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

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.

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

Phytopathology ◽

10.1094/phyto-99-7-0796 ◽

2009 ◽

Vol 99 (7) ◽

pp. 796-801 ◽

Cited By ~ 18

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.

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Extending the CSM-CERES-Beet Model to Simulate Impact of Observed Leaf Disease Damage on Sugar Beet Yield

Agronomy ◽

10.3390/agronomy10121930 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1930

Author(s):

Emir Memic ◽

Simone Graeff-Hönninger ◽

Oliver Hensel ◽

William D. Batchelor

Keyword(s):

Sugar Beet ◽

Leaf Area ◽

Leaf Spot ◽

Leaf Spot Disease ◽

Root Weight ◽

Storage Root ◽

Cercospora Leaf Spot ◽

Area Index ◽

Spot Disease ◽

The Impact

A CSM-CERES-Beet pest damage routine was modified to simulate the impact of Cercospora leaf spot disease effects on sugar beet yield. Foliar disease effects on sugar beet growth and yield were incorporated as daily damage to leaf area and photosynthesis, which was linked to daily crop growth and biomass accumulation. An experiment was conducted in Southwest Germany (2016–2018) with different levels of disease infection. Data collected included time-series leaf area index, top weight, storage root weight and Cercospora leaf spot disease progress. The model was calibrated using statistical and visual fit for one treatment and evaluated for eight treatments over three years. Model performance of the calibration treatment for all three variables resulted in R2 values higher than 0.82 and d-statistics higher than 0.94. Evaluation treatments for all three observation groups resulted in high R2 and d-statistics with few exceptions mainly caused by weather extremes. Root mean square error values for calibration and evaluation treatments were satisfactory. Model statistics indicate that the approach can be used as a suitable decision support system to simulate the impact of observed Cercospora leaf spot damage on accumulated above-ground biomass and storage root yield on a plot/site-specific scale.

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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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Comparison of Visual and Multispectral Radiometric Disease Evaluations of Cercospora Leaf Spot of Sugar Beet

Plant Disease ◽

10.1094/pd-89-0153 ◽

2005 ◽

Vol 89 (2) ◽

pp. 153-158 ◽

Cited By ~ 61

Author(s):

K. Steddom ◽

M. W. Bredehoeft ◽

M. Khan ◽

C. M. Rush

Keyword(s):

Sugar Beet ◽

Disease Severity ◽

Leaf Spot ◽

Near Infrared ◽

Potential Bias ◽

Cercospora Leaf Spot ◽

Industry Standard ◽

Vegetative Indices ◽

The Individual ◽

Visual Assessments

Visual assessments of disease severity are currently the industry standard for quantification of the necrosis caused by Cercospora beticola on sugar beet (Beta vulgaris) leaves. We compared the precision, reproducibility, and sensitivity of a multispectral radiometer to visual disease assessments. Individual wavebands from the radiometer, as well as vegetative indices calculated from the individual wavebands, were compared with visual disease estimates from two raters at each of two research sites. Visual assessments and radiometric measurements were partially repeated immediately after the first assessment at each site. Precision, as measured by reduced coefficients of variation, was improved for all vegetative indices and individual waveband radiometric measures compared with visual assessments. Visual assessments, near-infrared singlewaveband reflectance values, and four of the six vegetative indices had high treatment F values, suggesting greater sensitivity at discriminating disease severity levels. Reproducibility, as measured by a test-retest method, was high for visual assessments, single-waveband reflectance at 810 nm, and several of the vegetative indices. The use of radiometric methods has the potential to increase the precision of assessments of Cercospora leaf spot foliar symptoms of sugar beet while eliminating potential bias. We recommend this method be used in conjunction with visual disease assessments to improve precision of assessments and guard against potential bias in evaluations.

