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

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.

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

Plant Disease ◽

10.1094/pd-89-1362b ◽

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.

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

Plant Disease ◽

10.1094/pdis-11-10-0803 ◽

2011 ◽

Vol 95 (4) ◽

pp. 494-494 ◽

Cited By ~ 1

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.

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

Plant Disease ◽

10.1094/pdis-91-4-0470b ◽

2007 ◽

Vol 91 (4) ◽

pp. 470-470 ◽

Cited By ~ 1

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.

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

Plant Disease ◽

10.1094/pdis-12-13-1217-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1004-1004 ◽

Cited By ~ 2

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.

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

Plant Disease ◽

10.1094/pdis.2003.87.2.200b ◽

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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First Report of Powdery Mildew Caused by Podosphaera aphanis var. aphanis on Potentilla fruticosa in Italy

Plant Disease ◽

10.1094/pd-89-1362c ◽

2005 ◽

Vol 89 (12) ◽

pp. 1362-1362

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Pathogenicity Test ◽

First Report ◽

Potentilla Fruticosa ◽

Erysiphe Polygoni ◽

Voucher Specimens ◽

White Mycelium ◽

Sphaerotheca Macularis

Potentilla fruticosa L. (bush cinquefoil), belonging to the family Rosaceae, is an ornamental plant used in parks and gardens. During the spring and summer of 2005, severe outbreaks of a previously unknown powdery mildew were observed in several private gardens located near Biella (northern Italy). The adaxial and abaxial surfaces of leaves as well as the stems were covered with white mycelium. Buds and flowers also were affected. As disease progressed, infected leaves turned yellow and dehisced. Conidia formed in chains and were hyaline, ovoid, and measured 24.0 to 36.0 × 15.8 to 24.0 μm (average 30.1 × 20.0 μm). Fibrosin bodies were present. Chasmothecia were numerous, sphaerical, amber colored, and diameters ranged from 84.0 to 98.4 μm (average 90.4 μm). Each chasmothecium contained one ascus with eight ascospores. Ascospores measured 26.5 to 27.2 × 13.2 to 15.6 μm (average 26.8 × 14.0 μm). On the basis of its morphology, the causal agent was determined to be Podosphaera aphanis (Wallr.) U. Braun & S. Takamatsu var. aphanis U. Braun (1). Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy P. fruticosa plants. Three plants were inoculated. Three noninoculated plants served as a control. Plants were maintained at temperatures ranging from 12 to 23°C. Ten days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on P. fruticosa in Italy. Erysiphe polygoni D.C. and Sphaerotheca macularis (Wallr.:Fr.) Lind were observed in the United States on P. fruticosa (2), while in Japan, the presence of S. aphanis var aphanis was reported (3). Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000 (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) S. Tanda et al. J. Agric. Sci. 39:258, 1995.

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First Report of Canola Powdery Mildew Caused by Erysiphe polygoni in Argentina

Plant Disease ◽

10.1094/pdis.2004.88.10.1163c ◽

2004 ◽

Vol 88 (10) ◽

pp. 1163-1163 ◽

Cited By ~ 5

Author(s):

S. Gaetán ◽

M. Madia

Keyword(s):

Powdery Mildew ◽

Buenos Aires ◽

Disease Incidence ◽

Fungal Growth ◽

The United States ◽

Climatic Conditions ◽

Width Ratio ◽

Infected Leaf ◽

First Report ◽

Erysiphe Polygoni

Canola (Brassica napus) is a developing oleaginous crop grown commercially in the Buenos Aires and Santa Fe provinces of Argentina. During the autumn of 2003, typical signs of powdery mildew were observed on canola plants in experimental field plots in Buenos Aires. Average disease incidence was 42% on 3- to 6-month-old canola cultivars developed in the following countries: Argentina (Eclipse, Impulse Master, Mistral, and Nolza); Australia (Oscar and Rainbow); Canada (Sentry); France (Cadillac, Camberra, and Capitol); and Sweden (Maskot, Sponsor, and Wildcat). The range of incidence on these cultivars was 35 to 93%. Other cultivars exhibited an apparent high level of resistance or escaped disease. These included: Charlton (Argentina); 46CO3, Dunkeld, Insignia, Mystic, Monty, Outback, Rivette, and Surpass 400 (Australia), and Caviar (France). Climatic conditions in Buenos Aires, especially rainfall, from March to May 2003 were apparently favorable for powdery mildew development. On susceptible cultivars, fungal growth was observed on leaves, stems, and pods that resulted in premature senescence of the tissues. The mycelium, with multilobed hausthoria, was white to gray, dense or fine, and in patches or covering the entire adaxial leaf surfaces. Appressoria were lobed and conidiophores were straight. Foot cells were cylindrical, straight, measured 35 to 42 × 7 to 10 μm, and were followed by two cells. Conidia were produced singly, cylindrical to ovoid, and measured 36 to 40 × 18 to 20 μm. The conidial length-to-width ratio was 2.0. No fibrosin bodies were observed in the conidia and conidia germinated at the ends. Cleistothecia were not observed. On the basis of mycelial, conidial, and hausthoria characteristics observed on six leaves for each affected cultivar, the fungus was identified as Erysiphe polygoni DC (1). Pathogenicity was confirmed on 5-week-old canola plants of cvs. Eclipse, Impulse, Master, Mistral, and Maskot by gently pressing (1 min) one adaxial infected leaf with abundant sporulation onto one adaxial healthy leaf. The experiment, which included five inoculated plants and three noninoculated control plants for each cultivar, was conducted in a greenhouse at 22 to 24°C and maintained at 75% relative humidity with no supplemental light. Inoculated and control plants were covered with polyethylene bags for 48 h after inoculation. Powdery mildew developed on all inoculated plants of all cultivars after 12 to14 days. The control plants did not develop disease. The experiment was repeated with similar results. E. polygoni has a worldwide distribution (2); however, the results suggest that this fungus may be a threat to the main cultivars being grown in Argentina (Eclipse, Impulse, Master, Mistral, and Nolza), since high levels of disease incidence, as much as 70%, were observed. Under propitious environments, this pathogen could cause severe yield losses in commercially grown canola in Argentina. To our knowledge, this is the first report of canola powdery mildew caused by E. polygoni in Argentina. References: (1) H. J. Boesewinkel. Rev. Mycol. Tome 41:493, 1977. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St.Paul, MN, 1989.

