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BACKGROUNDModern Scandinavian population registers provide excellent data sources that allow a user to quickly gain an impression of the level of fertility and its structure across subpopulations. This may also allow the analyst to check a feature of the much-cited disruption hypothesis, at least in part. OBJECTIVEThe purpose of this note is to exploit this potential to give an overview of the structure of recent total fertility after immigration to Sweden from various groups of sending countries, separately for males and females. In the process we demonstrate to what extent the post-migration fertility compensation which is part of the fertility disruption hypothesis is fulfilled in our study population. Due to the nature of our data we have refrained from studying fertility before migration. METHODBased on data from a combination of two Swedish administrative registers (the Historic Population Register and the Multi-Generation Register) that cover both men and women in the entire population for the years 2000-2011, we compute and plot TFR-like age-cumulated fertility levels, specific for years since immigration, for six groups of sending countries, separately for men and women. RESULTSWe find that the post-migration fertility compensation specified as part of the fertility disruption hypothesis is visibly confirmed in our Swedish study population for female European immigrants from non-EU countries and for female immigrants from nonEuropean countries with a low or medium UN Human Development Index, but not so for other female immigrants, i.e. not for those who come from a Nordic country or from

Phytophthora infestans (Mont.) de Bary, causing late blight on potatoes and considered to be a typical airborne disease, was found to be infective also by oospores in the soil. P. infestans is heterothallic, and is known to reproduce asexually in Sweden since only one mating type, A1, was present until 1986. Since the 1970s, the other mating type, A2, of P. infestans has migrated to most parts of the world from its original location in central Mexico (2). When A1 and A2 meet, they may form oospores, which are thick-walled, resting structures, giving the pathogen a possibility to recombine as well as survive without its host, for instance in the soil. The soil stages of the pathogen are now therefore under intense investigation. Oospores of P. infestans were produced from two Scandinavian A1 and A2 isolates in Rye A broth mixed with talcum powder and dried for 7 weeks. The inoculum was mixed with sterile, standardized soil in concentrations of 10, 150, 250, and 400 oospores per ml of soil. Cv. Bintje plants cultivated in vitro from nodal cuttings on Murashige and Skoog medium were transplanted to the soil after rooting. Brown discolorations were obtained on the underground stems and tubers on potato plants grown in the two highest concentrations of oospores for 1 month at 15°C and 16-h day length. After 3 days of incubation on P. infestans-selective medium (3), sporangia covered the tissue from plants grown in 250 and 400 oospores per ml of soil and the pathogen was reisolated. This shows that germinating oospores of P. infestans can infect underground stems and tubers of potatoes in soil and further explains the early attack of late blight as observed in a potato crop in Sweden 1996 and 1997 (1). References: (1) B. Andersson et al. Potato Res. 41:305, 1998. (2) D. Andrivon. Phytopathology 85:1053, 1995. (3) G. W. Griffith et al. Mycologist 9:87, 1995.

Polyacrylamide gel electrophoresis of ribonuclease from buds of bird‐cherry (Prunus padus L.) revealed four different bands (I–IV). The activity of band I, which probably corresponds to an in vivo free ribonuclease, increased from October to January — most rapidly between December, when 69% of the buds were dormant, and January when 43% were in the dormant state — but did not change from January to March, when growth was resumed. Bands II–IV may represent ribonucleases which are structure‐bound in vivo. The activity of band II decreased from October to a minimum in January and then increased from January to March. The activities of bands III and IV were very low from October to February but were enhanced with acceleration of growth in March. The results may indicate that the separate ribonucleases have different functions.