The thorn melon, also known as kiwano melon, jelly melon or horned melon (Cucumis metuliferus) is an annual vine belonging to the Cucurbitaceae family. It originates from the Kalahari Desert and mostly grows in the dry or semi-arid places of the world.
The fruits have orange skin when ripe and spikes on their outer surfaces but are pulpy inside with a refreshingly fruity taste. They are peeled and eaten in either the immature or the mature stages, or made into juice and the leaves can be used as vegetables.
In Kenya the fruits are targeted for export markets in Europe and are sold in supermarkets and local markets. Besides, they are gaining a lot of importance and production in Kenya is expanding due high demand, as consumers become aware of their medicinal and nutrients benefits.
Benefits of thorn melon
- Has 90% water content which helps remove harmful substances from the body ensuring overall health and wellness
- High in fiber which makes digestion easier and helps in preventing constipation and bloating, as well as preventing serious medical conditions like colon cancer and gastric ulcers
- Contains highs level of iron and other essential nutrients needed by the body. It as a ‘natural drug’ for treating anemia
- Rich in Vitamin E which is known to slow down the onset of dementia and Alzheimer’s disease
- Contains Vitamin A which improves eyesight as it has antioxidants properties which eliminate the radicals that lead to eye problems
- Enriched with Calcium and Zinc which are necessary for healthy and strong bones
- Vitamin C present in it helps in detoxifying the skin, production of collagen and repairing damaged skin tissues
- The zinc present in it helps in boosting the metabolic processes in the body and in protein production, which is important for the repairing of different organs, cells, tissues and blood vessels
- Contains Vitamin E which is good for the skin and heart.
- Contains high amounts of Magnesium which helps in proper management of blood sugar
- Has very low cholesterol levels
- Its seeds are rich in linoleic acid, which has unsaturated omega-6 fatty acids and oleic acid, which is important for a healthy heart as it is mono-saturated
Ecological requirements
Thorn melons can be grown outdoors or indoors. However, greenhouse tends to give better yields.
Soil
Thorn melon can grow in a wide range of soils but does best in well drained clay or loamy soils which are rich in nutrients and have full sunlight exposure, with a pH range of 6.0 and 6.5.
Altitude
the crop does well at low to medium altitudes of 200-1800 metres above sea level.
Temperature
the optimum temperatures for germination are between 20-300C. The crop’s growth is hardly affected by temperatures as high as 400C but temperatures above 300C affect flowering.
Rainfall
The crop does not particularly demand a lot of water and can perform well with as little as 350-600mm.
Propagation & Planting
Thorn melon is propagated by seeds, which can be sown directly or seedlings be raised in the nursery or trays and then transplanted when they have two true leaves. The seeds can be extracted from a well-developed ripe healthy fruit.
Direct planting
Land preparation should be done early to allow for weeds to dry and decompose before planting.
Procedure
- Spray weeds with Catapult® 480SL 200ml/20L, a non-selective herbicide which kills all kinds of weeds.
- Plough and level the land, ensuring a fine tilth; Mix soil with manure and DAP. For efficient and improved nutrient uptake as well as stabilizing soil pH, mix 1kg Humipower® with 50kg DAP and /or 1 ton of manure.
- Place 3-4 seeds per hole at a depth of about 2 cm and spacing of 60x60cm
- Cover with a layer of soil.
Usually, germination occurs within 2-3 weeks and can be improved by priming, which involves soaking the seeds in warm water for one hour before planting or soaking them overnight in Optimizer® 20ml/1L.
Thinning
This is done 5-7 days after emergence in order to remove the excess seedlings leaving one plant per hill if planted directly in the field.
Irrigation/watering
This depends on several factors including the prevailing weather, soil type, and stage of crop development. For instance, at flowering and fruiting stage, a more frequent irrigation will be necessary.
Weed control
Timely weeding is very important to prevent diseases such as the cucumber mosaic virus and tobacco ring spot virus. Besides, weeds compete with the crop for growth factors like nutrients and water.
Crop rotation
It should be practised using non-related crops like cereals, legumes, and brassicas, among others, which helps prevent build-up of pests and diseases as well as improve soil structure.
Training /trellising
Thorn melon is a climber hence requires an area near a trellis or fence to promote climbing. In a greenhouse, the plants can be trained upwards and supported by sisal strings which are tied to a wire about 2 meters above the ground.
Fertilizer application
Depending on the soil conditions, manure, compost or inorganic fertilizers can be incorporated. During planting, Young plants should be sprayed with Lavender Super Starter® 20ml/20L or Goldchance Super Start® 50g/20L one week after germination, which promote early crop establishment among other benefits.
Top dressing with nitrogenous fertilizers like CAN is recommended 3-4 weeks after germination. Spraying the crop with Goldchance Super Growth® 50g/20L or Lavender Super Growth® 20ml/20L also promotes a faster vegetative growth, increases crop resistance to diseases and weather stress and ensures a balanced growth of the crop.
