- 1 Cabbage Production
- 2 Soil and Climatic Requirements
- 3 Variety
- 4 Planting
- 5 Management Practices
- 6 Pest Control
- 7 Post-harvest Handling
- 8 Marketing
The cabbage (Brassica oleracea var capitata) belongs to the family Cruciferae and is related to cauliflower, broccoli and brussel sprouts. Cabbages are grown 12 months of the year in Victoria and production is concentrated in southern districts. Cabbages are grown for both fresh market and for processing.1
Cabbage can be grown in a variety of soils with high organic matter throughout the year under irrigation though it thrives best in deep well-drained loamy soils. Ensure a reliable source of water supply.
Field must be thoroughly hoed or ploughed (30cm deep) and harrowed. Prepare ridges or planting beds where necessary on which seedlings may be transplanted. Incorporate well-decomposed manure.2
Soil and Climatic Requirements
Although it prefers cool, humid weather, you can grow cabbage year round as long as you plant the right cultivars. It can survive temperatures below 0°C but grows optimally in the range between 15°C and 20°C.
High temperatures and low moisture levels can result in small plants and a low yield. If temperatures are too low during the growing period, the stems will grow out and the plant will bolt (form the flower stalk).
Cabbage needs about 400mm to 500mm of rainfall depending on the climate and length of growing season. Crop water use increases during the growing period with a peak towards the end of the season.
These nylon bags are ideal for cabbages from a marketing perspective.1
Soil, Nutrition, and Irrigation
Cabbage can be grown on a wide range of soils, but the crop is sensitive to soil acidity. The optimum pH is six to 6.5, and at pH’s greater than seven the disease club root can be prevented. Cabbage is a heavy user of nitrogen and potassium and requires frequent side-dressing. Cabbage is considered a hard crop on the land, and many growers will rotate to other crops that do not have such high fertility requirements. Cabbage is grown on mineral, sand and muck soils.
On sandy soil where there is a high water table, cabbage is irrigated by sub-surface irrigation. On deeper sands it is a perfect crop for drip irrigation since fertigation can be used. In many new fields where cabbage is grown on sandy soil, plastic mulch is being used to prevent wind damage from blowing sand particles. This will increase the use of drip irrigation. Regardless of the method used, cabbage requires about one inch of water per week. The supply of water should be even throughout the growing season to prevent cracking of the heads.3
Cabbages can be divided into three main groups: ball head (or roundhead), conical and the large drumhead types. There is a wide range of cultivars available with many suited for production at particular times of the year whereas others can nearly be grown year round. Red cabbages are also grown but the major production is of green cabbage.
There is a wide range of varieties and particularly for the newer cultivars, their suitability for a particular area can only be judged by growing them in the region.
Some cultivars and their appropriate production time slots include:
- Late spring to winter – Green Coronet, Kameron, Red Rookie.
- Late summer to autumn – Red Ball, Beauty, Stariha.
- Summer to winter – Grand Slam.
- Autumn to winter – Red Ranger, Neptune. Winter to spring – Ballhead, Greengold, Winterhead, Terrific.
The variety Savoy King is suited to year round production in southern production areas whereas most of the other main varieties are suited to more specific production times.
