CROP PRODUCTION V (VEGETABLES)

CROP PRODUCTION V (VEGETABLES)

CROP PRODUCTION V (VEGETABLES),Vegetable. Any crop that is grown and eaten fresh.

Vegetables are highly perishable.

Importance of vegetable crops.

Nutritional importance.

They provide the body with vitamins and minerals.  They help to keep the body healthy and helps to fight diseases.

Immature vegetables have unpleasant or bitter taste while overgrown vegetables may be fibrous and have little nutritional value.

Commercial importance of vegetables.

Vegetables fetch high prices when grown under irrigation.  Some are processed in industries into sauces, juices and jams for preservation.

Types of vegetables.

Vegetables are categorised on the basis of the part used as food.

1. Leaf vegetable.

The leaves are used as food.

Examples.

Cabbages, amaranthus, kales, spinach, cowpeas, Chinese cabbage, cauliflower etc.

They require a lot of nitrogenous fertilisers to stimulate vegetative growth.

2. Root vegetable.

The roots are used as food.

Examples.

Carrots, radish, beets roots and tulips

CROP PRODUCTION V (VEGETABLES)

3. Fruit vegetable.

The fruit is eaten as food.

Examples.

Cucumbers, tomatoes, melons, brinjals, pumpkins, squashes and pepper.

4. Pod vegetable.

Are mostly legumes.  Can be eaten when green or left to mature and dry.

Examples.

Beans, pigeon peas.

5. Stem vegetables.

The stem is used as food.

Examples.

Leeks, asparagus and spring onions.

6. Bulb onions.

The bulb is eaten as food. Example the bulb onion.

                                      TOMATOES.

Originated from the slopes of Andes Mountain in America. Varieties were developed in Europe.

Utilisation.

Ripe fruit may be cooked, eaten raw in salads or processed to make tomato juice and sauce.

Ecological requirements. 

Do well in warm climate at an altitude range of 0-2100M above the sea level.  Annual rainfall of 760-1300mm well distributed over the growing period.   Very heavy rainfall increases disease incidences and prolongs maturity.  Requires deep, fertile well drained soil.

 Varieties.

Fresh market varieties Processing varieties.

Fresh market varieties.

They are fresh and almost round in shape.

Have poor keeping quality.

Examples.

Money maker.

• Hundred fold
• Bee eater

• Marglobe .
• Super marmande.

Processing varieties.

Elongated/oval in shapes.

Good keeping quality.

CROP PRODUCTION V (VEGETABLES)

Nursery establishment. 

The nursery should be prepared to a fine tilth and should be raised 15cm above the ground in areas with a likelihood of flooding or sunken in dry areas.

Drills are made across the nursery bed 10-15cm apart using a stick and they should not be more than 1cm deep.  Seeds are dropped singly in drills and covered lightly the nursery bed should be watered well twice a day.  Alight mulch should be applied on the nursery bed and should be removed on the 4^th day or when seedlings start to emerge.  A shade should be erected over the nursery bed.  However avoid dark conditions as they cause seedlings to grow thin, tall and unhealthy.  2-3 weeks before transplanting, hardening off should be done to acclimatise them to the prevailing conditions in the seed bed.  Seedlings are ready for transplanting 4-6 weeks after sowing or when they have 4-5 true leaves or are 10cm high.

Land preparation. 

Select a portion where solanaceae family (e.g. Irish potatoes, pepper, and tobacco) have not been grow for the last 3 years.  This prevent diseases such as blight and pests such as nematodes.

Land should be dug deep removing all weeds.  Holes 15cm deep at a spacing of 90X60cm or 100X50cm depending on variety.

A handful of well rotten manure and one tablespoonful of DSP is added and thoroughly mixed with the soil.200kg DSP and 10tons manure/ha is required.

Transplanting.

The nursery bed should be watered well before lifting the seedlings to ensure they are lifted with a lump of soil around the roots.  Select healthy and vigorously growing seedlings.  Plant one seedling per hole and firm soil around the base of the plant.  Transplant late in the evening or on a cloudy day.

Field management practices.

Gapping.

Gapping should be done to maintain the correct plant population.

Topdressing.

Top dress when the seedling are 25-30cm with nitrogenous fertilizer such as CAN or SA 20kgN/ha or 100kg/ha. That is one tablespoonful per hole.

Effects of too much application of nitrogenous fertiliser. 

• Prolonged maturity.
• Cracking of fruits before maturity.
• Blossom end rot.
• Too much vegetative growth hindering fruit formation.

Weeding.

The field should be kept weed free to reduce competition for nutrients.  Care should be taken to avoid root damage and stems.  Too much shaking should be avoided as it may lead to immature fruit fall.

Staking.

For dwarf varieties, mulching should be done to keep the fruits clean and protect the fruits from rotting.  Tall varieties need support using sticks 2m high and sisal strings, banana fibre to tie the plants every 20cm intervals.

Reasons for staking.

• Enhances production of clean fruits.
• Facilitates spraying and harvesting.
• Controls incidences of disease outbreaks such as blight.  Prevent infestation by soil borne pests.

