Pathogenicity of cherry‐spruce rust, Thekopsora areolata, was investigated by inoculations with aeciospores from seven Norway spruce, Picea abies, seed orchards that had suffered from successive severe rust epidemics in the 2000s in Finland. Detached leaves of Prunus spp. were inoculated in the laboratory using aeciospores from cones of various ages. In the greenhouse, live Prunus padus plants were inoculated, and possible autoecism of the rust was tested by inoculations of Picea abies seedlings. Thirty‐five spore sources from the seed orchards formed uredinia on Prunus spp. in the laboratory 2 weeks after incubation, but no telia developed. In the greenhouse, uredinia developed on live P. padus, but no rust symptoms, cankers or sporulation were detected on Picea abies. Thus, no evidence of autoecism was observed among the T. areolata populations and therefore all populations, suggesting all those tested from the Finnish seed orchards were heteroecious.

A severe epidemic of Chrysomyxa ledi needle rust occurred over large areas in northern Finland in 2015. In late summer, young current-year cones and needles of 7-8 Picea species were sampled in a northern botanical garden, and the frequencies of cone rusts, Thekopsora areolata, Chrysomyxa pirolata and C. ledi, were investigated in cones, and C. ledi was investigated in needles. In addition, the frequency of C. ledi was estimated visually in current-year needles of ca. 400 trees of 17 species and varieties of Picea in the garden. Chrysomyxa pirolata was absent in cones of all Picea. No cone rusts were observed in cones of P. rubens and Picea mariana. Aecia of Thekopsora areolata occurred moderately in cones of P. abies (26% of cones) and rarely in P. engelmannii (3%) and P. omorika (6%). Chrysomyxa ledi was the most frequent rust in cones; aecia occurred abundantly in cones of P. abies (100%), P. engelmannii (69%), P. glauca (45%) and P. omorika (41%), and occasionally on P. pungens (13%). Thekopsora areolata from cones of the three Picea species showed 100% similarity in ITS2 sequence to one another and to samples in the GenBank. Samples of Chrysomyxa from needles and cones of Picea and leaves of Ledum palustre had ITS2 sequences 99.9%-100% similar to one another and 99.8%-100% similar to the closest sequence of C. ledi and C. rhododendri in the GenBank. Thekopsora areolata was recorded for the first time in cones of P. omorika and C. ledi in cones of P. engelmannii and P. pungens. In current-year needles of Picea, C. ledi was abundant on P. abies, P. obovata, P. engelmannii, P. jezoensis, P. glauca and P. sitchensis, the rust was scarce on P. asperata var. nobilis, P. mariana, P. pungens and P. omorika, and the rust was absent on P. glehnii and P. rubens.

No abstract

Leaf compounds may contribute to plant defense against Cronartium rusts. Secondary compounds are either natural or induced in leaves. We studied the variation of compounds in leaves of six alternate hosts of Cronartium pini and two of C. ribicola that represented either susceptible or resistant species to these rusts. Extracts from the plant leaves were analyzed using LC-MSMS (liquid chromatography tandem mass spectrometry) and compounds were compared between susceptible and resistant species of the same plant genera to identify significant differences between resistant and susceptible species. Also, LC–MS (liquid chromatography mass spectrometry) with external calibration was used to quantify 12 candidate compounds known from the literature. Among these compounds, the most abundant significant ones in C. pini -resistant Melampyrum pratense were chlorogenic acid and quercitrin, in Veronica chamaedrys ferulic acid, quercitrin and luteolin and in Impatiens glandulifera quercitrin, ferulic acid, kaempferol, rutin and hyperoside. In C. ribicola -resistant Ribes rubrum the most abundant significant compounds were caffeic acid, p-coumaric acid and quercitrin. Among all extracted leaf compounds, concentrations of three compounds were over 1000 times greater in rust-resistant M. pratense, three compounds in V. chamaedrys, eight compounds in I. glandulifera, and one compound in R. rubrum than in rust-susceptible species. Among the compounds, the most promising possibly linked to rust resistance were chlorogenic acid and quercitrin.

No abstract

The alternate host range of cherry-spruce rust is poorly studied although such information could be important in protecting spruce seed orchards from infections. Pathogenicity of cherry-spruce rust, (Fr.) Magnus, was investigated on potential alternate host species in a greenhouse and in a laboratory in Finland. Five common species of Ericaceae, L., L., L., L. and (L.) Spreng, were inoculated in the greenhouse using aeciospores from seven Norway spruce [ (L.) H. Karst.] seed orchards suffering from in 2018. In addition, young detached leaves of spp. and 17 other plant species of ground vegetation from eight Norway spruce seed orchards were inoculated with aeciospores from six seed orchards in the laboratory in 2019. Also, young leaves of L. trees growing within the seed orchards or close to them were inoculated as controls. None of the inoculated leaves of the potential alternate hosts formed uredinia either in the greenhouse or in the laboratory. In contrast, leaves of from the seed orchards were infected by the six spore sources from six seed orchards and produced uredinia. As spores were able to infect only , but not the other tested species belonging to ground flora, it was concluded that disperses only via spp. in Finnish seed orchards.Thekopsora areolataVaccinium myrtillusV. uliginosumV. vitis-idaeaEmpetrum nigrumArctostaphylos uva-ursiPicea abiesT. areolataVacciniumPrunus padusP. padusT. areolataP. padusT. areolataPrunus

