News - October 27, 2016

Wageningen is creating a resistant ash

Roelof Kleis

Nearly all the ash trees along the provincial roads in Gelderland are being uprooted as they are suffering from ash dieback. This fungal disease is also causing damage elsewhere in the country. Does that mean the end of ash trees in the Netherlands? No. Wageningen scientists are creating an ash that can cope with the disease.

Ash dieback is the name for the disease that ash trees get when they become infected with Chalara fraxinea, a fungus that has spread from Southeast Asia to Europe. The disease was first observed in the Netherlands in 2010. Trees that become infected lose their leaves and eventually die.

Gelderland is not waiting until the trees fall over. The provincial authority has announced that it will be taking down trees along the provincial roads. About 90 percent of all ash trees will be felled. The tree expert Sven de Vries, who has just retired from his job at Wageningen Environmental Research, is critical of that decision. He says it is definitely not the case that all the trees are affected. That could mean trees will be felled that are resistant to the fungus.

That such variants exist is revealed by research started up by De Vries and his colleague Jitze Kopinga (who is also retired). They sounded the alarm for the ash three years ago. Their crowdfunding campaign ‘Save the ash’ prompted a couple of tree nurserymen to take action. According to De Vries, it is clear by now that the ash can be saved.

'Save the ash'-initiators Jitze Kopionga and Sven de Vries
'Save the ash'-initiators Jitze Kopionga and Sven de Vries

De Vries searched various trial fields in the Netherlands for ash trees that had not been affected by the fungus, and found them. The genetic tolerance in these trees was then used to breed resistant varieties. This was followed by multiplication, and there are now hundreds of ‘clean’ saplings ready and waiting.

The idea is that field trials will show how resistant they are. To test this, they are deliberately being infected with the fungus or being planted in among infected trees around the country. Paul Copini, De Vries’ successor, will be doing this.