During the autumn of 2018 and the winter of 2019 virus-like disease symptoms were observed in four fields of lettuce in Kalamos, Marathonas and Leonidio regions of central and south-eastern Greece. In all cases, the disease affected 30-40% of the plants. Symptoms consisted of brown ringspots, necrotic lesions, vein necrosis and leaf distortion resembling those associated with tospovirus infections. Virologists at Benaki 5Phytopathological Institute of Athens collected six symptomatic plants (four in 2018 and two plants in 2019) from four different fields and tested symptomatic samples for the presence of tomato spotted wilt virus (TSWV), tomato chlorotic spot virus (TCSV), impatiens necrotic spot virus (INSV), groundnut ringspot virus (GRSV) and chrysanthemum stem necrosis virus (CSNV).
Lettuce from Kalamos field cultivation, infected with impatiens necrotic spot virus (A, B). Reproduction of INSV disease symptoms in virus tested-negative lettuce plants (C).
"RT-PCR assays and molecular sequencing confirmed that the causal agent was INSV, which was first described in Impatiens spp. plants on 1990 - the scientists explain - This virus is an important pathogen for several crops including ornamental plants, tomato and lettuce. The relatively high incidence of the virus in different regions of Greece suggests that INSV is an emerging pest for lettuce cultivation in Greece. This is the first report of INSV in Greece".
Source: Despoina Beris, Ioanna Malandraki, Oxana Kektsidou, Nikon Vassilakos, Christina Varveri, 'First report of Impatiens necrotic spot virus infecting lettuce in Greece', May 2020, Plant Disease.