Brassica Growing Guide - Nickerson-Zwaan

Brassica
Growing Guide
www.nickerson-zwaan.com

Preface
Most professional growers of Brassica crops are familiar with the great
reputation of The Netherlands (Holland) when it comes to the breeding
of Brassica varieties that have created success throughout Europe and
in many other parts of the world. Nickerson-Zwaan has been involved
in breeding of this important crop right from the beginning. That was
some 50 years ago, in the North-Western part of Holland which was
the cradle of European Brassica growing and breeding. It still is today,
as Nickerson-Zwaan has continued to be a leading company for all
types of the Brassica family.
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Contents:
Nickerson-Zwaan, the Brassica company!
The foundation of our success in Brassica breeding has always been to be very close to the growers and learn directly from themselves
about their needs. Growers and processors are continuously experiencing new developments and requirements resulting from new trends in
the market that we closely follow. By listening to growers and to markets worldwide, we managed to become the important player in the
Brassica seed industry that we are nowadays. Collaboration is the way to success, and we are very much convinced that we can contribute
to your success by bringing you the best varieties backed up by excellent technical information, to which this guide offers you an entry.
In this guide you will find detailed explanations on all the main aspects of Brassica cultivation. It will help you in a practical way to get
the best out of our high quality seeds, be it white or red cabbage, savoy cabbage, cauliflower, broccoli or Brussels sprouts. Of course local
Nickerson-Zwaan specialists will be happy to provide all necessary further advice whenever you wish. Because we just want to be your
preferred partner in the Brassica business!
For further information about the Nickerson-Zwaan company and the complete product range, please visit www.nickerson-zwaan.com,
or ask our latest product documentation by e-mailing to communications@nickerson-zwaan.com
The Nickerson-Zwaan Group, with its head office in Made (in the South of The Netherlands), is a highly experienced international
organisation dedicated to developing improved varieties of vegetable crops and producing, processing, marketing and selling a broad
range of vegetable seeds. Its products and services are the basis for the business activities of professional growers and plant raisers all
over the world. Nickerson-Zwaan’s activities are entirely dedicated to the professional market. We invest heavily in the development
of new vegetable varieties. These investments have already led to the development of leading varieties in our key crops cabbage,
cauliflower, onion, leek, radish, cucumber and Brussels sprouts. Nickerson-Zwaan’s business unit employs circa 620 staff; the work
environment is result-focused, flexible and informal.
The company is part of the Limagrain Group (France), an international cooperative agriculture enterprise specialised in field seeds, vegetable
seeds and cereal products. Limagrain, founded and managed by farmers, is the biggest seed company in Europe and number 4 worldwide.
1. Introduction 06
2. Field choice 10
3. Soil Preparation 14
4. Sowing and planting 16
5. Irrigation 20
6. Fertilizing 22
7. Weed Control 26
8. Pests and diseases 28
9. Physiological disorders 34
10. Harvesting 40
11. Storage 42
12. Finished product 44
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The Brassica oleracea originates from Southern Europe. People first ate the separate leaves of the wild species. About 500 years before
Christ, species similar to curly kale were developed by selection. Through the course of time plants with a wreath of young leaves in the
top became much preferred. 100 years after Christ the predecessor of our current headed cabbages derived from this. We know the actual
headed cabbages as the red, white, savoy or more recently cabbage. The next map shows the origin of different cabbage species.
1. Introduction
Brassicas belong to the most consumed vegetables worldwide.
The brassica species being consumed belong to the cruciferea family.
The Asian species, like Chinese cabbage for instance, are primarily
part of the Brassica rapa. In the western world we know the Brassica
oleracea in particular, to which belong headed cabbage, cauliflower,
broccoli and sprouts.
People later discovered that the soft buds of cabbage are also quite tasty; this is the way cauliflower entered our menu. The next discovery
took place in Italy: broccoli, of which the edible part is also the “flower screen”.
This genus’ youngest section is the sprout: this plant with lots of mini cabbages is first mentioned in 1696 when it is grown around Brussels
in Belgium. That is why this cabbage is called “Brussels Sprouts” in English.
A recent selection from early white headed cabbage is pointed cabbage, pointed cabbage is characterised by a very sweet taste and soft
leaves; hence becoming more and more popular. All these varieties are family originating from the brassica Olearacea.
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Brassica
Oleracea
Capitata
Headed cabbage
Gemnifera
Brussels sprout
Botrytis
Cauliflower
Italica
Broccoli
Rubra
Red Cabbage
Alba
White cabbage
Sabauda
Savoy Cabbage
Conica
Pointed cabbage
Current situation
Brassica plants originally grew easiest under moderate circumstances. Thanks to age-long selection, all over the world strains can be found
that have adapted to the specific local circumstances.
Because of the sheer variety in colour, leaf type, shape and taste within this group of plants, this vegetable easily finds its way to
consumers on all continents.
We do see big differences in the spread of the separate plants throughout the world. We tend to see the red cabbage and sprouts more in
Europe and Northern America. White cabbage and cauliflower are spread over all parts of the world, but there are big differences in shape,
use and growing conditions. Pointed cabbage and Savoy cabbage are mostly used in Western and Southern Europe.
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2.1 Particle size
The particle size determines the suitability of the soil for different crops. Sandy soils are generally being used to grow early crops which are
not stored. The fast growth renders the product unfit for storage. Heavier soils are more suitable for storage cabbage. The gradual growth
of the crop on these soils raises the dry matter content in the product and improves storability. The dry matter content in early cabbage is
generally four percent while the dry matter content of storage cabbage can go up to around eight percent.
The drainage of water is important in the field choice. The drainage on heavier soils can be a problem when there is a lot of rain. Drains are
used to improve this. The distance between the drain pipes and the depth of the pipes depends on the soil type and the drain ditch. Heavy
soils require a higher density of drains.
