Maize redness in Serbia is associated with ‘Candidatus Phytoplasma solani’ and possibly transmitted by Reptalus panzeri
A disease of maize (Zea mays) of unknown etiology and called ‘maize reddening’ has occurred intermittently in Serbia, Romania and Bulgaria since the 1960s. It was first observed in 1957 in Serbia (Banat region), and epidemic phases were observed in the late 1950s – early 1960s, and 40 years later in the late 1990s – early 2000s. Between these epidemic phases, the disease was always sporadically present in this part of Central Europe. Affected maize plants show a reddening of the midrib which then spreads to the stalk and eventually affects the whole plant. Symptomatic plants show abnormal cobs with poor, shrivelled grains. During epidemic phases, disease symptoms can affect up to 90% of the plants and yield reductions from 40 to 90% have been observed. In 2005, using molecular tools (PCR, RFLP, sequence comparisons), the presence of ‘Candidatus Phytoplasma solani’ (stolbur phytoplasma – EPPO A2 List) was consistently detected in diseased plants. This result also constituted the first report of ‘Ca. P. solani’ in maize. Further studies were carried out to identify the potential vectors of maize reddening. In the affected maize fields, high populations of Reptalus panzeri (Homoptera: Cixiidae) were observed in 2005 and 2006, and the phytoplasma could be detected in these insects. In cage experiments, healthy maize plants were exposed to R. panzeri populations collected from infested fields. Four weeks after, reddening symptoms were observed and ‘Ca. P. solani’ could be detected in the symptomatic plants. These preliminary results strongly indicate that R. panzeri could play a role in the disease transmission. Further research will be carried out in Serbia to confirm these preliminary results and better understand the epidemiology of the disease (e.g. identify natural plant reservoirs, stages at which R. panzeri acquire the phytoplasma, relationship with diseases caused by ‘Ca. P. solani’ on other crops such as Capsicum annuum).
Sources
Duduk B, Bertaccini A (2006) Corn with symptoms of reddening: new host of Stolbur phytoplasma. Plant Disease 90(10), 1313-1319.
Jović J, Cvrković T, Mitrović M, Krnjanjić S, Petrović A, Redingbaugh MG, Pratt RC, Hogenhout AS, Toševski I (2007) Maize redness in Serbia caused by stolbur phytoplasma is transmitted by Reptalus panzeri. Bulletin of Insectology 60(2), 397-398. http://www.bulletinofinsectology.org/pdfarticles/vol60-2007-397-398jovic.pdf
Jović J, Cvrković T, Mitrović M, Krnjanjić S, Redingbaugh MG, Pratt RC, Gingery RE, Hogenhout AS, Toševski I (2007) Roles of stolbur phytoplasma and Reptalus panzeri (Cixiinae, Auchenorrhyncha) in the epidemiology of Maize redness in Serbia. European Journal of Plant Pathology 118(1), 85-89.