Saturday, June 25, 2011

Cabbage cultivation



Introduction to cabbage

Cabbages belong to the Cruciferae family and are related to turnips, cauliflowers and brussels sprouts. The origin of the cabbage is rather obscure as it is one of the oldest vegetables grown, being well known by the

ancient Greeks. Cabbages are easily grown under a wide variety of conditions and are adaptable to most areas . Although cool moist weather results in the best quality heads, some varieties produce acceptable heads during the warmer period of the year. Therefore cabbages can be grown on a continuous basis.

Soil types

Cabbages grow well on a wide range of soils from light sand to heavier clays. Soils with high organic matter content give the best yields. The soil pH should be in the range 6.0–6.5 for ideal growth. Cabbages are less demanding than cauliflowers, and good crops can be produced on most soils.

Alluvial soils on major river flats are excellent for cabbage production, provided drainage is satisfactory.
Good drainage is important, and soils that become waterlogged after heavy rain or irrigation are unsuitable.

Varieties

Cabbages are sold by type, shape and colour of head rather than by individual variety. Green-coloured cabbages are the most common, with red cabbages available. The shape of the cabbage head can be classified in three groups:

• Ballhead (or roundhead). It has a soccer-ball-sized head, and smooth white-veined leaves tightly packed together.

• Conical (or sugarloaf). This type has a smaller pointed head.

• Large drumhead types. These are a larger cabbage with a flatter head shape.Savoy cabbages are distinguished by their wrinkly leaves with sawtooth-like leaf margins. Savoy cabbages range in colour from light green to grey-green to bluish-green with a reddish tint. The shape varies too, from rounded, soccer-ball size to cylinder-like.

Chinese cabbages (also known as ‘wong bok’). Chinese cabbages are usually more elongated than other cabbage types with broad, very pale green leaves which have white veins that are often less tightly packed

than in other types of cabbages.There is a wide range of varieties available and their suitability for a particular area can only be judged by growing them in the region.

Some varieties are:

• Corinth is suitable for processing and has good disease tolerance. It is similar to Green Coronet but with a larger frame (average weight 4 kg).

• Green Coronet is a good sized variety (average weight 3 kg). It is partially tolerant to black rot and is grown in small amounts during summer. It has a cream-green colour and a good flavour. Harvesting is about 12 weeks from seeding.

• Greengold (hybrid) is an early (12 weeks), slightly conical-headed cabbage, weighing about 3–4 kg. This type is a uniformly attractive, light green cabbage, but the heads do not hold as with the ballhead types.

• Hiyield or Beauty (hybrid) is a large cabbage of drumhead type, maturing in about 13 weeks and weighing about 3.5–4.5 kg. The variety  has some resistance to black rot. The colour is grey-green and the leaves are heavily veined.

• Kameron is a uniform cabbage with large size for cool-season production. Produces large, flattened, globe-shaped heads and has excellent holding ability.

• Red Ruby Ball (hybrid) is an early-maturing cabbage with purple-red leaves. The head is a very tight ball type weighing just over 1 kg.

• Savoy King (hybrid) is an early-maturing (12 weeks) Savoy-type cabbage . Its dark green leaves are coarsely blistered but the head (which weighs about 3 kg) is lighter green and is a flattened ball shape. The variety hearts during the summer in many areas.

• Savoy Prince (hybrid) is larger than Savoy King with reasonably good holding capacity. It matures a couple of weeks after Savoy King. It is more susceptible to black rot. The head tends to be flatter than that of Savoy King.

• Sugarloaf produces heads about 2 months after transplanting. The conical heads weigh about 2 kg.

• Warrior is a medium to large sized variety (average 4 kg) with a round to slightly globe-shaped head. The variety has some resistance to black rot and tip burn. Warrior is a popular processing variety.

• Cardinal Red (hybrid) is a red cabbage with a large round head (average 1.5 to 2 kg). This variety makes better size when growing into warm season.

Cell-grown transplants

The production of seedlings in cells, or individual pots, is the major method of raising transplants. Plants grown by this system are available from commercial nurseries or they can be raised on the farm. Transplants from this system suffer little transplanting shock and grow rapidly once transplanted into the field. Management of the young plants is easier than with bare-rooted seedlings.

Direct sowing

Direct sowing is still an option but is not practised much any more. When cabbage crops are sown directly into the field with a precision planter, they may still need to be thinned to the desired spacing. Good seedbed preparation is essential if this system is used. The young plants are easily damaged by heavy rain and wind and need to be irrigated regularly. Rates for direct sowing are given later.

Soil management

A well-prepared seedbed is important and preparation must commence well before transplanting. Cabbages require a soil with a pH of 6.0–6.5 for best growth. This can be achieved by applying dolomite or lime at a rate of 2–5 t/ha when cultivation is commenced. In most areas cabbages are transplanted into raised beds to reduce the effect of heavy rain, which would waterlog the soil. Beds should be formed as soon as possible to allow them to stabilise before transplanting.

Transplanting

Transplanting is carried out by machines. Transplanters can be as simple as a furrow opener and press wheel which ensures the plant is firmly bedded into the soil. More advanced machines can apply water and fertiliser to the root zone at transplanting. Transplanters require a tractor driver and at least one other operator. One hectare per hour is a good rate for cell-grown transplants.

A good watering immediately after transplanting is essential to ensure that the young plants become well established.

Spacing

Spacing depends on soil type, cultural methods, and the district.
Where two rows are planted per bed, a plant spacing of 75 cm is used on a 1.2 m bed.
A spacing of 40–60 cm is used on single-row plantings where the rows are 1 m apart.
Narrower plantings are used where smaller sized cabbages are produced. A favoured density is 20,000 plants/ha.

Direct sowing rates

There are about 100 seeds/g but the purity of the seed and the resultant germination percentage are critical for success with direct seeding. Cabbage seed loses its viability quickly, and fresh seed must be used each year unless proper storage facilities are available. Do not sow seed deeper than 2 cm.
The quantity of seed required for direct sowing can be accurately assessed by using the Bleasdale formula. According to this, the seed required (in kilograms per hectare) is equal to: (1000 × No. plants/m²) ÷ (No. seeds/g × lab. germ.% × field factor)

In the formula, 1000 is constant. The field factor varies, from 0.5 where seedbed conditions are poor, to 0.8 for a good seedbed condition.

For example, suppose that the seed supplied by the merchant has a stated laboratory germination of 85% and contains 100 seeds/g, and that the grower has a precision-belt drill and intends planting in rows 70 cm apart with plants every 60 cm in the row. Then each plant will have 4200 cm² (70 cm × 60 cm) of space and there will be about 2.4 plants/m² (10 000 cm² ÷ 4200). We will assume a good seedbed, and a field factor of 0.8.
Seed required = (1000 × 2.4) ÷ (100 × 85 × 0.8) = 0.3 kg/ha

Nutrition

Soil analysis prior to applying fertilisers is strongly advisable. Cabbages require large amounts of fertiliser but are not as demanding as cauliflowers. As cabbages benefit from high levels of organic matter, it is suggested that animal manure (if available) be the basis of the fertiliser program.