2.2 Organic matter
2. Field choice
Organic matter is an important addition to the soil. The presence of this matter improves the structure, soil life and prevents the leaching of
fertilizers and minerals. In sandy soils, organic matter acts as a buffer, the matter absorbs water and fertilizers. Organic matter can absorb
twenty times its own weight. This buffer makes the soils less vulnerable to droughts. The soil should at least have the organic matter
available as shown in the next table.
Soil type Percentage organic matter
Sand 4%
Peat 10 %
Clay
Depends on the calcium level of the soil, calcium improves
the growth of roots, roots improve the structure
In heavier soils organic matter improves the soil life. Worms and micro organisms feed on the organic matter. This soil life has a positive
effect on the structure of the soil.
The average decrease in organic matter is 2% per year. To keep the organic matter on the same level this has to be replenished. The growth
of cabbage brings around 1300 kilo organic matter per hectare back into the soil. Extra organic matter can be brought back into the soil by
growing green manure. For example perennial ryegrass increases the organic matter with 1100 kilo per hectare. Other crops that are used
for rotation are clovers, they have the added advantage that they also increase the nitrogen level of the soil.
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2.3 pH
pH is a very important characteristic of the soil, it determines the susceptibility to club root and the ability of the plant to absorb
minerals. The following table is showing the range of pH values for different soil types. It gives a general idea about the acidity
of the soil. To have the exact figure, the soil needs to be tested.
Soil tye pH High pH Low
Sand 6,8 4
Sand/loam 8 5
Clay 8,1 5,5
Clubroot is a soil disease, which cannot be controlled with
chemicals. Clubroot affects the roots of brassicas, the roots will
swell up. The plant will hang limp in a later stadium. To limit the
damage of clubroot, the PH should be around seven. When the pH
is lower the risk of clubroot root increases. Prevention is partly
possible by using Calcium Cyanamid, this fertilizer stimulates the
growth of the root system.
2.4 Rotation
For Brassica it is advised to use a field only once every three years. If there is no possibility of rotation the risks of diseases like clubroot,
Xanthomonas, Sclerotinia, Rhizoctonia, Fusarium and Verticilium will rise. Good preceding crops for brassicas are onions and potatoes.
For rotation it is important that the preceding crop is not a crucifer, these crops are all related to cabbage. Make sure that the green
manure in the rotation is not a crucifer.
As stated in the preceding paragraph, green manure can also be included in the rotation. Benefits of green manure are:
• Improvement of the structure
• Increase of the nitrogen level
• Increase of the organic matter level
The green manures are generally legumes (clovers) or grasses. The advantage of clovers is that they fix nitrogen from the air into plant, this
way the nitrogen level of the soil improves. Clovers are also deep rooting and improve the structure of the soil. Grasses are used to enlarge
the organic matter level of the soil and improve the structure. These characteristics make green manure a very valuable addition.
Another effect of pH is the ability of the plant to absorb minerals.
The ideal pH for the absorption of minerals is between 5,5 and 6,5.
The next figure shows which minerals are affected by the pH.
Clubroot
PH above 6.5. The plant
gradually stops to absorb
Iron, Manganese, Zinc and
Copper
PH below 5.5. The plant
gradually stops to absorb
Phosphorous, Potassium,
Sulfur, Calcium, Magnesium
and Molybdenum
When you combine the two last characteristics, Clubroot and absorption of minerals, the ideal PH for growing cabbage is 7.
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3.1 Main preparation
For the main preparation of the soil two techniques are being used. Those techniques are ploughing and the use of a bed lifter. Ploughing is a
good main preparation, it turns the soil. The benefits are that weeds and the remains of the old harvest are being removed. The downside of
ploughing is that after years of consecutive ploughing you will create an impenetrable layer in the soil, this layer is called a pan. A pan can
prevent water sinking through the soil and makes the crop more vulnerable to flooding.
To prevent this a sub soiler can be used. The sub soiler digs through the layer and improves the structure of the soil. These two methods are
commonly used for the main preparation.
Loamy soils are usually ploughed before winter. The cold of the winter will weather the soil and improve the structure, the soil will crumble
more easily in spring. The main tillage for sandy soils is usually in spring, since the soil is easier to manage than clay soils.
3. Soil Preparation
3.2 Plant bed preparation
For the uniformity of the product it is important to have a shallow and flat plant bed preparation. The rotor harrow is a good option for this
preparation. It is important that the plant bed preparation is not being performed under wet conditions. Under these conditions the
structure will deteriorate.
In a lot of areas in the world plant beds are being used. The use of plant beds to make it possible to apply drip irrigation, our put tunnels
over the planted crops. The field preparation stays the same.
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4.1 Direct sowing
The advantage of direct sowing is that the cabbage will develop a better root system, and the method is cheaper than transplanting
cabbage. There are also a number of disadvantages. The uniformity of germination of the seeds is uncertain, the field needs more irrigation,
the weed control is more difficult and if there are too many seeds shooting, the field needs to be thinned.
Direct sowing is used for processing cabbage. The sowing distances are:
• 20 x 60
• 20 x 75
• 12.5 x 75
4. Sowing
Generally speaking, there are two different methods for growing
cabbage. These methods are transplanting and direct sowing. The young
plants used for transplanting can be grown by a plant raiser or by the
cabbage grower.
If there are too many plants shooting, the field needs to be thinned. Sowing usually starts at the end of March. The sowing distance
depends on the desired outcome, more distance generally means bigger heads.
4.2 Planting bare roots
Planting bare roots essentially means that the grower raises his own
plants. The advantage over direct sowing is that the plants are more
uniform. The seeds are sown in lines, the distance between the lines
is 30 centimeter while the distance in the row is 1,5 centimeter.
Bare root plants are being sown in April and planted in May or June.
The plants need to be selected and picked before they are ready for
planting. The techniques used for planting bare roots are slower
than planting modules raised by professional plant raisers. Another
disadvantage is, that the bare root plants cannot be used for the
early cabbages, because of the sowing date.