These are just some of the cultivars available but it includes most of the major varieties grown. For more information on the range of cultivars and new releases seed companies should be contacted.4
Spacing and Plant Populations
Cabbage plant populations vary according to the target market for that particular crop. The ideal plant population per ha-1 for a crop destined for the bagging market would be 40 – 45 000 plants. This would produce firm heads with an average head mass of 2 – 2.5kg. For the hawker market 30 – 35 000 plants ha-1 is more suitable. This would produce larger and heavier heads with an average mass of 2.5 – 3kg. The most popular spacing for cabbage production is 50cm in the row and 60cm between the rows. A staggered planting regime is recommended to reduce competition between plants.5
Planting Cabbage may be planted by direct seeding or trans- planting of seedlings. If direct seeding is to be used, about 2 kg of seed per hectare may be required. Seedlings should be transplanted as soon as they reach the desired size and, only well-hardened, young, stocky plants should be used. Transplanting is done in moist soil. The soil around the roots should be firmed and irrigated as soon as possible after set- ting the seedlings. In wet areas cabbage should be planted on raised beds or ridges to reduce waterlog- ging and stem or root rot diseases. Plant populations of 40 000 to 45 000 per hectare are suggested for large-headed types while for cultivars with medium-sized heads, populations of 55 000 to 65 000 plants per hectare are said to be ideal. For baby cabbage, populations of 80 000 to 100 000 plants per hectare are recommended. It is recommended that large-headed cultivars should be planted 600 to 700 mm apart between rows and 450 mm apart within rows. Smaller-headed varieties are planted 600 mm between rows and 300 mm within rows.6
Fertilisation Cabbage is a heavy feeder and requires supplemental fertilisation in the form of manure or compost, nitrogen, phosphorus and potassium. Fertiliser programmes should be based on soil analyses and should be developed for each field. Cabbage requires 200 to 250 kg nitrogen per hectare. Nitrogen is supplied in split applications, where 50 % to 66 % is broadcast and ploughed in just before planting. The first application is made together with phosphorus and potassium. The remainder is side-dressed two to three weeks after transplanting and again three weeks later or applied once-off at about six weeks. If a fertiliser mixture is preferred, 1 500 kg of 2:3:2 (22) and 100 kg potassium per hectare may be broadcasted before planting. A top dressing of 300 kg LAN should be applied approximately four weeks after transplanting and again 4 weeks later if required. Cabbage also needs micronutrients for proper growth and development. The crop has a high requirement of calcium and deficiencies of this nutrient may occur on acid soils, on soils with very high potassium or on very dry soils. Foliar sprays of calcium nitrate can be used to supply calcium. Magnesium may also be deficient on acid soils, on very light soils or on soils that are very high in potassium. Spraying the plants with 5 kg magnesium per hectare can rectify the problem. Cabbage is very susceptible to molybdenum deficiency. Plants should be sprayed with 125 g of sodium- or ammonium molybdate in 500l of water per hectare as soon as signs of deficiency are noticed. The availability of molybdenum may be increased by providing enough lime prior to planting. Iron may be applied with a foliar spray with 1 % iron sulphate or chelate. The deficiency of iron is common on calcareous, alkaline soils. Manganese deficiencies are prevalent on soils with a pH of more than 5,5. A foliar spray of 5 kg per hectare of manganese sulphate or 2 to 3 kg/ha of manganese oxide is suggested as soon as symptoms of deficiency are observed. Cabbage may have boron deficiencies in areas with high rainfall. Three kilograms of Solubor are effective in controlling boron deficiency.7
The crop should be kept free of weeds especially in its younger stages to avoid losses due competition from weeds; which can also be a source of pests and should be controlled at all times.8
Aphids (several kinds)
Cabbage is attacked by several aphids but the grey cabbage aphid (Brevicoryne brassicae) and the green peach aphid (Myzus persicae) are the most common. Damage is caused when they suck sap from the plant and contaminate the edible product. Feeding of the cabbage aphid causes a chlorosis and malformation of the leaf.
Diamond-black moth (Plutella xylostella)
They suck sap from tender growth, resulting in a whitish, scarred appearance. Growth and yields can be seriously reduced by heavy infestation.
Bagrada bug (Bagrada hilarus)
They suck sap from tender growth, resulting in a whitish, scarred appearance. Growth and yields can be seriously reduced by heavy infestation.
American bollworm (Helicoverpa armigera)
The larvae feed on the leave. They cause severe damage in the early stages of growth by destroying the growing points of the plants.
Cabbage webworm (Helula spp.)
The larvae spin a thin web over their feeding places. Damage is severe during early attacks when they destroy the growing point of the plants
Greater cabbage moth (Crocidolomia binotalis)
The larvae spin a thin web over their feeding places Damage is severe during larvae spin a thin web over their feeding places. Damage is severe during early attacks when they destroy the growing point of the plants.
Red spider mite
Red spider mites are found on the underside of leaves, where they weave a fine web. Damage is caused by sucking, resulting in a bronzing and yellowing of leaves.
Cutworm (Agrotis spp.)
Cutworms cause damage when they cut off the stems of young seedlings close to ground level.
Plusia looper (Plusia spp.)
Plusia looper feeds on the leaves and causes damage by cutting the foliage.
Thrips tabaci is the most common species on cabbage. High populations of the insect contaminate the edible product, thus affecting its appearance or quality.