Broiler manure is ideal, as the sawdust and poultry manure are well mixed. A rate of 20 m³/ha is recommended, with the manure well cultivated into the soil. Phosphorus (as superphosphate) is essential and must be applied in the root zone before transplanting. Use about 300 kg/ha superphosphate.

Where poultry manure is not available adopt a program based on chemical fertilisers, using 60–80 kg/ha phosphorus (equivalent to 600–800 kg/ha superphosphate); 60–85 kg/ha nitrogen (equivalent to 180–225 kg/ha Nitram®); and 30–90 kg/ha potash (equivalent to 60–180 kg/ha muriate of potash). Apply this as a base dressing.

At least one side-dressing before head formation is needed, and in lighter soils crops would benefit from a second side-dressing shortly after the head forms. Side-dressing rates suggested are 40 kg/ha nitrogen (equivalent to 120 kg/ha Nitram®) and 30 kg/ha potassium (equivalent to 60 kg/ha muriate of potash). No benefit will be obtained from the superphosphate content of pre-mixed fertilisers applied as side-dressings.
Molybdenum deficiency could occur even though seedlings were treated in the nursery to give added protection against this problem. A follow-up spray of:

500 g sodium molybdate / 500 L water / ha
is recommended when the plants have become established in the field.

Irrigation

Cabbages need regular irrigation to ensure rapid growth and evenness of maturity. They can be irrigated by moveable spray lines, travelling irrigators or solid set, or, if the soil is suitable and water available, flood irrigation.

Cabbages grown in beds will require more irrigation than those grown on the flat. Soil type and weather will also influence the frequency of irrigation. The use of tensiometers or other measuring equipment will improve yields and reduce water costs.

Pest and disease control

DISEASES

BLACK ROT

Black rot (Xanthomonas campestris) occurs in all areas  and affects both seedlings and adult plants. It is the major disease of cabbages and prevents the production of good quality heads during the warmer months of the year. Areas such as Bathurst, which are much cooler than coastal regions, become important suppliers during the summer.

• Symptoms--- Infection occurs on the leaves through marginal waterpores or wounds. The bacteria move down the leaf veins into the stem and then invade other leaves. The movement of the bacteria causes the leaf to turn yellow, then brown and finally dry out. Movement is usually in a V-shape. Black rot is encouraged by warm, moist weather and rapidly growing soft tissue. It is carried both in and on the seed, and in crop debris. It can survive from year to year in the soil on leaves from diseased crops. Older plants carry the infection and it is transferred to young plants. Insects, water droplets, drainage water and windblown dust help spread this disease.

• Control:Treat seed with hot water. Sterilise the seedbed. Avoid using seedbeds where crucifers have been grown before. Remove infected plants, and rotate crucifer crops on a 4 year pattern. Bury all crop residues as deeply as possible. Control biting and sucking insects, which can spread the disease.

RHIZOCTONIA DISEASE 

Rhizoctonia disease (Rhizoctonia spp.) occurs throughout New South Wales and affects all stages of growth.

• Symptoms: Rhizoctonia causes damping-off in young seedlings, while older seedlings become stunted and the soft tissue at ground level dies, leaving the symptom known as ‘wire stem’. Older plants are prone to stem rot and root rot. Leaves usually take on a purplish red colour. The disease is favoured by cool, wet conditions and is spread by wind-carried spores. Contaminated soil is a source of infection.

• Control: Seedbed sterilisation. Wire stem can be checked in the seedbed by drenching the base of the plant with a registered chemical. Crop rotation of 4 years also assists.

CLUB ROOT 

Club root (Plasmodiophora brassicae) occurs mostly in the Sydney metropolitan area and Bathurst district but is also present in other districts. It is the most important disease of crucifer crops.

• Symptoms:   Swellings develop on the tap root, secondary roots and even parts of the underground portions of the stem. Roots are often spindle-shaped with thick centres and tapered ends. Diseased roots often decay before the end of harvest. Plants are usually stunted and wilt on hotter days. Plant collapse occurs with advanced decay and enlargement of roots. High soil moisture, acid soil and temperatures between 18.5°C and 25.5°C favour the disease. The fungus survives for long periods in the soil and on diseased crop trash. Club root is spread by infected seedlings, windblown soil and contaminated farm machinery.

• Control: Use disease-free seedlings and rotate crops so that crucifers are not grown for 3–4 years in the same ground. Lightly infested soil can be treated with lime, which reduces the symptoms in the plant. Drenching the root zone at transplanting with a suitable registered fungicide is also effective.

TURNIP MOSAIC VIRUS OR RINGSPOT  VIRUS 

Turnip mosaic virus or ringspot virus disease is caused by turnip mosaic virus transmitted on seed and by green peach aphids (Myzus persicae). The problem is serious in the Maitland area and also important in the Sydney metropolitan area, around Windsor, the Central and Southern Tablelands, and the Central Western Slopes.

• Symptoms: There is a yellow ringspotting of the younger leaves, which later become mottled with light and dark green rings and blotches. These symptoms are most prominent in temperatures over 18°C. In lower temperatures the virus shows a definite black ringspotting of the outer leaves. The disease is spread by the green peach aphid feeding on infected plants and weeds then  transmitting the disease to healthy plants. Aphids acquire the turnip mosaic virus after 10 seconds of feeding on infected plants, and transmit it after 5 seconds of feeding on healthy plants.

• Control: Plant disease-free seedlings, produce seedlings away from infected plants, avoid planting near diseased crops or residue, and remove all cruciferous weeds as these carry the virus. Regular spraying will help control green peach aphid populations and reduce the spread of the virus. The manufacturer’s directions regarding rates and the interval between last application and harvest must be observed.

SCLEROTINIA ROT

Sclerotinia rot (Sclerotinia sclerotiorum) is mostly a problem of coastal areas but can occur in all districts, with greatest losses as plants approach maturity.

• Symptoms:   A soft, rapidly spreading, light brown, watery rot develops. Under humid conditions this rotted area becomes covered with a white growth of mycelium in which irregular-shaped bodies similar to seeds develop. These are the sclerotia and are the means by which the disease survives in the soil for several years. Cool, moist conditions favour the development of the disease. Sclerotinia attacks almost all vegetables and a wide range of other plants.

