Key messages emerging from the project:

• Ergots were found in a wide range of arable environments and in many grass species in 2005.
• Methods for investigating the pathogenicity of ergots from different grass species have been established.
• There are indications that ergots from certain grass species are less of a risk to wheat than those from other grass species.
• Methods for evaluating the resistance of wheat varieties to ergot have been compared and refined.
• There were tentative indications of differences between current UK wheat varieties in their vulnerability to ergot infection, but consistency in ranking of varieties over sites and seasons will need to be demonstrated before any conclusions can be drawn.

Summary of results from reporting year:

• 160 individual ergot samples were collected in 2005, from a total of 30 grass species. Ergots were found in sown margins, naturally regenerated areas, field gateways, pathways, and hedge bottoms. The highest numbers of samples were received from cocksfoot, couch, blackgrass, perennial ryegrass and false oat grass.
• Honeydew inoculum was produced successfully from ergots from a number of grass species to establish pathogenicity testing methods.
• A range of techniques was used in the field to inoculate wheat ears with honeydew. Direct injection into florets and spraying honeydew onto damaged ears were both successful. The latter approach is less time consuming, and would permit a high number of isolates to be tested. Inoculation of wheat ears using conidia produced from agar plates was also successful, and gave an indication of relative pathogenicity similar to that from honeydew inoculum.
• Isolates showed differences in their pathogenicity to wheat. The results indicate that isolates made from ergots taken from Yorkshire Fog and Sweet Vernal Grass appear to be a low risk to wheat, but more extensive testing of isolates from these species is needed.
• The primers and hybridisation probe developed for PCR detection of the ergot pathogen (C. purpurea) have been screened against a wide range of ear pathogens and common saprophytes to ensure that there is no cross reactivity. Extraction of pathogen DNA from spore trap tape, passive trap tubes and plant host tissues has been optimised. Real time PCR is now being used to analyse spore traps and crop samples.
• The release of ergot ascospores was monitored using Burkard volumetric spore traps at two locations. At the first location no spores were trapped during a monitoring period running from early May to early June. At the second location, ascospores were first detected on the 8/9 June and continued to be detected until monitoring ended on the 30th June. Only trace levels of spores were detected on each occasion.
• Passive spore traps were employed at six locations, where they were sited in first wheat, second wheat, ELS margin and grassland situations. These are now being analysed.
• Ascospores released deliberately at the centre of a large plot of wheat resulted in visible ergots in mid July. These were found almost exclusively on late tillers in the wheelings of tramlines.  
• Various techniques for examining the resistance of wheat varieties to ergot were evaluated. These included direct inoculation of conidia into the florets, inoculation of damaged ears, spraying plants with conidial suspensions and secondary spread from infested blackgrass 'spreaders'. 
• There were preliminary indications of varietal differences in the number of visible ergots and mean ergot size resulting from direct inoculation into the florets. Inoculation success rate was uniformly high. There were also indications of differences between varieties when the conidial spray and secondary spread methods were used, although infection levels were low overall. Further data will be required to determine whether variety rankings are consistent over sites and years.
• Flowering characteristics thought to be associated with a variety's 'openness of flowering' were studied. These included ear density, anther extrusion, anther size and blind florets / ear. There were preliminary indications of varietal differences, but no obvious relationship at this early stage with vulnerability to ergot infection.
  

Key issues to be addressed in the next year:

1. Monitoring of ergot infection in field margins and other arable situations will be carried out for a second season.
2. Experiments have been set up to investigate infection gradients from primary inoculum (ergots on the soil surface) and secondary inoculum (infested blackgrass) during the 2006 season.
3. Spore trapping will be repeated at contrasting farm sites.
4. More extensive testing of the pathogenicity of ergot isolates from different grass species will be carried out using the methods developed in 2005.
5. Approximately 50 wheat varieties will be tested at 2 sites for their resistance to ergot, using the blackgrass spreader method to simulate natural infection.
6. A smaller number of varieties will be tested by direct inoculation, to examine tissue resistance.
7. Flowering characteristics will be studied for a second season to look for evidence of consistent varietal effects over sites and seasons.