Susceptibility of 13 plant species to Scots pine blister rust, Cronartium flaccidum, or white‐pine blister rust, Cronartium ribicola, was tested in Finland. The test species belonged to 10 genera in eight plant families, and they were inoculated in the laboratory or in the glasshouse. After 8 weeks of incubation, C. flaccidum sporulated on five species and provenances in the glasshouse and six species in the laboratory. After similar incubation, C. ribicola sporulated on one species in the glasshouse and two species in the laboratory. Cronartium ribicola formed uredinia and telia on Euphrasia nemorosa in the glasshouse and uredinia on E. nemorosa and Ribes nigrum in the laboratory. Cronartium flaccidum produced uredinia and telia on Odontites verna (two provenances), E. nemorosa and Euphrasia stricta both in the glasshouse and in the laboratory, on Papaver rhoeas in the glasshouse, and on Rhinanthus serotinus, Impatiens parviflora and Paeonia lactiflora in the laboratory. Rhinanthus serotinus, O. verna, I. parviflora and P. rhoeas are new alternate hosts for C. flaccidum, and for the first time, species of Odontites and Papaver were confirmed by molecular methods as alternate hosts for the rust. Cronartium ribicola was reported to sporulate on E. nemorosa for the first time. In conclusion, hemiparasitic genera of the family Orobanchaceae contain several forest species that are susceptible to C. flaccidum, although single highly resistant species also occur in these genera. Similarly, several genera of Orobanchaceae contain single species that are susceptible to C. ribicola, although most of the species in this family are highly resistant to the rust. In a severely damaged Scots pine stand in northern Finland, C. flaccidum was found to sporulate commonly on Melampyrum sylvaticum and E. stricta, and rarely on Rhinanthus minor. This is the first report of natural sporulation of C. flaccidum on Rhinanthus in its natural habitat.

Viherrakentamisen ja ennallistamisen kasvilajien valinta ja saatavuus on pohjoisen vaativissa kasvuolosuhteissa usein ongelma. Syksyllä 2007 päättyi laaja pohjoisille matkailualueille keskittynyt EU LIFE ympäristörahaston hanke Matkailualueet maisemalaboratorioina – Työvälineitä kestävän matkailun edistämiseen (LANDSCAPE LAB). Oulun yliopiston kasvitieteellinen puutarha oli hankkeessa mukana yhtenä kumppanina ja toteutti yhteistyössä Lapin ammattiopiston luonto- ja ympäristöalan toimipisteen kanssa Kestävän viherrakentamisen ja ennallistamisen kasvimateriaali, (LABPLANT) osahankkeen. Osahankkeen tavoitteina oli etsiä ja valita pohjoiseen viherrakentamiseen ja ennallistamiseen sopivaa kasvimateriaalia, kehittää kasvien lisäysmenetelmiä ja tuottaa kestävää kasvimateriaalia, perustaa näytealueita pohjoisiin matkailukeskuksiin ja kirjoittaa opaskirja pohjoisen matkailuympäristön kestävistä kasveista.Kestävien kasvien valinta perustui oleellisesti jo olemassa olevaan, aiemmista projekteista tulleeseen tietoon sekä Oulun yliopiston kasvitieteellisen puutarhan ja Lapin ammattiopiston Metsäruusun toimipisteen kasvikokoelmiin. Esiteltävän kasvimateriaalin valinnan kriteerit olivat ilmastollinen kestävyys sekä käyttökelpoisuus pohjoisessa ympäristössä. Kasvimateriaali koostuu perinteisistä viherrakentamisen kasveista, luonnonkasveista ja potentiaalisista uusista viherrakentamisen kasveista. Osahankkeen aikana lisättiin yhteensä lähes sata eri lajia tai kantaa monivuotisia ruohokasveja, varpuja, pensaita ja puita.Osatehtävän aikana perustettiin yhteensä kuusi näyteistutusaluetta, näistä kaksi Leville, kaksi Ylläkselle ja kaksi Pallakselle. Näytealueilla esitellään kasvien käyttöä erilaisissa pohjoisissa matkailuympäristöissä. Valmistunut opaskirja, Pohjoisen matkailuympäristön kestävät kasvit, kertoo pohjoisen ympäristön ja kasvien ominaispiirteistä sekä siitä, miten pohjoisen matkailukeskusten ympäristöistä voidaan kehittää viihtyisämpiä ja ekologisesti kestävämpiä. Opaskirjassa esitellään yli 300 pohjoisilla alueilla käyttökelpoista ja kestävää luonnon- ja viherrakentamisen kasvia lisäys- ja saatavuustietoineen.