Growing Ideas: Capsicum

Introduction

In the recent past, capsicum production has risen considerably in the country. This is attributed to many farmers adopting greenhouse farming and sustainable agribusiness. The crop is gaining popularity among farmers  due to high returns and is an alternative to tomatoes.To farmers they are good source of income as they have excellent prospects both for domestic and export market. It has been shown that an 8m by 15m greenhouse can earn a farmer over Ksh.300,000 in just over 6 months.

They are eaten raw in salads or cooked as a vegetable since they are a rich source of nutrients and vitamins. It is suitable for stuffing with fillings such as cheese, meat or rice and is also canned for sandwich making.

Varieties

There are two types of capsicum varieties: Determinate (open field) and Indeterminate (greenhouse) varieties.

Greenhouse or indeterminate varieties grow with a single apical stem and few secondary branches reach relatively high heights of up to 2m and have high yield production through out their life time. They include: Commandant F1, Admiral F1, Nemalite F1, Green bell F1, Golden sun F1, Top 168 evergreen, Hecco F1, Red bell F1, Pasarella RZ F1, Ilanga RZ F1 and Grandisimo F1.

The open field or determinate varieties are the bushy and have a defined growth, height and period of flowering and fruit development. They include: Yolo wonder, Green bell F1 and California wonder.

Ecological Requirements

Capsicum grow well at an altitude of 1600 m above sea level, medium rainfall of 800-120 mm per year, temperature of 20 -25⁰C and soil pH of 5.5-6.8

Land Preparation

Capsicum require slightly acidic soil with high organic matter, good moisture holding capacity, well drained and well aerated. It is important to carry out soil test analysis in order to establish nutrient status, pH, pests and diseases availability.

For open field, the land should be ploughed and harrowed to a fine tilth. Well decomposed manure should be incorporated with the soil.

Soil borne pests and diseases should be removed by fumigation, low pH(highly acidic soil) should be raised using lime and alkaline soil reduced by using gypsum.

Seedling

One can buy established and high quality seedlings from propagators or can establish their own nursery to raise seedlings. In this case, it is recommended that they use nursery trays rather than  raising on the ground. This is because nursery trays presents an ease of planting, reduces disease incidence, reduces wastage of seeds and makes transporting seedlings from one location to the next easy.

Transplanting

Seedlings are ready to be transplanted after 30-45  days and only healthy and strong seedlings are to be transplanted.

On the bed, holes should be dug with spacing from 60cm by 45cm or 60cm by 60cm.10g (equivalent of one tea spoon) of DAP fertilizer and 50g of starter fertilizer per hole should be mixed with soil. The seedling should be planted together with its ball of soil/coco peat.

Irrigation/Watering

The plant is highly sensitive to water deficiency especially in flowering and fruit development stages. It is recommended to water twice daily (morning and late afternoon) depending on the soil moisture level.

For a greenhouse of 8m by 15m, a 500 litre tank serving 350-400 plants per day  on drip irrigation can be installed. However the drip irrigation pipes should be flushed on weekly basis to avoid clogging by algae and precipitates.

Nutrient Management

The plant is a heavy feeder of nutrients. After 3-4 weeks of transplanting top dressing by CAN fertilizer at a rate of 10g per plant should be applied for good vegetative growth. At the onset of flowering (4-5 weeks) a compound fertilizer like NPK at a rate of 10g per plant  should be applied. During fruit development (5-9 weeks)  NPK should also  be applied at a rate of 10g per plant.

Caution should be taken as excess nitrogen as it can lead to poor fruit set, smaller fruits, hollow fruits, poor quality and excess vegetative growth.

Support

This is achieved by training and trellising. Training is supporting the plant to grow vertically. It is done by wires running parallel to the beds supported by greenhouse bars  and others held by four planks on the ends of the beds. Nylon strings are tied on the wires and trained on individual plants.

This should be done when the crop is at vegetative stage and before flowering and height nearing the knee height.

Pruning

Old leaves should be removed as well as diseased and dead leaves to prevent spread of diseases and pests, to increase light penetration, increase air movement and reduce high relative humidity.

Once fruits are formed, the leaves below should be removed. The pruned materials should be removed and used as compost or burned if infested or infected.

Weeding

Weeds are a nuisance to crops, they compete for sunlight, water and nutrients. They are also vectors for pests and diseases. The crop should be kept free of weeds. In order to avoid bruising roots, hand weeding is recommended. Plastic mulches are effective in suppressing weed germination and growth.

Harvesting

Depending on variety and environmental factors, maturity is usually attained between 75-90 days after transplanting. Maturity stages include: mature green, yellow, red or orange stages. The end-use is also a factor: For local market or processing purposes, harvesting is done after full maturity while for long distance shipping they are harvested at a less mature stage. Hand picking is the usual form of harvesting.

