening.

Ecological requirements

They need an altitude of 1,200m to 1,800m above sea level east of the rift and up to 2,000m above sea level west of the rift.

Temperature: Optimum temperature for purple passion fruit is between 180C to 250C and 250C to 300C for yellow passion fruit.

Rainfall: Well-distributed rainfall of 900mm to 2,000mm per year is suitable. Excess rainfall causes poor fruit set and encourages diseases.

Soils: Passion fruits do well in a variety of soils, which should be reasonably deep and fertile. A soil pH of 6.0 to 6.5 is the best. In high rainfall areas, the soils should be well-drained as plants will not withstand water-logging or flooding.

Planting and trellising: Passion fruit can be grown from seed but grafting often produces improved stock. Yellow passion fruit is best for production of rootstock because of superior disease resistance.

Seed is germinated after removal of the pulp and drying. Germination requires up to four weeks when the seedlings are planted in pots.

Up to three seeds are planted in each bag and then thinned to one after emergence. Seedlings will require up to four months to reach a suitable transplanting growth stage.

After about seven weeks of growth following transplanting, each plant should have up to four healthy lateral stems.

Transplanting should be done at the beginning of the rainy season. Passion fruit has deep roots, so soils should be well-tilled.

Transplanting should be done along a fence to provide support or wire trellis should be constructed. The vines are usually directed so that growth is in both directions along the supporting wires.

Yields are highest following a regular fertilisation regime. Old or dead shoots should be pruned. Intercropping with vegetables or other annuals is recommended.

Once established, the vines grow rapidly and the fruit should flower after about seven months. Ideally, young passion vines should be set in the field early in the growing season after danger of drought is over.

Passion vines are planted 2m apart in rows that are 3m apart. Horizontal trellises have cross-pieces at the top of each post with 2-4 wires strung horizontally 60cm apart along the top of each cross-piece.

Vertical trellises consist of heavy posts without cross-pieces, with two or three wires strung along the row like barbed wire fencing, attached to the posts from the top down at intervals about 30-40cm apart.

Trellis wires should be No. 9 or 10 of galvanised steel. The posts need to be stout enough to withstand the weight of the vines throughout a season that normally includes the buffeting of strong winds.

Ideally, they should be long enough to provide a trellis height of 1.5m, with 45-75cm in the ground. Trellis rows should be oriented north-south for maximum exposure to sunlight, and the vines should be allowed to grow together along the trellises to promote cross-pollination.

Fertiliser application: At planting, use 175g of triple super phosphate (TSP) and one ‘debe’ (about 20kg) of farmyard manure and mix well.

To obtain high yields, regular fertilisation is necessary. Apply 300g of calcium ammonium nitrate (CAN) per plant, per year in two applications of 150g each rainy season.

Spraying with foliar feeds and trace elements is also recommended.

Crop protection: Weeding is essential when the plants are first transplanted. Disease is usually sufficiently controlled by crop rotation as plantations are not kept for more than three years.

Infected plant material should be pruned and destroyed and vines kept as open as possible to allow thorough application of sprays.

Diseases can also be controlled by combination of good management, good orchard hygiene, and a suitable spray programme.

Pests lower fruit quality and should be controlled by regularly checking the areas around the orchard for signs of pest build up.

If necessary, spray to control the pests before they spread to the crop.

Harvest: When ready for harvesting, the skin of the fruit is deep purple/yellow in colour. Its pulpy interior is bright yellow, filled with small black seeds.

For fresh market or use, the fruit is picked when colour changes occur. For processing, the fruit is allowed to drop to the ground and then picked at least every second day.

At this stage the fruit is shrivelled but quite suitable for processing. Yields decline each year until harvests are not adequate in the fourth year.

Yield: Over 15-20 tonnes/ha are attainable.

Carol Mutua,
Department of Crops, Horticulture, and Soils,
Egerton University.