Occurrence of a new stunting disease of strelitzia recinaem\.




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OCCURRENCE OF A NEW STUNTING DISEASE OF STRELITZIA RECINAEM\. (BIRD OF PARADISE)

IN EGYPT ASSOCIATED WITH MOLLICUTE'LIKE ORGANISM (MLO).

By

A. E. badr* And eman M. Abo EUGhAiT**



* Agricultural Botany Department,

"•""Horticulture Department, Faculty of Agriculture, Moshtohor, Benha Branch, Zagazig University, Toukh , Qalubia, Egypt.

ABSTRACT

The naturally infected Strelitzia reginae Ait. (Bird of Paradise) plants show severely stunted plants, yellowish stunted leaves, abnormal flowers and malformed flowers and flower stalks. Also, it was noticed that some flowers carried on diseased plants were dead. Most of these symptoms were reduced or remissed on the newly formed leaves and flowers when diseased plants were treated with tetracycline (125 to 1000 ppm). Electron micrographs of thin sections of sieve elements of diseased but not of healthy leaf petioles revealed the presence of pleomorphic forms occurring as spherical, oval, elongated, filamentous and/or irregular mollicute-like organism (MLO) bodies that had unit membranes about lOnm thick. Ribosomlike particles and fine strands presumably nucleic acids within cells, also, some structures indicative of binary fission or budding were observed. The disease significantly reduced plant height, number of leaves, length of flower stalk, leaf chlorophyll and carotene contents. Treatment (foliar spray) with either tetracycline or gibberellin significantly decreased the deleterious effect of such disease nearly in all tested concentrations (125, 250,500,750 and 1000 ppm). Effect of tetracycline or gibberellin was increased by increasing the concentration. Thus, treated diseased plants exhibit significant increase in plant height, number of leaves, length of flower stalk, leaf chlorophyll and carotene contents when compared with untreated analogous in both seasons (1991 and 1992).



Egypt. J. Appl. Sci.; 9 (6) 1994 439 - 458


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