scholarly journals First Report of the Perfect Stage of Powdery Mildew of Sugar Beet in North Dakota Caused by Erysiphe polygoni

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 470-470 ◽  
Author(s):  
C. A. Bradley ◽  
P. Burlakoti ◽  
R. S. Nelson ◽  
M. F. R. Khan
Keyword(s):  
Powdery Mildew ◽  
Sugar Beet ◽  
North Dakota ◽  
Leaf Spot ◽  
Genetic Recombination ◽  
The State ◽  
Cercospora Leaf Spot ◽  
First Report ◽  
Perfect Stage ◽  
Erysiphe Polygoni

Powdery mildew caused by Erysiphe polygoni was widespread on sugar beet (Beta vulgaris) in North Dakota during 2006. This disease is generally not prevalent in the state because of the application of fungicides, which also have efficacy against powdery mildew, for control of Cercospora leaf spot caused by Cercospora beticola. Because Cercospora leaf spot pressure was low in 2006, fewer fungicide applications were made in the state, thus allowing for more observations of powdery mildew. Leaf samples from four fields near Amenia, Minto, Prosper, and St. Thomas, ND were collected in mid-September to look for the perfect stage of E. polygoni, since this has recently been observed in Idaho, Colorado, Montana, and Nebraska (1–3). Only the leaves collected from the field near Amenia had visible immature (yellow and brown) globose ascomata; ascomata were not observed on the leaves collected in the other fields. Additional leaves were collected from the field near Amenia in early October; these leaves had immature and mature (black) globose ascomata that were 70 to 105 μm in diameter. Mature ascomata contained ovoid to elliptic asci with one to four hyaline-to-golden pigmented ascospores (20 to 25 × 12 to 20 μm). The color, shape, and size of ascomata, asci, and ascospores were similar to previously reported observations (1–4). The prevalence of the perfect stage in North Dakota is unknown, since no statewide surveys were conducted. To our knowledge, this is the first report of the perfect stage of E. polygoni on sugar beet in North Dakota. The occurrence of the perfect stage could lead to a means for overwintering in this area. Because of the means for genetic recombination, the risk of fungicide resistance and the development of races may increase. References: (1) J. J. Gallian and L. E. Hanson. Plant Dis. 87:200, 2003. (2) R. M. Harveson. Plant Dis. 88:1049, 2004. (3) B. Jacobsen et al. Plant Dis. 89:1362, 2005. (4) E. G. Ruppel. Powdery mildew. Pages 13–15 in: Compendium of Beet Diseases and Insects. E. D. Whitney and J. E. Duffus, eds. The American Phytopathological Society. St. Paul, MN, 1986.

scholarly journals Occurrence of the Perfect Stage of Powdery Mildew of Sugar Beets in Southern Montana in 2003

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1362-1362
Author(s):  
B. Jacobsen ◽  
M. R. Johnston ◽  
H. C. Weltzien
Keyword(s):  
Powdery Mildew ◽  
Sugar Beet ◽  
Genetic Recombination ◽  
Its Region ◽  
The United States ◽  
Long Distance ◽  
Separate Species ◽  
Sugar Beets ◽  
Perfect Stage ◽  
Erysiphe Polygoni

Wide spread powdery mildew infections on sugar beets were observed at the Southern Agricultural Experiment Station in Huntley, MT during September, 2003. Throughout the area, lower leaves were frequently heavily covered by the vegetative stage of the fungus with plants at the edge of the field having clearly visible abundant mature (black) and immature (brown) globose ascocarps on the leaf surfaces and stems. The fruiting structures had mostly branched appendages and were imbedded in the superficial mycelium. Their diameter ranged from 70 to 100 μm. Each ascocarp contained five to eight asci with one to four ascospores (mostly three) per ascus. Elliptical ascospores were hyaline and measured 20 to 25 μm long and 12 to 20 μm wide. On the basis of the descriptions given for isolates from Idaho and Colorado (1) and the usage of Erysiphe polygoni DC for powdery mildew on sugar beet in the United States, this isolate may be classified as E. polygoni DC. However, measurements taken show that ascocarps, asci, and ascospores also fall within the range of E. betae (Vanha) Weltz. as described by Weltzien (2). We strongly suggest that these species be compared by using rDNA analysis of the ITS region to determine whether they are separate species. If survival of the ascocarps and the viability and pathogenicity of the ascospores can be confirmed, epidemics of sugar beet powdery mildew could be understood as local and regional events that are not dependant on long distance dispersal of conidiospores. The occurrence of the perfect stage also could lead to the more frequent appearance of new races through genetic recombination. References: (1) J. J Gallian and L. E. Hanson. Plant Dis. 87:200, 2003. (2) H. C. Weltzien. Phytopathol. Z. 47:123, 1963.

