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| Tomato Rio grande Variety |
Tomato
production in Tanzania has increased considerably in recent
years.Thetomato(Lycopersiconesculentum) is popular with both small scale farmers for its edible fruits both for
export and local consumption. The major tomato producing region in Tanzania
include Iringa, Morogoro, Arusha and Dodoma.
2.Plant type
Plants are either indeterminate
– which when side shoots are removed, produce a continuously growing single
stem – or determinate, ending in the formation of a flower
cluster and a bush-like structure.
Determinate
(eg ANNA F1 and TENGERU 97)
plants are usually earlier to mature, because, once flowers are formed they
divert all energy into filling and producing a uniform crop. They are more
often used where seasons are shorter and just one crop is produced. They are
bushy in character with a short main stem, and ideal for mechanical harvesting
of processed crops and field cultivation of fresh tomatoes.
Indeterminate plants continue to produce flowers. Such a crop, if
maintained, can make better use of an extended season. They ideally suit
greenhouse production and can grow over 32.8 feet in height after 9 to 10
months.
How to select the best
site for planting
Tomatoes grow best in areas with at least six hours of full
sun per day during the growing season. The ideal range of temperature for tomato production is 18 –
27 centgrade degree.
Production is reduced based on the number of hours the plant
spends in the shade. While tomatoes produce well on a wide range of soils, the
best yields are usually seen on deep, fertile loams and sandy loam soils. The upper layer needs to be
penetrable. Soil depth of 15 to 20 cm is needed to grow a healthy crop.
Most soils can be modified through the use of organic matter, lime and
fertilizer depending on what results soil tests yield. It is best to avoid
planting tomatoes in extremely sandy or heavy clay soils that are difficult to
manage when dry. In heavy clay soils, farmers should dig deeply to allow better
root penetration. In
addition, fields should be rotated out of tomatoes and related solanaceous
crops (e.g. tobacco, pepper, and potatoes) for a period of three years.
How to prepare land
Farmers should clear all bushes and trees if there are any.
Herbicides such as Round-up can be used to clear weeds like couch grass. Since
tomatoes do best in deep and well-drained soils, it is good to till the land to
about 8 inches deep adding local organic compost to the soil as you go. Plough
the wet soil and do a second ploughing in dry soil to obtain a loose fine deep
soil mix. Digging the land improves water movement in the soil.It also helps to
reduce soil-borne pests and diseases by exposing the soil to the hot sun.
Nursery preparation
Soil nursery method as well as trays can be used for growing
seedlings. In the soilnursery
method, a fine tilth is recommended because of small sized seeds. The nursery
should be raised 15 cm above the ground.Seeds should be planted at a depth of
1cm and a spacing of 15cm between the rows. The seeds are arranged along a
furrow, and then covered lightly with soil. The nursery can be covered with hay
or dry grass. This is done to increase moisture on the surface and prevent
splash during irrigation. Watering will be done lightly using a watering can
and timed in the morning to avoid conditions conducive for the development of
diseases The seeds will sprout within 8 days. It will take about a month before
the seedlings are ready for transplanting. Harden-off seedlings a week or two
before transplanting by reducing irrigation. The farmer will be required to
monitor the seedlings for pests, diseases and weeusing appropriate control methods
when need arises. Farmers can also use trays for raising the seedlings. Plants
raised in trays generally have a better survival rate.
Key issues to consider
during nursery preparation.
•
Nursury
should be establishided near to the water source
•
The
site should be flat or with gentle slop to avoid water logging
•
The
site for nursery establishment should be the one at which tomato was not grown
for 3 years.
•
The
nursery site should be near to the area where farmer wish to establish Tomato
field.
Transplanting
Farmers should transplant the seedling to the field 3 to 6
weeks after sowing. A week before transplanting, harden the seedlings by
reducing the application of water, but 12-14 hours before they are taken out of
the seedbed they should be thoroughly watered again to avoid excessive damage
to the roots. Seedlings with 3-5 true leaves are most suitable for
transplanting. When removing the seedlings from the nursery, keep a large clump
of soil attached to the roots to prevent them from being damaged. Transplanting
should be done in the afternoon or on a cloudy day to reduce the transplanting
shock.
