The need to improve control of cone rust epidemics led us to investigate seasonal fruiting and sporulation of cone rusts in Norway spruce ( Picea abies (L.) Karst.) cones and alternate hosts in 2006–2008. Spermogonia of Chrysomyxa pirolata Wint. and aecia of Thekopsora areolata (Fr.) Magnus developed in current-year cones in June, whereas C. pirolata aecia developed and started to sporulate in July. Thekopsora areolata aecia sporulated mainly in previous-year cones in May–August. Uredinia, telia, and basidia of C. pirolata developed in overwintered Pyrola sp. and Orthilia secunda L. leaves in May and sporulated in May–June. Uredinia of T. areolata developed in current-year Prunus padus L. leaves in June and sporulated in June–August. Telia of T. areolata developed in late summer, but no basidia were observed in overwintered Prunus padus leaves in March–May. Only minor variation occurred at the time of fruiting and sporulation of cone rusts both among cones and leaves of alternate hosts. Periods of high daily rainfall in May coincided with the epidemic peaks during female flowering in 2006. Dry periods in May coincided with high C. pirolata uredinia and low telia production on alternate hosts. However, monthly rainfall during pollination did not explain the epidemic rust patterns in cones. Timing of disease control is discussed.

Attached and detached leaves of 60 potential host species were inoculated in the greenhouse and laboratory with aeciospores of Cronartium ribicola J.C. Fisch. from six Finnish locations and of Cronartium flaccidum (Alb. & Schw.) Wint. from 20 locations in Finland and Sweden in 2011. Candidate hosts represented 16 plant families: Solanaceae, Verbenaceae, Asclepiadaceae, Grossulariaceae, Paeoniaceae, Balsaminaceae, Gentianaceae, Scrophulariaceae, Loasaceae, Tropaeolaceae, Acanthaceae, Myricaceae, Phrymaceae, Plantaginaceae, Orobanchaceae, and Apocynaceae. Inoculations of C. flaccidum produced uredinia after 2 weeks and (or) telia after 4 weeks of incubation on 25 hosts. Inoculation trials identified several new hosts for C. flaccidum in Fennoscandia, namely Impatiens balsamina, Swertia fedtschenkoana, Loasa tricolor, Myrica gale, Verbena canadensis, Saxifraga spp., Paeonia obovata, and Veronica daurica. Myricaceae and Saxifragaceae represent new host families for these rusts. Cronartium ribicola formed uredinia or telia on 10 species: Ribes spp. (7 species/cultivars), Pedicularis palustris subsp. palustris, Bartsia alpina, and Loasa triphylla. Results suggest wider alternate host ranges for both C. flaccidum and C. ribicola than previously recognized. Spores were virulent regardless of their source location, suggesting a lack of host-specificity among Fennoscandian populations of Cronartium.Key words: alternate hosts, Scots pine blister rust, white pine blister rust.

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Susceptibility of potential alternate host plants to pine stem rusts belonging to Cronartium spp. was artificially tested in Finland during 2012-2013. Forty-three species representing 11 plant families were inoculated in the laboratory; 34 species (11 families) were inoculated in the greenhouse with aeciospores of Cronartium flaccidum or C. ribicola. Twenty-one selected species (10 families) were also exposed to natural inoculum of C. flaccidum in the field in two severely affected Pinus sylvestris stands. After 5-8 weeks' incubation, C. flaccidum sporulated on 17 species (nine families) in the laboratory, 17 species (eight families) in the greenhouse and seven species (five families) in the field. Cronartium ribicola sporulated on three species (three families) in the laboratory or greenhouse. All of the hemiparasitic plants that belong to Orobanchaceae were infected by C. flaccidum, and several species supported rust sporulation when exposed to natural inoculum. Susceptible species belonged to genera Veronica,

A novel putative virus of Gremmeniella abietina type B (Ascomycota: Helotiaceae) has a composite genome with endornavirus affinities Ascospore and mycelial isolates of Gremmeniella abietina type B were found to contain three different dsRNA molecules with approximate lengths of 11, 5 and 3 kb. The 11 kb dsRNA encoded the genome of a putative virus and is named Gremmeniella abietina type B RNA virus XL (GaBRV-XL). GaBRV-XL probably exists in an unencapsulated state. We identified two distinct dsRNAs (10 374 and 10 375 bp) of GaBRV-XL, both of which coded for the same putative polyprotein (3249 amino acids) and contained four regions similar to putative viral methyltransferases, DExH box helicases, viral RNA helicase 1 and RNA-dependent RNA polymerases. While a cysteine-rich region with several CxCC motifs in GaBRV-XL was similar to that of putative endornaviruses, cluster analyses of conserved regions revealed GaBRV-XL to be distinct from a broad range of viral taxa but most closely related to Discula destructiva virus 3. Collectively, these findings suggest that GaBRV-XL represents a novel virus group related to endornaviruses. INTRODUCTIONRecently recognized by the International Committee on Taxonomy of Viruses (ICTVdB Management, 2006), endornaviruses are usually cryptic and non-enveloped plant and fungal dsRNA viruses that spread efficiently through mitotic and meiotic cells but not through grafts (Fukuhara et al., 1995;Moriyama et al., 1999;Wakarchuk & Hamilton, 1990;Pfeiffer, 1998 Fungal viruses of the G. abietina species complex have been studied thoroughly in type A and are known to include putative members of the virus families Narnaviridae, Totiviridae and Partitiviridae, some of which can co-infect a single fungal isolate (Tuomivirta et al., 2002;Tuomivirta & Hantula, 2005).The goals of this study include a survey of dsRNA molecules in G. abietina type B, molecular characterization of the most common dsRNA type and its comparison to representatives of similar viral taxa. METHODSG. abietina type B strains. G. abietina type B strains (see Supplementary Table S1, available in JGV Online) were identified by the random amplified microsatellite (RAMS) technique of Hantula & Müller (1997). Branches from P. sylvestris and Pinus contorta ,2 m in height (,20 years old) with symptoms of scleroderris canker were collected in artificially or naturally regenerated stands between June 1994 and June 1995 in northern Finland. Disease symptoms included death of lateral branches over several internodes, cankers, yellowgreen woody tissues, pycnidia and apothecia. Fungi were isolated either from pycnidia or from infected wood adjacent to apothecia.Nucleic acid isolation and electrophoresis. G. abietina type B isolates were grown at 20 uC on modified orange serum agar covered with a cellophane membrane (Müller et al., 1994). dsRNA isolationThe GenBank/EMBL/DDBJ accession numbers for the complete sequences of the 11 kb dsRNAs of isolates AU58 (GaBRV-XL1) and E46 (GaBRV-XL2) are respectively DQ399289 and DQ399290.Details of ...

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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.