Pruning.

One to three main shoots per plant is ideal.  Too many shoots and suckers makes the tomatoes bushy which uses most of the nutrients for vegetative growth at the expense of fruit development.   It also leads to waste of chemicals.  Fruits and leaves too near the ground should be removed to reduce chances of blight.

Tomato pests and their control.

American bollworm (Heliothis  amigera)

It is a larval stage of a moth brown. Green or pink in colour.  Adult moth lay eggs on young tomato fruits which hatch and larva bore holes into the fruits.  The worms feed with it head inside the fruit and the rest of the body remain outside.

Control.

Spraying using appropriate insectides.

CROP PRODUCTION V (VEGETABLES)

Other pest include:  cutworm, red spider mite, nematode, Tuta absoluta  (tomato leaf miner)

Tomato disease and their control.

Tomato blight.

Fungal disease caused by a fungus Phytophthora    infestans.

Symptoms.

Dry brown lesions on stems, leaves and fruits.  Affected fruit appear rotten and falls off prematurely.

Control.

• Preventive spraying using fungicides.
• Has no cure.
• Avoid irrigation methods that wet the leaves.

 Bacterial wilt.

Caused by bacterium (Pseudomonas solanacearum.) Symptoms.

The plant wither and dry even in wet weather conditions.

Control.

• Roquing
• Use of certified seeds.  Crop rotation.

 Blossom end rot.

Symptoms. 

Blossom ends of the fruit appear rotten and water soaked.

Causes.

• Too much nitrogenous fertilizer in early growth.
• Irregular/infrequent watering.
• Calcium deficiency in young fruits.

Control.

• Regular watering.
• Top dress the crop with the right amount of nitrogen.  Application of calcium compounds in the soil.

Harvesting and Marketing.

Tomatoes for canning should be left to ripen on the plant before they are harvested.

Tomatoes for fresh market should be picked as soon as a reddish colour start to appear.

Tomatoes picked green are of poor quality even after they ripen.  Fruits should be level with the tops of crates to allow pilling of crates on top of each other without crashing the fruits.

100ton/ha may be harvested.

CABBAGE. (Brassica spp) Originated from Europe.

Mineral/nutritional value.

Contain vitamin A and D, minerals such as iron potassium, phosphorus and calcium.

Utilisation.  Eaten raw in salads, steamed, boiled or cooked.

Other Brassica crops include:

Kales, cauliflower, Chinese cabbage, Brusel sprouts.

Varieties.

• Early maturing varieties.  Late maturing varieties.

Early maturing varieties.

• Sugar loaf 
• Golden acres.
• Gloria hybrid.
• Copenhagen market.

Late maturing varieties.

• Early drum-head.  Savoy cabbage.  Prize drum-head   Surc-head.

Ecological requirements.

Altitude.   1800-2900M above the sea level.  Small varieties do well at altitude as low as 900M.

Rainfall.  750mm for small headed varieties and 2000mm for large headed varieties.

Soils.  Requires deep well drained and fertile soils that are slightly acidic.  PH of 6.5.

Nursery establishment and Management.

Should be in an area where Brassica family crop has not been grown or the last 3 years.

Nursery bed should be prepared to a fine tilth removing all roots, stones and perennial weeds.

Shallow drills 10cm apart are made and seeds are evenly drilled and covered lightly.

Mulching is applied and should be removed on emergence of seedlings.  Construct a thin shade over the nursery and water seedlings regularly.  Hardening off should be done 2 weeks before transplanting.

 Land preparation.

Land is ploughed early and harrowed during the dry spell to allow all weeds to die.  Holes 10cm deep at a spacing of 90X60 or 60x60cm are dug and well rotten manure is added and thoroughly mixed with the top soil.

CROP PRODUCTION V (VEGETABLES)

Transplanting.

Transplant one month after sowing.  Select healthy and vigorous growing seedlings.  Water the nursery bed adequately before lifting the seedlings to ensure they have a lump of soil around the roots.  Plant at the same depth they were in the nursery bed and firm soil around the base of each seedling.  Transplant late in the evening or during a cloudy day.

Field Management practices.

Top dressing.

Top dress at 20-25 cm high with one teaspoonful of SA or CAN and repeat 3-4 weeks after the first top dressing.

Weeding.

The field should be kept weed free and hand weeding is done.  Do not break the leaves during weeding as it interferes with head formation.

Cabbage pest and their control.

Aphids.

Are severe during the dry spell.  Irrigation helps to control aphids during the dry spell.

Cutworms.

Larvae stage of a moth. Hides in the soil or moist rubbish.  Green or black in colour.

Control.

Mixing appropriate insecticide powder with soil in each hole during transplanting.

Other pests.  Cabbage saw fly controlled by crop rotation and use of insecticides.

Cabbage diseases and their control.

Damping off.

Attacks seedlings in the nursery.

Causes.

• Excessive shading.  Heavy watering.

Overcrowding of seedlings.

Symptoms. 

Cobweb –like black mass of fungi forming a ring on stems base above the soil.

