ORGANIC CONTROL OF CLUBROOT IN BRASSICAS

Clubroot is a serious disease that can affect crops from the brassica family. It is a fungal (although more correctly known as a slime mould) infection which attacks the plant through the soil via its root hairs. In a short period of time this will lead to massive swelling, distortion and severely retarded growth. Worst still, the fungus produces cysts that will remain in the soil until a suitable host comes available to re-infect, starting the cycle again.

The biggest problem is that these cysts can live in the soil for up to 20 years and are easily spread. In fact, just walking from an infected area onto a clean patch of land will infect your soil.

Be aware that clubroot disease will also easily contaminate your soil if it is brought in on infected plants, so do not accept brassica seedlings where the source is not known to be clean.

Clubroot can infect whenever the soil is moist and warm, so be aware that most new infections will tend to occur from mid-summer until late autumn.

Symptoms of Clubroot

The first sign of you crop contracting clubroot is a characteristic wilting of your plants, especially in dry weather. Infected plants will fail to develop properly and often the crop will fail. As mentioned before, by examining the roots you will notice unusual distortions and swellings.

Organic Control of Clubroot

If you have clubroot in your soil then unfortunately you are going to be stuck with it. Even so, don't worry - it is still possible to grow brassica crops successfully with some careful cultivation techniques.

Firstly, it is important to practice good hygiene. When your brassica crops have been harvested, carefully remove all the roots but DO NOT compost them, treat them either as household waste or burn them in an incinerator.

Remember that the brassica family also includes radishes and mustard, so do not use a mustard green manure on your land and remove radishes that have gone over and once again burn them, do not compost them. This will help to reduce the number of clubroot fungal spores and cysts left lying in the soil.

Keep down susceptible weeds like shepherd’s purse, charlock, and wild radish as this will also help to control the club roots life cycle.

Start your brassicas off in seed modules using fresh, sterilized compost to which a small amount of lime has been added, then pot them up to between 3 inch or 5 inch pots before planting out. This allows the plant a chance to develop a good root system prior to a possible infection.

Club root can be reduced, but not eliminated in open ground, by improving drainage and raising the soil pH by liming. On acidic soils, lime at the rate of 500g per sq m (15 oz per sq yd), with lighter dressings of 270g per sq m (8 oz per sq yd) in future years. Before planting, you may wish to try digging a decent sized hole- at least 1 ft deep - and then dusting the sides and base of the hole with lime before planting your seedlings.

Consider using clubroot resistant brassica varieties, but remember - this is just resistance and not total immunity.

Clubroot Resistant Varieties

Brussels sprouts ‘Crispus’
Cauliflower ‘Clapton’
Cauliflower ‘Clarify’
Cabbage ‘Kilaton’


For related articles click onto the following link:
HOW TO GROW BRASSICAS FROM SEED
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HOW TO GROW CABBAGE FROM SEED
HOW TO GROW CAULIFLOWERS FROM SEED
HOW TO MAKE A NATURAL AND ORGANIC INSECTICIDE SPRAY FOR APHIDS
MAKE YOUR OWN ORGANIC PYRETHRUM INSECTICIDE
ORGANIC CONTROL OF ASPARAGUS RUST
ORGANIC CONTROL OF CATERPILLARS
ORGANIC CONTROL OF CLUBROOT IN BRASSICAS
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EVERGREENS FOR DRY SHADE

One of the most common questions I get asked is this.

‘...what can I plant in my border – it is in the shade for most of the day and the soil is very dry...?’

It’s a good question. Plants require sunlight and water to grow, and by heavily restricting access to these vital elements most plants will just give up the ghost. However, this is not a very helpful answer and of course, there are always a few exceptions to every rule. Below is a list of evergreen plants that – with a little help – will cope in shady, dry conditions.

Just remember that although these plants will tolerate dry conditions, they are not cacti and as such will appreciate being watered every now and again!

Bergenia
A popular hardy perennial with evergreen, glossy leaves. Commonly known as ‘Elephant Ears’ this architectural plant is available in a wide range of colourful hybrids available. They can also make a great ground cover plant.




Christmas Fern (Polystichum acrostichoides)
Native to Eastern North America the Christmas Fern is a non-flowering, evergreen perennial. It will reach a height of 2 feet tall and the rhizomatous clumps will slowly grow to over 2’. It is very low maintenance and highly attractive with upright, evergreen foliage frond.




.
Comfrey (Symphytum grandiflorum)
An herb, long used medicinally, this perennial will tolerate dry shade once established. Growing about 12” with handsome, semi-evergreen foliage, comfrey does well under shrubs or small trees. Use comfrey in the shade garden and ways to use this early spring-flowering perennial plant.


