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The fungal ancestors of stem rust have infected grasses for millions of years and wheat crops for as long as they have been grown. [7] According to Jim Peterson, professor of wheat breeding and genetics at Oregon State University, "Stem rust destroyed more than 20% of U.S. wheat crops several times between 1917 and 1935, and losses reached 9% twice in the 1950s," with the last U.S. outbreak in ...
Puccinia graminis is a macrocyclic heteroecious fungus that causes wheat stem rust disease. [citation needed] The sexual stage in this fungus occurs on the alternate host – barberry – and not wheat. The durable spore type produced on the alternate host allows the disease to persist in wheat even in more inhospitable environments.
Wheat rusts include three types of Pucciniae: P. triticina , wheat leaf rust , leaf rust, wheat brown rust, or brown rust P. graminis , stem rust , wheat stem rust, barley stem rust, or black rust
Cronartium ribicola (White pine blister rust): the primary host are white pines, and currants the secondary. Hemileia vastatrix (Coffee rust): the primary host is coffee plant, and the alternate host is unknown. Puccinia graminis (Stem rust): the primary hosts include Kentucky bluegrass, barley, and wheat; barberry is the alternate host.
Other cereal rust fungi have macrocyclic, heteroecious life cycles, involving five spore stages and two phylogenetically unrelated hosts. P. striiformis was thought to be microcyclic for centuries until 2009, when a team of scientists at the USDA-ARS Cereal Disease Lab led by Yue Jin confirmed that barberry (Berberis and Mahonia spp.) is an alternate host. [3]
The Puccinia species causing wheat leaf rust has been called by at least six different names since 1882, when G. Winter (1882) described the Puccinia rubigo-vera. [5] During this time, wheat leaf rust was interpreted as a specialized form of P. rubigo-vera. Later, Eriksson and Henning (1894) classified the fungi as P. dispersa f.sp. tritici.
More common "base" metals can only be protected by more temporary means. Some metals have naturally slow reaction kinetics, even though their corrosion is thermodynamically favorable. These include such metals as zinc, magnesium, and cadmium. While corrosion of these metals is continuous and ongoing, it happens at an acceptably slow rate.
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