• Control: Removal and destruction of diseased plants prevents the sclerotia from developing. Regular cultivations reduce the humidity, kill the weeds and any apothecia — light brown saucer-shaped bodies which develop from sclerotia under suitable weather conditions. If the ground is heavily infected and the weather cool and humid, spraying as often as every 14 days is suggested.

Insect pests

Cutworms (Agrotis spp.) are stout, uniformly coloured, black, grey or reddish-brown caterpillars about 40 mm long when fully grown. They feed at night on the stems and foliage of plants.
They are found in the top 25 mm of soil and close to the damaged plant. Seedling plants may be destroyed and parts of crops may have to be replanted. Cutworms are often more prevalent in low-lying areas after rain.

• Control: Spraying the soil at the base of the plants with a registered chemical.

Black beetles (Heteronychus arator) are shiny black beetles, about 13 mm long, which may attack seedlings at about ground level, making ragged tears in the stem tissue. They are normally found in grasslands, and most damage is sustained when crops are planted into ground previously under pasture. They are found only in coastal areas and are active mainly in spring and early summer.

• Control:  There are two methods of control: baiting before transplanting, or spraying the soil at the base of the plants at planting and then 2–3 weeks later with a registered insecticide.

Aphids: Grey cabbage aphid (Brevicoryne brassicae) and green peach aphid (Myzus persicae). The grey cabbage aphid may occur in very large numbers and its feeding can cause distortion of leaves and stunting of the plants. The green peach aphid does not occur in large numbers, but it is important as the vector of the virus diseases cabbage ringspot and cauliflower mosaic.

• Control:  Regular spraying. To prevent the insect from transmitting virus disease to plants by feeding, spray the insects when populations are building up. The disease is transmitted within 5 seconds of the commencement of feeding.

Cabbage white butterflies (Pieris rapae) are probably the principal pest of crucifer crops, and are most active during spring and autumn. The yellow eggs are laid on the underside of the leaves, and the young, velvety green larvae (caterpillars) feed here. The fully grown larvae, which are about 30 mm long, are usually found on the upper leaf surfaces. The green or brown pupae are usually found attached to the leaves.

• Control: A program of rotating chemicals and avoiding the use of a chemical from the same chemical family in succession is essential for the control of this insect and Plutella species. The publication Integrated Management of Diamondback Moth in Crucifers — The Handbook, by the National Diamondback Moth Project Team, is essential reading for better control of cabbage white butterfly and diamondback moth.

Diamondback or cabbage moths (Plutella xylostella) are a major pest of crucifers. The adult is a small brown moth, active at night and hiding by day in the leaf litter at the base of the plants. The small yellow eggs are laid in clusters along the ribs and the lower parts of the plants. The first instar larva mines within the leaves. Later instars feed on the undersurface or in the inner leaves, often producing a windowpane effect. When fully grown the larvae are about 8 mm long and, if disturbed, fall from the leaf and hang on a thread. They pupate in silken cocoons in sheltered parts of the plant.

• Control:   As for cabbage white butterflies.

Budworms (Helicoverpa spp.) may cause severe damage in some years, particularly during autumn. The buff-coloured moths lay their eggs singly on the leaves, and the larvae (budworms) bore into the heart of the cabbage. The larvae are about 40 mm long at maturity and are conspicuously striped. The basic colour may vary from brown to red, yellow or green. Their habit of feeding within the heart makes them difficult to control.

• Control:  Regular spraying to kill the budworm just after hatching from the egg and before it has time to become established in the centre of the cabbage plant.

Other pests

The following are also occasionally found damaging cole crops:
• cabbage centre grubs (Hellula hydralis)
• looper caterpillars (Chrysodeixis spp.)
• onion thrips (Thrips tabaci)
• seedling maggots (Hylemya cilicrura)
• vegetable weevils (Listroderes costirostris).

Quality control

Cabbage growers aim to harvest their crop with the least possible number of cuts. To achieve this, good cultural methods are necessary at all stages of production. Careful attention to size of transplants, fertilising, irrigation, and pest and disease control help to ensure even maturity. Cell-produced transplants are more uniform in their maturing than are seedbed-produced plants. This is one of the major reasons growers are using this method of producing seedlings.

Harvesting and marketing

A cabbage is mature when the head is firm to the touch. Heads firm gradually until they become hard. After a period they will split and the
cabbage is then not suitable for sale. With some varieties the head can split when touched or after being cut. Earlier harvesting overcomes this problem.

Cutting is usually carried out in the morning when the cabbage is at its coolest — cabbage will travel better than if cut in the heat of the day. Cut so that a few wrapper leaves are present to protect the heart.
Infield conveyor belts and forklifts have streamlined cabbage harvesting on larger farms. On smaller properties cabbages are still cut and carried or thrown to the edge of the field. Harvested cabbages are put into collapsible wire crates or wooden crates, or stacked on pallets on the back of a truck.

Cabbages grown through the coolest period of the year and exposed to short days begin to form seed heads during late August and September. While this is not a desirable characteristic, all growers face the same problem and cabbages for sale are conical in shape. Breeders are trying to produce cabbages not so susceptible to this condition.

Cabbages can be stored successfully for up to 3 months at 0°C and at a relative humidity of 90%–95%.

Grading

At present there are no such grading regulations for cabbages , but the market demands a good product — medium to large firm cabbages with disease-free outer leaves and a solid heart. As retailers cut most cabbages into halves and quarters, a pleasing internal appearance is important.Cabbages are usually in plentiful supply so that buyers can purchase good quality produce at reasonable prices.

Processing

Some cabbages are grown for processing, and this industry is based on the variety Warrior. Considerable quantities of cabbage are used for coleslaw. Growers from a number of areas are supplying small processors who manufacture the product for use in the catering trade. Many of these small processors purchase their cabbage at the Flemington fresh fruit and vegetable market.

Always read the label

Users of agricultural (or veterinary) chemical products must always read the label and any Permit before using the product, and strictly comply with the directions on the label and the conditions of any Permit. Users are not absolved from compliance with the directions on the label or the conditions of the Permit by reason of any statement made or not made in this publication.

Warning

Pesticide residues may occur in animals treated with pesticides, or fed any crop product, including crop waste, that has been sprayed with pesticides.
It is the responsibility of the person applying a pesticide to do all things necessary to avoid spray drift onto adjoining land or waterways.

Cabbage varieties

 Varieties

            There are many varieties of cabbage based on shape and time of maturity. Cabbages grown late in autumn and in the beginning of winter are called coleworts; their leaves do not form a compact head."Colewort" may also refer to a young cabbage. The word comes from Latin caulis  and Old English wyrt . A drumhead cabbage has a rounded, flattened head. An oxheart cabbage has an oval or conical head. A pickling cabbage, such as the red-leafed cabbage, is especially suitable for pickling; krautman is the most common variety for commercial production of sauerkraut. Red cabbage is a small, round-headed type with dark red leaves. Savoy cabbage has a round, compact head with crinkled and curled leaves.Winter cabbage will survive the winter in the open in mild regions such as the southern United States; the name is also used for Savoy cabbage. Other traditional varieties include white cabbage, "Late Flat Dutch", "Early Jersey Wakefield"  and "Danish Ballhead" .

