In: Phyton, 51 Fasc. 2 (2011), S. 277-287, with 1 figure

Key words: Pinus nigra, Dothistroma, endophytic fungi.

Summary

KOWALSKI T. & DROZYNSKA K. 2011. Mycobiota in needles and shoots of Pinus nigra follo-wing infection by Dothistroma septosporum. – Phyton (Horn, Austria) 51 (2): 277–287, with 1 figure.

A 25-year-old Pinus nigra ARN. seed plantation in Miechów Forest District, in the south of Po-land, was studied. The P. nigra had shown symptoms of red band needle blight caused by Dothistroma septosporum (DOROG.) MORELET (Mycosphaerellaceae) since 1997. This disease leads to premature needle death and defoliation followed by dying of twigs and branches. The aims of the study were: 1. to recognize the extent to which needle infection by D. septosporum affects the structure of the needle endophyte community and colonization by other fungi which may contribute to needle loss, and 2. to determine whether stress caused by D. septosporum infection over many years facilitates latent infection of shoots by other potential pathogens, including contributors to bark and cambium necroses. Mycological analyses were done on three groups of P. nigra needles, i.e. A type needles (living, symptomless), B type (living, with necrotic bands typical of D. septo-sporum infection) and C type (prematurely dead as a result of primary infection by D. septosporum), and on living, 1-4-year-old shoots. Needles and shoots were colonized by 47 and 38 fungal species, respectively. Anthostomella formosa, Cenangium ferruginosum, Cyclaneusma minus, Lophodermium pinastri, Sclerophoma pythiophila and Verticicladium trifidum colonized more than 10% of needles. Fungi occurred at significantly different frequencies in needles with different health status. Cystodendron sp., Fusicoccum sp., Geniculosporium serpens, Mollisia cinerea, Pezicula eucrita, Phialocephala cf. dimorphospora, Phomopsis occulta, Sirodothis sp.1 and Therrya pini colonized more than 10% of shoots. Among the well-known causal agents of diseases of shoots, C. ferruginosum was recorded only sporadically, Gremmeniella abietina and Sphaeropsis sapinea were not isolated at all. The significance and importance of individual fungi in induction of diseases of needles and of shoot dieback are discussed.