Archive for the ‘ Plant advice ’ Category

Ash Die Back- Chalara fraxinea

Posted Saturday, 27 October, 2012 at 8:48 am

Ash Die Back

Once again we face the prospect of another disease that could result in the loss of a valuable native tree. I fear we will be too late in preventing this fungal disease spreading duplicating the damage seen in Denmark where they have suffered an 80% mortality of their ash trees. Ash trees suffering from symptoms likely to be caused by C. fraxinea have been found widely across Europe. These have included forest trees, trees in urban areas such as parks and gardens, and also young trees in nurseries.

Chalara dieback of ash is a serious disease of ash trees caused by a fungus called Chalara fraxinea (C. fraxinea).
The disease causes leaf loss and crown dieback in affected trees, and it can lead to tree death. Staining on the bark is evident which in time forms splits in the bark.

In order to control this outbreak there will need to be greater control of nursery stock at a time when the tree planting season will be starting. The latest news is that Ash imports will be banned from Monday 29th October 2012. Yet this response seems rather late considering the disease was first reported in the Spring.

There will also need to be controlled felling of diseased trees ensuring the wood is destroyed to reduce the spread of any pathogens.  Government advice on the treatment of the disease will be forthcoming and we will publish this once it is presented

Greater awareness of the symptoms will be needed to educate the public enabling them to report on suspected cases of the disease. C. fraxinea is being treated as a quarantine pest under national emergency measures, and it is important that suspected cases of the disease are reported.

Reports should be made to:

• Forestry Commission Plant Health Service 0131 3146414
• Fera Plant Health and Seeds Inspectorate 01904 465625

Locations affected so far

• In February 2012 it was found in a consignment of infected trees sent from a nursery in the Netherlands to a nursery in Buckinghamshire, England.

• In June 2012 it was found in ash trees planted at a car park in Leicestershire which had been supplied by a nursery in Lincolnshire, and the origins of the disease in this case are being investigated.

• In July 2012 the Food & Environment Research Agency (Fera) confirmed cases in the nursery trade in West and South Yorkshire and Surrey, and by September 2012 it had been reported in a nursery in Cambridgeshire.
• It has also been confirm that the disease has been found in both the mature ancient woodland and woodland creation areas at Pound Farm in Suffolk.

• It has also been found at four recently planted sites – a Forestry Commission Scotland woodland at Knockmountain, near Kilmacolm, west of Glasgow; the car park in Leicester, a college campus in South Yorkshire, and a property in County Durham, and is suspected at a Woodland Trust site in Hertfordshire.

This outbreak has highlighted the pressures placed upon our plant diversity due to imported plant material. In the 1970’s imported elm with its bark left on resulted in the loss of our Elm trees. We also have concerns about Sudden Oak death and recently larch trees have been placed under considerable threat as a result of a disease brought in on rhododendron.

Urgent consideration on importing native species needs to be taken to question the need for importing native trees that we can and do grow here in the UK.

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Frost Damage

Posted Wednesday, 8 February, 2012 at 2:52 pm

Throughout the many years I have been designing gardens I have often been asked questions relating to the garden in winter and potential damage to shrubs and herbaceous plants.  With the recent cold snap I thought it prudent to pass on some of the comments I share with my clients in order to educate and to help you prepare for such cold weather.

The most obvious cause for concern in the winter comes from a fear of frost damage to new plants.  This is where the plants following a frost display damage to their leaves often resulting in brown leaves and in some cases the death of the plant.  This was extremely noticable in the West Midlands following the winter 2010/2011 where a great number of Phormiums and Pittosporums died.  This damage displayed itself very quickly but sometimes the damage can take many months before any visible signs present.

What causes the damage?

Ground Frosts are when the temperature of the ground falls below freezing point (0ºC/32ºF) and air frost occurs when the temperature of the air falls below freezing point. Damage is often greater when there is repeat freezing then thawing and also where there is a rapid thawing.