Cyclamen coum and Cyclamen hederifolium
Although not strictly evergreen, they will hold their leaves over winter. These popular cyclamen species will produce exquisite blooms from late winter to early spring. The leaves, which have silver patterning over dark green, and the flowers appear at the same time from tubers underground. Flower colour can vary from white to deep red. Mulch annually with leaf mould to help prevent the tubers from drying out during the heat of the summer and from the cold of winter. Both species have been given an Award of Garden Merit (AGM).

Epimedium grandiflorum
A wide range of plants are available in this species from low-growing ground covers only 6” tall to much larger plants up to 2’ in height. Also known as Barrenwort, this perennial plant has foliage which can turn red or orange in the autumn and remain over winter providing winter interest.


Galanthus 'S. Arnott'
Another 'almost evergreen' choice.Whilst almost all snowdrops require a moist soil in order to thrive, Galanthus ‘S.Arnott does not. It produces flowers with a subtle fragrance, that are almost twice the size of common snowdrops, on stems that can reach 25cm (10in) tall.



Hypericum calycinum
This vigorous and spreading semi-evergreen shrub with lance-shaped leaves. It produces golden –yellow flowers up to 3 inches across through the summer and early autumn.is a fast-growing, spreading, semi-evergreen to evergreen shrub with lance-shaped leaves and yellow flowers throughout summer into early autumn is a fast-growing, spreading, semi-evergreen to evergreen shrub with lance-shaped leaves and yellow flowers throughout summer into early autumn. .


Liriope muscari 'Big Blue'
Predictably large with blue flowers. One of the best of the good flowering forms, to 40 cm tall and wide, evergreen.




Mahonia aquifolium
This is a suckering shrub with glossy, dark green, leathery foliage. Fragrant rich yellow flowers are produced in numerous dense clusters in March and April followed by blue/black berries. The variety ‘Atropurpurea’ has leaves which turn a rich-red-purple in winter.




Ruscus
Species from this family are well known for being hardy evergreens. They have unusual stemless leaves and while the flowers are inconspicuous they do display handsome, large red berries in the autumn on the female varieties.




Tellima grandiflora
This hardy evergreen is chiefly grown for its leaves which make good ground cover throughout the year. The variety ‘Forest frost ‘produces heavily mottled leaves which are to a burgundy colour, pink flowers in Spring.



Tiarella
Two species from this family of hardy evergreens are of particular interest – T. trifoliate and T. polyphylla. Happy in the shade they need a free-draining soil but these plants will die back if the soil dries out completely so enrich the soil before planting with plenty of organic matter.



Vinca major and Vinca minor
These popular ground cover evergreens are happy in any ordinary free draining soil. There are a number of varieties available flowering anytime from March until July.





For related articles click onto the following links:
EVERGREENS FOR DRY SHADE
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WHAT IS JOHN INNES COMPOST?

Up until the beginning of the 20th century there were no ‘standard’ compost mixes for plants. In fact, before the introduction of John Innes Composts, trained gardeners generally used a different compost recipe for each species of plant they wanted to take cuttings from or pot up. And of course, these recipes were guarded close to the chest.

Be that as it may, it was quite usual for the soil to be either sterilised or heat pasteurised and consequently plant seedlings were often attacked and destroyed by soil-borne diseases and insects.

In addition, the plant nutrition that was being added to the traditional composts was usually ‘unbalanced’, causing the plants to be either too soft in their growth and therefore more liable to diseases, or overly tough and slow growing.

In the 1930's two research workers at the John Innes Horticultural Institute, William Lawrence and John Newell, set out to overcome these problems by formulating composts that would give consistently good and reliable results. After six years of experiments they determined the physical properties and nutrition necessary in composts to achieve optimum rates of plant growth. They also introduced methods of heat sterilising the soil that eliminated pests and diseases, but did not cause any retardation of plant growth.

The result of this work was the introduction of two standard composts, one for seed sowing and one for potting. These ‘John Innes’ composts revolutionised not only the ways in which composts were produced, but also the growing of plants in pots.

William Lawrence and John Newell developed a blend of carefully selected loam or topsoil, sphagnum moss peat, coarse sand or grit and additional fertilisers. The loam is screened and sterilised and then thoroughly mixed with the other ingredients in proportions designed to achieve the optimum air and water-holding capacity and nutrient content for different types and sizes of plants. These ratio of these ingredients depended on which mix was being created

Now, after being used very widely for over 50 years, the basic formulae remain the same - tried and tested and still popular amongst gardeners for growing quality plants with the minimum of attention. Naturally, in today’s compost mixes the plant nutrients have been updated to gain the benefits of improved fertilizer technology.

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HOW TO GROW BRASSICAS FROM SEED

Vegetables for the Brassica family are not only amongst the easiest to grow, they can also provide a crop at almost any time of year. However there are few of us that would actually want to eat cabbages in the middle of summer so to get the best use out of your garden or allotment space it is better to grow brassicas for autumn and winter production. Not only will this leave a convenient ‘brassica free’ April-to-June gap, this three-month break will also helps to limit the incidence of common brassica pests such as whitefly.

