Bacteria associated with vascular wilt of poplar

In 2017, the 560-ha area of hybrid poplar plantation in northern Poland showed symptoms of tree decline. Leaves appeared smaller, turned yellow-brown, and were shed prematurely. Twigs and smaller branches died. Bark was sunken and discolored, often loosened and split. Trunks decayed from the base. Phloem and xylem showed brown necrosis. Ten per cent of trees died in 1-2 months. None of these symptoms was typical for known poplar diseases. Bacteria in soil and the necrotic base of poplar trunk were analysed with Illumina sequencing. The 16S rDNA was amplified with bacteria-specific primers: 16S-F 5' CAGCCTACGGGNGGCWGCAG, 16S-R 5' ACAGGACTACHVGGGTATCTAATCC (Klindworth et al. 2013).