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Apothecia

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Paul S Dyer – 1st expert on this subject based on the ideXlab platform

  • first report of Apothecia of tapesia yallundae occurring on the wild grass holcus lanatus yorkshire fog in new zealand
    Plant Pathology, 2002
    Co-Authors: Paul S Dyer, Rosie E Bradshaw

    Abstract:

    Tapesia yallundae is a causal agent of eyespot, a damaging stem base disease of cereal crops. The pathogen has also been detected on many wild and cultivated grasses even if characteristic eyespot symptoms are not visible (Lucas et al ., 2000). The pathogen exhibits a heterothallic mating system and Apothecia of the sexual stage have been detected on straw stubble in many European countries, Australasia, southern Africa and North America (Dyer et al ., 2001). During field studies in New Zealand in 1995, Apothecia resembling those of T. yallundae were discovered on decaying stem bases of Holcus lanatus (Yorkshire Fog) at the margin of one wheat field near Carterton, Wairarapa, North Island. To verify that Apothecia were indeed T. yallundae , ascospore discharge was induced and single ascospore cultures established. Resultant colonies were confirmed as T. yallundae on the basis of conidia and colony morphology, and growth rate (2·3 ± 0·1 mm day − 1 ) on potato dextrose agar (Dyer et al ., 1996). Isolates from H. lanatus also produced a 1·05-kb PCR product characteristic of T. yallundae following amplification with the speciesspecific primers Ty 16F and Ty 16R (Nicholson et al ., 1997). No product was obtained with primers specific to the closely related species T. acuformis . Furthermore, amplification with RAPD primer OPA-10 resulted in the production of 0·68and 1·32-kb bands, again characteristic of T. yallundae (Dyer et al ., 1996). Finally, inoculation of wheat seedlings (cv. Avalon) with conidial suspensions resulted in production of characteristic eyespot lesions. This represents the first report of Apothecia of T. yallundae occurring on H. lanatus and the first evidence of infection of H. lanatus by T. yallundae . The sexual stage of T. yallundae has also been detected on the wild grasses Bromus diandrus and Hordeum leporinum (barley grass) (Wallwork, 1987). Should the sexual cycle occur regularly on wild grasses then these species may provide an important reservoir of eyespot disease able to infect nearby cereal crops as a result of the dispersal of airborne ascospores. This problem may be exacerbated by the recent establishment of grassy islands (‘beetle banks’) as wildlife refuges in UK crops.

  • species and mating type distribution of tapesia yallundae and t acuformis and occurrence of Apothecia in the u s pacific northwest
    Phytopathology, 2002
    Co-Authors: Greg W Douhan, Timothy D Murray, Paul S Dyer

    Abstract:

    ABSTRACT Eyespot of wheat is caused by the discomycete fungi Tapesia yallundae and T. acuformis. T. yallundae is considered the most important causal agent of the disease in this region but no Apothecia of either species have been found in the U.S. Pacific Northwest (PNW). Two compatible isolates of T. yallundae from the PNW were used to inoculate a field plot in the fall of 1998 and Apothecia developed in the spring and fall of 2000 on standing wheat stubble. In the spring of 2000, wheat stubble from eight naturally infected fields was examined for the presence of Apothecia of T. yallundae and T. acuformis. Apothecia of T. acuformis were found in two fields but no Apothecia of T. yallundae were found. This is the first report of Apothecia of the eyespot pathogens occurring in the PNW. Species and mating-type distribution of T. yallundae and T. acuformis in the PNW were determined from 817 isolates collected from diseased wheat over 3 years at spatial scales ranging from within fields to across states. In…

  • development of Apothecia of the eyespot pathogen tapesia on cereal crop stubble residue in england
    Plant Pathology, 2001
    Co-Authors: Paul S Dyer, G L Bateman, Henry M Wood

    Abstract:

    A reservoir of infection of Tapesia yallundae may exist after harvest in bases of cereal stems due to the presence of Apothecia capable of discharging infective ascospores. Apothecia of T. yallundae developed in a seasonal pattern on winter barley inoculated with the pathogen, with maximum numbers of Apothecia produced on stubble 5-7 months after harvest. A similar pattern of development was observed on infected winter wheat. However, the peak in numbers of mature Apothecia was observed 2 months later than in winter barley. Apothecia capable of discharging ascospores were present for up to 6 months on stubble. Apothecia of T. acuformis were not detected on spring or winter barley, or spring or winter wheat stubble, despite inoculation of growing crops with isolates of compatible mating type.

