The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Paul S Dyer - One of the best experts 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, 2002Co-Authors: Paul S Dyer, Rosie E BradshawAbstract: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, 2002Co-Authors: Greg W Douhan, Timothy D Murray, Paul S DyerAbstract: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, 2001Co-Authors: Paul S Dyer, G L Bateman, Henry M WoodAbstract: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.
-
development of Apothecia of tapesia yallundae in contrasting populations selected by fungicides
European Journal of Plant Pathology, 1995Co-Authors: G L Bateman, Paul S Dyer, L ManzhulaAbstract:Apothecia of the eyespot fungus,Tapesia yallundae, were found on 0–18% of straws in plots of wheat stubble in February–March 1994. The fungicides carbendazim, prochloraz or carbendazim plus prochloraz had been applied repeatedly to the same plots in each of the previous 9 years in which successive wheat crops had been grown. The factors most strongly correlated with the incidence of Apothecia were the incidence and severity of eyespot in the preceding wheat crop and the frequency of carbendazim-resistant W-type fungus in populations recovered from that wheat crop. Plots treated with carbendazim, which had previously had more disease and more resistance to carbendazim in the pathogen population relative to untreated plots, therefore yielded most Apothecia. Plots treated with prochloraz, which had selected for predominantly R-type fungus and decreased eyespot, yielded few Apothecia. Single-ascospore isolates were all of the W-type and were more frequently carbendazim-sensitive than expected, except those from plots treated only with carbendazim. None showed decreased sensitivity to prochloraz. The implications of applying fungicides regularly for controlling eyespot on the capability of the eyespot fungus for genetic variation through sexual reproduction are discussed.
-
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, 1995Co-Authors: Paul S Dyer, J A LucasAbstract: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.
Timothy D Murray - One of the best experts 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, 2016Co-Authors: D I Vera, Timothy D MurrayAbstract: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, 2002Co-Authors: Greg W Douhan, Timothy D Murray, Paul S DyerAbstract: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 - One of the best experts 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, 1995Co-Authors: Paul S Dyer, J A LucasAbstract: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, 1994Co-Authors: Paul S Dyer, G L Bateman, J A Lucas, John F PeberdyAbstract: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.
G L Bateman - One of the best experts on this subject based on the ideXlab platform.
-
development of Apothecia of the eyespot pathogen tapesia on cereal crop stubble residue in england
Plant Pathology, 2001Co-Authors: Paul S Dyer, G L Bateman, Henry M WoodAbstract: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.
-
development of Apothecia of tapesia yallundae in contrasting populations selected by fungicides
European Journal of Plant Pathology, 1995Co-Authors: G L Bateman, Paul S Dyer, L ManzhulaAbstract:Apothecia of the eyespot fungus,Tapesia yallundae, were found on 0–18% of straws in plots of wheat stubble in February–March 1994. The fungicides carbendazim, prochloraz or carbendazim plus prochloraz had been applied repeatedly to the same plots in each of the previous 9 years in which successive wheat crops had been grown. The factors most strongly correlated with the incidence of Apothecia were the incidence and severity of eyespot in the preceding wheat crop and the frequency of carbendazim-resistant W-type fungus in populations recovered from that wheat crop. Plots treated with carbendazim, which had previously had more disease and more resistance to carbendazim in the pathogen population relative to untreated plots, therefore yielded most Apothecia. Plots treated with prochloraz, which had selected for predominantly R-type fungus and decreased eyespot, yielded few Apothecia. Single-ascospore isolates were all of the W-type and were more frequently carbendazim-sensitive than expected, except those from plots treated only with carbendazim. None showed decreased sensitivity to prochloraz. The implications of applying fungicides regularly for controlling eyespot on the capability of the eyespot fungus for genetic variation through sexual reproduction are discussed.
-
seasonal development of Apothecia of the cereal eyespot pathogen tapesia yallundae on straw stubble in the uk
Annals of Applied Biology, 1994Co-Authors: Paul S Dyer, G L Bateman, J A Lucas, John F PeberdyAbstract: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.
W. L. Pedersen - One of the best experts on this subject based on the ideXlab platform.
-
Effect of crop rotation and tillage system on sclerotinia stem rot on soybean
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2002Co-Authors: Daren S. Mueller, W. L. Pedersen, Glen L. HartmanAbstract:Sclerotinia stem rot (SSR) of soybean is a major disease in the North Central region of the United States. A 3-year study was done to determine if crop rotation and tillage, moldboard plowing then mulch tillage (MP + MT), mulch tillage (MT), and no-till (NT), affected the population density of sclerotia and Apothecia, incidence of SSR, and soybean yield. Crop rotation did not significantly affect the number or distribution of sclerotia or SSR incidence, but did affect the number of Apothecia and the yield. The highest number of Apothecia per square metre was observed in the plots in the continuous soybean rotation. Tillage affected both the number and distribution of sclerotia in the soil profile. Moldboard plowing lowered the number of sclerotia per litre of soil, compared to MT and NT plots, and buried the sclerotia deeper than 10 cm into the soil. Tillage did not affect the total number of Apothecia observed, but moldboard plowing did delay emergence of Apothecia compared to no-till. The MP + MT plots ...
-
development of sclerotia and Apothecia of sclerotinia sclerotiorum from infected soybean seed and its control by fungicide seed treatment
Plant Disease, 1999Co-Authors: Daren S. Mueller, Glen L. Hartman, W. L. PedersenAbstract:ABSTRACT Field and laboratory studies were done to evaluate the development of sclerotia and Apothecia of Sclerotinia sclerotiorum from soybeans and its control with fungicide seed treatment. Soybean seed infected with S. sclerotiorum produced mycelia on both seed coats and cotyledons after 48 h on potato dextrose agar (PDA). Obviously infected soybean seed also were placed in aluminum pans containing field soil and placed in soybean fields near Urbana, Illinois and Clinton, Wisconsin. In 1997, a total of 553 sclerotia, 20 stipes, and 10 Apothecia were produced from 500 infected seeds. In 1998, 201 sclerotia and 22 stipes were produced, but no Apothecia were observed from the 500 infected seeds. Fludioxonil was the most effective fungicide for reducing radial growth of S. sclerotiorum on PDA plates and suppressed 99% of the radial growth at 0.1 μg a.i./ml. S. sclerotiorum was recovered from 2% of soybean seed lots containing infected seed. When this seed lot was treated with several fungicides, captan + p...