For those who are unfamiliar with this brassicas, they are the edible stars of the spring and autumn garden. It is a comparatively large family containing a wide range of common leafy vegetables, such as cabbage, brussels sprouts, broccoli, kale and cauliflower. Root crops such as turnips, swedes and kohlrabi are also part of this nutritious group.

Growing Requirements

As a rule of thumb, brassicas are heavy feeders, preferring a well-drained soil rich in organic matter. They also prefer a site in partial shade with a soil pH between 6.0 to 7.5. To prepare the soil for planting, add a couple of inches of organic compost or well rotted manure to the ground and work it in - removing any large stones that turn up. Add lime - if necessary – to balance out the pH as your brassica crop can fail if the soil is too acidic. You can check the pH of your soil using an 'off the shelf' pH testing kit obtained from any good plant retailer. Once finished, tread over the soil to remove any air pockets, firming up the soil surface.

TIP. Autumn plantings of brassicas tend to do well following an earlier planting of peas or beans as these crops will naturally increase nitrogen levels with the soil.

Nearly all brassicas should be planted either directly into a seedbed, or singularly in modules under glass which can be transferred outside at a later date. When sown directly outside, the seeds should be sown relatively sparsely to reduce future thinning and the potential risk from pests. When lifting from modules try and keep the root ball as intact as possible to minimise any damage to the juvenile root system,

Broccoli, Brussels sprouts and cabbage seeds can be 'direct sown' outside when temperatures are as low as 4°C, but temperatures of 7°- 29°C will be more preferable for successful germination. Aim to sow brassica seeds in ½ inch deep in rows spaced 6in apart.


Cabbage and broccoli seedlings sown under protection will be ready for transplanting outside once they have reached between 3 -4 inches high. However, Brussels sprouts and kale should be about 6 inches in height before they go outside. Make sure that all protected seedlings are hardened off for at least a week or two before planting outside to make sure that they are tough enough to cope with ‘real’ weather conditions. Water the day before moving, and keep well watered once outside until they are established.

If you have them, space the plants according to their planting instructions which should automatically be printed with shop bought brassica seeds/baby plants. These distances can vary from 12 inches for small cabbages to 18 inches for Brussels sprouts. However, if you are without instructions keep to the safe side and thin all seedlings out to 18 inches apart.

Keep control of the weeds as they grow between your crop by hand weeding. Try and avoid using a how as this can disturb your crops roots and lead to the wind rock making the plants less productive

TIP. Avoid growing brassicas on the same piece of ground more often than one year in three, as this will help to avoid the buildup of soil pests and diseases.

TIP. Brassicas are a particular favourite of birds so use an appropriate and safe deterrent to stop them from picking off your seedlings. Brassicas are also susceptible to attack by the caterpillars of the cabbage white butterfly. Try covering crops with a crop protection mesh. It keeps the butterflies out, so they can't lay their eggs on the plants.

For related articles click onto the following links:
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HOW TO GROW BRUSSELS SPROUTS FROM SEED
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HOW TO GROW CAULIFLOWERS FROM SEED
HOW TO GROW CELERY FROM SEED
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HOW TO PLANT ASPARAGUS CROWNS

How to plant asparagus crowns

Although considered by many as a gourmet vegetable, the asparagus is often overlooked as a 'run-of-the-mill' garden crop. This is a real shame as shop bought, imported varieties really don’t have the same sublime flavour as quality home-grown produce.

How to plant asparagus crowns

Once established, asparagus shoots can be harvested from late spring when the new tips reach about 6 inches in height. From that point harvesting can be continued for a further six to eight weeks into early summer. Be warned though as harvesting spears from crowns less than two years old will only weaken the plant and effect cropping in subsequent years.

You can start preparing new asparagus beds as early as the autumn. They are happy in most soil types provided they are well drained, but if you are stuck with a heavy clay soil then you may wish to consider planting them into raised beds. Dig in plenty of well rotted manure and if your soil is particularly acid you may also need to add lime. Asparagus prefer a pH of between 6.5 and 7.5. Remove all perennial weeds from the start - and as you see them - as they will compete against the growth of your crop later on.

If you are using a traditional trench system you will need to dig it out to 1 foot wide and 8 inches deep, adding well-rotted farm manure to the bottom of the trench. Next, cover the manure with a couple of inches of the excavated soil and make a small ridge of no more than 4 inches along the bottom of the trench.

Place the asparagus crowns on top, spacing them 12-18 inches apart. Leave 18 inches between rows and stagger the plants if you are short of space. Spread the roots evenly and fill in the trench leaving the bud tips just visible. Water in and mulch with a couple of inches of well-rotted manure.

