WhatFinger


A faint ray of hope: Journal of Integrated Pest Management outlines a set of four options for communities to choose from as they plan for the impact of emerald ash borer.

A Kick in the Ash



A Kick in the Ash Fraxinus are threatened with extinction. North American species are under attack by an invasive East Asian beetle. In Europe, native ash is being decimate by a fungus, also apparently from the East. Despite dire and increasingly ominous warnings, most people seem entirely oblivious to these threats. On both sides of the Atlantic, the various species of ash have long been valued as both ornamental and timber trees. The European Ash, Fraxinus excelsior, is also steeped in mythology. It provided the wood for the spear hafts of Beowulf and King Arthur. Robin Hood and Little John dueled with quarter staves of F. excelsior--movies invariably depict such incorrectly. The resilient and shock-absorbing wood made it ideal for lances in the days of chivalry. Less militaristically, ash provided poles to grow hop vines on and for walking sticks. All this despite that most ash are dioecious--they may change sex with age from male and hermaphrodite to female. The winged seeds, or samura, in times gone by were recommended for flatulence; even pickled.
All this is threatened by highly invasive and fatal fungus, Hymenoscyphus fraxineus, known with grim accuracy as Ash Dieback. Diagnosed in the Moscow region late in the twentieth century, it reached Europe by the mid-1990s. In Denmark, 90% of the country's ash trees were reported infected. By October 2012 it was identified in a wood in the county of Suffolk, eastern England. Before that date it had only been detected on nursery stock imported from the EU. No measures appeared to contain the pathogen. By 2016 ash was reported as in danger of extinction in Europe. North America has not just one but sixteen species of ash. White Ash, Fraxinus americana, may grow to be an enormous tree with wide spreading but shallow roots Early settlers valued tough, elastic timber to provide their essential hoe and shovel handles, along with scythes, hay forks, and ploughs as well as oars for their boats. The sporting set relied on F. americana to provide the wherewithal for baseball bats, hockey sticks, polo mallets, and tennis racket frames. The leaves were said to relieve the itch of mosquito bites. The wood of Green Ash, Fraxinus pensylvanica, was crafted into canoe paddles. In the wild, it favoured river banks and lake sides, being able to withstand heavy wet clay soils. But it was found to be equally tolerant of urban conditions and became widely planted as a street tree--perhaps too widely as later events were to prove. North American ash are a colourful lot. Besides White and Green Ash, we have Red Ash, an alternate name for Green Ash (Fraxinus pensylvanica), Black Ash (Fraxinus nigra) and Blue Ash (Fraxinus quadrangulate). All may be doomed by Agrilius planipennis, Emerald Ash Borer, usually abbreviated in modern style to EAB. It arrived in North America from eastern Asia in solid wood packing late 1980s and early 1990s. Initially detected in Michigan it has since spread to devastate ash trees across 22 states plus the Canadian provinces of Ontario and Quebec. Late last year it was identified on street trees in Winnipeg, Manitoba and now in New Brunswick. Over north-eastern and central North America it is estimated to threaten seven billion ash trees. A faint ray of hope lies in the release of three predator wasps from Asia. Also, a paper published in the open-access Journal of Integrated Pest Management outlines a set of four options for communities to choose from as they plan for the impact of emerald ash borer.

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Wes Porter -- Bio and Archives

Wes Porter is a horticultural consultant and writer based in Toronto. Wes has over 40 years of experience in both temperate and tropical horticulture from three continents.


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