SOME CHARACTERISTICS OF CHRYSANTHEMUM YELLOWS DISEASE

Chrysanthemum yellows (CYD), a MLO-associated disease which affects marguerites (C. frutescens) in the Italian Riviera was transmitted experimentally by Euscelis spp. leafhoppers or by grafting to 13 of 48 plant species tested, including aster, carrot, celery and clover.
Two morphological types of MLOs were detected in infected plants: roundish, electron-transparent ‘mature’ cells, and pleomorphic, strongly osmiophilic cells which seemed to occur more frequently in plants inoculated by hoppers.
Testing single CYD-exposed E. incisus leafhoppers in weekly passages, the rate of transmission was 7.8% in the 3rd wk after acquisition, reached a maximum in the 5th wk (38.1%), then decreased until the 17th wk (5.0%). No CYD transmission was obtained in the three last weekly inoculation tests.
According to their transmission patterns, the leafhoppers could be classified as very efficient, efficient, inefficient, and non-vectors.
The results of field investigations indicated that the natural cycle of CYD seems to develop only between marguerites and E. incisus hoppers, and that infection of crops occurs mostly in late autumn.

VII International Symposium on Virus Diseases of Ornamental Plants

M. Conti, G. D’Agostino, A. Casetta, L. Mela

https://doi.org/10.17660/ActaHortic.1988.234.15