CROP PRODUCTION V ( VEGETABLES )

Introduction

  • A vegetable is any crop that is grown and eaten fresh.
  • Vegetables are important both for nutritional and commercial reasons.
  • They are categorized on the basis of the part used as food.

Such parts include;

  • Leaves,
  • Stems,
  • Roots,
  • Fruits,
  • Flowers,
  • Pods

Vegetables are grouped into the following categories:

  • Leaf vegetables for example kales and cabbages.
  • Root vegetables for example carrots, beets, radishes and turnips.
  • Fruit vegetables for example French beans and okra.
  • Stem vegetables for example asparagus, leeks and spring onions.
  • Bulb vegetables for example bulbed onions and garlic.

 

Tomatoes (Lycopersicon esculentum)

  • Tomatoes are fruit vegetables widely grown in Kenya.
  • The ripe fruit may be eaten raw cooked or processed to make tomato sauces, juices and pastes.

  Ecological Requirements

  • Altitude: 0-2100m above sea level.
  • Rainfall: 7S0-1300mm per annum.
  • Soils: deep, fertile and well drained.

Varieties

Fresh market varieties:

  • Money maker,
  • Marglobe, hundred fold,
  • Beef eater,
  • Hot set,
  • Super marmande

Processing varieties:

  • Kenya beauty,
  • San -marzano,
  • Roma,
  • Heinz 13S0,
  • Primabel,
  • Rutgers hybrid
  • Cal- J.

Nursery Practices

  • Choose a site which has not been grown Solanaceae crop in the last three years.
  • Nursery beds are raised about 15cm above the ground level.
  • Make drills of 20cm apart and 1cm deep drill and cover the seeds.
  • Provide shade or mulch material.
  • Water twice a day.
  • Apply phosphatic fertilizers during planting.

Seedbed Preparation

  • The land should be dug deeply to control weeds.

 

Transplanting

  • Seedlings are ready for transplanting when they are 10-15cmhigh after about one month.
  • Holes are made at a spacing of 60cm x 90cm.
  • Apply 20gm of DSP in the planting hole.
  • Transplant with a ball of soil around the roots.
  • Apply mulch around each seedling.
  • Transplanting is normally in the evening or on a cloudy day.

Field Maintenance

  • Early control of weeds is necessary.
  • Top dressing is done after crop establishes.
  • Pruning and staking are done to train the plants to grow vertically.

Pests Controls

  • American Bollworm
  • Nature of damage: boring holes on the fruits.
  • Control: spraying insecticides.
  • Tobacco White Fly
  • Nature of damage: suck plant sap from the underside of the leaf, hence may transmit viral diseases.
  • Control: Destroy infected plant and spray insecticides.

Disease Control

  • Late Blight
  • Cause: Fungus
  • Symptoms: dry patches on the leaves and fruits.
  • Control: use of fungicides, crop rotation and destruction of affected materials.
  • Blossom-end Rot

Caused by;

  • Too much nitrogen in early stages.
  • Irregular or infrequent watering.
  • Calcium deficiency.

Control: Apply calcium ammonium nitrate and correction of the above problems.

Harvesting

  • For canning, fruits should be fully ripe.
  • For fresh market, fruits should be partially ripe and packed in crates to avoid damage.
  • The fruits should be graded according to;
  • Size,
  • Colour,
  • Ripeness
  • Freedom from blemishes.

 

Cabbage

  • It is a leaf vegetable related to other brassica crops such as kales, cauliflower, Chinese cabbage and Brussels sprouts.
  • Cabbage leaves may be eaten raw in salads, steamed, boiled or cooked in a variety of ways.
  • The leaves can also be fed to livestock.

Ecological Requirements

Altitude:

  • Those with small heads: 900-1500m above sea level
  • Those with Large heads: 1800-2700m above sea level.

Temperature: require cool condition.

Rainfall:

  • 750-2000mm per annum.
  • Should be well distributed throughout the growing period.

Soils:

  • Deep,
  • Fertile
  • Well drained. 

Varieties

Early maturing:

  • Brunswick,
  • Sugar loaf,
  • Early jersey,
  • Copenhagen market,
  • Chinese cabbage,
  • Celery cabbage,
  • Cafe splits kool
  • Gloria, mukuki,
  • Golden acre .

Late maturing:

  • Drumhead,
  • Savoy,
  • Perfection,

Nursery Practices

  • The beds should be raised, dimension 1 m wide and any convenient length (usually 2-3m in length).
  • Make drills of 15-20cm apart.
  • Sow seeds by drilling and cover to a depth of 1 cm.
  • Provide shade or mulch material.
  • Apply phosphatic fertilizers and mix thoroughly with soil during planting.
  •  Water twice a day.

Seedbed Preparation

  • Cultivation should be done during the dry season so that all the weeds are killed.
  • Dig holes at the spacing of 60cm x 60cm.
  • Incorporate farm yard manure in the soil.

Transplanting

  • Water the seedlings before uprooting.
  • Seedlings are ready for transplanting after one month that is when they are 1O-15cm in height.
  • Select healthy and vigorous seedlings.
  • Transplant the seedlings with balls of soil to prevent root damage.
  • Plant to the same depth as they were in the nursery.

Field Maintenance

  • Apply fertilizers during planting and top dress later.
  • Control weeds to reduce competition.