 Red Cabbage


The red cabbage (Brassica oleracea var. capitata f. rubra) is a sort of cabbage, also known as Red Kraut or Blue Kraut after preparation. Its leaves are coloured dark red/purple. However, the plant changes its colour according to the pH value of the soil, due to a pigment called anthocyanin (flavin). On acidic soils, the leaves grow more reddish while an alkaline soil will produce rather greenish-yellow coloured cabbages. This explains the fact that the same plant is known by different colours in various regions. Furthermore, the juice of red cabbage can be used as a home-made pH indicator, turning red in acid and blue in basic solutions. It can be found in Northern Europe, throughout the Americas, and in China.

Uses


Red cabbage is often used for salads and coleslaw. This vegetable can be eaten raw or cooked.


Cultivation


It is recommended to start red cabbage seeds indoors 4 weeks before the last frost. Sow in containers that allow for movement of water through the bottom of a cell. Popular seedling starting containers are peat pots, egg cartons, plug trays or milk cartons. Once the seedlings grow to about 2 inches tall, and have developed their first leaves, they can be hardened off and moved outside for transplanting. Red cabbage prefers climates that remain moist and cool for most of its vegetative growth stage, so they can be placed in the ground shortly after the last frost, while the spring is still cool. The cabbage plants can be spaced about 12-26 inches from one another. They will need watering often but are otherwise low maintenance plants

cabbage varities

There are several cabbage varieties available to the backyard vegetable gardener. They vary in size and taste. Smaller varieties tend to mature faster, while larger varieties take a little longer. If you live in an area with a short spring season, you may want to plant smaller varieties in the beginning of the year. If the fall season tends to last a little longer, you can plant a larger variety then.


Here is a list of some common cabbage varieties, along with plant descriptions, etc..
  • Earliana - heads average 5 inches across and weigh about 2 pounds, good flavor, ready in 60 days after transplanting, light green outside and creamy white inside
  • Orient Express - this Chinese cabbage variety matures in 45 days from seed, small heads average 1 1/2 pounds, dense center with dark green outer
    leaves, peppery and sweet flavor, good crisp texture
  • King Slaw - this large variety averages 15 pounds, ready in 105 days from seed, large blue/green outer leaves, creamy white center is dense, mild flav                                                                        
  • Two Seasons - this Chinese variety is oblong in shape, averaging 10 inches tall and 7 inches across, dense leafy center is creamy yellow, light green outer leaves, matures in about 65 days after transplanting, sweet and tangy flavor 

  • Salad Delight - this red cabbage matures in 50 days after transplanting, heads are maroon in color and average 3 pounds, inside is dense and almost purple in color with distinct white ribs throughout, sweet and peppery flavor
  • Early Flat Dutch - this variety features light green outer leaves and a creamy white center, heads average 8 pounds, ready in 80 days after transplanting, dense heads are more flat than other varieties
  • Early Jersey Wakefield - this variety matures in 70 days after transplanting, heads average 3 pounds, dark green outer leaves and a light colored center, head is almost cone shaped and dense and features a sweet flavor, holds well for a couple of weeks on the plant after maturity
  • Golden Cross - this cabbage variety matures in 45 days after transplanting, small green heads average 2 pounds and are about the size of a softball, medium green outer leaves and a creamy white center, heads are tight and well-formed, sweet flavor

         Savoy Cabbage    



       A.k.a. curly cabbage. With ruffled, lacy, deeply ridged leaves, Savoy cabbages are perhaps the prettiest cabbages around. The leaves are more loosely layered and less tightly packed than green or red cabbage, although its uses are similar. it is delicious thinly sliced in salads or quickly stir-fried.

Napa Cabbage

Image of Napa Cabbage
A.k.a. Chinese cabbage or celery cabbage. Napa cabbage doesn't look like the head cabbages listed above. It has long light green leaves that flower off of thick, white stalks. It looks a bit like a cross between romaine lettuce and pale Swiss chard. It has a lovely mild flavor with a peppery kick that is delicious in salads or stir-frys. You can also turn it into spicy kimchi.

Bok Choy

Bok Choy (and its youthful friend, baby Bok Choy) has distinct leaves growing from a central stalk. It looks a fair amount like Swiss chard but with pale green stalks and leaves. It has a mild but bright cabbage-y flavor. Bok Choy is most often used in stir-frys, but braising also brings out its sweet flavor. Baby bok choy can be cooked whole, if you like, but all bok choy is perhaps at its best when the leaves are separated and cooked loose.
Brussel sprouts



Brussels Sprouts don't just look like tiny cabbages, they are! They're usually sold loose, which is a fine and dandy way to buy them. But if you find them sold on the stalk, know that they will keep for several weeks if chilled.
Trim the ends, peel off any dark green leaves from each sprout, and roast, steam, or sauté them. Or, keep it simple and just slice them into a salad.

Red Cabbage

Red cabbage looks like green cabbage except, well, it's red. Or, to be more specific, it's a lovely magenta.
Red cabbage heads tend to be a bit smaller than green cabbages, but look for similarly tightly packed,


moist-looking leaves and heads that feel heavy for their size. Red cabbage is delicious thinly sliced in salads like Red Cabbage Slaw, mixed into slaws with green cabbage, or cooked

Green Cabbage

 

Basic. Solid. Compact. Long-lasting. Green cabbage is the Toyota (or Honda!) of cabbages. Use it in salads and slaws, stir-fry it, or long-cook it to bring out its essential sweet nature.
Look for heads that feel heavy for their size (which can range from softball to almost basketball size),
with tightly packed, moist looking leaves. Classic Creamy Cole Slaw calls for plain-Jane green cabbage, as does Beet and Cabbage Borscht and Grilled Cabbage.

    Cabbage - Harvesting


    Harvest cabbages by cutting with a sharp knife close to ground level. A quick tip when growing spring and summer cabbage - cut a 13mm(1/2") deep cross in the top of the stump and a secondary crop of small cabbages will grow from the cut surface.
    Cabbages are mainly cut as required for immediate use. But both red and winter white cabbages can be cut in November and stored for later use.

    The roots and stem are trimmed off and outer leaves removed. Put them in boxes lined with straw and place them in a cool dry place - you should be able to cook these until March.