4.3 Transplanting
Transplanting, from trays or peat blocks, has the advantages that
the plantings are very uniform, that early planting is possible,
and that there is no thinning. Transplanted cabbage will have a
clear advantage in comparison with weeds. The plants used for
transplanting are being grown by professional plant raisers. For
this purpose precision seed is recommended, because of the high
germination and usable plant count. The precision seeds can also be
coated with fungicide or insecticide depending on the conditions.
Coatings can also be used for direct sowing.
For transplanting two different systems can be used. Peat blocks are being
used for the early transplanting. The plants are grown in a greenhouse
during the winter in mini trays. The seedlings are then inserted into soil
blocks. After the plants are hardened outside they are ready for transplanting.
This technique makes it possible to transplant earlier. In Western
Europe the first sowing is in October, in a greenhouse. The plants are
then ready for transplanting in March. Not all varieties are suitable for
this method. Some varieties have an elevated risk for heartless plants in
this period. During the winter period the plants are also grown in heated
green houses. The risk of blind plants is lower using this method.
The cold temperatures at the start of the season can cause the crop
to bolt. So the variety used for early cropping should have a good
bolting resistance.
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In spring and summer the seeds are directly sown in trays. The
plants are ready for transplanting between four and six weeks.
The advantage of the modules is that the pots are not as firmly
pressed as the peat blocks. The young plant will grow more easily.
The plants can also be planted on beds. This method is generally
used in areas where drips are necessary. Using beds is also effective
in areas with heavy rain falls, because elevated beds improve the
drainage. Another advantage of growing cabbage on beds is that
the structure of the soil will stay intact.
4.5 Planting under cover
The earlier crops can be advanced by covering them with fleece. The cover can accelerate the start of the harvest by at least one week and
it protects the cabbages against frost. Although an investment in time and money is necessary to cover the crops, growers are still happy to
do it because prices are generally better at the start of the season.
Very early cabbage varieties are being grown in tunnels. This method has a couple of advantages. The first advantage is to be ahead of the
cycle of pests and diseases. The second advantage of earlier cropping is that prices of products can be a lot higher early in the season.
4.4 Plant distance
The following table shows the densities that are being used
for the different brassica types, and the desired head size.
Trayplants
Transplanted field
Acryl cover
Tunnel production in Uzbekistan
Crop Density Distance Desired head size
Headed
cabbage
100.000 Early white cabbage 25 x 50 cm 1 kg.
55.000 Early white cabbage 35 x 50 cm 1,5 - 2,5 kg.
55.000 Storage 35 x 50 cm 1 – 2 kg.
45.000 Storage 40 x 50 cm 2,5 - 3 kg.
22.000 Processing 55 x 75 cm 5 – 7 kg.
Broccoli 40.000 - 60.000 45/50 x 50 cm 300 gr. – 500 gr.
Cauliflower 25.000 - 30.000 60 x 60 cm Fresh market big heads. (6 in a box)
35.000 - 45.000 40 x 60 cm Fresh market small heads. (8 in a box)
Brussels
sprouts
30.000 - 40.000 33/44 x 75 cm Depending on earliness, earlier varieties are planted more
widely.
The relation between planting distance and plants per hectare can be found in the appendix.
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The following table shows an estimate of the demand for water for the different crops on different soil types. This is during the period the
cabbage is forming a head. If the available water reaches the levels stated in the table a water gift of approximately 20 mm is necessary.
This is an estimate for Dutch conditions.
Crops
Percentage of
absorbable water
Sand
Sandy loam
Headed Cabbage 80% 75%
Broccoli 65% 40%
Cauliflower 65% 40%
Brussels sprouts 60% 50%
5. Irrigation
The availability of water is important during two periods during growth.
The first period is right after planting. When the cabbage is transplanted
it needs water to make a good start. It is advisable to bring the top 30
centimeter of the soil up to full capacity. The amount of water needed
depends on the soil and the availability of water. When the crop starts to
make a head, the demand for water rises too. During these periods the
plant needs to have enough water at its disposal.
There are different ways to irrigate the crop. The following table shows the methods and their advantages and disadvantages.
Method Advantages Disadvantages
Sprinklers The best system for small and medium fields Takes a long time to set up
Irrigation of the whole field at the same time Must be removed before harvest
Sprinkler can cool down the soil
The wind can prevent complete irrigation of the field
Rain gun Easy to set up Difficult to use small water quantities
Movable
Limited area
Pivot Large irrigated area High investment
Uniform irrigation
Drip Saves water Needs a high technical level
Can be used to apply fertilizers
Requires more labour
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6.1 Application of fertilizers
A common method of fertilizing is a fertilizer spreading device, a machine that dispenses the fertilizer in small pellets. This method is used
after the main tillage. When the plant bed is prepared the fertilizer is already in place.
Another method is the application of liquid fertilizers. This can be done by drips or by a fertilizer attachment on the planting machine.
The advantage of drips is that the fertilizer is directly applied to the right spot, the dose is very precise. The disadvantage is the initial
investment needed to apply this method. Drips are used in areas where water is scarce. The advantage of the fertilizer attachment on the
planting machine is that the grower can do all the preparations in each pass.
The third method is applying the fertilizer with a sprayer. This is a good way to apply extra magnesium, a good option for additional
fertilizing, but not for the main application.
6. Fertilizing
An important part of growing cabbage is the application of fertilizers.
Fertilizers are an important addition to help the plant develop. The
quantity that needs to be applied, depends on the soils and the amount
of minerals that is already available in the soil.
6.2 Nitrogen
A soil analysis must be done to check the need for nitrogen. Excessive use of nitrogen has a bad influence on the environment and can
make the plant more vulnerable to diseases. The following table shows the average nitrogen dispensing in The Netherlands.
Crop
Kg. N/Ha.
Headed cabbage 300
Brussels sprouts 350
Broccoli/Cauliflower 300
Nitrogen is important to maximize the yield of the crops. Fast growing types of cabbage like cauliflower and broccoli require a high level of
nitrogen in the early stages. Slower growing crops like storage cabbage have a more gradual intake of Nitrogen.