Asparagus beds will need a certain amount of maintenance and must be kept weed free. This is best done by hand as asparagus plants have shallow roots which can be easily damaged by using a hoe or mechanical means, reducing the plants vigour for next years crop. This would mean that you would end up with less spears. Also keep an eye out for berrying female stems which - if their seeds turn red, ripen and fall amongst your rows - can germinate and muscle out the productive male varieties and again reducing the amounts of spears produced the following year. If you see these tell-tale female stems then cut them off at the base before their seeds ripen.

How to plant asparagus crowns

In subsequent years mulch asparagus beds with well-rotted manure after harvesting. Not only will this help the plants develop strong healthy fronds to support valuable root growth, it will also help to keep down the incidence of weeds.

Main image credit - Ryan Freisling released this work into the public domain.

In text Image credit - Permission granted to use under GFDL by Kurt Stueber. This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or less.
In text credit - Attribution: Photograph by Longhair https://creativecommons.org/licenses/by/2.5/deed.en

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HOW TO BREAK DORMANCY IN SEEDS

During the evolutionary course of plant development, the design of seeds has become as diverse and varied as any other group of living creatures. While all seeds have been created with the double purpose of first protecting the embryo within, and then enabling the juvenile seedling to emerge at the most opportune time for optimum growth, the way that some plant species achieve this is akin to a Chinese puzzle box. Without the required periods of dry, cold, wet or heat the protective seed coat will not allow the embryonic seed within to break out into life. However, some seeds will still refuse to germinate! This is known as seed dormancy and - simply put - seed dormancy can be defined as the failure of mature, intact seeds to germinate

under favourable conditions.

So secure is this method of protection offered by some seeds that without the correct environmental responses they can remain dormant for hundreds of years. In fact, ancient magnolia seed retrieved from a Japanese tomb have been germinated after a period of some 2000 years!

While some seeds are extremely easy to germinate, others are clearly not and if somebody wished to bypass the enforced dormancy that many seed coats offer a certain amount of work is needed. Below is a list of common techniques used in bypassing the dormancy process.

Chipping

Some seeds, e.g. Sweet peas, Ipomoea etc. have hard seed coats which prevent moisture being absorbed by the seed.

All that is needed is for the outer surface to be scratched or abraded to allow water to pass through. This can be achieved by chipping the seed with a sharp knife at a part furthest away from the 'eye', by rubbing lightly with emery paper or, with very small seed, pricking carefully once with a needle etc.

Pre-chilling

In some packet seed instructions you will find a reference to 'pre-chilling'. This is a pre-treatment of the seed which often helps to speed up the germination of otherwise slow to germinate seeds. However, even after pre-chilling some seeds can stubbornly refuse to germinate until a year or more has passed, so never be too hasty in discarding a seed container.

Pre-chilling was traditionally done by standing the pots outside in a cold frame during the winter. It is often quicker to adopt the following technique using a domestic refrigerator and this is of particular value if you obtain your seed outside the winter months.

To pre-chill seeds, first sow the seed on moistened seed compost, seal the seed container inside a polythene bag and leave at 60-65F (15-18C) for 3 days then place in a refrigerator for the recommended period. For convenience large seeds can be mixed with 2-3 times their volume of damp seed compost, placed direct into a polythene bag which is sealed and placed in the refrigerator. However, there must always be sufficient air inside the bag and the compost should NEVER become either too dry or over wet. After pre-chilling these seeds can then be spread with the compost on top of a seed container and firmed down.

The seeds must be moist whilst being pre-chilled, but it will harm them if they are actually in water. During the period in the refrigerator, examine the seeds once a week and remove all the seeds into the specified warm conditions if any of them start to germinate.

Light also seems to be beneficial after pre-chilling, so pre-chilled seeds should have only the lightest covering of compost, if any is required, and the seed trays or pots, should be in the light and not covered in paper.

Soaking

Soaking is beneficial in two ways; it can soften a hard seed coat and also leach out any chemical inhibitors in the seed which may prevent germination. Anything from 1-3 hours in water which starts off hand hot is usually sufficient.

If soaking for longer the water should be changed daily. Seeds of some species swell up when they are soaked. If some seeds of a batch do swell within 24 hours they should be planted immediately and the remainder pricked gently with a pin and returned to soak. As each seed swells it should be removed and sown into the growing media before it has time to dry out.

Double dormancy

Some seeds have a combination of dormancies and each one has to be broken in turn and in the right sequence before germination can take place. For example some Lilies, Tree peonies, Daphne etc. need a warm period during which the root develops followed by a cold period to break dormancy of the shoots, before the seedling actually emerges.

Some seeds need a cold period followed by a warm period and then another cold period before they will germinate.

For related articles click onto the following links:
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