Before transplanting, the following should be applied by the
farmers.
•
Irrigating
the seedlings few hours before transplanting to easen the uprooting process .
•
Prepare
the planting holes in the field
•
Transplanting
should be done during evening hours
•
Transplanting
should be done when tomato seedlings have 2-6 number of leaves.
A seedling transplanted with a ball of soil
6. Actual planting
Tomato field should be prepared 1 – 2 Months before
transplanting .Spacing between plants and rows depends on the cultivar growth
habit, soil type, cropping system and also whether the plants are to be
supported by stakes or left on the ground. The common spacing is 50 cm between
plants and 75 - 100 cm between rows. If the tomatoes are to be supported by
sticks, then the distances between rows can be decreased to 20-40 cm. Make the
holes for the plants deep enough so that the ball of soil is in the ground.
Press the soil firmly and gently around the root, and water around the base of
the plant to settle the soil.
7. Care after
transplanting
After transplanting, mulch can be placed on the ground around
the plants to protect them from heat during the first five days. Farmers should
not put mulch near the plants as they can damage the stems. Mulch can also be
used to control weed growth, prevent erosion and conserve water. Care should be
taken not to wet the lowest leaves, as this can cause the growth of fungus.
Sources of Improved
Seeds
Farmers select
varieties that perform best under the local conditions.Seed can be produced by
farmers from their fields. Altanatively it is advised that to optimize
production, farmers should use the improved varieties which in Tanzania it is
mainly supplied by Mosanto agent which is Kibo, Balton Tanzania Limited,Alpha Seed Co., Seed
Co.TanzaniaTanSeed International
Varieties and Yield
Currently, Tanzania Tomato
farmers prefer the improved tomato varieties than local varieties. This is
mainly because the improved varieties yield better and tolerant to disease and
pest . The varieties which is being increasingly adopted by Most of Tanzania
farmers include Anna F1, Assila F1, Eden F1, Tanya, Tengeru 97,Roma etc.
MANAGEMENT PRACTICES
Mulching
Mulch is simply a covering over the
soil that keeps moisture in, suppress weeds and protectslow-growing tomatoes
from resting on the ground and developing rot. There's some extrabenefit to
using organic mulches such as grasses,hay, leaves or sawdust because
thesematerials unlike plastic, aluminum or other synthetic mulches decompose,
providing food forthe millions of microorganisms that live in the soil, making
nutrients available to your plantsand improving soil structure. Staked and
trellised plants usually benefit from a mulch to savemoisture. More exposed to
sun and wind than un staked plants, they lose more water throughtheir leaves.
Staking and training
Staked tomatoes provide ease of
harvest and higher fruit quality by keeping fruits off the ground and resulting
in less rot. Staked tomatoes are normally pruned to 1-2 main stems.Staking is
done 2-3 weeks after transplanting. Wooden stakes 120-150cm long are driven
intothe ground halfway between each plant or between alternating plants. Plants
are trained bytying the plants with plastic twine or construction wire onto the
trellis beginning 3-4 weeks after transplanting and is repeated 3 or 4 times
during the growing season. The twine is tiedaround each stake and on both sides
of the plant to provide vertical support. Height of thestakes and training
technique varies depending on wind conditions during the growth cycle,or on
traditional practices followed in the different tomato production areas of the
world.
Irrigation
Sufficient moisture should present
for germination or quick recovery of transplants. Tomatoplants may never
recover from water stress during their early development therefore the useof
water by the plant increases until the fruit load is developed. Tomato are
relatively deep –rooted crop, whose roots can extend to a depth of 15cm ,thus
average water requirementsranges from 600mm to 1200mm.Drip irrigation for
tomatoes has gained popularity becauseof increased water use efficiency and
because it allows for the application of fertilisers and pesticides with the
irrigation water . With drip irrigation it is possible to closely
synchroniseweekly water and nutrient application rates with the corresponding
stage of cropdevelopment. However furrow and sprinkler irrigation systems can
be used.
