The distribution ofDothistroma septosporumand its mating types in Poland

Abstract

SummaryDothistroma needle blight (DNB), one of the most dangerous foliar diseases of pines, is the cause of much economic loss in pine plantations worldwide. The threat to pine‐dominated Polish forestry from this disease is therefore very large. However, the impact ofDNBhas not been high mainly due to the planting ofP. sylvestris, a less susceptible native species. Until now,DNBwas recorded in Poland only on highly susceptible exoticP. nigra. The current situation concerning the disease in Poland is described in this article. This disease, caused byDothistroma septosporum, was first recorded in a single location (Domiarki) in southern Poland in 1990. This study reports the occurrence ofD. septosporumin 37 new locations, demonstrating that the disease has now spread across the whole country.Pinus nigraremains the predominant host species in Poland. However, three new hosts for this fungus are reported, that isP. sylvestris,P. mugoandP. ponderosa. The ratio ofD. septosporummating types varies significantly between sites, ranging from an equal proportion of each mating type to single mating type populations. For the oldest known Polish population ofD. septosporum,the mating type ratio has shifted towards equilibrium over time.