Tree Health in England

Lord Harries of Pentregarth Excerpts

Thursday 9th June 2022 Grand Committee

Asked by

[Lord Harries of Pentregarth]

To ask Her Majesty’s Government what assessment they have made of the health of trees in England; and what progress they have made towards developing a variety of ash that is resistant to ash dieback.

[Lord Harries of Pentregarth (CB)]

I know that two fundamental assumptions will underly all the contributions to this debate by your Lordships: first, trees are absolutely essential for the environment, the future of the climate and human well-being; secondly, many of them are in a very poor state indeed. They are under threat, notably because of ash dieback.

In 2018 the Government produced their Tree Health Resilience Strategy. Four years later is a very good time to ask the Government what progress has been made on what they set out to do in that. What success has there been? I know your Lordships will want to focus on a range of issues, not least bio protection, but I want to concentrate on ash and elms.

We know how ash dieback came into the country, how rapidly it spread and how devastating its effect has been. But there is some good news to report. In 2009 it was reported that researchers from Queen Mary University of London and Kew sequenced the DNA from over 1,250 ash trees to find inherited genes associated with ash dieback resistance. About this, Professor Richard Nichols said:

“Now we have established which genes are important for resistance we can predict which trees will survive ash dieback. This will help identify susceptible trees that need to be removed from woodlands, and provide the foundations for breeding more resistant trees in future.”


This is obviously very hopeful, but the words are “This will help”. It would be good if the Minister could say anything more certain about how far it is now possible to identify resistant trees and whether they are being successfully developed.

There is more good news. Research from the Nornex project led by the John Innes Centre in Norfolk was reported in April. It has developed three genetic markers which enable it to predict whether a tree is likely to be tolerant of disease, and even whether it is likely to be mildly or strongly tolerant. In particular, it has developed a tree it has named Betty that shows strong tolerance. Again, it would be good if the Government could say any more about the timescale and when any significant proposals for replanting might come about.

All this is encouraging, and I recognise that this kind of research is complex and time consuming, but there is an urgency about this task. It is now some 50 years since the devastation caused by Dutch elm disease. It was once one of the most familiar and loved trees of the English landscape, painted by John Constable among others, but 25 million elms were wiped out: 90% of the population. Again, there is some good news to report here. Apparently, in 2019 some elms resistant to the disease had been developed, but the information is somewhat sparse.

More recently, nursery and garden centre company Hillier has described a variety of elm called Ulmus New Horizon that it states is 100% resistant to Dutch elm disease. It has been cultivated since the 1990s, but it took until 2019 to build enough stock to launch it commercially. This is not a native English elm and, from what has been said, it looks as though we will not be able to get native elms back, but it is a closely related hybrid.

It is also worth noting the Great British Elm Projects, which stated:

“This involved a propagation programme … of a large number of Sapporo Autumn Gold elms, a disease resistant hybrid developed by the University of Wisconsin.”


I also note the Centre for Forest Protection, which was established as part of the 2021 English trees plan and launched in May this year along with the new Forest Research Holt Laboratory. Their work will be vital for the future.

A lot is going on around the place, and I recognise that research takes a long time, especially with slow-growing organisms such as trees, but with the kind of genetic testing now being used for the ash, which was simply unavailable 50 years ago for the elm, surely it must be possible to speed up research and replanting. We cannot afford to wait 60 years for the ash, as we have for the elm. There is an urgency because of climate change. As has been well put:

“Trees are the ultimate carbon capture and storage machines. Like great carbon sinks, woods and forests absorb atmospheric carbon and lock it up for centuries … They also … help … Prevent flooding … Reduce city temperature … Reduce pollution … Keep soil nutrient-rich”.


The Government have a policy to try to increase tree planting. Their target, as set out in 2018, was to increase tree cover in England to 12% by 2060 by planting 180,000 hectares of trees, including a new northern forest. Can the Minister say anything more about what progress has been achieved towards that target?

To conclude, there is good news, but there is urgency about this task. If more money was put into research in this area, would it in fact speed it up? If it would, it would surely be justified. It is obvious from what I have said that research is going on in all sorts of different institutions in different places. Does Defra have a special subunit monitoring what is going on and keeping on top of it? It would be very useful if it had, because this information needs to be widely propagated and kept under permanent review.