The August Cieszkowski Agricultural University, Poznań, Poland THE EFFECTS OF FUNGI FROM ACORNS WITH SYMPTOMS OF BLACK ROT AND NECROTIC TWIGS OF OAK ON QUERCUS SEEDLINGS

11 fungi sampled from Quercus acorns with symptoms of black rot and mummification and from necrotic twigs of Q. petraea were tested for pathogenicity towards seedlings of Q. petraea, Q. robur and Q. rubra in a field experiment. Six months after inoculation, necrosis on the main stem and the subsequent death of Q. robur and Q. petraea plants were observed after inoculation with Aureobasidium pullulans, Ceuthospora sp., Ciboria batschiana, Cryptosporiopsis melanigena, Cylindrocarpon didymum, Melanconium bicolor, Paraphaeosphaeria michotii or Phomopsis glandicola. 12 months after inoculation, necrosis on the main stem was observed on single plants of Q. robur inoculated with C. batschiana or C. melanigena, and Q. petraea inoculated with C. didymum. The fungal species used for inoculation were not re-isolated from the diseased stems or observed to be sporulating on them when incubated in wet chambers.