Effects of temperature on maturation of pseudothecia of Leptosphaeria maculans and L. biglobosa, closely related species which coexist on UK oilseed rape, were investigated. Stages in pseudothecial maturation on naturally infected oilseed rape debris were examined, both in controlled environments (5, 10, 15 or 20°C) under continuous wetness and in natural conditions (debris exposed in September and December 2000, and July, September and November 2002). Pseudothecia sampled weekly were assigned to maturation classes A (asci undifferentiated), B (asci differentiated), C (ascospores differentiated) or D (ascospores mature). Progress in pseudothecial maturation (assessed by time until 50% of pseudothecia reached each class) was similar for L. maculans and L. biglobosa at 15–20°C, but L. biglobosa matured more slowly at < 10°C. Maturation time decreased almost linearly with temperature from 5 to 20°C under continuous wetness but was longer in natural conditions, especially when periods of dry weather occurred. Differences in pseudothecial maturation are likely to contribute to epidemiological differences between L. maculans and L. biglobosa, which may explain their coexistence. It is appropriate to use the degree‐day approximation to assess pseudothecial maturation at temperatures between 5 and 20°C, providing debris is wet.

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In China, the incidence of phoma stem canker observed in pre-harvest surveys from 2005 to 2012 was greater on winter oilseed rape in provinces in central China (in May) than on spring oilseed rape in north China (in August). In all 742 cases when the causal pathogen was isolated from stem cankers, it was identified as Leptosphaeria biglobosa by morphology in culture and/or by species-specific polymerase chain reaction. Both L. biglobosa and Leptosphaeria maculans were detected on crop debris and seed in shipments of oilseed rape seed imported into China through Shanghai or Wuhan ports in 2009-2011. Descriptions of the observed spread of L. maculans into areas previously colonized by L. biglobosa across a spring oilseed rape growing region (Alberta, Canada, westwards, 1984-1998 and across a winter oilseed rape growing region (Poland, eastwards, 1984(Poland, eastwards, -2004 were used to estimate the potential westward spread of L. maculans in China across spring oilseed rape growing regions (north China) and winter oilseed rape growing regions (central China, generally provinces along the Yangtze River), respectively. The rates of spread were estimated as 47 km per year across spring oilseed rape in north China and 70 km per year across winter oilseed rape in central China. Dispersal modelling suggested that the rate of spread of L. maculans across Alberta, Canada (c. 17 km per year) could be explained by windborne dispersal of ascospores.

Ascospores of both A‐group and B‐group Leptosphaeria maculans germinated at temperatures from 5 to 20°C on leaves of oilseed rape. Germination of ascospores of both groups started 2 h after inoculation and percentage germination reached its maximum about 14 h after inoculation at all temperatures. Both the percentage of A‐/B‐group ascospores that had germinated after 24 h incubation and germ tube length increased with increasing temperature from 5 to 20°C. Germ tubes from B‐group ascospores were longer than those from A‐group ascospores at all temperatures, with the greatest difference at 20°C. Hyphae from ascospores of both groups penetrated the leaves predominantly through stomata, at temperatures from 5 to 20°C. A‐group ascospores produced highly branched hyphae that grew tortuously, whereas B‐group ascospores produced long, straight hyphae. The percentage of germinated ascospores that penetrated stomata increased with increasing temperature from 5 to 20°C and was greater for A‐group than for B‐group L. maculans after 40 h incubation.

The complete nucleotide sequences of both RNAs of oat golden stripe virus (OGSV) and a wheat-infecting furovirus isolate from France, previously thought to be soil-borne wheat mosaic virus (SBWMV), have been determined. Both viruses had a similar genomic organisation to SBWMV and Chinese wheat mosaic virus, the two other furoviruses previously sequenced but had <70% nucleotides identical to them. The French isolate has been named European wheat mosaic virus (EWMV). Phylogenetic analyses supported the recognition of these isolates as distinct viruses in the genus Furovirus. Analysis of the coat protein readthrough domain on RNA2 of all furoviruses strongly predicts two mutually compatible conserved transmembrane domains that may be significant for fungus transmission. The second of these regions is eliminated by a deletion in the isolate of OGSV studied. Leaky opal (UGA) stop codons occur on both RNAs of all four furoviruses characterised and, in common with most other leaky opal codons identified in plant viruses, they are followed by a CGG codon.