    Medicinal properties in cabbage

    Medicinal properties 

              Cabbage is an excellent source of vitamin C. It also contains significant amounts of glutamine, an amino acid that has anti-inflammatory properties. Cabbage can also be included in dieting programs, as it is a low calorie food.Along with broccoli and other brassica vegetables, cabbage is a source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells.The compound is also used as an adjuvant therapy for recurrent respiratory papillomatosis, a disease of the head and neck caused by human papillomavirus  that causes growths in the airway that can lead to death. Boiling reduces anti-cancer properties.In European folk medicine, cabbage leaves are used to treat acute inflammation. A paste of raw cabbage may be placed in a cabbage leaf and wrapped around the affected area to reduce discomfort. Some claim it is effective in relieving painfully engorged breasts in breastfeeding women. Fresh cabbage juice has been shown to promote rapid healing of peptic ulcers.Cabbage is also known for slowing down growing cancer cells. 

    Friday, June 24, 2011

    Cabbage diseases

    Black Rot (Xanthomonas campestris pv. campestris): 


    This bacterial disease is common in areas having a warm and wet climate.
    Plants can be infected during any growth stage and the symptoms resemble nutritional
    deficiencies. Infected seedlings become yellow, drop lower leaves, and may die.

    Leaves may be affected on only one side of a seedling. Plants infected because of contaminated
    seed may not develop symptoms for many weeks. The classic symptom of black rot is caused by
    local infection that results when bacteria enter leaves through natural openings of leaf margins.
    The infected tissue turns pale green-yellow and then turns brown and dies. Affected areas are
    usually wedge- or V-shaped. These areas enlarge as the disease progresses, and severely
    affected leaves may drop off. The veins in infected leaves, stems, and roots sometimes become
    black.  The heads of the infected plants remains small and its quality is reduced making it unfit for
    marketing.

    Control:


    An integrated approach is needed to manage black rot successfully. Use of black rot tolerant varieties
    is the best method to control the disease. Considerable reduction in disease has been observed when
    seeds are treated with Agrimycin-100 (100ppm) or Streptocycline (100 ppm). Planting should be done
    on raised beds to facilitate drainage. Cultivation in the fields where crucifers have been continuously
    grown during last 2 years should be avoided. Plants should be thoroughly inspected for black rot
    symptoms and the affected plants should be removed and destroyed.

    Downy Mildew (Perenospora parasitica):

    The disease is very serious in nursery and it can also appear in field planting. High humidity, fog,
    drizzling rains, and heavy dew favour the disease development and spread.
    The first symptom observed are small, light green-yellow lesions on the upper leaf surface, later
    showing on the undersurface. The spots turn yellow as they enlarge.


    During periods of high
    humidity, a grayish white moldy growth is developed on the undersurface of the leaf. Later the leaf
    may become papery and die. Cabbage heads develop sunken black spots. Though, some plants
    are infected at the seedling stage, the symptoms does not become apparent until near harvest.

    Control:

    All the weeds serving as alternate host to the fungus should be destroyed. The crop should be
    irrigated judiciously to avoid periods of high humidity. Spraying the seedlings in the nursery beds with
    Copper Oxychloride (0.3%) is effective in controlling the disease. The first spray should be given as
    soon as the seedlings appear. Subsequent sprayings are given at weekly intervals until the plants are
    transplanted in the field. For controlling the disease in the field, the crop is sprayed with Copper
    Oxychloride (0.5%).

    Wire Stem (Rhizoctonia solani):


    This disease is more serious in nursery beds. The affected young seedlings show reddish brown
    discolouration of the stem near the ground level. This area gets constricted and the plants bent or
    twist without breaking.

    In some cases, the seedling continues to grow even though the lesion
    girdles the stem. The lesion is quite sunken, and the stem resembles a wire, hence the name
    'wirestem'. The girdled seedling eventually dies. Cool, cloudy weather, high humidity, wet and
    compact soil, and overcrowding especially favours development of the disease.

    Control:

    Soil used for preparing raised beds should be well- drained. Excessive irrigation should be
    avoided to reduce humidity around the plants. The seedlings in the seedbed should be adequately
    spaced to allow maximum air movement. While transplanting, the seedlings showing symptoms of
    'wirestem' disease should be discarded.
    Preventive measures such as seed treatment with antagonist fungal culture of Trichoderma viride
    (3-4 g/kg of seed) or Thiram (2-3 g/kg of seed) are effective. Soil around the affected seedling
    should be drenched with Dithane M 45 (0.2%) or Bavistin (0.1%) to control the spread of the
    disease.

    Leaf Spot and Blight (Alternaria brassicae and A. brassiciola):


    It is a destructive disease on seed crop. Older leaves are more susceptible. The initial symptoms are in
    the form of small dark yellow spots on the leaf surface. Later on the spots enlarge to circular areas with
    concentric rings and possibly surrounded by yellow halos. In severe cases, the entire plant defoliates.
    Violets to tan spots develop on infected cabbage seed pods which intensifies in wet weather.

    Control:

      Use of disease free seeds, practicing proper crop rotation and seed treatment with hot
    water (50OC for 30 minutes) helps to minimize the disease incidence. Crops grown for seed
    purpose should be sprayed at full bloom, pod set and pre- harvest stage with Captan (0.2%) or
    Copper Oxychloride (0.5%) for the control of disease.

    Yellows or Fusarium Wilt (Fusarium oxysporum f. sp conglutinans):


    The disease affects the seedlings in nursery stage, however plants exhibit symptoms 2 to 4 weeks
    after transplanting. Disease development is promoted by warm weather conditions. Initial symptom
    appears as the development of yellowish green colour on one side of the plant. A lateral warping or
    curling of the stem and leaves occurs. The lower part of the leaf blade adjoining the petiole or
    midrib wilts and dies.

    The lower leaves turn yellow and later the upper leaves are affected. With
    time, the yellow leaves turn brown and the affected tissue becomes dry and brittle. The speed of
    progress of disease in the plant depends upon the degree of varietal susceptibility and the soil
    temperature.

    Control:

    The conventional controls such as rotation, seed treatment, fungicide sprays, and
    destruction of crop refuse are of little value once the fungus has established itself on a farm or in a
    specific field. Therefore, the use of resistant varieties is the only control. However, as a preventive
    measure the vulnerable stage of the young seedlings to the infection can be avoided by very early
    sowing of cabbage.
    Black Leg

    Black Leg (Phoma lingum):


    This disease generally does not reduce seed crop yields; however, low levels of seed infection
    coupled with weather favorable for disease spread in seedbeds can lead to severe losses after
    transplanting.

