Rust fungi parasitize on vascular plant specimens from numerous botanic families. It is significant, that the life cycle of this fungus has several forms of sporification. Also it’s common for them to produce spores and disseminate them in quantity, which may cause an epyphytoty.
Genus Puccinia Pers. is the largest in the order Uredinales. It includes both monoecious and dioecious species, with Puccinia allii (DC.) Rudolphi affects differet species of genus (Allium сера, A. sativum, A. porrum, A. fistulosum, A. ursinum, A. atroviolaceum, A. brevidens, A. monadelphum, A. platyspathum). It occurs everywhere. On the surface of onion’s leaves there appear prolonged, dispersed, sometimes interfluent pustule with urediniospores (fig. 1).
First they are covered with suberect epidermis, through which one can see masses of yellowish-brown urediniospores (fig. 2). Epidermis breaks and urediniospores flow out on the leaf’s surface (fig. 3, 4, 5). Urediniospores are more or less globular, elliptic or egg-shaped, aculeolate, 18-32х18-24 µm (fig. 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16). Teliospores are positioned in black, flat, differently shaped, covered with epidermis acervulus, bicellular, mostly oblongly-clavate or clavate, rounded on top, often dulled, coarctate or truncated, with solid sporoderm, slightly constricted, narrowed to the bottom, smooth, 35-80х17-30 µm, brown, on a very short, firm stem, numerous paraphyses are at hand (fig. 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30).
| 1. Onion affected with rust (Image by G. Pestsov)
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| 2. Pustule of Puccinia allii fungus (Image by G. Pestsov)
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| 3. Uredinia with urediniospores of Puccinia allii fungus (Image by G. Pestsov)
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| 4. Puccinia allii urediniospores are breaking the epidermis (Image by G. Pestsov)
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| 5. Uredinia with urediniospores and forming up Puccinia allii telia (Image by G. Pestsov)
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| 6. Formation of urediniospores in the Puccinia allii uredopustules (Image by G. Pestsov)
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| 7. Puccinia allii urediniospores and paraphyses (Image by G. Pestsov)
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| 8. Young urediniospores of Puccinia allii (Image by G. Pestsov)
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| 9. Puccinia allii urediniospores colored with fuchsin (Image by G. Pestsov)
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| 10. Formation of Puccinia allii urediniospores and paraphyses (Image by G. Pestsov)
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| 11. Acanthaceous surface of Puccinia allii urediniospores (Image by G. Pestsov)
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| 12. Formation of Puccinia allii urediniospores (Image by G. Pestsov)
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| 13. Puccinia allii urediniospores (Image by G. Pestsov)
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| 14. Diversity of sizes and forms of Puccinia allii urediniospores (Image by G. Pestsov)
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| 15. Mature Puccinia allii urediniospores (Image by G. Pestsov)
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| 16. Rough surface of Puccinia allii urediniospores (Image by G. Pestsov)
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| 17. Puccinia allii telia on the onion (Image by G. Pestsov)
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| 18. Puccinia allii teliospores breaking the epidermis (Image by G. Pestsov)
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| 19. Formation of teliospores of Puccinia allii (Image by G. Pestsov)
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| 20. Teliospores of Puccinia allii (Image by G. Pestsov)
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| 21. Cut through the telia, Puccinia allii teliospores and paraphyses (Image by G. Pestsov)
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| 22. Various forms of Puccinia allii teliospores (Image by G. Pestsov)
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| 23. Truncated teliospores of Puccinia allii (Image by G. Pestsov)
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| 24. Сoarctate and truncated teliospores of Puccinia allii (Image by G. Pestsov)
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| 25. Oblongly-clavate, constricted teliospores of Puccinia allii (Image by G. Pestsov)
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| 26. Puccinia allii teliospore on the stem (Image by G. Pestsov)
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| 27. Dulled and rounded teliospores of Puccinia allii (Image by G. Pestsov)
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| 28. Mature teliospores of Puccinia allii (Image by G. Pestsov)
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| 29. Teliospores of Puccinia allii on the onion’s leaf surface (Image by G. Pestsov)
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| 30. Narrowed to the bottom teliospores on the short stem (Image by G. Pestsov)
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| All images by G. Pestsov. |
(This page was moved here from http://phytopathology.net/Portal/Puccinia_allii )