Strong winds will increase plant water lose particularly with evergreen shrubs.  As the ground is frozen the plants can not replace this lost water and the leaves brown and wither as a result.

Tender plants survive the winter better when they are planted in a sheltered sunny position. This is because new wood is ripened by the sun during the growing season, making it more frost resistant.  Newly planted nursery stock is more prone to frost damage particularly if we have a prolonged winter.  They will tolerate a reasonable level of cold (most plants are grown in container and these plants and the conditions prior to planting do not differ greatly from them being on the nursery growing beds).

Living in Alvechurch which is situated in a naturally formed bowl formed by the hills surrounding the village.  This creates a frost pocket with the cold air travelling down the slopes often resulting in temperatures that are 2 ºC  colder than Solihull.

There are things however that can be done to reduce the risk of frost damage.

Avoid feeding your plants with a high Nitrogen feed late in the season as this will encourage the plant to make soft tissue growth which is likely to be checked by the cold weather.

We have already mentioned planting tender plants in a sheltered sunny location.  Applying a mulch to the surface will help, I like to use bark mulches but always keep this at least 600 mm/2′ from the border edge to avoid it being flicked about by black birds.  This provides a blanket over the soil protecting the plants roots and reducing the depth of frost penetration in the soil.

Tender plants such as Penstemons benefit from a shelter over them, this can be achieved using the old plant growth and also using the dried fronds of ferns.  This helps keep the cold off the plant and helps shed surplus water off the plant.

Selection of suitable plants is also important and if you know you are in a frost pocket adjust your plant range to reflect the colder conditions.  I live on a heavy clay soil and know to my cost this combination together with the frost pocket make growing Hebes difficult unless I spend time providing them with greater protection.  If very cold bubble wrap can be used to insulate the plant but do not leave it on too long.  It looks unsightly and unless we are having very cold weather I find it can encourage the plant to put on growth too early.

Protection of fruit trees can be achieved by wrapping straw around the trunk.  With standard bay trees I have even suggested the use of pipe lagging foam which will help protect this vital part of the bay.  Even if the upper growth suffers the protection will help the plant to recover in the spring.

What to do if your plants are damaged.

Newly planted shrubs can be lifted out of the ground caused by the frost heave.  Check the plants and ensure they are healed in once the weather improves.

Prune out the damaged growth once the risk of frosts has past ensuring you cut the plant back to the next viable bud.

Apply a slow release fertiliser such as Growmore to encourage the plant to put on new growth.

If the site is exposed consider planting a shelter belt to reduce the wind speed through the garden.  Also you can erect simple structures such as hazel hurdles that will allow wind through but at a reduced speed.

Sometimes you need to be patient with what looks like a dead plant.  Last year the number of Phormiums that looked completely dead put on new growth.  Check to see if the plant is still alive before you throw them away.  If you have cut them back and feed them there is always a chance the effort is rewarded by the sight of new growth.

We are expecting more snow in the next few days.  Heavy snow can cause limbs to break due to the physical loading upon a plant.  This is particularly valid for conifers and evergreen shrubs.  If we have a heavy fall of snow it is important to reduce the weight of this upon the plant by brushing it off the shrub or conifer.  This is a simple task and only takes seconds but can help protect a shrub from recognisable damage.

The current weather for the West Midlands can be found on the Met Office web site Met Office West Midlands

 

 

 

 

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How to prune roses

Posted Thursday, 26 January, 2012 at 1:21 pm

Guide to Rose Pruning

Often there is a fear about pruning, which is often unfounded and based upon complicated gargon.  The notes below provide some simple to follow rules, which will help you understand the methods required.  the key is to know what type of rose you have and then to follow the guides.

Winter Pruning

This is generally carried out in January and February but in regions where there are cold winters it is best to defer the pruning work until the spring growth has just started.  In the west Midlands I prefer to wait until I see this new growth as I have found pruning too early can result in die back which then has to be cut out.