Fertilizing can also limit the risk of clubroot. Calcium cyanamide which combines Calcium and Nitrogen. The calcium will improve the
development of the root system and increase the pH, as a result the pressure of clubroot is decreased.
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The importance of Nitrogen is illustrated by the following example:
6.4 Potassium
Brussels sprouts are a particularly difficult
crop to fertilize. The amount of nitrogen
depends on the soil condition and the growth
stage of the crop. This is why the fertilizing
is done in portions. The time and amount of
fertilizer depends on the variety. Earlier type
of Brussels sprouts tend to be a bit short, with
an early forming of sprouts on the stem. These
varieties need a considerable basis Nitrogen
gift and small additional application. The basis
Nitrogen application is around 200 kg. and
the additional application is around 70 kg.
The amount of fertilizer for the later varieties
really depends on the variety. It is important
that the plant has enough Nitrogen for a
continuous growing cycle.
The Potassium requirements of brassicas are quite high. Potassium is needed during the complete growth cycle, so it has a big effect on the
yield. Potassium is vital for transport of all the elements in the plant. If there is a shortage of potassium the evaporation will decline and
cause tip burn. The following table shows the average Potassium dispensing in The Netherlands.
Crop
Headed cabbage 250
Brussels sprouts 100-350
Broccoli/Cauliflower 200
6.5 Magnesium
Kg. Potassium / Ha.
Brassicas do not require high amounts of Magnesium, The uptake of brassica is between 25 – 50kg. per hectare. The availability of
magnesium depends on the pH of the soil, if the pH is lower than 6,5 the plant loses the ability to extract Magnesium from the soil. The
amount of Potassium in the soil has an effect on Magnesium. Magnesium and Potassium are opposites, if there is a high level of Potassium
in the soil the level of Magnesium will automatically drop. The mineral is important for the leaf growth. If there is not enough Magnesium
available, leaves will start to turn yellow. This can be restored by additional fertilizing. Spraying the leaves with magnesium salt will clear
up the deficiency symptoms.
6.6 Boron
6.3 Phosphorus
Phosphorus is important for the root development of the brassicas, so it is important in the early stages of growth. This is why Phosphorus
is usually applied in the planting bed before planting. The following table shows the average Phosphorus dispensing in The Netherlands.
Crop
Headed cabbage 80
Kg. Phosphorus / Ha.
Boron is a trace element that is important for the development of the plant. If there is not enough available, deficiency disorders will occur.
These disorders are hollow stems in broccolis and headed cabbages. browning and rotting core in headed cabbages. These symptoms
cannot be restored before harvest. It is only possible to prevent the disorder for the next harvest. This means it is important to have a good
boron level before planting.
6.7 Molybdenum
Insufficient availability of Molybdenum will cause deficiency symptoms. Especially cauliflower is susceptible to Molybdenum deficiency.
The foliage will develop whip tailing with a prominent main vein. Molybdenum deficiency cannot be corrected by additional fertilizing.
The grower can only improve the molybdenum level to make sure the next harvest is not affected by this deficiency.
Brussels sprouts 140
Broccoli/Cauliflower 80
A phosphorous deficiency can cause problems in Brussels Sprouts. The head of the plant will be affected by tip burn.
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7.1 Mechanical
Weed control is important because weeds compete with the plant for water, light and minerals. Weeds can also be carriers for pests and
diseases. Mechanical control can be done by cutting the weeds. There are machines available which can cut weeds between the rows.
Another method being used is hoeing. Hoeing is done by hand, it is more precise, but requires a lot of labor, so it is a more costly method.
7. Weed control
There are two techniques to control weeds. The use of herbicides and
mechanical control. The use of herbicides depends on the legislation
in different countries. That is why the active ingredients will not be
discussed.
Mechanical control can be done by hand or machine. The use of machine
is a more cost efficient method but requires a steep investment.
7.2 Chemical
Another method that is commonly used is spraying herbicides. This method is the cheapest and most efficient way to get rid of
unwanted weeds. The downside of herbicides is that some types of weeds cannot be removed, because they are not susceptible to the
active ingredient. These weeds still need to be removed by hand.
Herbicide is sprayed before the tillage of the soil, to make sure the soil is clean. This way the plant can have a good start and get the
advantage over weeds. If the weed pressure is high, some types of herbicides can be sprayed over the crop, a week after planting.
Before herbicides are sprayed over the crop, the plants have to be hardened, get used to outside conditions, to limit negative effects
on the cabbage.
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8.1 Pests
The first pest discussed in this growing guide is the cabbage root
fly or Delia radicum. The fly, 4 to 7 seven millimeter, will lay around
30 eggs close to the main stem of the brassica plant. The maggots
coming from these eggs feed off the lower parts of the plant.
Every year three generations can be active. The damage can be
extreme in dry periods, since the maggots will hinder the plant from
developing roots.
8. Pests and diseases
Pests and diseases are a big threat in the cultivation of brassicas.
The most commonly found pests and diseases will be explained in
this chapter.
A plant affected in a young stage will stay weak wilt and eventually die.
The damage of the maggots can be observed at the base of the stem.
If the plant is affected at a later stage the plant will remain smaller.
Prevention is the best option to limit damage from this insect. This
can be done by using coated seeds our a chemical treatment for
young plants.
Thrips, Thrips tabaci or Thrips angusticeps is another insect
affecting brassicas. Thrips survives the winter in the soil, this ability
makes crop rotation very important to prevent this disease. The first
generation of this pest will spread in spring as the winged insects
fly out. The insects feed themselves with the plant juice of the crop,
they prick the cells to get the plant juice. These pricks develop into
small silvery spots on the cabbage called oedema.
The damage on the plant is mainly cosmetic, but it takes time to
make the cabbage marketable again. If the plant is really damaged
Thrips will make the product unfit for the market.
Cabbage root fly
The small size of Thrips (1 milimeter) make the insect hard to
control with chemicals. The insects fit between the wrapper leaves
of the cabbage.