Several nematodes affect cabbage. Plants infested with nematodes are unthrifty and may become stunted. Plants may also have signs of moisture or nutrient stress.
General control measures
Control measures such as crop rotation, using resistant cultivars, using registered chemicals (information from Department of Agriculture, Forestry and Fisheries resource centre)
Damping off (Altenaria spp., Rhizoctonia solani, Pythium spp.)
Infected seedlings wilt, turn purple and die, and often have no lateral roots.
- Using treated seed
- Sterilising the seedbed before planting
- Removing infected plants when symptoms appear symptoms appear Sclerotonia rot or white mould (sclerotinia sclerotiorum)
The disease is favoured by cool, wet conditions and it can survive for two to three years in the soil. Above-ground parts of infected plants may be covered with a white cottony growth. The tissue beneath the mould turns soft and watery.
- By crop rotation
- Planting on ridges or raised beds
- Removal and destruction of infected crop residues
- Good water management aimed at keeping the soil dry
Clubroot (Plasmodiophora brassicae)
The disease is soil-borne and the spores can survive for up to 20 years in the soil. It is most severe on acid soils or moderate pH soils that are poorly drained or have a high clay content. Infected plants are characterised by stunting, wilting and purpling of leaves. The roots change into a mass of large, elongated or rounded swellings or clubs. The clubs rot and form bad smelling wet masses.
- By practising sanitation
- Practising crop rotation
- Grow transplants in fumigated beds
- Lime the soil
Fusarium wilt or cabbage yellows (Fusarium oxysporum F. conglutinans)
Fusarium wilt is more prevalent in summer and the fungus persists indefinitely in the soil. Initially the symptoms appear as yellow foliage, often mainly on one side of the plant. The leaves become distorted and gradually turn brown and drop prematurely. The vascular area also discolours.
- By planting resistant cultivars planting resistant cultivars
- Growing cabbage in winter
- Planting on soils free of disease
- Soil fumigation before planting
- Practising crop rotation
- Practising sanitation
Black rot (Xanthomonas campestris)
The disease is introduced to fields in seed and its spread is very rapid under hot, rainy, windy conditions. The disease survives for three to five years in fields and in the stems of host plants.
The symptoms first appear as yellow to light brown patches at the margins of leaves and later a network of black veins develops within these areas. Affected areas turn brown and dry out and often leave a characteristic triangular-shaped lesion on the leaf margin, with one point of the triangle directed towards the midrib. Older infected leaves also drop and the vascular tissue turns brown as the bacteria move into the main veins and vascular system. Plants infected at the seedling stage may die or remain stunted.
- Planting tolerant or resistant cultivars
- Using disease-free seed or seed treated with hot water
- Practising crop rotation
- Control cruciferous weeds
- Avoiding the use of sprinkler irrigation
- Increase the interval between irrigation
- Deep-ploughing of all infected plant material
Downy mildew (Peronospera parasitica)
Downy mildew is common in cool, humid weather. The fungus survives in debris and is spread by air-borne spores in large numbers. Infected leaves appear as if they have been lightly sprinkled with pepper. The leaves become yellow around the pepper spots. Lesions merge to cover large areas of leaves. Fine, fluffy white mould appears on the lesions on the underside of the leaf during humid conditions.
- Plants should not be irrigated irrigated afte r 15:00 pm and before 10:00 am.
- Treat seedlings with fungicides.
- Fumigation of the seedbed.
- Ensure good seedbed preparation and practices to ensure aeration and drying.
Black leg (Phoma lingam)
Black leg is seed-borne and it can infect the whole seedbed when an infected seed germinates. The whole plant wilts when infected. White to light brown lesions with a purple to black margin develop on the stem and on leaves. The lesions have small black dots in the centre. The centre of the lesion gets woody and cracks.
- Use containerised seedlings.
- Do fungicide treatment of seedbed.
- Seedbeds should be situated far from old production fields.
- Seedbed should be destroyed if leaf lesions are found.
- All cabbage material remaining in seedbeds should be removed.
- Remove of cruciferous weeds from production fields.
- All debris should be removed after harvesting.
Bacterial leafspot (Pseudomonas syringae pv. maculicola)
Bacterial leafspot is more severe in cool, moist weather. The symptoms initially appear as small, faint, water-soaked areas on the underside of leaves. The affected areas develop into brownish to purplish grey necrotic spots, fairly irregular after a few days. They may coalesce to form large irregularly shaped spots. The leaf becomes wrinkled and the tissue may tear when the lesions are many.