Pruning shrub roses

English Roses and other repeat flowering shrub roses should be cut down by between 1/3 and 2/3 but only thinned a little.

Non repeating shrubs should be left alone or lightly pruned by no more than 1/3 and thinned very lightly.

Bush Roses (hybrid teas and floribundas) should be cut down by between 3/4 and 1/2 thinning out some of the older main stems to encourage strong new growths.

Pruning Ramblers and Climbing Roses

Ramblers as the name suggests should be left to ramble at will and are generally only pruned back to remove older growth if this becomes too dense. Some varieties of ramblers are extremely vigorous which may require you to prune the rose back if it becomes too big. If this is the case it may be pruned in the same way as a climber. Heavy pruning can greatly reduce the next season’s flowering, so when selecting a rambler, always make sure the rose you have selected is will not grow too large for the desired position.

When pruning climbers it is important to consider how the plant grows and responds to your pruning.  The first task is to tie in the strong, new stems, cutting out older ones as necessary.  I like to tie these tall growths to my horizontally formed wires on my wall/fence as this encourages the buds to break along the length of the strong growth allowing me to generate a great number of flowers.  I then reduce the previous year’s flowering shoots which should be reduced to 3 or 4 buds or about 6” (15cms).  Cutting out the older stems encourages the rose to put on more young and health growths which will ultimately have the most flower.

Summer Pruning English Roses

Vigorous repeat flowering roses can be heavily pruned to encourage better repeat flowering and ensure the plants do not grow taller than desired.  To summer prune the flowering stems need to be cut back leaving two or three buds on the current seasons growth.  Whether you wish to do this is dependent upon your own taste and needs.

Dead Heading

Dead heading is a task that should be carried out to encourage greater repeat flowering.  This task can be undertaken as part of your own daily visit to the garden during the summer and does not need secateurs as the spent flowers will snap off easily.  Blooms that have balled in wet weather should be removed in a similar manner.  Dead heading will ensure your roses look neat and tidy during the summer.

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How to take hardwood cuttings

Posted Wednesday, 28 December, 2011 at 12:13 am

Hardwood cuttings are often grown outdoors in the ground in a prepared trench located in a sheltered location.  Whilst it is not necessary to provide protection to these cuttings you can provide additional protection in the form of a cloches or coldframe.  Should you require only a few cuttings you can also consider using a container instead of the prepared trench.

Select vigorous healthy shoots that have grown in the current year.

Remove the soft tip growth as this will not be required and would wilt.

Cut your selected cuttings into sections 15-30cm (6-12in long, cutting cleanly above a bud at the top, with a sloping cut to shed water.  This will also serve as a reminder which end is the top and which end will be placed into the soil.

Cut straight across at the base below a bud or pair of buds and dip the lower cut end in a hormone rooting powder.   (the use of hormone rooting compounds helps to promote root formation, surplus should be tapped of.  The hormone compounds often contain a fungicide which helps protect against rotting). Cut though the ‘heel’ where the shoot joins a branch for shrubs with pithy stems such as Sambucus (elder).

Prepare a trench outdoors in a sheltered site with well-drained soil adding horticultural grit if the soil is heavy. Additionally dig in a bucketful of garden compost or other organic matter every square metre or yard.

Insert the cuttings into the ground or pot with two-thirds of the cutting below the surface, with a layer of sand in the base. The roots will form along the stem. A few buds remain above the ground to allow the plant to grow away in spring.

Allow 10-15cm (4-6in) between cuttings and 40cm (16in) between trenches.

Check the trench after frosts and firm back if required.

Cuttings should be left in place until the following autumn ensuring that they do not dry out in dry periods in summer.

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How to winter prune apples and pears

Posted Wednesday, 30 November, 2011 at 3:47 pm

How to winter prune apples and pears

The type of pruning technique depends on whether the tree fruits on spurs or towards the tips of shoots made the previous summer.