The pressure of Thrips can be reduced by a good crop rotation, and
the use of more resistant varieties.
Thrips
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The Diamond back moth, Plutella xylostella, is the most destructive
caterpillar in brassicas. The caterpillar comes from a yellow egg which
can be found underneath the leaves. The light green larvae coming
from this egg, eat all upper parts of the brassica, leaves and growth
points. The larvae will form a cocoon from which the moth emerges.
The caterpillar feeds on the above ground parts of the plant and
can leave massive damage. The main damage is done to the leaves,
but also growth points are attacked.
8.2 Diseases
Fusarium, Fusarium oxysporum f.sp. conglutinans, is a fungus that
damages brassicas. Spores of this fungus can survive in the soil for
several years, but they need a soil temperature of around 18°C to
become active. This explains why Fusarium can only be found in the
more hot regions of the world. The fungus enters the plant through
the roots and enters the vascular system. In the vascular system the
fungus obstructs the correct transport of elements.
There are no resistant varieties available. Insecticides provide
the only treatment against this pest, but are not always efficient
enough. It is very important to prevent the adults will lay their eggs.
Diamond back moth
Fusarium only shows in spots in the field, the symptoms are
yellowing leaves, on one side of the leaf and the stunting of growth.
In the worst case the plant will die. Fusarium can be spotted by a
brown discoloration in the plant stem.
Aphids, Brevicoryne brassicae, are small grayish insects They survive
the winter as eggs on crucifers. In the spring they will start to form
the first generations. The first generations are wingless, the winged
generations will appear and will start laying eggs to survive winter.
Aphids are about 2 millimeters long and look grayish. They can
reproduce very quickly and form colonies at the bottom of the plant.
The leaves covered by a colony will look rough and curly and will be
stained with white and purple spots. This pest can be controlled with
pesticides and coated seeds give the plant protection against aphids.
Aphids
There is no chemical method to protect the plant against Fusarium.
The best protection is the use of resistant varieties.
Spores of Mycosphaerella (ringspot), Mycosphaerella Brassicicola,
can survive in the soil and debris and can spread by wind, water and
soil. The ideal conditions for this disease are temperatures between
15°C- 21°C and high humidity (90%).
The first signs of this disease are lesions on the lower leaves, small
black spots that can be seen on both sides of the leaf. The lesions
will get bigger, turn brownish and will be surrounded by a yellowish
ring. The spots cannot be found in the middle of the leaves. There
are no resistant varieties available, but there are big differences in
susceptibility between varieties. A good crop rotation helps minimizing
the risk. This fungus can be controlled with chemicals.
Fusarium
The life cycle of the white fly, Trialeurodes vaporium/ Bemis Tabaci,
starts as an egg. From this egg a larva emerges, which sucks the sap
of the plant. This larva will form a pupa, after this stage the fly will
appear. The eggs can usually be found on the younger leaves of the
bottom of the plant, this is also the place where the larvae will feed.
The fly sucks the sap out of plant cells, this will lead to malformation
of the plant. A side effect of white fly damage is fungus
forming on the honeydew discharged on the plant. White flies live
together in large groups and can completely destroy a plant.
To prevent damage caused by white fly, make sure you start a new
cycle with a clean plot. White flies survive on debris from old harvests
or weed. Pesticides are also an effective tool to reduce the pressure.
White fly
Alternaria (black leaf spot), Alternaria Brassicicola, survives in the
soil and plant debris. It is spread by seed, wind, water and soil. The
fungus favors warm (20°C- 25°C) and humid conditions.
The disease starts off with many black spots on the leaf, stem and
head of the cabbage. When the infection level rises the head will
rot and the leaves will have gunshot like holes. Seeds can also be
contaminated with this disease, affected seedlings will die.
Crop rotation is an important method to prevent this disease from
spreading, since the fungus survives on the soil and in plant debris.
Seed disinfection and coated seeds can give the growth a good start.
Mycosphaerella
Alternaria
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Another common disease in brassica is clubroot, Plasmodiophora
brassicae. Clubroot is a soil borne fungus that affects the roots. The
fungus enters the roothairs and causes a malformation of the roots.
The affected roots will swell up and lose their function. The loss of
these functions will cause the plant to turn pale green and wilt.
The fungus mainly occurs in wet and acid soils, higher PH, caused
by liming the soil, will reduce the risk of clubroot. The ideal
temperature for this fungus to develop is between 13°C to 25°C.
The spores are spread by soil and water.
The symptoms of Xanthomonas (Black rot), Xanthomonas
campestris pv. campestris, start with yellow to brown v- shaped
spots, these infected parts will die at a later stage. The bacteria can
easily migrate into plant through the veins and infect other parts
of the plant. The veins will turn black, the inside of the veins will
reveal black spots. The plant will very often start to rot after being
affected by black rot.
Black rot thrives under hot (>25 °C ) and humid conditions. The
disease can be seed born or transmitted by crop residu, water,
contact with infected plants and machinery. The infection occurs
through wounds and natural openings of the plant (stomates).
Clubroot
White blister, Albugo candida, is an elevated blister on the lower
side of the leaves. The blister ruptures the superficial layer of the
cells and shows chalky white dust in a circular form. Infected areas
may become swollen and distorted.
The oomycete migrates by wind, rain, insects and human handling
of plants. The optimal temperature is between 10°C and 25°C. The
spores need moisture to infect the plant. Dry and warm weather
slows the disease down. The oomycete overwinters in living plants.
There are no resistant varieties available at the moment, but there
is a difference in susceptibility. Chemical control is possible with the
use of fungicides. Crop rotation is important, that means that it is
also important to control susceptible weeds.
Verticillium, Verticilium dahliae/Verticillium longisporum, is a
disease that is connected with a lack of crop rotation. Continuous
cropping will cause the fungus to build up. The fungus develops
under cool conditions (15-19ºC). Symptoms are V- shaped lesions
formed along leaf margins of lower leafs. A particular symptom for
this disease is that only one side of the leaf can be discolored.
