THE ROLE OF WEEDS IN THE EPIDEMIOLOGY OF GLADIOLUS VIRUSES AND MLO

During a survey of italian gladiolus (Gladiolus spp.) crops from 1985–’87, herbaceous weeds and shrubs growing in gladiolus fields were examined in order to discover which species were natural reservoirs of mycoplasma-like organims (MLO) and viruses infecting these flowers.
The weeds showing typical MLO and virus symptoms (yellowing, dwarfing, flower phyllody, mottling, chlorosis, leaf-deformation, mosaic, crinkling, etc.) were collected and identified.

This material was then tested in order to ascertain the presence of MLO, bean yellow mosaic virus (BYMV) and cucumber mosaic virus (CMV), as these pathogens are the most important agents affecting gladiolus plants and are also usually associated with severe symptomatology on its flowers.
MLO were found to occur naturally in: Convolvolus sp., Capsella sp., Cirsium sp.. BYMV was found in: Chenopodium sp., Trifolium sp. and CMV in: Mentha sp., Melandrium sp., Solanum sp., Galeopsis sp., Amaranthus sp., Lamium, Cirsium sp.; Beta sp. and Nicotiana sp. as voluntary host plants, were found infected by MLO and CMV respectively.

This survey revealed that biennal and pereenial weeds in particular are able to sustain MLO and viruses even if no gladioli are being cultivated.
In order to keep gladiolus plants healthy, it would therefore seem advisable to eliminate weeds, either chemically or mechanically, from the immediate surroundings.

VII International Symposium on Virus Diseases of Ornamental Plants

V. Vicchi, M.G. Bellardi

https://doi.org/10.17660/ActaHortic.1988.234.44