    Pale, irregular spots develop on leaves, which later become ashy gray with scattered black dots on
    the surface. Stem lesions are elongated with purple
    borders near the ground level and extend below the soil
    surface, causing a black rot of lower stem and roots.
    Severely affected plants remain stunted and finally wilt.
    As plants mature, they fall sideways from lack of root
    anchorage. Seed crop symptoms include occasional
    cankers on stem bases and spots may appear on
    overwintered leaves. Symptoms on seed pods are rare
    and inconspicuous. Infection can spread to the base of leaves of cabbage heads in storage.

    Control:

    Disease free seeds should be used for planting. As the main infection is through seeds,
    hot water treatment of seeds is recommended. For seed production plots, seed stock used should
    be free from fungal pathogen.
    Cultivation in the fields where crucifers have been continuously grown during last 2 years should
    be avoided. Seedbeds and seed plots should be regularly inspected for obvious foliar infections.
    Seedlings before transplanting should not be dipped in water. Plant debris and disease susceptible
    weeds should be removed and destroyed.

    Clubroot of Cabbage (Plasmodiophora brassicae):


    Cool, wet and acidic soils favours the development and
    spread of the disease.
    Roots develop clubs (swellings) that can be 12-15cm
    wide. The largest clubs are usually on the larger roots just
    below the soil surface. Affected seedlings do not show
    any root swellings until about 3 weeks after infection.
    Infection in the nursery stage results in the death of
    seedlings. When plants are attacked at a later stage, the
    disease rarely kills the plant, but the capacity of the
    affected roots to absorb minerals and water gets reduced.
    Plants wilt in hot weather but partly recover at night. Finally leaves become stunted, yellowish and
    prematurely bolt in hot weather.

    Control:

    Early infection of seedlings can be destructive, so it is important to use only uninfected
    seedbeds and clean equipment. Long rotations (6 years or longer) help prevent a pathogen buildup
    and reduce disease incidence.
    When susceptible varieties are grown in acidic soils, finely ground limestone is thoroughly mixed
    into the soil six weeks before planting to raise the soil pH above 7.0. Lime inhibits disease
    development, but will not prevent a disease outbreak if the spore load in the soil is sufficiently high.
    The quantity of lime is determined by initially measuring the pH of the soil.
    Club root

    Sclerotinia rot/ White Mould (Sclerotinia sclerotiorum):


    This fungus can cause serious losses in the field, in storage, and under transit and market
    conditions. Generally, damp weather favours the occurrence of the disease.
    Infections may occur on the stem at the ground level, on the leaves at their bases, or where the
    foliage comes in contact with the soil. The infections begin as water-soaked, circular areas, which
    soon become covered by white, cottony fungal growth. The affected tissue becomes soft and
    watery as the disease progresses. The fungus eventually colonizes the entire cabbage head and
    produces large, black, seedlike structures called sclerotia on the diseased tissue.

    Control:

    The disease can be managed most successfully by combining cultural practices that
    discourage disease development. Planting cabbage in fields that are surrounded by dense woods
    will restrict air circulation and subsequently delay drying. Rows should be planted in the direction of
    the prevailing winds to promote free flow of air movement within the plants.
    Fields with a history of white mold should be planted with non-susceptible crops such as grains (corn,
    rye, wheat, etc.). Cabbage and other susceptible crops (cauliflower, beans, peas, etc.) should not be
    planted in fields where white mold has become a problem because continuous cropping of susceptible
    crops will result in a buildup of the fungus in the soil and increased disease incidence.
    Mechanical injuries to cabbage heads during harvesting operations should be avoided.

    Damping off (Pythium debaryanum):

    The disease causes severe damage in the nursery. Cool, cloudy weather, high humidity, wet soils,
    compacted soil, and overcrowding especially favor development of damping-off. Damping-off kills
    seedlings before or soon after they emerge. Infection before seedling emergence results in poor
    germination. If the decay is after seedlings emergence, they fall over or die which is referred to as
    "damp-off." The destructiveness of the disease depends on the amount of pathogen in the soil and
    on environmental conditions. Seedlings that emerge develop a lesion near where the tender stem
    contacts the soil surface. The tissues beneath the lesion become soft due to which the seedlings
    collapse.

    Control:

    In the nursery, soil used for preparing raised beds should be well- drained. Excessive
    irrigation should be avoided to reduce humidity around the plants. Seed treatment with antagonist
    fungal culture of Trichoderma viride (3-4 g/kg of seed) or Thiram (2-3 g/kg of seed) and soil
    drenching with Dithane M 45 (0.2%) or Bavistin (0.1%) affords protection against the disease. The
    nursery should be regularly inspected for the disease affected seedlings. Such seedlings should be
    removed and destroyed.

    Natural habitat

    The coconut palm thrives on sandy soils and is highly tolerant of salinity. It prefers areas with abundant sunlight and regular rainfall , which makes colonizing shorelines of the tropics relatively straightforward. Coconuts also need high humidity for optimum growth, which is why they are rarely seen in areas with low humidity, like the south eastern Andalusia, even where temperatures are high enough .
    Coconut palms require warm conditions for successful growth, and are intolerant of cold weather. Optimum growth is with a mean annual temperature of 27 °C , and growth is reduced below 21 °C . Some seasonal variation is tolerated, with good growth where mean summer temperatures are between 28–37 °C , and survival as long as winter temperatures are above 4–12 °C ; they will survive brief drops to 0 °C . Severe frost is usually fatal, although they have been known to recover from temperatures of −4 °C . They may grow but not fruit properly in areas where there is not sufficient warmth, like Bermunda.
    The conditions required for coconut trees to grow without any care are:
    • mean daily temperature above 12-13 °C every day of the year
    • 50 year low temperature above freezing
    • mean yearly rainfall above 1000 mm
    • no or very little overhead canopy, since even small trees require a lot of sun
    The main limiting factor is that most locations which satisfy the first three requirements do not satisfy the fourth, except near the coast where the sandy soil and salt spray limit the growth of most other trees .
    The range of the natural habitat of the coconut palm tree is delineated by the red line in map C1 to the right .

