cedar-apple rust

cedar-apple rust

 common disease in North America of red cedar (Juniperus virginiana (eastern red cedar)), related Juniperus (juniper) species, apple, and crab apple, caused by the fungus Gymnosporangium juniperi-virginianae. Both hosts, the junipers and the apples, are required for completion of the rust life cycle. Greenish-brown to chocolate-brown galls (cedar apples) that are round to kidney-shaped and up to two inches (5 centimetres) in diameter form on red cedar and other juniper twigs. In rainy spring weather, the galls are covered with jellylike, yellow to orange-brown spore horns up to two inches long. A single gall may produce several billion spores (basidiospores or sporidia). The wind-borne spores infect young leaves and fruits of apple and crab apple. Pale yellow to orange-yellow spots that develop sticky centres and minute, black fruiting bodies (pycnia) form on the leaves and usually near the calyx end of fruit. Orange, tubelike structures (aecia) later develop on the undersides of leaves and on fruits, which drop early. Spores produced in the aecia (aeciospores) are wind-borne in late summer to junipers on which leaf infections occur. Galls do not produce spores until the second spring, completing the two-year life cycle.

      Control is by eradication of either host or by timely application of a fungicide, in spring for junipers and in summer for apples.

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Universalium. 2010.

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  • cedar-apple rust — noun rust fungus causing rust spots on apples and pears etc • Syn: ↑apple rust, ↑Gymnosporangium juniperi virginianae • Hypernyms: ↑rust, ↑rust fungus • Member Holonyms: ↑Gymnosporangium, ↑ …   Useful english dictionary

  • cedar apple rust — noun see apple rust …   Useful english dictionary

  • cedar-apple rust — noun Date: 1946 a gall producing disease especially of the apple caused by a rust fungus (Gymnosporangium juniperi virginianae) that completes the first part of its life cycle on the common red cedar (Juniperus virginiana) and the second on the… …   New Collegiate Dictionary

  • apple rust — noun rust fungus causing rust spots on apples and pears etc • Syn: ↑cedar apple rust, ↑Gymnosporangium juniperi virginianae • Hypernyms: ↑rust, ↑rust fungus • Member Holonyms: ↑Gymnosporangium, ↑ …   Useful english dictionary

  • cedar apple — noun also cedar ball : a hard brown more or less spherical excrescence on cedar trees of the genus Juniperus formed by various rusts (genus Gymnosporangium) during their telial stage compare apple rust * * * a brown gall on the branches of the… …   Useful english dictionary

  • cedar apple — a brown gall on the branches of the juniper, produced by several rust fungi of the genus Gymnosporangium. [1840 50, Amer.] * * * …   Universalium

  • rust fungus — noun any of various fungi causing rust disease in plants • Syn: ↑rust • Hypernyms: ↑fungus • Hyponyms: ↑flax rust, ↑flax rust fungus, ↑Melampsora lini, ↑ …   Useful english dictionary

  • cedar rust — noun : apple rust * * * cedar rust, 1. a destructive disease caused by a fungus that begins its life cycle on cedar trees and later spreads to apple trees. 2. the fungus that produce this disease …   Useful english dictionary

  • 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 …   Universalium

  • crab apple — 1. a small, sour, wild apple. 2. any of various small, tart, cultivated varieties of apple, used for making jelly and preserves. 3. any tree bearing such fruit. [1705 15] * * * ▪ tree also called  Crab,    any of several small trees of the genus… …   Universalium

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