The Blight. Student Objectives Friday, September 18, 2015 After today’s lesson, you will be able to: Identify and describe what happened to the American.

The Blight

Student ObjectivesWednesday, April 19, 2023

After today’s lesson, you will be able to:• Identify and describe what happened to the American

Chestnut– Describe the fungus that caused the blight.

• Realize the significance of the loss of the American chestnut tree population.

Warm-up

• Brainstorm what the following words mean and how they relate to one another…– BLIGHT– FUNGUS– AMERICAN CHESTNUT

Today’s Activities

• Research and define FUNGUS

• Set-up a lab to grow fungus

• Describe how a fungus can kill a tree

Range

http://www.apsnet.org/online/feature/chestnut/

This is where they were, but they aren’t anymore

Discussion--What do you know?

• Look at the section of the Chestnut tree– What is the blight?– What caused it?

• Where did it come from?

– What was the end result?• What effect did the blight have on

the American Chestnut?

Demise of the Native American Chestnut

• In 1904, cankers (tree sores) were evident in New York City

• By 1926, the fungus was reported throughout the native range.

• Some trees were still blight free due to isolation until cankers were found in 1986.

http://www.apsnet.org/online/feature/chestnut/

• By 1940, virtually all the chestnut trees in the native range (an estimated 4 billion) were either dead or infected with the blight

• What had happened by 1950?

• Are there surviving trees?

• Infects trunk and branches – Only above ground parts of trees

active growth & sporulation

Chestnut Blight

Canker

Notice h

ow the

tree l

ooks like

it has

a blis

ter

What is a fungus?

• The blight is caused by a fungus• Cryphonectria parasitica• A member of the fungus kingdom

– A heterotroph/consumer (eats something else)

• Specifically a decomposer that eats dead, decaying matter

– multicellular

Fungus Reproduction• Reproduces asexually

– They create spores which float through air and land on substances

– If the substances meet the 4 basic needs of the spore, it will grow into the fungus

• Food, water, space, oxygen

– As it grows, it reproduces asexually and creates more spores

• This is how the fungus spread over the entire east coast

Other fungus among us…

• Ringworm

• Athlete’s foot

• Yeast Infections

• Mold

• Mushrooms

First discovered in 1904 in New York City, the blight - an Asian fungus to which our native chestnuts had very little resistance - spread quickly. In its wake it left only dead and dying stems. By 1950, except for the shrubby root sprouts the species continually produces (and which also quickly become infected), the keystone species on some nine million acres of eastern forests had disappeared.

Where did the fungus come from?

How does it kill the tree?• Enters through fissures or

wounds in the bark• Grows in and under the

bark, girdling the cambium.– Cambium is the only

living layer of the tree– Girdling means to

surround the tree, eating into the living layer

• Kills the tree above the point of infection by cutting off it’s supply of water and nutrients

• Causes swollen or sunken orange-colored cankers on the limbs and trunks of the chestnut trees.

• According to Dr. Donald L. Nuss at the University of Maryland, blight cankers that are swollen indicate that the tree is sucessfully fighting the blight.

• Sunken cankers indicate advancing disease

How does it kill the tree?

• The leaves above the point of infection die, followed by the limbs.

• Within two to ten years the entire tree is dead.

• Not uncommon to find many cankers on one tree

How does it kill the tree?

The fungus has girdled the tree and is producing yellow spores

Sprouts from Old Stumps

• New sprouts will grow up from the stumps of fallen, dead chestnut trees.

• Many sprouts will die due to the blight and the cycle will repeat.

Population of ChestnutsToday

• Some of the sprouts may become the size of a small tree

• The problem is that before these trees can reach any considerable size, the blight infects and kills the trees.

Closure:

• What is a fungus?

• How does it’s way of reproduction make it so successful at killing the trees?