    Mustard diseases

    MList of mustard diseases
    whitespot disease on mustard leaves

    1 Bacterial diseases
    2 Fungal diseases
    3 Miscellaneous diseases and disorders
    4 Nematodes, parasitic
    5 Viral diseases


    Bacterial diseasesBacterial diseases


    Bacterial black rot Xanthomonas campestris pv. campestris
    Bacterial soft rot Erwinia carotovora

    Pseudomonas marginalis pv. marginalis
    Xanthomonas leaf spot Xanthomonas campestris pv. armoraciae

    Fungal diseasesFungal diseases
     Alternaria black spot
    Alternaria brassicae
    Alternaria brassicicola
    Alternaria raphani
    Anthracnose
    Colletotrichum gloeosporioides
    Glomerella cingulata [teleomorph]
    Colletotrichum higginsianum
    Black leg (leaf, root and stem rot)
    Leptosphaeria maculans
    Phoma lingam [anamorph]
    Black root
    Aphanomyces raphani
    Cercospora leaf spot
    Cercospora brassicicola
    Clubroot
    Plasmodiophora brassicae
    Damping-off
    Fusarium spp.
    Rhizoctonia solani
    Thanatephorus cucumeris [teleomorph]
    Downy mildew
    Peronospora parasitica
    Head rot
    Rhizoctonia solani
    Leaf spot
    downy mildew caused by hyaloperonospora(peronospora)


    Myrothecium roridum
    Phyllosticta brassicae
    = Phyllosticta brassicina
    Powdery mildew
    Erysiphe polygoni
    Sclerotinia stem rot
    Sclerotinia sclerotiorum
    Southern blight
    Sclerotium rolfsii
    Athelia rolfsii [teleomorph]
    White rust
    Albugo candida
    (Peronospora sp. commonly present in staghead phase)
    White leaf spot
    Pseudocercosporella capsellae
    Wirestem
    Rhizoctonia solani
    Yellows
    Fusarium oxysporum

    Miscellaneous diseases and disordersMiscellaneous diseases and disorders

    Autogenic necrosis Genetic disorder
    matodes, parasiticNematodes, parasitic
    Root-knot Meloidogyne spp.


    Viral diseasesViral diseases

    Mosaic Cauliflower mosaic virus
    Rai mosaic virus Turnip yellow mosaic virus

    Sunday, June 19, 2011

    Introduction to Turmeric


    Turmeric (Curcuma longa) is a rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae. It is native to tropical South Asia and needs temperatures between 20 °C and 30 °C and a considerable amount of annual rainfall to thrive. Plants are gathered annually for their rhizomes, and propagated from some of those rhizomes in the following season.

    When not used fresh, the rhizomes are boiled for several hours and then dried in hot ovens, after which they are ground into a deep orange-yellow powder commonly used as a spice in curries and other South Asian and Middle Eastern cuisine, for dyeing, and to impart color to mustard condiments. Its active ingredient is curcumin and it has a distinctly earthy, slightly bitter, slightly hot peppery flavor and a mustardy smell.

    In medieval Europe, turmeric became known as Indian saffron, since it was widely used as an alternative to the far more expensive saffron spice.

    Erode, a city in the south Indian state of Tamil Nadu, is the world's largest producer and most important trading center of turmeric in Asia. For these reasons, Erode in history is also known as "Yellow City"[citation needed] or "Turmeric City". Sangli, a town in the southern part of the Indian western state of Maharashtra, is the second largest and most important trading center for turmeric in Asia. Turmeric is commonly called haridra or haldi in India. Turmeric is known as "Manjal" and turmeric powder is known as "Manjal Thool" in Tamil language and in Tamil Nadu, India., it is also known as "Manjal" in Kerala and the Malayalam Language.

    Usage of Turmeric

    Culinary uses
    Turmeric grows wild in the forests of Southeast Asia. It has become the key ingredient for many Indian, Persian and Thai dishes such as in curry and many more.

    In Indonesia, the turmeric leaves are used for Minangese or Padangese curry base of Sumatra, such as rendang, sate padang and many other varieties.

    Although most usage of turmeric is in the form of root powder, in some regions (especially in Maharashtra), leaves of turmeric are used to wrap and cook food. This usually takes place in areas where turmeric is grown locally, since the leaves used are freshly picked. This imparts a distinct flavor.

    In recipes outside South Asia, turmeric is sometimes used as an agent to impart a rich, custard-like yellow color. It is used in canned beverages and baked products, dairy products, ice cream, yogurt, yellow cakes, orange juice, biscuits, popcorn color, sweets, cake icings, cereals, sauces, gelatins, etc. It is a significant ingredient in most commercial curry powders. Turmeric is mostly used in savory dishes, as well as some sweet dishes, such as the cake sfouf.

    Although usually used in its dried, powdered form, turmeric is also used fresh, much like ginger. It has numerous uses in Far Eastern recipes, such as fresh turmeric pickle, which contains large chunks of soft turmeric.

    Turmeric (coded as E100 when used as a food additive) is used to protect food products from sunlight. The oleoresin is used for oil-containing products. The curcumin/polysorbate solution or curcumin powder dissolved in alcohol is used for water-containing products. Over-coloring, such as in pickles, relishes, and mustard, is sometimes used to compensate for fading.

    In combination with annatto (E160b), turmeric has been used to color cheeses, yogurt, dry mixes, salad dressings, winter butter and margarine. Turmeric is also used to give a yellow color to some prepared mustards, canned chicken broths and other foods (often as a much cheaper replacement for saffron).

    Turmeric is widely used as a spice in South Asian and Middle Eastern cooking. Many Persian dishes use turmeric as a starter ingredient for almost all Iranian fry ups (which typically consist of oil, onions and turmeric followed by any other ingredients that are to be included). In Nepal, turmeric is widely grown and is extensively used in almost every vegetable and meat dish in the country for its color, as well as for its medicinal value. In South Africa, turmeric is traditionally used to give boiled white rice a golden color.

    In Goa and Dakshina Kannada (Karnataka state, India), turmeric plant leaf is used to prepare special sweet dishes, patoleo, by layering on the leaf — rice flour, and coconut-jaggery mixture, and then closing and steaming in a special copper steamer (goa).

    Preliminary medical research

    Turmeric is currently being investigated for possible benefits in Alzheimer's disease, cancer, arthritis, and other clinical disorders. As an example of preliminary laboratory research, turmeric ameliorated the severity of pancreatitis-associated lung injury in mice.

    In the latter half of the 20th century, curcumin was identified as responsible for most of the biological effects of turmeric. According to a 2005 article in the Wall Street Journal, research activity into curcumin and turmeric is increasing, with supplement sales increased 35% from 2004. The U.S. National Institutes of Health currently has registered 19 clinical trials underway to study use of dietary turmeric and curcumin for a variety of clinical disorders (dated February 2010).

     Uses in folk medicine

    In Ayurvedic practices, turmeric has been used as an anti-inflammatory agent and remedy for gastrointestinal discomfort associated with irritable bowel syndrome and other digestive disorders. Some may use turmeric in skin creams as an antiseptic agent for cuts, burns and bruises. It is popular as a tea in Okinawa, Japan.
     

    Cosmetics

    Turmeric paste is traditionally used by Indian women to keep them free of superfluous hair and as an antimicrobial. Turmeric paste, as part of both home remedies and Ayurveda, is also said to improve the skin and is touted as an anti-aging agent. Turmeric figures prominently in the bridal beautification ceremonies of India, Bangladesh, and Pakistan. Staining oneself with turmeric is believed to improve the skin tone and tan. Turmeric is currently used in the formulation of some sunscreens.[citation needed]

    The government of Thailand is funding a project to extract and isolate tetrahydrocurcuminoids (THC) from turmeric. THCs are colorless compounds that might have antioxidant and skin-lightening properties, and might be used to treat skin inflammations, making these compounds useful in cosmetics formulations.

