Watermelons have grown to become one of the staple fruits in Kenya and the world. This has made its demand increase attracting more supply from farmers. Unfortunately, its one of the most sensitive enterprises and if done wrong losses are inevitable. In this article, we gonna focus on the dos and don’ts of melons farming.
Market Review
Watermelon is an anti-dehydrant that quenches the thirst of many, especially in hot-dry seasons. Due to this reason, there is a high market demand for watermelon especially from January to March when there are no rains. This combined with low supply tends to raise market demand and therefore the prices.
Always ensure you’ve carried out an adequate market survey before planting to determine the peak demand and the best melon’s shape and colour that does well in your region. Then work backwards to determine from the month there is a peak demand to prepare farm activities preceding the period.
Climatic Requirements
The quality and quantity of watermelons highly depend on the climatic conditions under which they are grown. They include;
- Long, warm growing periods with bright hot days of 27-350C.The warmer and hotter the conditions the sweeter and faster the melons grow.
- Altitudes of 0-1500m above sea level with an average annual rainfall of 400-600mm
- Melons tend to grow well in sandy loam soils which are well-drained and slightly acidic.
These conditions tend to represent the coastal, eastern, northeastern regions and some parts of the North Rift regions of Kenya. Melons grown in highlands regions of Kenya tend to have a slow growth with delayed germination, poor fruiting and hallow fruits with a watery test.
How to plant melons
Single row system
- Row spacing 2.0-2.5m
- Plant spacing 60cm
Double row spacing
- Row spacing 3.5-4.0m
- Plant spacing 60cm
Fertilizer Application
Always carry out a soil test analysis to determine the nutrient requirements. Use D.A.P during planting and then topdress with N.P.K after every two weeks. The ratios in use highly depend on the results of the soil analysis.
Ensure you also use 5-8 tonnes of well-decomposed farmyard manure.
Importance of Pollination in melon farming
Melons are highly dependent on pollination which makes the honey bee a key thing. To ensure a sustainable bee population, we often recommend installing 1 or 2 beehives in your garden while avoiding excessive use of insecticides especially imidacloprid as they tend to kill bees.
When it comes to spraying; Always avoid spraying during morning hours especially (9 am-12 pm) as this is the most active time for pollination.
The use of biological and cultural methods of controlling pests and diseases may help. Avoid planting melons next to or close to farms with crops that may increase bees competition such as sunflower or canola as this will lead to poor pollination which causes misshapen fruits.
Mulching
Mulching with plastic mulch, straws or dry leaves helps in moisture conservation, weeds suppression and preventing fruit rot due to contact with the soil.
Pruning
This involves the removal of any diseased, yellowing or infested leaves or shoots at the joint where they connect to the main stem while removing deformed and blossom-end rot fruits. Maintain 2-3 vines and remove extra vines and if the market demand larger melon, leave 3-4 well shapes melons per plant. Do NOT prune when the vines are wet.
Pests Management
1. Melon Fly
Identification:
- An adult has a yellow stripe in the middle of the thorax between the wings
- A black (often incomplete) T-shaped marking on the abdomen (the rear body section)
- Additional dark patches towards the outer edge of the wings
- Head yellowish with black spots
Damages:
- Larvae usually tunnel into the fruit causing a watery ooze to form on the surface that can later turn brown and resinous
- Exit holes by the larvae (2 – 3 holes) are visible on the fruit surface
- Affected fruit will rot and often fall from the plant prematurely
- Larvae can also feed on flowers and plant stems
Control:
Field Monitoring/ Biological control:
- Use of pheromone traps e.g.) cue lure baited traps, and
- Bactrolure L® (a.i. Methyl Eugenol) used together with Malathion
Cultural Control:
- Wrap fruits with an eco-bags
- Remove fruits with dimples and oozing clear sap
- Kill the maggots by burning, burying or tying collected fruits in black plastic bags
Chemical Control:
Difficult since larvae feed inside the fruit Use of pesticides, such as
- Decis or 8ml of Engeo or Belt in 20l of water
2. Aphids
Identification
- Colonies of green-yellow to blackish aphids are found on tender shoots wit excretion of honeydew
Damages:
Attacked leaves are curled and twisted Sooty mould,
Control:
Ensure plants are not water-stressed.Use of pesticides, such as
- 10ml of Thunder or 8gms of Actara in 20l of water
3. Spider Mites
Identification:
- Mites are tiny spider-like pests which spin silk threads for anchoring to the plant.
- Their bodies are yellow-green to reddish-brown in colour.
- They flourish at low humidity and high temperature (hot dry conditions).