Weeding
Weeding is done after two to three
weeks after transplanting depending on weed emergence.An integrated approach
can be used to manage weed competition in tomato production. TheIPM program for
weed control utilizes weed identification, monitoring, sanitation,
alternativecultural practices, and timely herbicide applications. Cultural
control practices for weed control include shallow cultivation, ploughing,
hoeing, crop rotation, cover cropping,
organic or plastic mulching and
herbicides. Useful crops for rotation with tomato includealfalfa, sugar beets,
and onions. Solanaceous crops such as potatoes and pepper are notrecommended as
rotation crops with tomato. Problem weeds in tomatoes include
perennials,dodder, weeds of the nightshade family (solanaceous family), and
grasses.
Pest and disease management
Tomato yields may be reduced by a
myriad of insect and diseases pests. Integrated pestmanagement (IPM) is a
systems approach to reduce pest damage to tolerable levels using avariety of
techniques such Pest as natural enemies, genetically resistant plants, sound
culturalpractices, and when appropriate, chemical pesticides
Insect pest Managment
Important insect pests of tomato
include aphids, army worms, cutworms, tomato fruit worm,
leaf miners, mites, thrips, and
whiteflies.
Aphids
Aphids feed on plant sap which may
reduce plant vigour. Aphids may also act as vectors ofplant viruses, and may
also introduce toxins into the plant, resulting in growth deformations.Growers
should use natural enemies, botanical insecticides as neem extracts,
removealternative host of aphids and if aphids are severely attack use systemic
insecticide
Army worms
Beet army worm, Spodopteraexigua,
and nutgrass army worm, S. exempta, infestations ontomato may result in up to
25% fruit losses. Armyworm is larva stage of Adult moths.Feeding by young
caterpillars can reduce leaves to veins leaving behind webs.Caterpillarsnormally
begin feeding on the fruit after molting. Damage to the fruit consists of
superficialfeeding wounds that dry out as the fruit matures. Small
caterpillars, however, may penetrate
the fruit and cause damage similar
to the feeding damage caused by the tomato fruit worm.
Control by applying insecticides
such as stomach poisoning and systemic.
Cutworms
These caterpillar pests which
include the variegated cutworm,Peridromasaucia, and the black cutworm,
Agrotisipsilon, can devastate young tomato plants,by chewing through the stems
at the soil line. Cutworms are active at night.Control is warranted when high
populations are present in the field prior to planting, earlyploughing to
expose cutworms to predators, use repellent botanicals around the plant(s) and
.Baits containing Bacillus thuringiensis or insecticides are available for
cutworm controlwhen are spread within the field.
Leaf miners
Leaf miners are normally a secondary
pest which are kept in check by natural enemies.However both the vegetable leaf
miner, Liriomyzasativae, and the celery leaf miner, L.trifolii, may become
primary pests in tomato fields where intensive pesticide use havedestroyed
their natural enemies. Leaf miners are small yellow maggots which form trails
beneath the leaf epidermis as they
feed.
Control
A monitoring program consists of
insecticide application Insecticides which areRecommended when average counts
rise above 20 pupae per pan per day. Because contactinsecticides won't reach
the larvae inside the leaf, systemic are recommended.
Mites
Outbreaks of carmine spider mites,
Tetranychuscinnabarinus, and the tomato russet mite,Aculopslycopersici, may
occur during hot and dry weather. Tomato russet mites are tinyspider-like
animals which feed preferentially on the lower stem, and then move on to feed
onthe upper section of the plant and on leaves.Presence of the mites is
manifested in the bronze and greasy appearance of stem and leaves.Its feeding
causes leaves to become stripped with light coloured dots. Leaves may later
turnyellow and drop. Silk webbing may be present when infestation is heavy.