scholarly journals The Perfect Stage of Powdery Mildew (Erysiphe polygoni) of Beta vulgaris Found in Michigan

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 494-494 ◽  
Author(s):  
L. E. Hanson ◽  
J. M. McGrath
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Sugar Beet ◽  
North Dakota ◽  
Beta Vulgaris ◽  
The United States ◽  
Perfect Stage ◽  
Swiss Chard ◽  
Erysiphe Polygoni ◽  
Powdery Mildew Infection

Powdery mildew (Erysiphe polygoni DC [synonym E. betae {Vanha} Weltzien]) affects several different crops of Beta vulgaris, including sugar beet, Swiss chard, and table beet. The disease has been prevalent in many sugar beet-growing areas of the United States since the first major epidemic in beet in 1974 (3). Powdery mildew in the United States was primarily associated with the asexual stage of the pathogen until the perfect stage was found, first in western states such as Idaho and Colorado (2), then in more Midwestern states such as Nebraska, and most recently in North Dakota (1). Similar to North Dakota, powdery mildew has not been a major problem in the Michigan growing area. It does appear sporadically, particularly on sugar beets that have not been sprayed to control other foliar diseases. In 2010, powdery mildew infection on sugar beet was observed in late August in a field in the Saginaw Valley of Michigan. Plants were inspected periodically for the presence of the sexual stage. In early October, sugar beet and Swiss chard plants with heavy powdery mildew infection also were observed at the Michigan State University (MSU) Horticultural Demonstration Gardens in East Lansing and on sugar beet at the MSU Plant Pathology and Botany research farms. On both the Saginaw Valley sugar beet and Swiss chard on the MSU campus, ascomata were observed on a few leaves in mid-October. No ascomata were found on sugar beet at the other two locations. The majority of ascomata were dark brown to black when located, although a few light tan ascomata were observed on the Swiss chard. Ascomata varied from 70 to 100 μm in diameter. Asci contained one to four hyaline or golden yellow ascospores similar to those described in other growing regions on sugar beet (1,2). No ascomata had been detected on powdery mildew-infected sugar beet from either the Saginaw Valley or the MSU research farms the previous two years. These results appear to indicate a spread of the ability to form the perfect stage eastward from the western United States. This may be due to movement of one mating type because E. polygoni has been reported to be heterothallic on some crops (4). The presence of the perfect stage indicates that sexual recombination could occur in E. polygoni on Beta species in Michigan, creating the potential for more rapid development of new strains that might vary in fungicide sensitivity and response to host resistance. References: (1) C. A. Bradley et al. Plant Dis. 91:470, 2007 (2) J. J. Gallian and L. E. Hanson. Plant Dis. 87:200, 2003. (3) E. G. Ruppel. Page 13 in: Compendium of Beet Disease and Insects. E. D. Whitney and J. E. Duffus, eds. The American Phytopathological Society, St. Paul, MN, 1986. (4) C. G. Smith. Trans. Br. Mycol. Soc. 55:355, 1970.

scholarly journals MGS Esmeralda: new large seed mungbean cultivar

2008 ◽  
Vol 43 (6) ◽  
pp. 781-782 ◽  
Author(s):  
Rogério Faria Vieira ◽  
José Eustáquio Souza Carneiro ◽  
Trazilbo José de Paula Júnior ◽  
Roberto Fontes Araújo
Keyword(s):  
Powdery Mildew ◽  
Research And Development ◽  
Leaf Spot ◽  
Seed Mass ◽  
Minas Gerais ◽  
The State ◽  
Cercospora Leaf Spot ◽  
Large Seed ◽  
Development Center

