rust

/rust/, n.

1. Also called iron rust. the red or orange coating that forms on the surface of iron when exposed to air and moisture, consisting chiefly of ferric hydroxide and ferric oxide formed by oxidation.

2. any film or coating on metal caused by oxidation.

3. a stain resembling this coating.

4. any growth, habit, influence, or agency tending to injure, deteriorate, or impair the mind, character, abilities, usefulness, etc.

5. Plant Pathol.

a. any of several diseases of plants, characterized by reddish, brownish, or black pustules on the leaves, stems, etc., caused by fungi of the order Uredinales.

b. Also called rust fungus. a fungus causing this disease.

c. any of several other diseases of unknown cause, characterized by reddish-brown spots or discolorations on the affected parts.

6. reddish yellow, reddish brown, or yellowish red.

v.i.

7. to become or grow rusty, as iron.

8. to contract rust.

9. to deteriorate or become impaired, as through inaction or disuse.

10. to become rust-colored.

v.t.

11. to affect with rust.

12. to impair as if with rust.

13. to make rust-colored.

14. rust out, (of metal pipes, machinery, etc.) to decay and become unusable through the action of rust.

15. rust through, to develop holes, breaks, or the like, because of rust.

16. rust together, to join two metal pieces, as iron pipes, by causing the joint to rust.

adj.

17. having the color rust.

[bef. 900; (n.) ME; OE rust; c. G Rost; (v.) ME rusten, deriv. of the n.; akin to RED]

Syn. 2. corrosion. 9. decay, decline.

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▪ plant disease

      disease of thousands of economically important plants, as well as weeds, caused by more than 4,000 species of fungi.

      During their life cycle rust fungi parasitize either one species of plant (autoecious, or monoecious, rust) or two distinct species (heteroecious rust). One heteroecious rust with five spore forms during its life cycle is black stem rust (Puccinia graminis) of wheat and other cereals and grasses. Other heteroecious rusts include those that use junipers (red cedar) as one host and apple, Japanese quince, hawthorn, rose, and related plants as the other; white pine rust (Cronartium ribicola), with five-needled pines as one host and currant and gooseberry (Ribes) species as the other; and a rust with Douglas fir as one host and poplars as the other. Autoecious rusts include those that attack asparagus, bean, chrysanthemum, coffee, hollyhock, snapdragon, and sugarcane.

      Rust usually appears as yellow, orange, red, rust, brown, or black powdery pustules on leaves, young shoots, and fruits. Plant growth and productivity are commonly reduced; some plants wither and die back. Control involves growing resistant varieties and rust-free plants; destroying one of the alternate host plants within several hundred yards of the other; observing stringent sanitation measures; and spraying or dusting at 7- to 10-day intervals, starting two weeks before rust normally appears, using appropriate fungicides.

      White rust, caused by several fungi in the genus Albugo, differs from the true rusts in not requiring an alternate host. It attacks many herbaceous plants. Light yellow areas develop on leaves, with chalky-white, waxy, and then powdery pustules that finally darken on the underleaf surface and other aboveground parts. Leaves may wither and die early, stems and flower parts may be greatly swollen and distorted, and growth is stunted. Control methods are similar to those employed for other rusts.

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