what is dutch elm disease and how does it spread
Dutch elm disease Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into America and Europe, where it has devastated native populations of elms that did not have resistance to the disease. It has also reached New Zealand. The name "Dutch elm disease" refers to its identification in 1921 and later in the Netherlands by Dutch phytopathologists Bea Schwarz and Christine Buisman who both worked with Professor Johanna Westerdijk.[1][2] The disease affects species in the genera Ulmus and Zelkova, therefore it is not specific to the Dutch elm hybrid.[3][4][5]
History of smallpox After first contacts with Europeans and Africans, some believe that the death of 90–95% of the native population of the New World was caused by Old World diseases.[39] It is suspected that smallpox was the chief culprit and responsible for killing nearly all of the native inhabitants of the Americas. For more than 200 years, this disease affected all new world populations, mostly without intentional European transmission, from contact in the early 16th century to until possibly as late as the French and Indian Wars (1754–1767).[40]