Mungbean cultivar MGS Esmeralda was developed by Asian Vegetable Research and Development Center (Shanhua, Taiwan), as a result of crossing between the lines VC 1973A and VC 2768A. In ten trials conducted in the State of Minas Gerais, Brazil, it produced 13.5% more grains than 'Ouro Verde MG-2' (control cultivar), and its highest yield was 2,550 kg ha-1. The cultivar MGS Esmeralda is more susceptible to lodging, and its pods mature more uniformly than Ouro Verde MG-2 pods. One hundred-seed mass of 'MGS Esmeralda' ranged between 5.5 and 6.8 g. Both cultivars are susceptible to powdery mildew and cercospora leaf spot.

scholarly journals Impact of Application Rate and Interval on the Control of Powdery Mildew and Cercospora Leaf Spot on Bigleaf Hydrangea with Azoxystrobin

2004 ◽  
Vol 22 (2) ◽  
pp. 58-62 ◽  
Author(s):  
A. K. Hagan ◽  
J. W. Olive ◽  
J. Stephenson ◽  
M. E. Rivas-Davila
Keyword(s):  
Powdery Mildew ◽  
Leaf Spot ◽  
Application Rate ◽  
Cercospora Leaf Spot ◽  
Thiophanate Methyl ◽  
Hydrangea Macrophylla ◽  
Application Rates ◽  
Erysiphe Polygoni ◽  
Causal Fungus ◽  
Paraffinic Oil

Abstract Efficacy of azoxystrobin (Heritage 50W™) was assessed over a range of application rates and intervals for the control of powdery mildew (Erysiphe polygoni) and Cercospora leaf spot (Cercospora hydrangea) on bigleaf hydrangea (Hydrangea macrophylla) ‘Nikko Blue’. Rooted hydrangea cuttings were transplanted in a pine bark/peat mixture. In 1998 and 1999, azoxystrobin at 0.16 g ai/liter and 0.32 g ai/liter, as well as 0.24 g ai/liter myclobutanil (Eagle 40W™) and 0.84 g ai/liter thiophanate methyl (3336 4.5F™), greatly reduced the incidence of powdery mildew compared with the untreated control where 75% of the leaves of were infected by the causal fungus. When applied at 1-, 2-, and 3-week intervals, both rates of azoxystrobin were equally effective in both years in preventing the development of powdery mildew on bigleaf hydrangea. In 1998, all fungicides except for thiophanate methyl protected bigleaf hydrangea from Cercospora leaf spot. In the last two trials, the incidence of powdery mildew increased significantly as the application rate for azoxystrobin decreased from 0.16 to 0.04 g ai/liter and the application interval was lengthened from 1 to 3 weeks. In general, all rates of azoxystrobin applied on a 3-week schedule failed to provide the level of powdery mildew control needed to produce quality bigleaf hydrangea for the florist and landscape market. When applied at 2-week intervals, myclobutanil was equally or more effective in controlling powdery mildew than any rate of azoxystrobin applied on the same schedule. When compared to the untreated controls, significant reductions in the incidence of powdery mildew on bigleaf hydrangea were obtained with weekly applications of paraffinic oil. No symptoms of phytotoxicity were associated with the use of any of the fungicides screened.

scholarly journals First Report of QOI-insensitive Powdery Mildew (Erysiphe polygoni) on Sugar Beet in the United States

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 1004-1004 ◽  
Author(s):  
M. D. Bolton ◽  
O. T. Neher
Keyword(s):  
United States ◽  
Disease Management ◽  
Powdery Mildew ◽  
Sugar Beet ◽  
Untreated Control ◽  
The United States ◽  
Nucleotide Position ◽  
Cytb Gene ◽  
First Report ◽  
Erysiphe Polygoni

