rust (redirected from Chemistry rust)

rust, in botany

rust, in botany, name for various parasitic fungi of the order Uredinales and for the diseases of plants that they cause. Rusts form reddish patches of spores on the host plant. About 7,000 species are known. Some grow entirely on one plant; others require two hosts, plants of two species, in order to complete their life cycles. Cedar rust, for instance, grows on cedar and on apple trees, needing both for development. Blister rust of pine grows on pines and either currant or gooseberry bushes. Black stem rust Puccinia graminis is one of the most destructive to wheat, rye, and other grasses; barberry is an alternate host. Rusts attack all cereal crops and many fruits, vegetables, forage crops, ornamental plants, and forest trees. Rusts are hard to eradicate; control measures include the use of rust-resistant varieties of seed and the elimination of alternate hosts in agricultural areas. Rusts are classified in the kingdom Fungi, phylum (division) Basidiomycota, order Uredinales.

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rust

1. a reddish-brown oxide coating formed on iron or steel by the action of oxygen and moisture

2. a strong brown colour, sometimes with a reddish or yellowish tinge

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rust [rəst]

(metallurgy)

The iron oxides formed on corroded ferrous metals and alloys.

(plant pathology)

Any plant disease caused by rust fungi (Uredinales) and characterized by reddish-brown lesions on the plant parts.

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Rust (microbiology)

Plant diseases caused by fungi of the order Uredinales and characterized by the powdery and usually reddish spores produced. There are more than 4000 species of rust fungi. All are obligate parasites (require a living host) in nature, and each species attacks only plants of particular genera or species. Morphologically identical species that attack different host genera are further classified as special forms (formae speciales); for example, Puccinia graminis f. sp. tritici attacks wheat and P. graminis f. sp. hordei attacks barley. Each species or special form can have many physiological races that differ in their ability to attack different cultivars (varieties) of a host species. Rusts are among the most destructive plant diseases. Economically important examples include wheat stem rust, white pine blister rust, and coffee rust. See Uredinales

Rust fungi have complex life cycles, producing up to five different fruiting structures with distinct spore types that appear in a definite sequence. Macrocyclic (long-cycled) rust fungi produce all five spore types, whereas microcyclic (short-cycled) rust fungi produce only teliospores and basidiospores. Some macrocyclic rust fungi complete their life cycle on a single host and are called autoecious, whereas others require two different or alternate hosts and are called heteroecious. See Fungi, Plant pathology