Checking for Chalara Ash Dieback

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A couple of days ago I visited a friend in Norwich who has an Ash tree in his garden. He was concerned that it might have Chalara Ash Dieback disease. Fortunately, after we’d had a look, we realised his fears were unfounded.

When I wrote about Ash trees in July 2012 Ash Dieback disease (caused by the fungus Chalara fraxinea) had already been found in Britain in a tree nursery in Buckinghamshire, but it wasn’t until October 2012 that the first cases were confirmed in East Anglia (reference). It was a shock to hear that the disease had been discovered not far from Norwich in Ashwellthorpe Lower Wood, a lovely Norfolk Wildlife Trust reserve that I have visited on several occasions.

I have looked at  number of Ash trees in Norwich, for example in Earlham Cemetery, but I still haven’t seen the symptoms of the disease first hand. But a lot of information is available on the internet. I started with the Woodland Trust’s page “How to identify ash dieback“.

The page led me to some Forestry Commission videos, which are clear and easy to follow. They are on YouTube and I have embedded them below. (The first two are also embedded in the Woodland Trust’s web page.)

How to identify Chalara ash dieback in the field:

Chalara ash dieback – identifying symptoms in the winter:

Chalara dieback of ash – Spring symptoms:

Chalara Ash Dieback has now been found in many parts of the UK (see map).

If you discover an outbreak of the disease, you can use the Forestry Commision’s tree alert form to report it. Photographs are very useful and priority is given to reports which include pictures. There is also a Tree Alert App, which you can use if you have a smartphone.

Chalara fraxinea has caused the loss of ash trees in a number of European countries, including between 60 and 90 per cent of Denmark’s ash trees. The worry is that the effect will be devastating in Britain too. Hopefully the genetic diversity of our ash trees may mean that there are naturally resistant trees already growing in our countryside.

In Britain, there appear to be two sources of infection. In East Anglia and along the east coast wind-borne fungal spores have brought the disease to Britain from continental Europe. Further west, trees have been planted with infected stock imported from continental Europe (reference). Regulations were introduced to control the import of infected trees in late October 2012 (reference), but only once many infected newly-planted trees had already been discovered.

The Forestry Commission have issued advice to forest visitors, which should be followed to limit the spread of the disease. However, they advise that the risk of visitors spreading the disease is very small and they have not suggested that woods or forests should be closed to visitors.

Chalara Ash Dieback affects other species of ash as well, including Fraxinus angustifolia, F. ornus, F. nigra, F. pennsylvanica, F. americana and F. mandschurica. The least susceptible species are reported to be F. americana and F. mandschurica (reference).

Common Polypody, Polypodium vulgare

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I love ferns. In shady, moist conditions it’s possible to grow many varieties. But where the soil is drier, it’s still possible to grow one species of fern, the Common Polypody, Polypodium vulgare.

The Common Polypody is a tough and resilient perennial and, once established, it thrives in dry conditions. In the wild it grows in the forks of tree branches and on top of dry banks and drystone walls. In very dry weather the fern will roll up its leaves to conserve water, but rain will cause the leaves to unfurl again. It is an evergreen plant, so it provides lovely greenery throughout the year. We planted it beneath Birch and Italian Alder trees at the Belvedere Centre in Norwich, where it has established well.

For gardeners, Polypodium vulgare is a very useful plant. Several varieties can be grown, as well as the related Licorice Fern, Polypodium glycyrrhiza ‘Longicaudatum’.

In the wild, the Common Polypody can be found almost throughout Britain (see map). It is easy to tell that it’s a Polypody, but less easy to pin it down to species. There are actually three species of Polypodium in the British Isles: Polypodium vulgare, P. interjectum and P. cambricum, as well as hybrids between the species.

In Norfolk, we have P. vulgare, P. interjectum and P. x mantoniae (a hybrid between P. vulgare and P. interjectum). P. vulgare tends to grow in more acidic conditions than P. interjectum, which likes slightly alkaline growing conditions, whether from the mortar on walls or from salt-bearing seaside winds. Polypodium cambricum perfers milder winters and has a more south-westerly distribution in the British Isles.

You need to look closely at the ferns to make an identification. Although leaf shape can be a useful guide, the real test relies on the structure of the sporangium (plural sporangia), the structure that encloses the spores and, when they are ripe, catapults them away from the parent plant. (See also http://blogs.scientificamerican.com/artful-amoeba/wonderful-things-ferns-eject-their-spores-with-medieval-style-catapults/.) There are some good photos of Polypodys on the Nature Spot website, and more information on the Fern Id and Ferns In Britain and Ireland websites.

The Plants for a Future website reports that the root can be eaten and has a “unique, rather unpleasant odour and a sweet (cloying) flavour at first though it quickly becomes nauseating”. The plant also has several possible medicinal uses.

Common Polypody

Polypody ferns, Polypodium sp., growing on the North Norfolk coast

Updated 18th January 2016 with details of other Polypodium species found in the British Isles.

Tree Planting at Wensum View Park

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I spent yesterday morning leading a task to fruit trees and an edible hedge at Wensum View Park in Norwich.

I wrote about the park in March last year, when we’d just planted some bulbs.

Since then, Norwich City Council have held a public consultation and, following favourable comments to the proposals to establish a community garden in the park, work to transform the space began this autumn.

So far there have been two gardening tasks, which I have led.

In early October we created a herb bed and planted crocus bulbs. Then yesterday about twenty-five of us planted fruit trees and an edible hedge. A Norfolk Master Gardener Grant for £45 went towards the cost of the fruit trees and the 105 small saplings for the edible hedge were supplied by the Woodland Trust. The rest of the money came from the Norfolk Community Foundation.

We planted nine fruit trees: single trees of Apples “Golden Noble” and “Discovery”, Figs “Brunswick” and “Brown Turkey”, Medlar “Nottingham” and Quince “Champion”, two Plums “River’s Early Prolific” and an unnamed variety of Plum, which was donated by a local resident. The hedge consists of Elder, Dog Rose, Blackthorn, Hazel and Crab Apple and will add to the edible harvest once it is established.

Our next task, planned for January or February 2014, will be to build a raised bed for planting herbs and vegetables.

Wensum View Park Community Garden Group have now signed up for Master Gardener support and I will continue to provide them with free growing advice for the next twelve months.

Wensum View Park (also known as “Wensum View play area”) is located on Dereham Road in Norwich. Its entrance is between numbers 319 and 321 Dereham Road and it is open to all, free of charge, every day during daylight hours.

Tree planting at Wensum View Park

Tree planting at Wensum View Park

Finished Planting

The fruit trees and hedge