Post-harvest handling

Post-harvest practices include: sorting to remove damaged, bruised, malformed or diseased fruits; cleaning to remove soil particles; grading by size, color or shape; packaging in corrugated cartons, wooden boxes and plastic crates; storage at 12⁰C and 86% relative humidity and transportation in cool condition.

Marketing

The demand for capsicum is higher than the supply. Market opportunities for capsicum include: processors, exporters, institutions, whole sale markets, supermarket chains etc.

Pest And Diseases Affecting Capsicum

Capsicum like many horticultural crop is faced with the menace of pests and diseases. Though studies on management of this menace continues, researchers are making tremendous strides, however they have not yet achieved 100% control. It is advisable that regular scouting be administered on the crop. Common practices such as observing field hygiene, proper irrigation management, using tolerant/resistant varieties and crop rotation.

Common Pests

White flies

Signs of infestation

• Small white-moth like insect on the underside of leaves.
• Presence of black sooty mould.
• Yellowing and curling of leaves.

Control

• Observe hygiene by removing weeds.
• Use yellow sticky traps,
• Growing African marigold which is a repellent.
• Use pesticide.

Red spider mites.

Signs of infestation

• Presence of web on the underside of leaves.
• Leaf curlingoutwards.
• Presence of white speckling that turns bronze.
• Leaf defoliation.

Control

• Observe field hygiene by removing weeds.
• Using resistant varieties.
• Inter planting with onions and garlic as they are repellant.
• Using recommended miticides.

Cut worm

Signs of infestation

• Presence of caterpillars on leaves of seedlings.
• Cut stems at the base.
• Plant death.

Control

• Observe field hygiene by removing weeds.
• Drenching soil with a systemic insecticide

Aphids

Signs of infestation

• Presence of insect colonies around young stems, stems and lower buds.
• Leaf curling.
• Presence of black sooty mould.
• Stunting and wilting of plants.
• Premature die back.

Control

• Ensure field hygiene by removing weeds.
• Remove and destroy infested plant parts.
• Introduce natural enemies like ladybird beetle, predaceous midges, lacewings and syrphid bugs.
• Apply pesticides.

Nematodes

Signs of infestation

• Roots appear to be severely distorted and swollen.
• Plants exhibit stunted growth and wilting.

 Control

• Ensure field hygiene by cleaning and disinfecting farm tools which will be used in the soil.
• Disinfect the soil by burning the top soil.
• Cover the soil with clear polythene sheet for 2-3 months to allow solar radiation to heat and kill nematodes.
• Use resistant varieties.
• Practice crop rotation with grain cereals like sorghum and millet.
• Apply fumigation like nematicides.

Thrips.

Signs of infestation

• Presence of small, slender and winged insect on leave surface.
• Leaves show speckling and necrotic patches.
• Flower and fruit abortion.
• Delayed leaf and flower development.
• Wilting and leaf curl diseases due to viral infection. •

Control

• Apply pesticides
•  Plough and harrow before transplanting to kill pupae

 Bollworm (African Fruit Borer)

Signs of infestation

• Presence of caterpillars on flowers and fruits.
• Holes on fruit that are also infected.
• Flower abortion.

Control

• Regular scouting for infestation, eggs and caterpillars.
• Planting trap crops like cucumber and maize.
• Plough the soil before planting to kill pupae.
• Apply bio-control agents like neem extract and bacillus thuringinesis.
• Apply pesticides.

Leaf miner.    

Signs of infestation

•  Presence of maggots in the leaves.
• Presence of whitish tunnels on the foliage.
• Poor flower and fruit development.
• Presence of shiny wandering tracks.

Control

• Introduce pheromones traps to catch males.
• Introduce sticky traps trap both sex.
• Remove and destroy damaged plant parts.
• Practice crop rotation with different family crop like maize.
• Apply pesticides.

Tuta absoluta

Signs of infestation

• Presence of caterpillars on leaves and fruits.
• Holes on fruits and stems.
• Leaf drop.

Control

• Introduce pheromone traps to catch males.
• Introduce sticky traps which catch both sexes.
• Apply pesticides,

Fruit flies.      

Signs of infestation

• Presence of soft spots on fruit skins.
• Fruit rotting.
• Presence of fruit fly on fruits.

Control

• Soil fumigation and disinfection to kill pupae.
• Plough and harrow the soil before planting to kill pupae.
• Regular scouting.
• Practice crop rotation.
• Apply insecticide.

Diseases Affecting Capsicum

Bacterial Spot

Signs of Infection.     

• Leaf spots are sunken on upper surface and slightly raised on lower surface.
• Spots on stems are much elongated.
• Small water soaked spots on green fruits which turn brown and appears like warts.