Timothy D Murray – 2nd expert on this subject based on the ideXlab platform

  • occurrence and survival of Apothecia of the eyespot pathogens oculimacula acuformis and o yallundae on wheat stubble in the u s pacific northwest
    Plant Disease, 2016
    Co-Authors: D I Vera, Timothy D Murray

    Abstract:

    Eyespot is a chronic disease of wheat caused by Oculimacula yallundae and O. acuformis that results in premature ripening of grain, lodging, and reduced grain yield. Discovery of the sexual stage of these Oculimacula spp. in the Pacific Northwest (PNW) of the United States is relatively recent and the role of Apothecia in the epidemiology of eyespot is unclear. Our goals were to determine whether and when Apothecia of these Oculimacula spp. are found in the PNW, and monitor their ability to survive over summer and over winter. Seventy-three harvested commercial wheat fields in Idaho, Oregon, and Washington were surveyed for Apothecia during spring and fall 2012 and spring 2013. Apothecia of both species were found in both spring and fall in 19% of fields. Apothecia survived on straw placed on the soil surface over the summer but not the winter. This is the first report of O. yallundae Apothecia in commercial wheat fields in the PNW. Occurrence of Apothecia in spring and fall demonstrates that sexual repro…

  • species and mating type distribution of tapesia yallundae and t acuformis and occurrence of Apothecia in the u s pacific northwest
    Phytopathology, 2002
    Co-Authors: Greg W Douhan, Timothy D Murray, Paul S Dyer

    Abstract:

    ABSTRACT Eyespot of wheat is caused by the discomycete fungi Tapesia yallundae and T. acuformis. T. yallundae is considered the most important causal agent of the disease in this region but no Apothecia of either species have been found in the U.S. Pacific Northwest (PNW). Two compatible isolates of T. yallundae from the PNW were used to inoculate a field plot in the fall of 1998 and Apothecia developed in the spring and fall of 2000 on standing wheat stubble. In the spring of 2000, wheat stubble from eight naturally infected fields was examined for the presence of Apothecia of T. yallundae and T. acuformis. Apothecia of T. acuformis were found in two fields but no Apothecia of T. yallundae were found. This is the first report of Apothecia of the eyespot pathogens occurring in the PNW. Species and mating-type distribution of T. yallundae and T. acuformis in the PNW were determined from 817 isolates collected from diseased wheat over 3 years at spatial scales ranging from within fields to across states. In…

J A Lucas – 3rd expert on this subject based on the ideXlab platform

  • incidence of Apothecia of tapesia yallundae at setaside sites in england and sensitivity of the ascospore offspring to the fungicides benomyl and prochloraz
    Plant Pathology, 1995
    Co-Authors: Paul S Dyer, J A Lucas

    Abstract:

    A total of 45 field sites in England were surveyed once for the presence of Apothecia of Tapesia yallundae from 1992 to 1994. Apothecia were found at 21 locations and were mainly present on less than 3% of stems. However, Apothecia were found on 15-32% of stems at four sites. Analysis of the growth characteristics of ascospore isolates from seven sites showed that most produced colonies characteristic of the W-type of T. yallundae, with only one site yielding the R-type. Most ascospore isolates were resistant to the fungicide benomyl and effectively all remained sensitive to prochloraz. The results of the study are discussed in relation to the fungicidal control and epidemiology of T. yallundae, and the risk of spread of disease from set-aside sites.

  • seasonal development of Apothecia of the cereal eyespot pathogen tapesia yallundae on straw stubble in the uk
    Annals of Applied Biology, 1994
    Co-Authors: Paul S Dyer, G L Bateman, J A Lucas, John F Peberdy

    Abstract:

    Five field sites growing winter wheat were inoculated with isolates of the W- and R-types of Tapesia yallundae in 1990 and 1991. After harvest, plots of uncultivated stubble were monitored for the production of Apothecia during 1992 and 1993. Apothecia were found on the stem bases of straw stubble over a 9-month period from mid-October to July, but with a peak in numbers present during late January to March, 5 to 7 months after harvest. This was associated with mean monthly temperatures between 3 degrees C and 8 degrees C. Rainfall appeared to be less important than temperature in Apothecial development. Single ascospore isolates obtained from Apothecia collected from areas inoculated with W-, R-, or mixed W- and R-type isolates all produced colonies with morphologies and growth rates characteristic of the W-type. Thus there was no indication that the W- and R-types are sexually compatible.