- Do chemical control.
- Plant tolerant or resistant cultivars.
- Use disease-free seed or seed treated with hot water.
- Practise crop rotation.
- Avoid using sprinkler irrigation.
- Increase the interval between irrigation.
- Control Control cruciferous weeds. cruciferous weeds.
- All infected plant material should be deep-ploughed.
Alternaria leaf spot (Alternaria spp.)
The disease is common during cool, rainy weather. Initially, symptoms appear as small, dark areas and they rapidly enlarge to form large circular lesions that develop a bull’s-eye pattern or target spot. The lesions are dark brown during wet periods. A brown, velvety, spore-bearing growth can be noticed on the older lesions.
- Use disease-free or treated seed
- Removal or ploughing in plant refuse
- Chemical control 7
Harvested cabbage is particularly susceptible to wilting and should be removed from the field and direct sunlight as soon as possible. The cabbage should be taken to a well ventilated shaded area for packing and transport to market. When there is delay of more than an hour or two between harvest and packing, a spray of clean water to the leaves can help prevent dehydration. A simple field packing station can be constructed from wooden poles and a sheet of polyethylene. Thatch over the roof will provide shade and keep the station cool. The structure should be oriented so that the roof overhang keeps out the majority of the sun’s rays.
The first step in preparing cabbage for market is to remove the torn and loose outer wrapper leaves so the head has a clean, compact, and fresh appearance. Only 3 to 6 tight wrapper leaves should be left on the head. Loose leaves interfere with ventilation between heads, which is important whether the cabbage is packed for market or put into storage. The stem end should be trimmed close to the base of the head so it does not protrude more than 2 cm (.75 in). A fresh cut of the stem end will be necessary if it is discoloured. However, it is very important not to cut the stem end too short so part of the base of the head is cut. This will cause a loss of wrapper leaves and head integrity. Harvested cabbage should be taken to a shaded, well ventilated packing area.
Cabbage should be sorted according to size, shape, and compactness of the head. There
are 3 established size categories (small, medium, large) for domestic marketing of
cabbage, based on the weight of the head. Small sized heads weigh 0.8 kg (1.7 lb) or less,
medium sized heads weigh between 0.9 kg and 1.4 kg (1.7 lb and 3 lb), and large sized
cabbage heads weigh 1.5 kg (3 lb) or more. Only the cabbage with crisp and turgid leaves
should be packed for market. The heads should be a colour typical of the cultivar (i.e. green, red, or pale yellow-green), firm, heavy for the size and free of insect, decay, seed stalk development and other defects.
Heading-type cabbages are generally packed in fiber board cartons, wooden or wire-bound crates, or mesh bags holding about 23 kg (50 lb). Uniformity of head size and the proper count per carton are important. Normally 18 to 22 heads are packed in a 23 kg (50 lb) container.
Cartons and crates are easier to stack and load and provide considerably more protection to the cabbage than mesh bags. Cabbage should be packed in fibre board cartons usually holding between 10 kg to 18 kg (22 lb to 40 lb), depending upon market preference. Cabbage may be bunched into groups of 3 to 5 plants using a string or rubber band. Care must be taken as plants
The optimal storage temperature for all cabbage types is 0°C (32°F). This maintains a very low respiratory activity in the cabbage and greatly inhibits decay. Chinese cabbage
Well-trimmed stem end of pak choi ready for packing. Uniform sized cabbage
packed in strong well-ventilated wooden crates.
This is much more perishable than heading types and should be cooled within several hours after harvest and held as close to the ideal postharvest temperature of 0°C (32°F) as possible. The maximum market life of pak choi under ideal conditions is 2 weeks. At ambient temperatures the pak choi leaves will rapidly wilt and become unmarketable after only 1 to 2 days. The need for immediate cooling after harvest is not as necessary for heading types of cabbage. However, for maximum storage life, heading types should be cooled within a day after harvest. Market life at 0°C will be 4 to 6 weeks.
Deterioration of cabbage is accelerated under non-refrigerated temperatures and is associated with discolouration of the stem end, leaf wilting, loss of fresh green colour, and postharvest decay. Storing cabbage at ambient temperature will require extensive trimming of the leaves to maintain a marketable head.