The $2.1 billion United States sugar beet (Beta vulgaris L.) industry is the primary provider of domestic sucrose. Sugar beet powdery mildew is caused by Erysiphe polygoni DC and occurs principally in sugar beet growing regions in the western United States. In these regions, the quinone outside inhibitor (QOI) fungicides pyraclostrobin (Headline, BASF, NC) and trifloxystrobin (Gem, Bayer Crop Science, NC) have been important tools to manage powdery mildew since registration in 2002 and 2005, respectively. However, researchers in Idaho reported poor disease management despite QOI application starting in 2011. In 2013, a research plot near Parma, ID, containing natural powdery mildew infection received treatments of pyraclostrobin, trifloxystrobin, or was untreated (control). Since there was no significant reduction in disease levels between QOI-treated blocks and untreated control blocks, experiments were conducted to clone a partial fragment of the E. polygoni cytochrome b (cytb) gene to gain insight into the molecular basis of QOI resistance in this pathosystem. The primers MDB-920 (5′-CACATCGGAAGAGGTTTATA-3′) and MDB-922 (5′-GGTATAGATCTTAATATAGCATAG-3′) were designed based on consensus sequences of several fungal cytb genes obtained from GenBank (data not presented) and used to amplify a 575-bp fragment of the E. polygoni cytb gene using DNA isolated from 12 infected leaf samples collected in September 2013 from the Parma research plot. Each sample consisted of three leaves harvested from three plants (one leaf per plant) in an experimental block. All DNA extraction, PCR, and sequencing procedures were as described previously (1). PCR products derived from six QOI-treated samples and six untreated samples were sequenced directly. Without exception, all QOI-treated samples harbored a point mutation at nucleotide position 143 that encoded a G143A mutation compared with cytb sequence from untreated samples. The two identified cytb haplotypes have been deposited in GenBank under accession numbers KF925325 and KF925326. This is the first report of QOI resistance and the associated cytb G143A mutation in E. polygoni. The G143A mutation has been reported in most QOI-resistant pathogens to date (2). When the G143A mutation dominates in a pathogen population, there is a consistent association with a loss of disease management despite QOI application (3). Careful monitoring and judicious use of QOI fungicides will be necessary to ensure QOI fungicides remain efficacious for sugar beet powdery mildew management in the United States. References: (1) M. D. Bolton et al. Pest Manag. Sci. 69:35, 2013. (2) N. Fisher and B. Meunier. FEMS Yeast Res. 8:183, 2008. (3) U. Gisi et al. Pest Manag. Sci. 58:859, 2002.

First Report of Alternaria alternata Causing Leaf Spot on Beta vulgaris in North Dakota, USA

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Haque E ◽  
◽  
Parvin MS ◽  
Keyword(s):  
Sugar Beet ◽  
North Dakota ◽  
Leaf Spot ◽  
Sanger Sequencing ◽  
Leaf Tissue ◽  
Reference Sequence ◽  
Single Spore ◽  
Isolation Technique ◽  
First Report ◽  
Dark Green

Sugar beet is an economically important crop which is contributing 55% of the total sugar in the USA. In June 2018, irregular dark brown somewhat circular spots were observed on sugar beet leaves in Hickson, North Dakota. The symptoms covered approximately 5% on the lower leaves. Symptomatic leaf tissue were excised from the junction of diseased and healthy tissue. Small pieces (5 mm²) were surface sterilized with 10% sodium hypochlorite for 1 min, rinsed thrice with sterile distilled water, air dried and transferred to Potato Dextrose Agar (PDA), and incubated at 24°C with a 12-h photoperiod for 5 days. Dark-green velvety colony appeared in two weeks. Three isolates were developed by the single spore isolation technique. Conidia were club-shaped, two to four transverse septa, and pale brown, without any beak, often in chains (4 to 8 conidia) and or solitary. The dimension of conidia varied from 25-40x7-14 μm [1,2]. Based on the morphological characters, the fungus was tentatively identified as Alternaria species. Genomic Deoxyribonucleic Acids (gDNAs) were extracted from the culture generated from a single spore using Qiagen kit. ITS4/ITS5 were used to amplify the fragments of the Internal Transcribed Spacer (ITS) region. The amplified PCR products were cleaned and sent for Sanger sequencing by GenScript (GenScript, Piscataway, NJ). The sequences from GenScript were congruence to the reference sequence ID MT126620.1. The entire sequences were deposited at NCBI (GenBank accession nos. MK441717). Koch postulates were followed by spraying conidia suspension (5×105 conidia/ml) to 8-week age of 20 plants of and kept in humidity chamber at 28-30 °C, 80-85 % RH. Mock-inoculated seeds were also sown as a control. Three weeks of post inoculation, the similar irregular dark brown symptoms observed in twelve plants. No symptoms were found in the mock. The experiment was conducted twice. The fungus was reisolated from the diseased leaf tissue, as described above. Macroscopic and microscopic analysis indicated the similar dark-green colony and morphology, respectively. Molecular detection performed using the same ITS primers and sent for Sanger sequencing by GenScript, this study further confirmed that the isolate was similar to A. alternata [3]. Another close species of Alternaria was recently reported in sugar beet to cause leaf spot in Minnesota [4,5]. To our best knowledge, this is the first report of A. alternata causing leaf spot on sugar beet in North Dakota.

