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Rapid screening for Chalara resistance using ash trees currently in commercial nurseries - TH0132

It is estimated that there are between 1 million and 2 million ash seedlings currently in British nurseries. These seedlings will soon be destroyed by the nursery owners’ as the space they occupy is required to raise new stock of alternative species. Meanwhile, information from Denmark suggests that around 1% of ash trees demonstrate an increased level of resistance. The ash trees in the beds of commercial nurseries represent a massive resource if they could be subjected to mass screening for Chalara tolerance.

It is proposed to identify up to 25 sites along the eastern portion of England where Chalara is already present and plant large number of ash trees which would immediately be subjected to the disease.

Each site will be a minimum of 2 hectares in size and will be planted at a higher than normal density of 5,000 trees/ha. This design represents 10,000 planted trees/site (minimum) which might result in 100 trees per site showing higher degrees of resistance; or 2,500 trees if all 25 sites are planted. If available, larger sites will be selected and the number of sites will be reduced such that the total area does not exceed 50ha. The total number of ash tree planted will be 250,000.

Sites will be planted on land belonging to:
i. Forestry Commission,
ii. Land-based charities
iii. Individual private owners.

It is envisaged that the experiments would have a life of 5-years after which the more resistant individuals would be identified for further breeding work.

The experiments will contain a good representation of the 24 Native Seed Zones (provenances) from across Britain ( sourced from a wide spread of currently Chalara-free nurseries. If possible the trial will also include sources from native woodlands, the Future Trees Trust ash seed orchard, and perhaps representative material from Europe.

The sites will be fully maintained for a 5-year period after which time the surviving trees will be identified.

Fast establishment of new ash woodlands will benefit both the ash timber industry and provide ecosystem services for the public good (e.g. woodland biodiversity, landscape value). Ash represents some 5% of woodland cover in Britain. Ash is used widely in the joinery and furniture production industry which could be lost due to the Chalara infestation. Also, new resistant woodland would prevent the lost of a precious ecosystem which supports some 140 insect species, 60 of which are among the rarest insect species in the UK and are sanctuaries for rare woodland flowers, mosses, and important lichens.
1. Identify and source the widest range of UK provenances within the current UK nursery supplies (at least, but not limited to, 10 UK provenances, plus a limited number of wider European provenances as appropriate and as available).

2. Establish and maintain experimental sites (25 x 2 ha sites, or equivalent area) that exposes seedlings from the widest range of provenances (obtained from objective 1) to high levels of Chalara fraxinea inoculum.

3. Assess resistance across the planted provenances and facilitate the exploitation of any identified resistance in breeding programmes (e.g. via Future Trees Trust).

4. Provide information and tissue as appropriate for the Defra and BBSRC co-funded Nornex project.
Time-Scale and Cost
From: 2013

To: 2018

Cost: £824,000
Contractor / Funded Organisations
Forest Research Agency