    Dye

    Turmeric makes a poor fabric dye, as it is not very light fast (it fades with exposure to sunlight). However, turmeric is commonly used in Indian clothing, such as saris.

    Gardening

    Turmeric can also be used to deter ants. The exact reasons why turmeric repels ants is unknown, but anecdotal evidence suggests it works.

    Ceremonial uses

    Turmeric is considered highly auspicious in India and has been used extensively in various Indian ceremonies for millennia. Even today it is used in every part of India during wedding ceremonies and religious ceremonies.

    It is used in Pujas to make a form of Hindu god Ganesha. Lord Ganesha, the remover of obstacles, is invoked at the beginning of almost any ceremony and a form of Ganesha for this purpose is made by mixing turmeric with water and forming it into a cone-like shape.

    During the south Indian festival Pongal, a whole turmeric plant with fresh rhizomes is offered as a thanksgiving offering to Suryan, the Sun god. Also, the fresh plant sometimes is tied around the sacred Pongal pot in which an offering of pongal is prepared.

    In southern India, as a part of the marriage ritual, dried turmeric tuber tied with string is used to replace the Mangalsutra temporarily or permanently. The Hindu Marriage act recognizes this custom. Thali necklace is the equivalent of marriage rings of west.

    Modern Neopagans list it with the quality of fire, and it is used for power and purification rites.

    Friedrich Ratzel in The History of Mankind reported in 1896 that in Micronesia the preparation of turmeric powder for embellishment of body, clothing and utensils had a highly ceremonial character. He quotes an example of the roots being ground by four to six women in special public buildings and then allowed to stand in water. The following morning, three young coconuts and three old soma nuts are offered by a priestess with prayer, after which the dye which has settled down in the water is collected, baked into cakes in coconut moulds, wrapped in banana leaves, and hung up in the huts till required for use.

    Composition of Turmeric

    Turmeric contains up to 5% essential oils and up to 5% curcumin, a polyphenol. Curcumin is the active substance of turmeric and curcumin is known as C.I. 75300, or Natural Yellow 3. The systematic chemical name is (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione.

    It can exist at least in two tautomeric forms, keto and enol. The keto form is preferred in solid phase and the enol form in solution. Curcumin is a pH indicator. In acidic solutions (pH <7.4) it turns yellow, whereas in basic (pH > 8.6) solutions it turns bright red.

    Sunday, June 5, 2011

    Introduction to tea




    Tea is the agricultural product of the leaves, leaf buds, and internodes of various cultivars and sub-varieties of the Camellia sinensis plant, processed and cured using various methods. "Tea" also refers to the aromatic beverage prepared from the cured leaves by combination with hot or boiling water, and is the common name for the Camellia sinensis plant itself. After water, tea is the most widely consumed beverage in the world. It has a cooling, slightly bitter, astringent flavour which many enjoy.
    There are at least six varieties of tea: white, yellow, green, oolong, black, and post-fermented teas of which the most commonly found on the market are white, green, oolong, and black. Some varieties, such as traditional oolong tea and Pu-erh tea, a post-fermented tea, can be used medicinally.

    tea garden
    The term "tea" is sometimes loosely used to refer to "herbal teas", which are an infusion or tisane of leaves, flowers, fruit, herbs, or other plant material that contains no Camellia sinensis. In East Asian culture, the term "red tea" has always been used to represent what the West understands as "black tea". This can be confusing in the English speaking world because the same term is now also used to represent the drink made with the South African rooibos plant which contains no Camellia sinensis.

    Tea Cultivation and harvest

    Camellia sinensis is an evergreen plant that grows mainly in tropical and sub-tropical climates. Nevertheless, some varieties can also tolerate marine climates and are cultivated as far north as Pembrokeshire in the British mainland and Washington in the United States.


    Leaves of Camellia sinensis, the tea plant.
    Tea plants are propagated from seed or by cutting; it takes approximately 4 to 12 years for a tea plant to bear seed, and about 3 years before a new plant is ready for harvesting. In addition to a zone 8 climate or warmer, tea plants require at least 127 cm. (50 inches) of rainfall a year and prefer acidic soils. Traditional Chinese Tea Cultivation and Studies believes that high-quality tea plants are cultivated at elevations of up to 1,500 metres (4,900 ft): at these heights, the plants grow more slowly and acquire a better flavour.
    Only the top 1-2 inches of the mature plant are picked. These buds and leaves are called flushes. A plant will grow a new flush every seven to fifteen days during the growing season, and leaves that are slow in development always produce better flavored teas.
    A tea plant will grow into a tree of up to 16 metres (52 ft) if left undisturbed, but cultivated plants are pruned to waist height for ease of plucking.
    Two principal varieties are used: the China plant (C. sinensis sinensis), used for most Chinese, Formosan and Japanese teas (but not Pu-erh); and the clonal Assam plant (C. sinensis assamica), used in most Indian and other teas (but not Darjeeling). Within these botanical varieties, there are many strains and modern Indian clonal varieties. Leaf size is the chief criterion for the classification of tea
    plants, with three primary classifications being: Assam type, characterized by the largest leaves; China type, characterized by the smallest leaves; and Cambod, characterized by leaves of intermediate size.

    Tea Processing and classification








    A tea's type is determined by the processing which it undergoes. Leaves of Camellia sinensis soon begin to wilt and oxidize, if not dried quickly after picking. The leaves turn progressively darker as their chlorophyll breaks down and tannins are released. This enzymatic oxidation process, known as fermentation in the tea industry, is caused by the plant's intracellular enzymes and causes the tea to darken. In tea processing, the darkening is stopped at a predetermined stage by heating, which deactivates the enzymes responsible. In the production of black teas, the halting of oxidization by heating is carried out simultaneously with drying.

    Tea harvest on the eastern shores of the Black Sea, ca. 1905-15.

    Without careful moisture and temperature control during manufacture and packaging, the tea may become unfit for consumption, due to the growth of undesired molds and bacteria. At minimum it may alter the taste and make it undesirable.

    Tea is traditionally classified based on the techniques with which it is produced and processed.

    White tea: Wilted and unoxidized
    Yellow tea: Unwilted and unoxidized, but allowed to yellow
    Green tea: Unwilted and unoxidized
    Oolong: Wilted, bruised, and partially oxidized
    Black tea: Wilted, sometimes crushed, and fully oxidized
    Post-fermented tea: Green tea that has been allowed to ferment/compost