A dark brown discoloration of the vascular tissue is another
symptom used to identify verticillium. Cauliflower and Chinese
cabbage are most susceptible to verticillium.
White blister
There are no resistant varieties available, but there is a big
difference in susceptibility between varieties. A clean start with
non contaminated seeds is very important. There is no chemical
treatment of Xanthomonas, the effective method is preventive
treatment with copper. Crop rotation of at least four years is also
preferred to avoid this disease. Avoid any contact with infected
plants and make sure the plants do not stay humid for long periods.
Remove cruciferous weeds that host the bacteria.
The next disease discussed is a fungus, Downy mildew,
Hyaloperonospora parasitica. This mould favors a moderate climate,
temperatures between 8°C and 16°C at night and day temperatures
below 23ºC are the optimal conditions for this disease. Spores can
also enter the vascular system, resulting in systemic damage.
The first symptoms of this disease can be seen when the bottom/low
side of the leaves of young plants turn white gray. The upper parts
of the leaves show yellow, purple to brown spots corresponding to
the spores on the bottom of the leaves. The curds of cauliflower,
white cabbage and broccoli can also be attacked, with internal
rotting as consequence.
Seed coated with fungicide provides a good protection during the
young stage of the plant. There are no resistant varieties available,
but there is a big difference in susceptibility between varieties.
Chemical treatment is available but prevention is the best option.
Prevent the disease from spreading by performing a good crop
rotation, keep the humidity level low, destroy infected fields after
harvest and control weeds around the field.
Xanthomonas
Downy mildew
The last disease reviewed in this growing guide is Sclerotinia,
Sclerotinia sclerotorium. Like a lot of the other fungus Sclerotinia
survives in the soil. The ideal conditions for this disease are moist
weather with temperatures between 10°C and 25°C. The spores are
spread by the wind, these spores require nutrients to infect the
cabbage. Weeds usually serve as nutrient for the spores. If these
infected weeds come into contact with brassica the disease spreads.
The infection starts at the base of the stem, and spreads down
decaying the roots, and up killing the leaves. Characteristic for this
fungus are a white cottony growth and black seed sized bodies,
called sclerotia. This infection also causes losses in storage.
It is important to keep the weeds under control, since they act as a
nutrient base for Sclerotinia. A long rotation can also prevent the
disease from spreading. Fungicide can also reduce the pressure of
this disease.
Verticillium
Sclerotinia
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9.1 Headed cabbage
The physiological disorders found in headed cabbages are tipburn,
black petiole (internal black), bolting and side shoots.
Tip burn is caused by a shortage of calcium. It causes the edges of
leaves to turn brown. When the air humidity is high the plant will
start to transpire, this transpiration disturbs the internal transport
and causes the calcium deficiency. The susceptibility to tip burn
differs between varieties. In headed cabbage it can be found
externally and internally. Tip burn affects headed cabbage close
to maturity that is not well suited for hot conditions.
Bolting
9. Physiological disorders
These disorders are a factor that should be taken into account.
There is a difference in susceptibillity to physiological disorders between
varieties, depending on the abillity to cope with different conditions.
These disorders determine for an important part if the variety is suitable
for a climate.
Red cabbage can have a physiological disorder similar to tip burn.
This disorder is called tobacco leaf. When the cabbage grows too
fast, internal leaves will crack, the separated part of the leaf then
turns brown. The susceptibility to this disorder depends on the
variety.
Bolting affects the early cultivation of the headed cabbage. If the
night temperature is low in spring, the cabbage will start to bolt.
The plant is already flowering. This disorder mainly affects early
varieties. Some early varieties are resistant against bolting.
Black Petiole (internal black) is believed to be caused by a
potassium and phosphorous imbalance. It especially occurs when
the potassium level is high and the phosphorous level is low.
When the cabbage is being stored the internal blackening becomes
more evident.
Internal black usually occurs when the growth of the cabbage was
irregular. This normally happens on lighter soils, which is one of the
reasons storage cabbage is grown on heavier soils.
Tobacco leaf in red cabbage
Black Petiole
Side shoots occur when the crop is raised during (heat) stress
conditions. Instead of using the available energy to form one big
head, the plant starts to form a series of smaller heads on the stem.
Varieties that are grown in the wrong conditions are susceptible
to this disorder. For example a non heat tolerant variety in hot
conditions.
Side shoots in white cabbage
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9.2 Broccoli
9.3 Cauliflower
Broccoli is affected by bolting, just like the headed cabbages. It has
the same symptoms and causes. Another physiological disorder that
is being found in broccoli is hollow stem. Hollow stem is a disorder
that is linked to a boron deficiency. If the plant grows very fast, and
there is not enough boron available, the cells will lack elasticity and
break, thus forming a hollow stem.
Side shoots are a physiological disorder that also affects broccoli.
It is caused by heat stress. If a non heat tolerant variety is grown
in hot conditions, the plant will start to form smaller heads on the
stem. These heads consume valuable energy, that is not being
delivered to the main head. For some markets side shoots are
considered to be a good thing. After the harvest of the main head,
the side shoots will be harvested.
Hollow stem broccoli
The physiological disorders found in cauliflower are bolting,
tip burn, hollow stem, hairiness, riciness and pinking.
Tip burn in cauliflower is caused by a lack of calcium, it has the
same cause and symptoms as tip burn in the headed cabbages.
Hollow stem is a disorder caused by boron deficiency. These three
disorders are similar to the disorders in broccoli and headed
cabbages.
Tip burn
Bracting is when covering leaves grow through the curd. The head is
not smooth anymore because of the bracting. It is caused by growth
under stressful conditions, such as lack of water and excessive heat.
The susceptibility to bracting depends on the variety, some varieties
are more vulnerable than others.
Another physiological disorder is purpling. Purpling is caused by
exposure to sunlight, and can be prevented by covering the crop.
The susceptibility to purpling depends on the variety. The purpling
can occur externally and internally.
