invasive species

Ash trees that survive ‘dieback’ may struggle to fend off bugs

Ash trees that can resist the deadly dieback fungus may be more vulnerable to attacks by insects, according to new research.

Scientists examined trees that are resistant to ash dieback and were surprised to find the trees had very low levels of chemicals that defend against insects.

With efforts under way to protect ash trees from dieback, the scientists warn that selecting trees for fungal resistance could put them at risk to attacks from pests.

dead ash trees
(Credit: BarbaraLN/Flickr)

Aside from ash dieback, the other major threat to European ash trees is the emerald ash borer beetle, which has already devastated vast tracts of ash in the United States and is currently spreading westwards across Europe.

“Our research highlights the danger of selecting trees for resilience to ash dieback at the expense of resistance to insects that threaten this iconic UK tree species,” says joint lead author Christine Sambles of the University of Exeter.

“Ash dieback, which is caused by a fungus called Hymenoscyphus fraxineus, can kill young trees in a season.”

“Ash dieback, which is caused by a fungus called Hymenoscyphus fraxineus, can kill young trees in a season, while older trees tend to decline and die over several years.”

The research, published in the journal Nature, is part of a study involving several universities and government institutes which looked at the DNA of ash trees in the hope of identifying ash dieback resistance.

Emerald Ash Borer invaded N. America earlier than we thought

Instead of focusing on DNA, the scientists looked at differences in chemical composition between tolerant and susceptible ash trees.

“Plants use a vast range of chemicals to defend against fungal attack, and the primary objective was to identify differences which could be used to screen young ash trees and choose the best ones for replanting,” says study coauthor Murray Grant, a professor at the University of Warwick.

“Our findings underline the need for further research to ensure that we select ash trees resilient to present and future threats,” says Grant.

Source: University of Warwick

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