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Inheritance of Powdery Mildew Resistance in Sugar Beet Derived from Beta vulgaris subsp. maritima

Plant Disease ◽

10.1094/pdis.2001.85.6.627 ◽

2001 ◽

Vol 85 (6) ◽

pp. 627-631 ◽

Cited By ~ 25

Author(s):

R. T. Lewellen ◽

J. K. Schrandt

Keyword(s):

Powdery Mildew ◽

Sugar Beet ◽

Beta Vulgaris ◽

Powdery Mildew Resistance ◽

Major Gene ◽

Mildew Resistance ◽

Breeding Lines ◽

Erysiphe Polygoni ◽

Moderate Resistance ◽

High Level

Powdery mildew of sugar beet (Beta vulgaris), caused by Erysiphe polygoni, was introduced into North American in 1974. Since then, chemical control has been needed. Moderate resistance of a slow-mildewing type is known and has been used commercially. High resistance was identified recently in B. vulgaris subsp. maritima accessions WB97 and WB242 and has been backcrossed into sugar beet breeding lines. These enhanced lines were used as sources of powdery mildew resistance to determine the inheritance of resistance. Analyses of segregating testcross families showed that resistance from both sources is inherited as a single, dominant, major gene. The gene symbol Pm is proposed for the resistant allele. The allelism of the resistance from the two wild beet sources was not determined. Pm conditions a high level of resistance, but disease developed on matured leaves late in the season. This late development of mildew on lines and the slow-mildewing trait in susceptible, recurrent lines tended to obfuscate discrete disease ratings.

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QoI Resistance in Sugar Beet Powdery Mildew (Erysiphe betae) in Scandinavia

Plant Health Progress ◽

10.1094/php-01-19-0004-br ◽

2019 ◽

Vol 20 (3) ◽

pp. 179-179 ◽

Cited By ~ 1

Author(s):

Thies Marten Heick ◽

Anne Lisbet Hansen ◽

Annemarie Fejer Justesen ◽

Lise Nistrup Jørgensen

Keyword(s):

Powdery Mildew ◽

Sugar Beet ◽

The United States ◽

Field Trials ◽

Active Ingredients ◽

Management Measures ◽

Real Risk ◽

Erysiphe Betae ◽

European Union Legislation ◽

Qoi Resistance

Powdery mildew caused by Erysiphe betae is one of the major fungal diseases in sugar beet in Denmark and Sweden. Frequent applications of fungicides mitigate the risk of powdery mildew epidemics and, consequently, reduce yield losses conferred by the disease. So far, mixtures of quinone outside inhibitors (QoIs) and triazoles have provided good efficacy against E. betae in field trials and common farming practice. However, development of fungicide resistance is a real risk, because only a limited number of active ingredients are available for the control of powdery mildew in sugar beet, and several other active ingredients are expected to be banned following reevaluation when the most recent European Union legislation is implemented. The G143A mutation associated with QoI resistance has been previously found in the United States. In this brief, its presence in Europe is reported for the first time. The current finding strongly encourages the adoption of anti-resistance strategies that minimize the spread of QoI resistance in sugar beet powdery mildew. Those strategies should be based on integrated pest management measures, including disease monitoring, the use of resistant cultivars, and the use of biological products. A sole reliance on QoI fungicides for sugar beet powdery mildew control should be avoided.

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An Early Traffic Scheme for the English Channel

Journal of Navigation ◽

10.1017/s0373463300037966 ◽

1979 ◽

Vol 32 (2) ◽

pp. 266-271

Author(s):

Charles H. Cotter

Keyword(s):

United States ◽

New York ◽

North Atlantic ◽

United States Navy ◽

The United States ◽

Separation Scheme ◽

English Channel ◽

The North ◽

High Incidence ◽

The North Atlantic

The anonymous author of a paper published in the November 1857 issue of The Nautical Magazine, introduced a novel philosophy in relation to the location of lighthouses. At the same time he discussed the proposition for a coastal traffic separation scheme for the English Channel — notorious then, as it still is, for its high incidence of collisions and groundings. The proposal was made just two years after Walter R. Jones of New York made his suggestion to Lieut. M. F. Maury of the United States Navy for an ocean traffic separation scheme which materialized in the form of Maury's ‘steam lanes’ for the North Atlantic.

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