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EFFICACY OF SOME FUNGICIDES ON CONTROLLING CERCOSPORA LEAF SPOT AND THEIR IMPACT ON SUGAR BEET YIELD COMPONENTS

Journal of Plant Protection and Pathology ◽

10.21608/jppp.2014.87868 ◽

2014 ◽

Vol 5 (1) ◽

pp. 79-87

Author(s):

M. Gouda ◽

A. El-Naggar

Keyword(s):

Sugar Beet ◽

Leaf Spot ◽

Yield Components ◽

Cercospora Leaf Spot

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Epidemiology and management of bacterial leaf spot on watermelon caused byPseudomonas syringae

Plant Disease ◽

10.1094/pdis-11-16-1628-re ◽

2017 ◽

Vol 101 (7) ◽

pp. 1222-1229 ◽

Cited By ~ 4

Author(s):

E. A. Newberry ◽

L. Ritchie ◽

B. Babu ◽

T. Sanchez ◽

K. A. Beckham ◽

...

Keyword(s):

Disease Severity ◽

Pseudomonas Syringae ◽

Leaf Spot ◽

Negative Relationship ◽

Disease Outbreaks ◽

Field Trials ◽

Multiple Regression Model ◽

Bacterial Leaf Spot ◽

Progress Curve ◽

Cool Conditions

Bacterial leaf spot of watermelon caused by Pseudomonas syringae has been an emerging disease in the southeastern United States in recent years. Disease outbreaks in Florida were widespread from 2013 to 2014 and resulted in foliar blighting at the early stages of the crop and transplant losses. We conducted a series of field trials at two locations over the course of two years to examine the chemical control options that may be effective in management of this disease, and to investigate the environmental conditions conducive for bacterial leaf spot development. Weekly applications of acibenzolar-S-methyl (ASM) foliar, ASM drip, or copper hydroxide mixed with ethylene bis-dithiocarbamate were effective in reducing the standardized area under the disease progress curve (P < 0.05). Pearson’s correlation test demonstrated a negative relationship between the average weekly temperature and disease severity (–0.77, P = 0.0002). When incorporated into a multiple regression model with the square root transformed average weekly rainfall, these two variables accounted for 71% of the variability observed in the weekly disease severity (P < 0.0001). This information should be considered when choosing the planting date for watermelon seedlings as the cool conditions often encountered early in the spring season are conducive for bacterial leaf spot development.

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Genetics of Cercospora Leaf Spot Resistance in Mungbean [Vigna radiata (L.) Wilczek] through Generation Mean Analysis

Legume Research - An International Journal ◽

10.18805/lr-4456 ◽

2021 ◽

Author(s):

Priyanka Choudhary ◽

Ramesh Chand ◽

Anil Kumar Singh

Keyword(s):

Latent Period ◽

Leaf Spot ◽

Vigna Radiata ◽

Generation Mean Analysis ◽

Cercospora Leaf Spot ◽

Progress Curve ◽

High Heritability ◽

Efficient Breeding ◽

Important Disease ◽

Selection Of

Background: Cercospora leaf spot (CLS) is a fungal disease of mungbean [Vigna radiata (L.) Wilczek] caused by Cercospora canescens and now emerged as an important biotic stress. A better understanding of the genetics of CLS resistance will help in formulating efficient breeding procedures in mungbean.Methods: The present investigation focused on genetics of CLS resistance through generation mean analysis (six parameter model) in two intra-specific mungbean crosses namely, Kopergaon × HUM12 and Kopergaon × ML1720. Four quantitative disease resistance components, viz., Area under disease progress curve (AUDPC), Incubation period (IP), Latent period (LP) and degree of sporulation (SP) were studied.Result: A high correlation of AUDPC with latent period (r = –0.68 to –0.79, P less than 0.0001) and SP (r = 0.72 to -0.81, P less than 0.0001) advocated that both are main contributor for CLS disease development. High heterosis along with high heritability in terms of AUDPC ( greater than 0.09) indicated the importance of genetic factor(s) in controlling CLS resistance. Generation mean analysis of both the crosses revealed duplicate epistatic interaction and involvement of two genes for CLS resistance in terms of AUDPC. This study supports oligogenic nature of inheritance, advocating AUDPC along with IP, LP and SP as important disease indicator for selection of CLS resistance in mungbean.

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