Fusarium circinatum research on pinus sylvestris of different provenances and interaction with other pine-inhabiting fungi

Abstract

Fusarium circinatum Nirenberg & O’Donnell (anamorph of Gibberella circinata) is a pathogenic fungus causing pitch canker of Pinus spp. and Douglas fir (Pseudotsuga menziesii). It can damage seedlings in nurseries and adult trees in forests. Symptoms for seedlings are damping-off and wilting, and for adult trees are bleeding resinous cankers on stems or thick branches and branch die-back. In Europe F. circinatum is known from Spain, Portugal, France and Italy and is treated as serious potential invasive forest pathogen in Europe which spreads via contaminated seeds, seedlings, wood material, soil, wind, insect vectors and human activities. In the future, fungus is more likely to spread to the pine forests of southern Europe, but there is also possibility of spread in Central and Northern Europe. In Lithuania there are no records of F. circinatum so far. In 2018 we tested susceptibility of three different Lithuania native Pinus sylvestris provenances to this pathogen. To represent each provenance we used 38 pines from every. We inoculated soil with F. circinatum suspension and after four weeks following soil inoculation extracted DNA from few plants that looked unhealthy. The RT-PCR method did not detect F. circinatum in our samples. The reason, however, might lay in too low proportion of fungal biomass comparing to the host biomass. We also checked interaction between Fusarium circinatum and several pine-inhabiting fungi known in Lithuania: Dothistroma septosporum, Fusarium oxysporum, Lecanosticta acicola. We found that F. oxysporum grew somewhat faster than F. circinatum and suppressed F. circinatum growth rate. Dothistroma septosporum produced dothistromin which seemed to slow down F. circinatum culture growth as well. Meanwhile L. acicola was outgrown by F. circinatum.