Another physiological disorder are the heartless plants. This
phenomenon is caused by damage to the growing point, during the
early stage of growth. Especially early cultivations of broccoli are
vulnerable when the temperature drops below eight degrees, the
first heart leaves will be damaged. This can also be caused by a
molybdenum deficiency and the cabbage midge.
The last physiological disorder in broccolis are cat eyes. Cat eyes are
the premature opening of the flower buds, forming a small yellow
flower. The susceptibility to this condition depends on the variety.
Side shoots broccoli
Purpling cauliflower
Doubling is caused by interrupted growth and development.
The interruption is caused by an irregular availability of nitrogen,
causing vigorous growth. The risk of this happening is higher at
high densities. The susceptibility depends on the variety.
Cat eyes
Doubling cauliflower
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Hairiness is a vegative disorder, caused by high temperatures.
Small leaves (1-5 mm) will grow through the curd. This will happen
under hot conditions. The susceptibility depends on the variety.
9.4 Brussels sprouts
Bolting affects Brussels sprouts just like the other cabbage varieties.
Riciness is a generative symptom, caused by fast induction of the
curd. The fast induction is caused by big temperature differences
between day and night. This disorder usually occurs in spring.
Hairiness on cauliflower
One of the disorders in Brussels sprouts is lodging. Lodging happens
when the sprout grows too fast in the earlier stadiums of growth.
The stem will grow long and thin, and when the sprouts start to
grow on the stem it will lodge. This will make it difficult to harvest
and the grower will lose yield. Lodging can be prevented by growing
varieties with good resistance and a good fertilizing regime. It is
important that the Brussels sprout grows gradually. To achieve this
the grower needs to know the characteristics of the soil and the
effect of the fertilizer.
Under difficult conditions, the plant can form a big head. This head
looks like a small cabbage and will absorb a lot of energy from the
plant, energy that is not going to the sprouts on the stem.
This disorder affects the yield of the crop, only when the variety
is susceptible.
Lodging
Riciness on cauliflower
Bracting is an extreme form of hairiness. Covering leaves will grow
through the curd. The disorder is caused by difficult conditions.
Mostly excessive heat, and drought.
Bracting in cauliflower
Big head
Bolting brussels sprouts
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10.1 Manual harvest
Manual harvest is mainly chosen for the harvest of storage cabbage and crops that cannot be harvested in one time. During the harvest the
cabbage is cut by hand. The product is then transported by a conveyor to a wagon. Here the cabbage will be packed or prepared for storage.
Harvesting needs to be done by hand because the product is very fragile. Even a little damage can reduce the storability of the cabbage.
This is especially valid for white cabbage which can sometimes be stored for six months. Products like broccoli and cauliflower for fresh market
are also vulnerable and need to be cut by hand.
Developments in mechanization are changing the harvest of all the agricultural products. At this moment a machine has been designed for
harvesting broccoli. The only difficulty is in the crop: for mechanical
harvest 90% of the broccoli needs to be ready for harvest. At this
moment no variety has this uniformity in maturity.
10. Harvesting
10.2 Mechanical harvest
Mechanical harvest is used for the harvest of industry cabbage,
cauliflower for deep freezing and Brussels sprouts. The mechanical
harvest of broccoli is still in development.
For example in Brussels sprouts it is important that the varieties
used for mechanical harvesting have a cylindrical build. In case of
Brussels sprouts this means that the sprouts on the stem ideally all
have the same size. Lodging is another important issue. If the stem
is lodging, mechanical harvest is very hard. After harvest the sprouts
are sorted and stored in cool store.
Brussels sprouts mechanical harvest
The harvesting of industry cabbage (sauerkraut) is also usually done
by a machine. For this method of harvesting it is important that the
cabbage has a high stem and is not lodging. This product is not stored
but directly cut up and fermentated. It is not a problem if this cabbage
is damaged during the harvest, unlike the storage types.
Mechanical harvest sauerkraut
Cauliflower is usually cut by hand for fresh market and industry.
After cutting cauliflower for industry is immediately processed on
the field. After processing the florettes are sent to the freezer.
Semi-mechanical harvest cauliflower
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Cabbage is stored to extend the season. When there is no more cabbage coming directly from the field, demand for cabbage is fulfilled by
storage cabbage. The advantage is flexibility. Growers are able to wait for a good price and are not forced to sell. The only downsides are
the big investment that is needed and the high operating costs (energy).
The storage time depends on the product, maturity and storage conditions.
Variety Temperature in degrees Celsius Storage time
Red cabbage Early 0-1 1 month
Autumn 0-1 2 months
Storage 0-1 6 months
Savoy cabbage Summer 0-1 1-3 weeks
11. Storage
Cool storage
A lot of headed cabbage is being stored in cool storage. The other crops
are also stored, but not nearly as long. Some varieties of white cabbage
can be stored for six or seven months, while broccoli and cauliflower can
only be stored for two weeks. The temperature at which white cabbage
is stored is between 0,0 and 0,5 degrees Celsius. If the temperature is
higher or lower the cabbage will deteriorate in quality.
Autumn 0-1 2-4 weeks
Storage -1 to -1,5 4-5 months
Pointed cabbage 0-1 2-5 weeks
White cabbage Early 0-1 1 month
Autumn 0-1 2 months
Storage 0-1 8 months
11.2 CA storage
CA is an abbreviation for Controlled Atmosphere storage. It means that cabbage is being stored in a changed and controlled atmosphere.
During CA storage the amount of oxygen in the cooler (the product is still cooled like in regular storage), is lowered from 21% until 3%.
The lack of oxygen extends the storage period and improves the quality of the products in storage. The low oxygen level reduces the release
of ethylene. Ethylene is a hormone that ages the cabbage, and reduces the storage period.
Ethylene is also the reason that cabbage preferably cannot be stored in the same cooler as fruit and fruited vegetables. These products
release a big amount of the hormone and the cabbage in the cooler will deteriorate very quickly.