Controlled byWettablesulphur and other miticides are effective on mites.
Root-Knot Nematodes
Root-knot nematodes are microscopic
round-worms which feed on the roots of plants.Symptoms on the foliage caused by
the affected root system include stunting, wilting, andleaf yellowing. Infested
roots develop gall-like swellings.
Control
Root knot nematodes can be
controlled by soil fumigation, use of resistant varieties,
practicing crop rotation, removal of
alternative host plants.
DISEASES MANAGEMENT
Early blight disease (Alternariasolani)
the fungus is seed borne the disease
occur during period of warm rainy or humid weather as
well as arid zones.
Disease symptoms are; concentric
lesions of dead tissue on leave and stems, as well asspotting on leaves and
fruits. The disease can result in crop defoliation during wet and warmweather
any time during the crop cycle.Controls include a three-year rotation, removing
infected plants starting from the nurseryplanting on wide, high beds, and
fungicide treatments example mancozeb.
Late blight disease (Phytophthorainfestans)
The pathogen (fungus) survives on
the weeds of tomato family or volunteer tomato or potato.The disease develop
faster in the cool and wet condition.
Symptoms; the disease causes severe
defoliation, stem girdling, and severe fruit rot andirregular water soaked
spots which turn brown and wrinkle at the surface.Control includes crop
rotation, use of healthy seedlings, field sanitation after harvesting, useof
wide spacing, careful monitoring and use of fungicide applications.
Bacterial wilt (Pseudomonas solanacearum)
Bacteria wilt is the most serious
disease of tomatoes in the tropics and sub-tropics.Symptoms include rapid wilt
and death of the entire plant without any yellowing of theleaves. If the stem
is cut and placed in a glass of water, grey bacterial ooze is visible.Control
The disease is difficult to control because it remains in the soil for many
years.
Contaminated fields should be
rotated with non-solanaceous crops. Prevent machinery andfield personnel from
moving from contaminated to non-contaminated soils. The diseasepenetrates the
plant through wound openings in the roots and use of resistant varieties such
asimproved tomato can help to reduce the
problem
Fusarium wilt (Fusariumoxysporumand F. lycopersici)
Is a soil-borne fungi which enters
the plant through the root and interferes with the plant's vascular system by stopping
the transpiration flow. As a consequence the lower leaves are first to turn
yellow and wither. The symptoms progress and eventually the entire plant are
affected, with a dark-brown discolouration in the bark of affected areas, and
with live leaves limited to the branch tips.
Control
Commercial cultivars are available
with resistance to the diseseaslike Tengeru 97, Assila F1 , Anna F1 and Eden F1.In
addition, field sanitation, crop rotation with grass crops, soil fumigation, and
soil pH near 6.5should be used for control .
Damping off disease (Pythiumspp)
The disease affects tomato seedlings
at pre and post emergence because the fungal spores can
remain dormant in the soil for long
period. Causes several effects including; death of seedling
before emergence and emerged
seedling tends to rot at ground surface in excessive moist
nursery.
Controlled by providing good soil
structure and drainage, avoid overwatering, apply woodash in seedbed, soil
sterilization, use of treated seeds and thinning to adjust plant density so
asto avoid moist microclimate, remove weak and diseased plant.
Blossom-end rot
This is physiological disease may
cause severe yield reductions in tomato.The initial symptom will be a slight,water-soaked
discolouration on the blossom-end offruits. The lesions enlarge and turn dark
brown or black. An irregular water supplycompounded with a fast growing crop
may promote blossom end rot. The disease resultsfrom a localized calcium
deficiency in the fruit. Calcium is translocated in the plant through
the transpiration flow.
Control
Factors which have an effect on the
plant's calcium supply should be monitored including
cultivar, plant nitrogen status,
soil fertility, pH, and an even moisture supply in the root zone.
Nitrogen over-fertilization may
accentuate blossom end rot by promoting excessive shoot
growth.
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