scholarly journals Widespread Occurrence of the Perfect Stage of Powdery Mildew Caused by Erysiphe polygoni on Sugar Beets in Nebraska

Plant Disease ◽  
2004 ◽  
Vol 88 (9) ◽  
pp. 1049-1049
Author(s):  
R. M. Harveson
Keyword(s):  
Powdery Mildew ◽  
Sugar Beet ◽  
The United States ◽  
Pathogen Resistance ◽  
Widespread Occurrence ◽  
Perfect Stage ◽  
The North ◽  
High Incidence ◽  
Erysiphe Polygoni ◽  
Severe Infections

Powdery mildew, caused by Erysiphe polygoni DC (synonym E. betae [Vanha] Weltzien), has been a sporadic and relatively minor problem for sugar beet (Beta vulgaris L.) growers in western Nebraska. Yield losses in this region have been limited, in part because of the use of effective fungicides, but also because infection occurs late enough in the season that treatment has often been unnecessary. The perfect stage had been reported only once in the United States until 2001-2002 when it was identified from Idaho and Colorado (1). The teleomorph was also noted from several fields in Scotts Bluff County in Nebraska in October 2002. The first appearance of the disease in 2003 occurred during the second week of August within five miles of the fields where the perfect stage was noted in 2002. On the basis of these observations, a survey was conducted between mid-August and mid-October to map the appearance and distribution of the perfect stage of E. polygoni within the Nebraska Panhandle growing region. During this time, between 45 and 50 fields were surveyed in six Nebraska counties. This represented the majority (70%) of the sugar beet acreage in Nebraska. The first finding of the perfect stage occurred in early September from multiple fields in the vicinity of and including the field where the asexual stage was first reported in August 2003. Ascomata measured 85 to 110 μm with one to four (mostly three) ascospores per ascus, resembling previous pathogen descriptions (2). Subsequently, every other field in the North Platte Valley where the oidial stage had been found also contained the perfect stage by the third week in September, including the Nebraska counties of Scotts Bluff (15 fields) and Morrill (7 fields). Outside the North Platte Valley, powdery mildew was not detected until mid-September and mid-October for the Northern Panhandle (Box Butte County) and Southern Panhandle (Kimball, Banner, and Cheyenne counties) growing areas, respectively. By October 1, the perfect stage was found in 9 of 10 fields exhibiting the disease in the North Panhandle, whereas the perfect stage was not found in the Southern Panhandle before harvest. Over 85% of surveyed fields infected with powdery mildew also harbored the perfect stage (31 of 36). Not only is the new and continued presence of the perfect stage potentially problematic for managing fungicide resistance and developing new cultivars with pathogen resistance (1), but it may also provide a means for overwintering in this area. This could result in earlier and more severe infections that would additionally require uncustomary treatment for powdery mildew control. The unusually early appearance of the disease and the high incidence of the perfect stage in Nebraska fields during 2003 further highlights these concerns and warrants closely monitoring future crops for continued epidemics. References: (1) J. J. Gallian and L. E. Hanson. Plant Dis. 87:200, 2003. (2) E. G. Ruppel. Powdery mildew. Pages 13–15 in: Compendium of Beet Diseases and Insects. E. D. Whitney and J. E. Duffus, eds. The American Phytopathological Society, St. Paul, MN, 1986.

scholarly journals Improving the Cercospora Leaf Spot Management Model for Sugar Beet in Minnesota and North Dakota

Plant Disease ◽  
2007 ◽  
Vol 91 (9) ◽  
pp. 1105-1108 ◽  
Author(s):  
J. Khan ◽  
L. E. del Río ◽  
R. Nelson ◽  
M. F. R. Khan
Keyword(s):  
Sugar Beet ◽  
North Dakota ◽  
Disease Severity ◽  
Leaf Spot ◽  
Management Model ◽  
Initial Symptom ◽  
Cercospora Leaf Spot ◽  
Progress Curve ◽  
Management Recommendations ◽  
The Impact

