![chestnut blight chestnut blight](https://acf.org/wp-content/uploads/2017/04/04-Chestnut-Blight.jpg)
By 1940, most mature American chestnut trees had been wiped out by the disease. In 1905, American mycologist William Murrill isolated and described the fungus responsible (which he named Diaporthe parasitica), and demonstrated by inoculation into healthy plants that the fungus caused the disease. It was first found in the chestnut trees on the grounds of the New York Zoological Garden (the "Bronx Zoo") by Herman W. The chestnut blight was accidentally introduced to North America around 1904 when Cryphonectria parasitica was introduced into the United States from East Asia from the introduction of the cultivation of Japanese chestnut trees into the United States for commercial purposes. These two species have co-evolved with the pathogen, making them resistant to its ill effects. mollissima) and the Japanese chestnut ( Ca. The fungus originally infects the Chinese chestnut ( Ca. However, these regrown shoots seldom reach the sexually reproductive stage before being killed by the fungus. The root collar and root system of the chestnut tree have some resistance to blight infection due to soil organisms adversely reacting to the fungus consequently, a large number of small American chestnut trees still exist as shoots growing from existing root bases. Infection is local in range, so some isolated American chestnuts survive where there is no other tree within 10 km (6.2 mi). The fungus is spread by wind-borne ascospores and, over a shorter distance, conidia distributed by rain-splash action. The pathogen can persist in these trees, producing spores that may infect other trees.
![chestnut blight chestnut blight](https://cached.imagescaler.hbpl.co.uk/resize/scaleWidth/885/cached.offlinehbpl.hbpl.co.uk/news/WOH/Cryphonectria_sweet-chestmut-blight_WkmC-20170707035243216.jpg)
Once infected, these trees also exhibit orange bark with cankers but they do not die. The fungus can infect other tree species such as oaks, red maples, staghorn sumacs, and shagbark hickories. sativa) is also susceptible but due to widespread CHV1 hypoviruluence, blight-induced tree death is less common. pumila) are highly susceptible to chestnut blight. The American chestnut ( Castanea dentata) and American chinquapin ( Ca. CHV1 is one of at least two viral pathogens that weaken the fungus through hypovirulence and helps trees survive. Less severe impacts have occurred in Europe due to widespread CHV1-induced hypovirulence. In the first half of the 20th century it killed an estimated four billion trees - or by another count 3.5 billion trees through 2013. The fungal disease has had a devastating economic and social impact on communities in the eastern United States.
![chestnut blight chestnut blight](https://bugwoodcloud.org/images/1536x1024/5507877.jpg)
Naturally found in South East Asia, accidental introductions led to invasive populations of C. This disease came to be known as chestnut blight.