CA storage is primarily used for the storage of pointed cabbage. Pointed cabbage is harder to store than white cabbage. To extend the
season of pointed cabbage growers use CA storage.
The following table shows the loss in weight after storage in cool storage and CA storage. The weight loss is caused by loss of moisture,
and cleaning.
Storage conditions 68 days 103 days 161 days
Cool storage (0-1 degrees, 21% Oxygen) 16,2% 25,3% 53,3%
CA storage (0-1 degrees, 3% oxygen) 9,9% 12,2% 35,9%
Some varieties of pointed cabbage perform better in CA storage. These varieties can be stored up to four months, depending on the quality.
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To make the product look fresh, some of the outer leaves are
removed. After that the product will be sorted and packed in the
desired product form.
The shelf life is a very important characteristic for the fresh market.
The product should look fresh when it is being sold. The shelf life can
be improved by proper handling of the product. For some markets the
products are packed air tight to improve the shelf life. The shelf life
also depends on the variety, some varieties look more fresh.
Cleaning broccoli
12. Finished product
After harvesting or storage the product will be prepared for the fresh
market. The early types of cabbage are usually directly prepared for the
fresh market, because of their limited storage potential. The storage
types will be cleaned and prepared for the fresh market, at the end of
the storage season.
The demands for the products on the fresh market are very
different. Generally products for the fresh market are sold as whole
heads. The size of the heads, packaging, type of product, taste and
use depend on the market. In the UK consumers prefer small, fresh
looking heads while the market in Germany is more focused on
price, with a preference for bigger heads. In Eastern Europe people
still make sauerkraut at home, so they also prefer big heads.
For the grower it is important to know what the demand of the
market is. This knowledge should be used to determine the right
variety and product form for the market.
The important consumer trends at the moment are, especially on
more evolved markets, sustainability, convenience and health. These
trends are visible in the retail sector. The selection of pre cut
vegetables is growing and retail organizations mark products which
are sustainable and healthy. These trends are important for the
grower, because customer requirements can change cabbage
cultivation.
Market cabbage
On the shelf in supermarket
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12.2 Processing
There are three slots in the processing market: deepfreeze
pre-cut, composed salads and sauerkraut. The products used for
deepfreeze are mostly cauliflower, broccoli and Brussels sprouts.
For deepfreeze cauliflowers it is important that the curd is dense and
that the florettes are short. The Brussels sprouts used for deepfreeze
are smaller sized sprouts. The broccoli used for deep freeze are from
the same varieties as those used for the fresh market.
All brassica types are being used for pre-cut mixed salads and
convenience packs for retail. For this type of product the
structure of the head is very important. Generally the structure
of the heads used for salads needs to be smooth and fine, so the
biggest part of the head can be used for processing. One of the
main salads made of cabbage is coleslaw. This salad can contain
several different types of cabbage chopped up with a dressing.
Convenience goods are ready to use vegetable mixes for stir frying.
Red cabbage is another important product for the processing
industry. The important characteristics for this product are yield,
structure and internal color. Red cabbage is used in salads and as
a pre-cut product. Red cabbage is also used for another industrial
purpose: a coloring agent can be extracted from the cabbage.
The last processing slot is the sauerkraut segment. Sauerkraut is
fermented white cabbage. For this processing type, big heads are
the standard. The outer leaves and the core are removed. The
remains of the cabbage are stored air tight and salt is added.
After this process the fermentation starts. Other important
criteria are the dry matter and vitamin c content of the head.
These substances are vital for the fermentation. In some
countries fermentation is also used to store cabbage in pots.
Dried cabbage is another way to preserve the vegetable. The dried
cabbage is used for soups and as a powder, for the flavor.
Cauliflower florettes
Coleslaw
Density with different transplanting distances (in 1000 plants / hectare)
CM 10 15 20 25 30 40 50 60 70 80 90 100 150 200 250
10 1000 666 500 400 333 250 200 166 143 125 111 100 67 50 40
15 667 444 333 267 222 167 133 111 95 83 74 67 44 33 27
20 500 333 250 200 167 125 100 83 71 63 56 50 33 25 20
25 400 267 200 160 133 100 80 67 57 50 44 40 27 20 16
30 333 222 167 133 111 83 67 56 47 42 37 33 22 17 13
40 250 167 125 100 83 67 50 47 37 31 28 25 17 12 10
50 200 133 100 83 67 50 40 33 28 25 22 20 13 10 8
60 167 111 83 67 56 41 33 28 24 21 18 16 11 8 7
70 142 95 71 57 47 36 29 24 20 18 16 14 9 7 6
80 125 83 62 50 41 31 25 21 18 16 14 12 8 6 5
90 111 74 56 44 37 28 22 18 16 14 13 11 7 5,5 4,4
100 100 67 50 40 33 25 20 17 14 12 11 10 6 5 4
150 67 44 33 27 22 17 13 11 9 8 7 6 4,4 3 2,7
200 50 33 25 20 17 12 10 8 7 6 5,6 5 3,3 2,5 2
250 40 27 20 16 13 10 8 6,7 5,7 5 4,4 4 2,7 2 1,6
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Nickerson-Zwaan B.V.
P.O. BOX 28
NL - 4920 AA MADE
Tel.: +31 (0) 162 690 900
Fax: +31 (0) 162 680 970
info@nickerson-zwaan.com
www.nickerson-zwaan.com
TECHNICAL DISCLAIMER
Nickerson-Zwaan B.V. and/or its representants give no guarantee that the information
provided, including but not limited to variety descriptions and technical advice, is complete
and accurate and suitable for all purposes the user may choose. Technical data and
recommendations are based on Nickerson-Zwaan trials and general experience. An important
part of the information given is based on Northern hemisphere or Northwest-European
circumstances. All information is only supplied to assist professional growers and users who
should always take account of their local conditions or specific situations which may be
different. Hence these recommendations do not provide a guarantee of a successful crop.
Nickerson-Zwaan, therefore, accepts no responsibility or liability whatsoever for any damage
or loss of profits resulting from the use of this publication.
September 2011