Damage:
- Attacked leaves show white to yellow speckling
- Where there is a high infestation, the plant is covered with an orange cloud of mites and webs
Control:
- Adequate irrigation
- Mulching to conserve water
- 10ml Dynamec or 10ml of thunder in 20l of water
4. Epilachna Beetles
Identification:
Adults resemble ladybird beetles
Damages:
- Feed on leaves leaving a fine net of leaves
- Damaged leaves shrivel and dry up
Control:
Spray with insecticides, such as
- 10gms of Bamako or12ml of Jacpot in 20l of water
5. White Flies
Identification:
Small soft-bodied insects with wings covered with a white powdery wax
Presence of honeydew and sooty mould
Damage:
Sucking sap
Vector of viral diseases (Cucurbit Yellow Stunting Disorder)
Control:
Use of pesticides such as:
- 8gms of actara or 25ml of Match or 4ml of belt in 20L
6. Root-knot Nematode
General Description:
Most cucurbits are extremely susceptible to Root-knot Nematodes
Symptoms:
- Stunting, general unthriftiness (Weak/unhealthy), premature wilting, and slow recovery to improved soil moisture conditions
- Root symptoms cause swollen areas (galls) on the roots of infected plants which result from
- exposure to multiple and repeated infections
- Leaf chlorosis (yellowing)
Control:
Cultural Control:
- Crop rotation of less susceptible crops or resistant varieties
- Use of resistant varieties e.g.) Crimson Sweet
- Use adequate amount of manure
Chemical Control:
- MOCAP or 7ml of Velum Prime in 20l of water
Diseases Management
- Powdery Mildew
General Descriptions:
It is a fungal disease which is favoured by dry condition
Symptoms:
- White powdery growth start on lower leaf surface and later on the upper surface
- At advanced stage necrotic areas develop on the leaves
Control:
Use of fungicides, such as
- 20ml of score or15ml of luna Sensation in 20l of water
2. Anthracnose
General Descriptions:
This disease is caused by fungus and affects leaves, vines and fruits
Plants can be infected at any stage
Symptoms:
- Round to angular reddish brown spots on older leaves
- Spots may dry, turn black and tear out
- Sunken spots on the rind of fruits which may produce pinkish colored ooze
Control:
Cultural Control:
- Crop rotation
- Plant clean seeds
Chemical Control:
Use of fungicides, such as
- Antracol or 20ml of Ortiva or Score in 20l of water
3. Downy Mildew
General Descriptions:
A fungal disease which attacks leaves of Watermelon
The pathogen is airborne
Symptoms:
- Small, irregular, chlorotic spots on upper leaf surface becoming brown and necrotic; entire leaf may become blighted
- Infected leaves tend to curl upward from the margins
- Gray to purple downy growth may be visible on underside
Cultural Control:
- Reduce canopy density
Chemical Control:
- 40gms of Milraz or 20ml of Revus
Study how to control tuta absoluta in your farm
4. Fusarium Wilt
General Descriptions:
- It is a fungal disease which can infect crop at any stage of growth
- Pathogen can be spread by seed, soil or drainage water
Symptoms:
- Wilt symptoms develop from one or few runners
- Vascular tissue of lower stem and roots brown colouration
Control:
Crop rotation
- Rouging/removal and destruction of diseased plants
- Plant in well drained soils and avoid water logging
- Use of certified seed
- Use of well decomposed manure and compost
Read Also: Simple home experiment to identify Bacterial wilt
5. Gummy Stem Blight (Black Rot)
General Description:
The disease affects leaves, stem and fruits
Symptoms:
- Brown round or irregular lesions on leaves
- Lesions on stem are brown and later turn white
- Gum oozes from stem cracks
- Affected fruits are soft and discolored
Control:
Use of chemicals, such as Funguran, a 50% copper-based fungicide.
6. Watermelon Mosaic Virus (WMV).
General Descriptions:
This disease is transmitted by aphids It infects only cucurbit crops
Symptoms:
- Mottling of leaves
- Stunted growth, shortened internodes with bushy erect growth for some runner tips
- Mottled appearance on fruit surface
Control:
Field sanitation: removal of weeds (they are potential hosts)
Harvesting
Harvesting Indices
- Tendrils near fruit stem have changed color from green to brown
- Ground spot on the belly of the melon has changed from white to yellow
- The fruits when thumped with the hand produce muffled dull tone (immature fruits produce clear
- metallic ringing tone)
- Leave the stalk attached to the fruit
- Mature fruits have sweet flavor, crisp texture and deep red color
- Sugar content (measured as soluble solids by use of hand held refractometer) of 10 % or more in the flesh near the center of the melon
- Yields: 25,000 – 50,000kg per acre
Main harvesting stages:
- Mature but before full ripeness for distant markets
- Mature and ripe for nearby markets
Notes:
Watermelons don’t ripen after they are picked so harvest time is important
- If harvested immature, red color will develop but sugar content does not increase after harvest
- Harvesting should be done by cutting the vine and NOT pulling, twisting or breaking off the vines
Recommendations: Water Melon variety of choice -Sukari F1
Read the complete guide on tomatoes farming
Reference: SHEP-PLUS, Watermelon Production
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