|Authors: ||P. Restuccia, G. Mancini, A. Bertaccini, M.G. Bellardi|
|Keywords: ||Ranunculus, virus survey, CMV, potyvirus, tospovirus, diagnosis, control|
Ranunculus asiaticus L. is an ornamental species grown in many areas of the world for tuber, potted plant, and cut flower production.
In Italy, the crops of Ranunculus hybrids are mainly located in the Liguria region, where virus diseases represent a serious problem in cut flower production.
However, the impact of virus infections on the crop has not been carefully evaluated.
For this reason, in 2005-2007, two hundred samples of Ranunculus hybrids collected in the Sanremo area (Imperia province) were examined to verify the presence of viruses associated with severe symptoms on leaves (chlorosis, mosaic, “parsley-like” appearance, vein-yellowing, necrotic spots and rings on the lamina) and flowers (colour breaking, malformations), petiole and stem necrosis, stunting and/or premature death of plants.
By applying virological tests (mechanical inoculations on herbaceous plants, electron microscopy, PAS-ELISA, IME “decoration”, and RT-PCR) several virus species of different lengths (from 700 to 800 nm) and sizes (from 30 to 90-100 nm) either singly or in mixed infections were detected. Cucumber mosaic virus (CMV), in a few cases alone, more often in combination with Tomato spotted wilt virus (TSWV), was identified in plants showing leaf mosaic, necrosis, stunting and severe flowers symptoms.
Both TSWV and Impatiens necrotic spot virus (INSV), in some cases also with Potato virus Y-Ranunculus strain (PVY-R), were detected in leaves with mosaic, stem and petiole necrosis, and “parsley-like” symptoms. Turnip mosaic virus (TuMV) and other unidentified potyvirus-like viruses were also found.
Data obtained clearly showed not only the widespread distribution of different species of viruses in Ranunculus crops in the Sanremo area, but also that the correlation between symptom expression and virus presence is very difficult to make.
Considering the increasing economic damage to cut flower production recently observed in this area, control measures to prevent virus spreading are required, such as monitoring and virus-testing programs for a rapid removal of inoculum sources combined with a large-scale indexing of propagation materials.
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