In 2008, during a survey conducted in commercial carnation greenhouses in Coatepec Harinas County, Mexico, symptoms of yellow streak were observed in many young plants and severe deformation and dwarfing in blooming state being both symptoms similar to those recorded for viral diseases in carnation crops. The causal pathogens were identified as carnation mottle virus (CarMV) and carnation etched ring virus (CERV) based on various genetic analyses. This is thought to be the first report of CarMV and CERV in Mexico. There are 15 different viruses are known at present. Most of carnations leaves may be mottled, have yellow spotting, dead flecks, line or ring spot patterns once infected by virus. Plant may be distorted or have flower color breaking.
Types of Common Carnation viruses
Seven types of common carnation viruses are carnation mottle virus (CarMV), carnation etched ring virus (CERV), carnation ringspot virus (CRSV), carnation latent virus (CLV), carnation necrotic fleck virus (CNFV).
Carnation mottle virus is an important viral agent infecting carnation cut-flower crops. Carnation mottle virus is the type member of genus Carmovirus and belongs to the Tombusviridae family. It is naturally transmitted by grafting and contacting between plants. Although its infection lead to mild symptoms, it weakens the plant to infection by other pathogens.
In the leaves of infected carnations, carnation etched ring virus (CERV) causes necrotic flecks, rings and line patterns which sometimes enlarge to form blotches. In mixed infection with other viruses, symptoms are more severe including leaf chlorosis, necrotic spots and rings, and streaking and flecking of stems.
Carnation ringspot virus infection in carnations results in diagnostic ring spots, mottling and leaf and flower distortions . The disease symptoms are enhanced when carnations are co-infected with carnation mottle virus. On experimental systemic hosts, Carnation ringspot virus (CRSV) causes concentric ringspots with necrotic centers on the inoculated leaves and mosaics, necrotic flecks and often veinal necrosis on the systemically infected leaves. In severe infections, or in susceptible carnation cultivars, leaf tip necrosis can also occur. In general, CRSV infections do not kill the host plants; however, necrosis and symptom severity can become quite severe at sustained temperatures between 15 and 20°C compared with temperatures above 20°C.
Carnation latent virus (CLV) usually occurs symptomlessly in its two hosts. Cytopathological studies have shown that, within infected cells, the virus particles occur scattered in the cytoplasm and in parallel arrangement in non-membrane bound bundle-shaped aggregates.
Carnation necrotic fleck virus causes greyish-white or reddish-purple necrotic flecks, streaks or spots on leaves and stems, with yellowing and complete necrosis on older leaves. Symptoms are milder on younger leaves. Flowers generally do not show symptoms, but owing to the severity of symptoms on leaves and stems, flowers from infected plants are of poor quality and mostly unmarketable. Symptoms can vary according to cultivar and, at least in the Mediterranean area, are particularly severe in spring on young plants. In many cultivars infection can be almost symptomless, especially under cool conditions. Symptoms are greatly increased by mixed infection with other viruses, particularly with carnation mottle virus.
Older leaves of infected carnation often remain symptomless, but younger leaves develop diffuse chlorotic spotting and mottling with darker green spots and flecks along some leaf veins; flowers may be distorted and ‘broken’, especially in summer. Symptom severity is variable in Sim cultivars and seedlings.
1.Safari M, Koohi Habibi M, Mosahebi G, et. Carnations mottle virus, an important viral agent infecting carnation cut-flower crops in Iran. Communications in Agricultural and Applied Biological Sciences. 2009;74(3):861-5.
2. Plantwise Knowledge Bank.