02477nas a2200217 4500008004100000022001400041245009800055210006900153260001600222300001600238490000800254520178300262653001502045653001702060653002702077100002402104700002002128700002802148700001802176856006502194 2015 eng d a0031-949X00aWinter Conditions Correlate with Phytophthora alni Subspecies Distribution in Southern Sweden0 aWinter Conditions Correlate with Phytophthora alni Subspecies Di cJan-09-2015 a1191 - 11970 v1053 a

During the last century, the number of forest pathogen invasions has increased substantially. Environmental variables can play a crucial role in determining the establishment of invasive species. The objective of the present work was to determine the correlation between winter climatic conditions and distribution of two subspecies of the invasive forest pathogen Phytophthora alni: P. alni subspp. alni and uniformis killing black alder (Alnus glutinosa) in southern Sweden. It is known from laboratory experiments that P. alni subsp. alni is more pathogenic than P. alni subsp. uniformis, and that P. alni subsp. alni is sensitive to low temperatures and long frost periods. By studying the distribution of these two subspecies at the northern limit of the host species, we could investigate whether winter conditions can affect the geographical distribution of P. alni subsp. alni spreading northward. Sixteen major river systems of southern Sweden were systematically surveyed and isolations were performed from active cankers. The distribution of the two studied subspecies was highly correlated with winter temperature and duration of periods with heavy frost. While P. alni subsp. uniformis covered the whole range of temperatures of the host, P. alni subsp. alni was recovered in areas subjected to milder winter temperatures and shorter frost periods. Our observations suggest that winter conditions can play an important role in limiting P. alni subsp. alni establishment in cold locations, thus affecting the distribution of the different subspecies of P. alni in boreal regions.

10aAlnus spp.10ainvasiveness10aPhytophthora plurivora1 aRedondo, Miguel, A.1 aBoberg, Johanna1 aOlsson, Christer, H. B.1 aOliva, Jonàs uhttp://apsjournals.apsnet.org/doi/10.1094/PHYTO-01-15-0020-R