Pest Control

Diamond Black Moth

  • Damage: Eats the underside of the leaf making windows or holes in the leaf.
  • Control: Spray recommended insecticides.

Cutworms

  • Damage: Attacks the stem at the ground level causing he plant to fall.
  • Control: Spray recommended insecticides.

Disease Control

Black Rot

  • Cause: Bacteria
  • Symptoms: Leaves turn yellow and rotting of the stem giving an offensive odour,
  • Control: Closed season, crop rotation, use certified seeds and spray appropriate chemicals.

Black Leg

  • Cause: Fungus
  • Symptoms: Brown to black spots on seedlings and dark canker on the stem.
  • Control: crop rotation, destroy infected materials.

Harvesting

  • Cabbages are ready for harvesting 3-4 months after transplanting.
  • The heads are cut when they are solid and compact.
  • Harvested cabbages are sold immediately.

Carrots (Daucus carota)

  • It is a root vegetable grown in the cool areas of Kenya.
  • It is commonly eaten raw in salads but can also be cooked.

   

Ecological Requirements

Altitude: 0-2,900m above sea level.

Rainfall:

  • 750 – 1,000mm.
  • Well distributed throughout the growing period.

Soils:

  • It requires deep,
  • Fine tilth
  • Well drained soils that are free from obstacles to allow for root expansion.

Temperatures: it requires cool to warm temperatures as very high temperatures result in the production of pale and short roots.

Varieties

  • Fresh market varieties for example Chantenay and Nantes.
  • Canning varieties for example Nantes
  • Fodder varieties for example Oxhast.

Land Preparation

  • The field should be well dug to a depth of about 20cm.
  • The soil clods should be broken to give a fine tilth before planting.
  • Manure should not be applied as it induces forking which reduces the crop quality.

Planting

  • Carrots are planted directly into the main seedbed.
  • Seeds are drilled into rows made 20-30cm apart.
  • The seeds are then covered lightly and the soil pressed down.
  • 90kg/ha of DSP should be applied at planting time in the drills.
  • It should be mixed well with the soils before placing the seeds.

 

Field Practice

  • Thinning — it is done 2 weeks after germination.
  • Weed control– the field should be kept weed free.
  • Earthing up should be done while weeding to encourage root expansion ..
  • Topdressing: after weeding 60kg of nitrogen per hectare should be applied as top dress.
  • Irrigation – this should be carried out where or when there is not enough rainfall.

Pest Control

  • Carrots do not have many field pests except the green aphids.
  • These can be controlled by use of the appropriate pesticides.

Disease Control

  • Occasionally attached by the mildews especially in wet and humid environment.
  • Thinning can be done to reduce humid conditions.

Harvesting and Marketing

  • Carrots are ready for harvesting 3-5 months after planting depending on the variety.
  • They are lifted from the soil and sold fresh or canned.

 

Onions (Allium cepa)

  • Onions are bulb vegetables grown in the warm areas of Kenya.
  • They are used as a vegetable in salads and for flavouring foods, soups and stews.

    Ecological Requirements

Altitude: 0-2, 100m above sea level.

Rainfall:

  • 1,000mm of rain per year
  • Irrigation in dry areas .

Soils:

  • Requires well drained fertile soils
  • pH of 6.0 – 7.0 .

Temperatures:

  • Onions are a warm climate crops.
  • However, some varieties prefer cool conditions.
  • They require a fairly long dry period for ripening.

Varieties

  • Red creole,
  • Tropicana hybrid
  • White creole.

Land Preparation

  • The land should be well prepared leaving a fine tilth.
  • Farm yard manure at 40 – 50 tonnes per hectare should be applied and mixed well with the soil.

Planting

  • Direct: Seeds are drilled in rows 30cm apart and 8cm within the rows. 20kg/ha of DSP fertilizer is used.
  • Indirect: Seeds are established in the nurseries before transplanting them in rows 30cm apart and 8 cm within the rows.
  • Shallow planting is recommended for bulb expansion.

Field Management Practices

Thinning

  • It is carried out only in the crop that has been directly planted so as to achieve spacing of 8cm between two plants within the row.
  • The thinned plants referred to as spring onions are used as vegetables in salads.

Topdressing

  • Calcium ammonium nitrate at the rate of 250kg per hectare is recommended for topdressing onions.
  • This is done 3 months after planting.

Pest Control

Onion Thrips:

  • These cause silvering and withering of leaves from the tips downwards.
  • They are controlled by spraying with appropriate insecticides such as Diazinon or fenthion.

Disease Control

Purple Blotch and Downey Mildew

Purple blotch;

  • Characterized by oval greyish lesions with purple centres on leaves.
  • This causes leaf curling and die back.

Downey mildew;

  • Characterized by brown spores covering the leaves leading to death of the whole plant.
  • The two diseases are effectively controlled by crop rotation and application of appropriate fungicides.

Harvesting and Marketing

  • Onions are ready for harvesting 5 months after planting.
  • When leaves start drying the tops are broken or bent at the neck.
  • This hastens the withering of the stems.
  • The bulbs are then dug out and left to dry in a shade for a few days.
  • Onions are graded according to size and marketed in nets of about 14 -16kgs.
(Visited 403 times, 1 visits today)
Share this:

Written by