No matter whether your tree is a spur- or tip-bearer, the first stage of winter pruning is the same for both:

Always use a sharp pair of secateurs, loppers and a pruning saw.  I use Felco’s and find that whilst expensive it is money well spent.

Start by removing crossing, rubbing, weak, dead, diseased, damaged and dying branches.

Keep the centre of the tree open by removing larger branches with a sharp pruning saw. The old saying was that you should be able to throw a hat through the tree.  This promotes good air circulation and helps prevent mildews. If several large branches need to be removed, spread the work over two or three winters as very hard pruning encourages even more vigorous growth.

Reduce the height and spread of any branches that have grown too large by cutting them back to a vigorous lower branch (making sure this lower branch is at least one-third of the diameter of the branch being removed)

Then continue for a spur- or tip-bearer.

Spur-bearing varieties

A majority of apples and pears are spur bearing varieties.

Shorten the previous year’s growth on each main branch by about one third to a bud facing in the required direction to encourage the development of new branches and spurs.

Cut back any young laterals (side shoots) growing from the main framework to five or six buds if there is not enough space to allow them to grow as secondary branches.

Remove any badly placed shoots that will cramp or interfere with others.

On older trees, remove any spur systems that have become overcrowded.

 Tip-bearing varieties

Prune the previous year’s growth on each main branch and the most vigorous laterals (side-shoots) to the first strong bud. Leave un-pruned laterals less than 30cm (1ft) long

Cut back a proportion of older fruited wood to a young shoot or leaf bud to reduce congestion.

Neglected trees and very old trees

If you inherit an overgrown apple or pear tree it may be possible to bring it back into productive cropping but this can be time consuming.  I usually suggest you enjoy the plants form and as a designer would sometimes in very old trees suggest running a Rose such as Climbing Rose ‘Alchymist’ up it.

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Planting Tulips in your garden

Posted Wednesday, 9 November, 2011 at 2:06 pm

Tulip ApeldoornPlanting Instructions

Tulips will thrive in almost any type of soil where there is reasonable drainage. During the growing season they enjoy plenty of moisture but they will not tolerate water logged growing conditions. Tulips should not to feed during the growing season as this will produce ‘leggy’ plants. Tulips can be planted from October until late December.  Planting the bulbs 100 mm (4 inches deep) and approximately 125-150 mm (5 to 6 inches) apart.  Ensure when preparing the hole that the base of the pit is prepared as well in order to prevent the bulbs sitting in water within the hole.  This is an important consideration when using one of the many bulb plants available.

Tulip failures are mostly due to damage by slugs and snails. Apply a slug repellant immediately after planting and repeat at monthly intervals until the plants stand well above the ground.

After Flowering

Remove flower heads (deadheading) allows the tulip to transfer energy back into the bulb.  Once the flowers have been removed allow the plant to die back before removing the foliage. This allows the food supply in the plant to swell and feed the main bulblet that will produce next year’s flower.

To prevent ‘Tulip fire’ (a fungal disease of tulips caused by Botrytis tulipae), which produces brown spots and twisted, withered and distorted leaves leaves and petals should be removed.

 

Uses for Tulips

Tulips can provide a great deal of interest to the garden in spring as additional colour to a border where a group of herbaceous perennials have yet to appear or where a deciduous shrub permits under planting. With types of tulip you may find that the second and subsequent years are not as good as the first depending on where the tulips are planted in your garden. This can be influenced by shade, drainage, planting depth so it is best to experiment. If this is the case we would recommend that you lift the tulips after the foliage has died back and store them until replanting the following Autumn.

Tulips for Naturalising

The small flowering tulip species and Darwin Hybrids will naturalise easily and can be left undisturbed from one year to another, some seeding themselves freely.

Tulips in Containers and Pots

Tulips are well suited for growing in containers and provide a superb display provided a few basic principles are followed. Protect from severe frosts particularly when combined with penetrating winds. It is essential during dry periods in the growing season that tulips are sufficiently watered to prevent stunted and shriveled flower heads.

 

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