Rust

Rusts are diseases caused by fungal pathogens of the order Pucciniales. The taxonomy of this order is complex and the darker coloured smut is often mistaken for rust. About 2000 species are known. Rusts are so-named after the reddish rusty looking spores and the disease is usually noticed after the first rains. The group is considered as one of the most dangerous pathogens to agriculture and horticulture. Cereal crops can be devastated in one season and trees that get infected in the main stem within the first five years, invariably die. The disease is known as a foliar disease but it can affect a variety of plants; leaves, stems, fruits and seeds. It is not a common disease, but can be fatal in a severe attack during summer.

Species

 * Aecidium cantensis
 * Potato deforming rust
 * Arthuriomyces peckianus
 * Orange rust of Rubus
 * Coleosporium helianthi
 * Yellow rust of Helianthi
 * Puccinia
 * P. allii
 * Onion rust
 * P. aristidae
 * Red rust
 * P. horiana
 * Chrysanthemum white rust
 * P. menthae
 * Mint rust
 * P. tanaceti
 * Brown rust

Symptoms
Orange spores can be seen on the surface of foliage.

Treatment
Diseased leaves should be cut from the plant and burnt. Common fungicides containing sulfur generally halt the progress of rust.

Prevention
Avoid watering from above, water the base of plants or use a soaker hose. Do not grow leeks or onions on affected land for 1 year.