Control

• Use resistant varieties.
• Practice crop rotation with legumes.
• Remove and destroy infected plant parts.
• Apply copper sprays.

Bacterial Soft Rot

Signs of Infection.

• Soft rot on harvested fruit at peduncle and calyx tissue.
• Fruit collapse and hang like water.
• A dry shell fruit when liquid content pour out

Control

• Minimize injury to fruits.
• Avoid overhead irrigation.
• Practice crop rotation with different crop family.
• Harvest fruit when dry and store at cool temperatures.

Bacterial wilt.

Signs of Infection.     

• Rapid wilting and death of entire plant without yellowing or spotting of leaves.
• Whitish substance oozing when a piece of stem is cut and dipped in a glass of clean water.
• Greyish slimy ooze which are stream of bacteria is produced when a wilted plant is squeezed.

• Control

• Avoid growing crops in soil where bacterial wilt has occurred.
• Use seedlings which are free of the disease.
• Disinfect the soil.
• Remove and destroy diseased plants.

Damping off and root rot

Signs of Infection.

• Decay of germinating seeds.
• Death of seedlings.

Control

•  Avoid excessive watering.
• Apply fungicide.
• Disinfect the seedbed.
• Use resistant varieties.
• Avoid planting on infested seedbed.

Early blight

Signs of Infection.

• Presence of dark leathery sunken spots on fruits.
• Presence of brown spots on older leave with concentric patterns.

Control

• Use resistant varieties.
• Apply fungicides.
• Practice crop rotation.

Late blight

Signs of Infection.

• Death of seedlings.
• Presence of irregular or round shaped dark green to black water soaked patches on leaves.
• Presence of water soaked brown streaks on stem.
• Presence of water soaked spots on fruits that expand rapidly to cover the entire fruit.
• Infected fruit appears wrinkled and flaccid but remains attached to the plant.
• Sudden wilting of entire plant after prolonged infection period.

Control

• Use certified disease free seeds.
• Practice crop rotation with unsusceptible families like brassicas.
• Apply preventive fungicide.
• Apply curative fungicides.
• Remove and destroy infected plants.
• Grow crops on elevated ground-raised beds in greenhouse.
• Practice proper irrigation

Collar rot

Signs of Infection.

• Presence of white fungal growth at base of stem.
• Soft rot at attached part of stem.
• Bending of plant.

Control

• Practice crop rotaion with different family crops.
• Observe field hygiene.
• Do deep ploughing.
• Add lime to the land.

Verticillium wilt

Signs of Infection.

• Wilting of entire plant.
• Stunted growth.
• Presence of brown streaks on cut stems.

Control

• Use disease free seedlings.
• Fumigate the soil before planting.
• Remove and destroy infected plants.

Cercospora leaf spot

 Signs of Infection.

• Presence of brown spots with circular light grey centres with dark brown margins.
• Rapid leaf fall under severe infestation.
• Presence of elliptical spots on petioles, peduncles and stems.

Control

• Use certified seeds
• Observe field hygiene by removing weeds and debris.
• Apply copper based fungicides.

Powdery midew

Signs of Infection.

• Presence of a white, powdery growth of fungal mycellium on top of leaves.

Control

• Avoid using overhead sprinkler to minimize spread.
• Remove and destroy infected plants.
• Apply preventive fungicides.
• Apply curative sulphur based fungicides.

Anthractcnose

Signs of Infection.

• Presence of small, round, dark, sunken spots on green and ripe fruits.

Control

• Remove and destroy diseased plants.
• Apply preventive fungicides.
• Apply copper sprays

Fusarium wilt

Signs of Infection.     

• Seedling show stunted growth.
• One sided wilting.
• Vascular tissue appear dark brown.

Control

• Use certified seeds.
• Lime the soil.
• Use resistant varieties.
• Avoid excessive fertilization.
• Fumigate the soil.

Chilli leaf curl.

Signs of Infection.     

• Leaves are chlorotic.
• Leaves curl upwards and are small in size.
• Flower dropping.
• Reduced number of fruits.

Control

• Use resistant varieties.
• Use certified seeds.
• Remove and destroy infected plant.
• Control white-flies.

Tomato spotted wilt (TSW)

Signs of Infection.     

• Presence of small, light brown flecks on leaves.
• Drooping and death of leaves.
• Presence of brown to purple brown streaks on stems.
• Stunted growth.
• Presence of striking brown rings on red-ripe fruit.
• Concentric rings of yellow ir brown color appear on green fruit.

Control

• Regular scouting.
• Use resistant varieties.
• Avoid inter cropping.
• Observe field hygiene by removing weeds.
• Control thrips which are vectors.