Fungus Fact Friday

Tagged: disease

fungi that cause disease

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Fungus Fact

#019: Apiosporina morbosa, Black Knot

And now for something completely different: how to recognize different types of trees from quite a long way away.*  Black Cherry (Prunus serotina) is the easiest tree in eastern North America to identify, thanks to the fungus Apiosporina morbosa, commonly known as Black Knot.  Most Black Cherry trees are infected with A. morbosa, which causes dark swellings on branches and trunks.  Older tree trunks are often marred by large swellings caused by A. morbosa that are up to twice the size of the trunk.  These “knots” are easy to spot from a distance (especially in winter), so take advantage of this and amaze your friends by pointing out Black Cherry trees without relying on bark, leaves, or other details!  On twigs and smaller branches, Black Knot makes the branches lumpy and thickened in places, looking remarkably like “dried cat poop on a stick” (thank Michael Kuo for that apt analogy).

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Fungus Fact

#228: Dutch Elm Disease

Elm trees were once the defining tree of American life, widely planted in cities, suburbs, and farms.  This changed beginning in the early 1900’s when Dutch Elm Disease arrived on the continent.  Caused by the fungi Ophiostoma ulmi and O. novo-ulmi, Dutch Elm Disease blocks off the water transportation tissues in elm trees, leading to wilting and death.  The fungus moves between trees by using elm bark beetles as vectors and by growing from tree to tree, making it a difficult pathogen to control.  The best way to manage Dutch Elm Disease today is by planting resistant cultivars – fortunately, there are many resistant options available.

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News Update

2018 Fall and Winter Fungal News Update

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of news stories that have taught me something about fungi from September through December 2018. Read each summary to learn about: zombie ants, mushroom poisonings, White Nose Syndrome, Bananas, and more.

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Fungus Fact / That's Not A Fungus!

#224: Pythium insidiosum, Pythiosis

It’s a new year and already a fungus-like disease is making national headlines.  Four wild ponies on Chincoteague were euthanized due to a disease called “Swamp Cancer” on December 28, 2018, bringing the total Chincoteague ponies killed by the disease in 2018 up to seven.  Swamp Cancer is not a cancer at all; the disease is caused by the oomycete Pythium insidiosum.  If you have a pet you may have heard of this disease before: P. insidiosum occasionally infects dogs and cats, often killing its hosts.  Rarely, P. insidiosum causes disease in humans.  P. insidiosum normally decays plant matter in flooded tropical to sub-tropical environments, so it is most often contracted in warm stagnant water.  Because it reproduces only in those environments, P. insidiosum cannot spread from one animal to another.

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Fungus Fact

#222: Cryphonectria parasitica, Chestnut Blight

The American Chestnut Tree, Castanea dentata, was once one of the dominant trees in eastern North American forests. It rivalled oak trees in terms of size and abundance. The trees were also highly valued for their rot-resistant wood and edible seeds, making it one of the most economically important trees in eastern North America. So, if the trees were so common and so important, where are they today? The downfall of the American Chestnut began in New York in 1904, when a disease called Chestnut Blight suddenly appeared and swept across the continent. By 1950, the disease had infected and killed almost every American Chestnut. Chestnut Blight is caused by the Asian fungus Cryphonectria parasitica, which grows in the outer wood of the tree and essentially chokes trees to death. The aggressive pathogen has doomed the American Chestnut to extinction, unless humans can come up with a solution.

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News Update

2018 Summer Fungal News Update

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of news stories that have taught me something about fungi from mid-May through Early September 2018. Read each summary to learn about: zombie ants, mushroom poisonings, White Nose Syndrome, Bananas, and more.

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Fungus Fact

#020: Aleurodiscus oakesii, Smooth Patch Disease

Aleurodiscus oakesii is an unusual mushroom that grows on living trees but isn’t considered a parasite. The fungus decomposes the outer layer of hardwood tree bark. This doesn’t harm the bark but does cause smooth patches (thus the name “Smooth Patch Disease”). The mushrooms themselves appear occasionally inside these smooth patches. Each mushroom is a small tan roughly circular crust fungus, so some other common names for the fungus include: “Oak Parchment,” “Hop Hornbeam Disc,” and “Oake’s Crust.” These nondescript mushrooms are easier to identify by their ecology than morphology.  Additionally, you can always see the smooth patches, but the mushrooms are more elusive.  Despite regularly finding smooth patches, it took me four years to find the actual mushrooms.

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Fungus Fact

#221: Massospora cicadina

It’s hard being an insect. Despite being numerous, insects have many predators, have to deal with human pesticides and cars, and are susceptible to dreadful fungal pathogens. Some of these entomopathogenic fungi take control of their hosts’ bodies in innovative but disturbing ways. One such fungus is Massospora cicadina, which infects periodical cicadas (Magicicada spp., which appear in eastern North America every 13 or 17 years). After spending over a decade in the soil waiting for its hosts to emerge, the fungus infects the cicadas and causes their abdomens to pop off. The cicadas then fly around and try to mate with each other, spreading the fungal infection both through the air and through contact. It’s hard to imagine a more horrific sexually transmitted infection, even in the insect world.

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News Update

Spring 2018 Fungal News Update

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of news stories that have taught me something about fungi from mid-February through mid-May 2018. Read each summary to learn about: gut fungi, ambrosia beetles, gravity detection, prehistoric mushroom use, diseases of toes, ants, frogs, bats, and ohia trees, and more.

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Fungus Fact

#081: Phellinus robiniae, the Cracked Cap Polypore

Phellinus robiniae, commonly known as the “Cracked Cap Polypore,” is a woody bracket fungus that is most easily identified by its habitat. This fungus grows almost exclusively on locust trees. In fact, the fungus is such a common pathogen of locusts that nearly every Black Locust tree has at least one P. robiniae mushroom on it. The mushroom is also distinguished by its furrowed cap – which gives the fungus its common name – and its dull brown pore surface.