Survey of 'Candidatus Liberibacter solanacearum' in carrot crops in Norway
In Norway, ‘Candidatus Liberibacter solanacearum' (EPPO A1 List – Solanaceae haplotypes) was detected for the first time in 2011 on carrots (Daucus carota, Apiaceae) in the Southeastern part of the country (see EPPO RS 2012/120). This bacterium is transmitted by the carrot psyllid, Trioza apicalis. A survey was carried out in the main carrot-growing regions in 2011 and 2012 to determine the occurrence of ‘Ca. L. solanacearum’ in carrot plants and in psyllids, based on PCR tests. Carrot plants were collected from 30 commercial and research fields in 9 municipalities located in the counties of Akershus, Hedmark, Oppland, Østfold, Vestfold, (Southeastern Norway) and in the county of Rogaland (Southwestern Norway). In studied fields, the rate of symptomatic plants (showing leaf curling, discoloration) ranged from 10 to 100%. Carrot psyllids were collected with sweep nets and sticky traps from 10 commercial carrot fields in the municipalities of Rygge (Østfold county) and Larvik (Vestfold county). ‘Ca. L. solanacearum’ could be detected in carrot plants and in T. apicalis from all municipalities surveyed in 2011 and 2012, except in samples collected from Rogaland county. The infection rate ranged from 33% to 100% in symptomatic carrot plants and from 21% to 56% in psyllid specimens. These results showed that ‘Ca. L. solanacearum’ is widespread in several counties in Southeastern Norway, where most carrot crops are grown.
Sources
Munyaneza JE, Sengoda VG, Sundheim L, Meadow R (2014) Survey of 'Candidatus Liberibacter solanacearum' in carrot crops affected by the psyllid Trioza apicalis (Hemiptera: Triozidae) in Norway. Journal of Plant Pathology 96(2), 397-402.