Canna rust a medium threat to biosecurity and agriculture. The Canna rust damages the crop and can impact all of its potential uses by damaging photosynthetic material and reducing plant productivity and value. In the United States it is a popular ornamental for home gardens. The rust lowers the value of lilies for sale and can kill canna plants that home gardeners are trying to grow themselves. Canna rust Canna rust is a fungal disease of canna caused by "Puccinia thaliae". Symptoms include yellow to tan spots on the plant's leaves and stems. Initial disease symptoms will result in scattered sori (clustered
Rust for corrosion of iron and its alloys, such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called rust. Other forms of rust exist, like the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in underwater concrete pillars, which generates green rust, is an example. Although rusting is generally a negative aspect of iron, a particular form of rusting, known as "stable rust," causes the object to have a thin coating of rust over the top, and if kept in low relative humidity, makes the "stable" layer