Further pathogenicity testing of , a biocontrol agent against the invasive Tree of Heaven (), on non-target tree species in Europe.

UNLABELLED

is an effective biological control agent against the highly invasive Tree of Heaven () in Europe, and previous research on ten economically and ecologically important tree species occurring in Austria have so far not revealed undesired non-target effects. In this study, another nine tree species including five native, two non-native as well as two invasive alien tree species were tested for susceptibility to the particular strain of .  (Vert56) used for biological control of . Stem inoculations on potted seedlings revealed that this strain of .  is generally host-adapted to . It induced chlorosis, necrosis and wilting already within two weeks post inoculation on and resulted in almost completely defoliated or dead seedlings at the end of the vegetation period. Apart from two species ( and ), that suffered from other abiotic/biotic agents, no mortality was observed on all other tree species tested; however, symptoms caused by other abiotic factors were also found on and . All tested tree species exhibited vascular discolorations and the fungus could be re-isolated at varying frequencies (6-100%) from inoculated seedlings of all non-target tree species, although five of these species exhibited no external symptoms. Results confirmed high susceptibility (S) of to  , whereas , , , and were considered as tolerant (T), and , and were rated as possible resistant (PR) due to the low rates of re-isolation.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12600-022-01032-z.