Relative Humidity Control
Cabbage is a leafy vegetable susceptible to significant moisture loss and wilting after harvest. The high surface area and numerous openings in the leaf surface (stomates) make an easy route for tissue water loss. In order to minimize the loss of crispness and wilting of the leaves it is very important to maintain a high relative humidity (RH) in the storage atmosphere. The optimal RH for cabbage is 95%. Pak choi can be stored at 0° C (32°F) for several weeks, as long as the relative humidity is greater than 85%.
Principal Postharvest Diseases
The most common postharvest decays of cabbage are bacterial soft rot, gray mould, dark leaf spot, Phytophthora rot, Rhizoctonia rot, and watery soft rot. Storage diseases can be controlled by preventing wounds during harvest and handling, trimming off the infected outer leaves, followed by storing the cabbage as close to 0°C (32°F) as possible. In addition, the use of clean seed and pre-harvest application of fungicides will reduce inoculum and lower the incidence of postharvest diseases. Effective fungicides include chlorothalonil (Daconil), iprodione (Rovral), and copper products.
Bacterial Soft Rot
Bacterial soft rot is caused by various bacterial species including Erwinia, Pseudomonas, and Xanthomonas. These bacteria are typically secondary disease pathogens that enter the tissue at the time of wounding or follow primary fungal invasions. Infected tissue quickly decays and
turns into a soft, slimy, foul-smelling mess at ambient temperatures. Care should be taken to avoid injury during harvest and handling. Cabbage should also be held at a cool temperature to minimize.
Bacterial soft rot decay of cabbage.
bacterial soft rot growth. Development of bacterial soft rot at the cut stem end can be
prevented by spraying with a 15% solution of alum (aluminum potassium sulfate) in
water (Figure 10). After treatment, the stem end should be allowed to dry for 20 to 30
minutes before packing. Application of lime powder to the stem end will also help
minimize the establishment of bacterial soft rot. http://pdf.usaid.gov/pdf_docs/Pnacy841.pdf
It is important to use containers that can be easily handled by one person. Rough handling of heavy packages results in damage to cabbage. (See figure 5) Packaging of cabbage may vary in packaging from wholesale to retail. The following may be used: One layer wooden or plastic crates, ventilated cardboard boxes, or perforated polythene bags
Cabbage has a very short post-harvest shelf-life, especially under ambient conditions. Under refrigeration of 0 o C (320F) and 98-100 relative humidity cabbage remain in good condition for up two weeks.
The appropriate type of transport for cabbage should help maintain the shelf life and value. Water losses by the produce should be restricted to a minimum. Suggested practices: Fig. 8: Refrigerated truck Fig. 7: Covered truck Vehicle should not stop under the sun and the produce should be protected with a cover. Cover the top boxes with tarpaulin to avoid sun damages and overheating the produce. Use refrigerated trucks where possible. http://www.fao.org/3/a-au100e.pdf
To market a crop successfully, producers must always be aware of the supply and demand, which vary with season and locality. Although per capita consumption of vegetables in the United States increased nearly 30 percent between 1980 and 1990, cabbage consumption apparently declined somewhat. In 1990, cabbage farm cash receipts were 18 percent lower than 1980 levels, and interstate shipments of cabbage to selected major markets were about 20 percent below 1980 levels. It is estimated that North Carolina cabbage production decreased 10 percent during that decade. California, Florida, and Texas remain the dominant cabbage supply areas, providing nearly 60 percent of the nation’s supply.
United States production and consumption of leafy greens have increased somewhat in recent years, and import competition has intensified. North Carolina collard and leafy greens production increased 40 percent between 1980 and 1990, with most production occurring in the eastern part of the state. Peak supply availability for greens usually occurs during the winter season, with California, Georgia, and Texas leading in production. To gain and retain a market for their crops, cabbage and greens producers need to reduce cost per unit and offer buyers improved quality by using proper postharvest practices, such as cooling and strict quality control. A market window may exist for summer marketing of cabbage grown in the mountains. Supply is smallest and grower prices are highest for cabbage and leafy greens during the summer months. A prudent grower always makes marketing and postharvest handling arrangements before planting. https://content.ces.ncsu.edu/postharvest-cooling-and-handling-of-cabbage-and-leafy-greens
Overview Global Market Cabbage
About 90 percent of the world’s cabbage is produced in Europe and Asia. In Northern Europe, there is a good market for cabbage. This situation is partly due to the growth of the convenience market. Cabbage is added to many of these products. While small cabbages thrive in these countries, Russian consumers actually have a preference for the large sizes. In the US, growers are facing problems with the cultivation that are delaying the supply and pushing prices up.