Seedlings wither and die.

Control.

• Removing shade.
• Thinning/pricking out overcrowded seedlings,  Controlled watering.
• Use of copper based fungicides in heavy infestation.

Black rot.

Bacterial disease of Brassicas.  Attack the pith of the stem.  Infected stem has a black ring when cut. Control is by crop rotation.

Downy mildew.

Fungal disease.  Occurs where heavy mists are frequent.

Control.

• Uprooting and burning affected crops/Roquing.
• Crop rotation.
• Nursery hygiene.
• Copper fungicides in heavy infestation.

Harvesting and Marketing.

Takes 3-4 months after transplanting.  Heads are cut when solid and compact.  Delay harvesting after maturing makes the heads to crack and start rotting especially during the rainy season except for Gloria hybrid.

CARROTS.  (Daucus  carota)

Biennial vegetable commonly grown as annual.  Originated in Europe.

Importance.

Carotene content in carrots is needed for manufacture of vitamin A.

Varieties.

• Fresh market varieties. Chantenary, Nantes.  Canning varieties.   

Oxhart.  Grown for livestock feed.

 Ecological Requirements.

Altitude.  0-2900M above the sea level.

Requires cool to warm temperatures.  Very high temperatures results in production of pale and short roots.

Rainfall.  750-1000mm well distributed throughout the growing period.

Soils.  Requires deep, fine tilth and well drained soils free from obstacles to allow for root expansion.

CROP PRODUCTION V (VEGETABLES)

Land preparation.

Seed bed should be well dug to a depth of 20cm and harrowed to a fine tilth.

N/B manure should not be applied as it induces forking (production of many and short roots) thus lowering crop quality.

Planting.

Planted directly into the main seedbed.  Seeds are drilled into rows 20-30cm apart, covered lightly and soil pressed down.  90kg/ha DSP is applied at planting and should be well mixed with soil before seeds are placed in the drills.

Field Management practices, Thinning.

Done two weeks after germination to attain a distance of 3-4cm between plants within the rows.

 Weeding.

Keep the field weed free.  Soil should be earthed up around the carrots roots during weeding to encourage root expansion.

Top dressing.

After weeding, 60kgN/ha should be applied.

Control of pests.

Does not have many pest.  Green aphids that are found at the base of leaves and should be controlled using appropriate pesticides.

Harvesting and Marketing.

Takes 3-5 months after planting.  Harvested by lifting plants using a fork jembe or uprooting manually.

ONIONS. (Allium   cepa) 

Originated from Mediterranean region of South East Asia.  Biennial but commonly grown as an annual.

Utilisation.  Flavouring foods, soups, stews and also as a pickle.

Varieties.

• Red creole.
• White creole.
• Tropicana hybrid.
• Red passion.
• Jambar f₁

Ecological requirements.

Does well in hot or warm climate.  Requires long dry period for ripening.  Does well at an altitude of 2100M above the sea level.  Requires fertile well drained soils with a pH of 6.07.0 and rainfall of 1000mm per year.

Land preparation.

Prepared early and harrowed to a fine tilth.  All weeds are removed and farm yard manure 4050ton/ha well rotten is added and mixed well with the soil.

 Planting.

Can be sown directly into the main seedbed or started off in a nursery bed.  250kg DSP/ha should be applied in rows that re 30cm apart. For indirect planting seedlings are transplanted at 8cm apart.  Deep planting of seedlings inhibits bulb expansion.

Field Management practices.

Thinning.

Carried out in direct planting to achieve a spacing of 8cm between plants within a row.  Thinned plants (spring onions) are used as vegetables in salad.

Weeding.

Keep the field weed free. Take care not to damage the shallow roots.  Remove excess soil from the root region to expose the bulbs for expansion and do not compact soil around the bulbs.

Top dressing.

Use CAN 250kg/ha 3 months after planting.

Pest and disease control.

Onion thrips. (Thrips  tabaci)

Causes silvering and withering of leaves from the tips downwards.  Common in dry weather.

Control. Use appropriate insecticides e.g. Diazion, or Fenithion.

Diseases.

CROP PRODUCTION V (VEGETABLES)

Purple blotch. (Alternaria  porri)

Causes oval greyish lesions with purple centres on leaves causing leaf curing and die back.

Downy mildew.

Brown spores covering the leaves leading to death of the whole plant.

The above disease are control by:  crop rotation and use of appropriate fungicides.

Other diseases include Bacterial soft rot (Erwinia   carotovora) Harvesting and Marketing.

Takes five months after planting.  The tops are bent at the neck when leaves start drying to hasten the withering of stems.  Bulbs are then then dug up and left to dry in a shade for a few days and should be turned daily to ensure uniform drying.  Yield 17ton/ha.  Should be inspected regularly to remove the spoilt one.  They are graded according to size and marketed in nets.

CROP PRODUCTION V (VEGETABLES)

ALL AGRICULTURENOTES FORM 1-4 WITH TOPICAL QUESTIONS & ANSWERS

PRIMARY NOTES, SCHEMES OF WORK AND EXAMINATIONS