During the flowering and fruiting growth phases, potassium-rich fertilizers like N.P.K 23.23.0 are recommended for production of quality fruits. Besides, spraying the crop with Goldchance Super Flowers & Fruits® 50g/20L or Dimiphite® 20ml/20L or Lavender Flowers & Fruits® 20ml/20L induces flowering, promotes good fruit set and quality, increases crop resistance to infections and weather stress, ensures a balanced crop growth and improves crop productivity, among other benefits.
Maturity, Harvesting & Post-harvest Handling
The fruit matures in 3-4 months. At the end of the growing season, the stems die back while the fruits remain attached and continue ripening to a bright orange colour.
Harvesting is done by picking the ripe fruits and this can be done over successive months. Immature fruits may be harvested at any time during the growing period.
The fruits have spines/thorns which can cause them to pierce each other, thus shortening their storage life. Therefore, they should be packed in single separated layers in crates.
A single plant can produce up to 30 fruits especially during the warm seasons and the shelf life of a harvested thorn melon fruit is 6 months.
Pests & Disease control
Thorn melon are hardly susceptible to pests and diseases. The following are some of the pests and diseases which attack the crop.
Melon flies
The adults pierce the young fruits and lay eggs in them. The maggots feed on the internal part causing sunken, discoloured patches, distortions and open cracks. The cracks create avenues for entry of pathogens.
Spray Kingcode Elite® 50EC 10ml/20L or Profile® 440EC 30ml/20L
Aphids
These are soft-bodied green to blackish insects found on the tender shoots and leaf surfaces where they suck sap. Heavy infestation leads to stunting of shoots while leaves become curled and twisted. Aphids also transmit viral diseases.
Spray Kingcode Elite® 50EC 10ml/20L or Lexus® 247SC 8ml/20L or Pentagon® 50EC 10ml/20L
Red Spider Mites
These feed by piercing and sucking. Attacked leaves have a stippled appearance which turn yellowish to whitish and dry up. They form webs on the undersides of the leaves. Plants under water /drought stress are more likely to suffer damage by spider mites.
Spray Alonze® 50EC 5ml/20L or Bazooka® 18EC 10ml/20L
Leaf miners
The larvae mine under the leaf surface, resulting into white mines/windings. This reduces photosynthetic area, leading to eventual leaf wilting/death.
Spray Alonze® 50EC 5ml/20L or Escort® 19EC 10ml/20L or Sinophate® 750SP 20g/20L
Whiteflies
These suck plant sap causing leaves to curl and become distorted. They also secrete honeydew which encourages the growth of sooty mold, which affects plant growth. Whiteflies are vectors of viral diseases which cause significant damages.
Treat as for aphids above.
To get rid of the sooty mold, spray Jambo Clean® 100ml/20L
Diseases
Damping off
This is a soil borne disease which attacks seeds and seedlings. Diseased seeds do not emerge while seedlings rot and eventually die. The roots of these infected seedlings exhibit a white cottony growth.
Drench the planting holes/soil with Pyramid® 700WP 100g/20L
Spray the plants with Gearlock Turbo® 250WP 25g/20L
Mosaics
These are viral infections caused by viruses including Cucumber mosaic virus and watermelon mosaic virus which are transmitted and spread by several vectors eg aphids, melon flies and whiteflies. Leaves show symptoms of reduced size, patches of dark-green tissue alternating with yellow-green. The plant becomes stunted and fruits develop water soaked lesions with central solid spots.
Control vectors ina way simlar to Aphids above.
Spray Optimizer® 10ml/20L to boost the crop’s immunity.
Fusarium wilt
Initially, symptoms appear as chlorosis of the leaves and as infection continues, leaves begin wilting from bottom to top. The brown vascular discolouration inside infected stem or root leads to the death of plants.
Drench soil with Green Cop® 500WP 100g/20L and foliar spray the crop with Pyramid® 700WP 50g/20L or Absolute® 375SC 10ml/20L after every 2 weeks.
Note
- In all foliar sprays, mix the chemical with Integra® 3ml/20L, which is a sticker, spreader and penetrant which increases the efficacy of the product.
- Optimizer® is an organic bio-stimulant which is essential for plant growth and stress management. It can be applied at all or any growth and development phase of the crop.
- Post-harvest interval (PHI) and re-entry interval (REI) for all the applied chemicals should be observed.
- All basal fertilizers should be mixed with Humipower® at a rate of 1kg of Humipower® into 50Kg of fertilizer.
- Before ripening, the bitter forms of thorn melon can have dangerous levels of chemical compounds which are absent in the ripe fruits, whose toxicity can cause fever, stomach issues and headaches.
In greenhouse production, pollinators such as bees should be introduced at the time of flowering