Cabbage market grows in Belgium
In Belgium, the popularity of white cabbage is on the rise. While this variety is already very common in the Netherlands, in Belgium it is still much lesser known. A grower stated they were unable to meet the high demand for this cabbage. He plans to have it available for 6 months. The red variety is even less known than the white, with some interest from the hospitality industry, but almost none from the market. In general, the Belgian cabbage market is recording a positive flow. The demand for cabbage is switching towards smaller sizes, weighing between 1.3 and 2.2 kilos. Thanks to ready-to-eat meals, the demand for cabbage has increased in recent years.
Russians demand large cabbages
Up until November, there is enough domestic cabbage available on the Russian market. Afterwards, Serbia comes to the market. A major importer explains that the market has been negatively affected by the boycott. The company says that they used to import from the Netherlands, Germany and Poland, three countries which have been cut off as trading partners by the boycott. There is some smuggling through Belarus, mainly of Polish cabbage, but the market for those products seems to be shrinking.
The Russian consumer has a preference for white, Chinese and red cabbage, with the white being the big favourite. There is a especially good demand for the large sizes. In general, there is little demand for the smaller sizes that do just fine in other parts of Europe. The market records a peak in the winter months, while in summer the demand is considerably reduced. Furthermore, the market is prone to price fluctuations and changes in the supply.
Germany: Cabbage remains popular
A trader explains that a large share of the cabbage they market is imported from Italy. Over the last two years, the demand for cabbage has increased. The product remains popular among German consumers, with the green, red and white varieties doing particularly well. According to a trader, this is due to the versatility of cabbage. Traditional vegetables such as cabbage and potatoes do well on the German market. A company explains that in the wake of the growing demand in recent years, their production has also expanded by 5%.
Portugal grows cabbage for export
Although Chinese cabbage is not a popular product among Portuguese consumers, a company managed to see the potential of the product on the Nordic markets. The grower currently produces cabbage in the winter months for the Nordic countries and the UK. This way, the country fills in the gaps in the seasons of the Nordic countries. The season runs from November to May. Last year, Portuguese growers had a good season. Several countries suffered problems with the quality and demand was good. The southern European country was almost alone on the market for over a month. The grower tested the cultivation of red Chinese cabbage, a product which they believe has a good potential. Portuguese consumers have a preference for more traditional types of cabbage.
Italy expects good harvest
The main growing areas are located in southern Italy. Lazio, Veneto and Emilia Romagna, are the largest cabbage producers. The cabbage supply is very diverse, ranging in colour from white to dark red. The season in Verona, Padua and Rovigo has started well for the 300 growers based there. The summer months were not too hot, so prospects point to a good harvest in the middle of this month. The acreage devoted to savoy cabbage is under pressure, with a 30% decrease already confirmed.
Due to the large supply of vegetables, the price on the market in Lusia was low in early October. The sudden drop in temperatures led to increased demand for cabbage in the Turin market. The sale of savoy cabbage has been doing well, with prices ranging between 0.40 and 0.45 Euro per kilo for cabbage from Piedmont and Veneto. A new trend is the growing popularity of kale in the market. This cabbage owes its growth to its status as a superfood.
Prices in France range from 50 to 75 cents per piece, depending on the variety and quality. Organic cabbage is much more expensive, with a price of between 3 and 4 Euro.
Market Specification: Cabbage must be hard, the head full and conveyed in appropriate containers. http://mofa.gov.gh/site/?page_id=14160
Cabbage is a difficult crop to grow because it is susceptible to many insects, diseases and pest. Ensuring a quality pack can be a problem for hand harvesters. Cabbage has to be harvested only at optimum maturity to meet potential buyer’s quality standards. The amount of profit made from cabbage crop depends on how well it meets market specifications. Cabbage crop quality is frequently measured using physical and sensory criteria. Rising consumer concerns about food safety have come to impact the assessment of cabbage crop quality. http://www.nda.agric.za/docs/AMCP/CabbageVCP2010-11.pdf