Management of Cercospora leaf spot, caused by Cercospora beticola, is necessary for the economic production of sugar beet (Beta vulgaris). The objectives of this study were to evaluate the impact of two relative humidity thresholds (87 and 90%) on the daily infection values (DIVs) used to determine when fungicide applications were required, to determine whether current Cercospora management recommendations for northern areas of Minnesota and North Dakota could be used by growers in the southern areas of these states, and to compare the utility of calendar-based fungicide applications with the Cercospora management model. Research was conducted in Breckenridge, MN and St. Thomas, ND in 2003 and 2004. Fungicide applications significantly (P = 0.05) reduced maximum disease severity (ymax) and area under the disease progress curve (AUDPC) when compared with the nontreated control at both locations during 2003 and 2004. Fungicides applied according to DIVs calculated at RH ≥ 87% or RH > 90% gave similar results. The mandatory second fungicide application 14 days after the first application for southern areas did not significantly decrease disease severity or AUDPC, or improve root yield or recoverable sucrose compared with treatments without the mandatory application. This research illustrates that a DIV calculated at RH ≥ 87% would result in similar timing of fungicide applications compared with DIVs calculated at RH > 90%. The results further show that the recommendation of fungicide applications at initial symptom and subsequent applications based on DIV and disease severity should be used for both northern and southern growers. Finally, this research showed that fungicide applications based on the Cercospora management model provided similar, effective disease control with fewer fungicide applications compared with calendar-based applications.

scholarly journals Fluctuations in Number of Cercospora beticola Conidia in Relationship to Environment and Disease Severity in Sugar Beet

2009 ◽  
Vol 99 (7) ◽  
pp. 796-801 ◽  
Author(s):  
J. Khan ◽  
A. Qi ◽  
M. F. R. Khan
Keyword(s):  
Relative Humidity ◽  
Sugar Beet ◽  
North Dakota ◽  
Disease Severity ◽  
Leaf Spot ◽  
Forecasting Model ◽  
Cercospora Beticola ◽  
Disease Forecasting ◽  
Cercospora Leaf Spot ◽  
Average Temperature

Cercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P < 0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.

scholarly journals The Perfect Stage of Powdery Mildew of Sugar Beets Found in Idaho and Colorado

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 200-200
Author(s):  
J. J. Gallian ◽  
L. E. Hanson
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Sugar Beet ◽  
Genetic Recombination ◽  
The United States ◽  
Breeding Lines ◽  
Perfect Stage ◽  
South Central ◽  
Ascigerous Stage ◽  
Single Field

Powdery mildew (Erysiphe polygoni DC [synonym E. betae {Vanha} Weltzien]) of sugar beet (Beta vulgaris L.) has been a significant problem in many sugar beet growing areas of the United States since the first serious epidemic in 1974. Disease has been attributed solely to the asexual stage of the pathogen in the United States, except for one report of the perfect stage in a single field in Washington coincidental with the 1974 epidemic (1). In August 2001, ascomata were observed in several fields in Owyhee County in southwestern Idaho near Grand View. The perfect stage was widespread and easily found, and in one field the surfaces of leaves collected from 50 randomly sampled plants were between 10 and 90% covered with ascomata. Subsequently, the ascigerous stage was found in September and October in multiple fields in three additional counties in southwestern and south-central Idaho and two counties in northern Colorado. Ascomata were found on 12 commercial varieties in the two states and six breeding lines in Colorado. Asci contained one to four hyaline or yellow-to-golden pigmented ascospores per ascus. Ascomata observed in Idaho and Colorado are similar to those described from Europe (2). Ascospores appeared intact after leaves were dried and stored at 4 to 7°C more than 4 weeks. However, after leaves with ascomata were dried and stored at 24 to 27°C for 1 week or more, ascomata and asci appeared intact microscopically, but ascospores were no longer delineated and appeared desiccated or degraded. Because the ascigerous stage provides a means of genetic recombination, there is the potential for races of the pathogen to arise with greater frequency. This has serious implications for managing fungicide resistance and breeding for disease resistance to sugar beet powdery mildew. References: (1) D. L. Coyier et al. (Abstr.) Proc. Am. Phytopathol. Soc. 2:112, 1975. (2) S. Francis. Mol. Plant Pathol. 3:119, 2002.

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