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Knudsen, G. R., C. S. Johnson, and H. W. Spurr. "Use Of a Simulation Model to Explore Fungicide Strategies for Control of Cercospora Leafspot of Peanut1." Peanut Science 15, no. 1 (January 1, 1988): 39–43. http://dx.doi.org/10.3146/i0095-3679-15-1-11.
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Abstract A sub-model describing persistence and efficacy of chlorothalonil fungicide was incorporated into a computer simulation model of Cercospora leafspot of peanut. The resultant model was validated using independent data sets from field trials over a two-year period. Predicted disease progress curves and area under the disease progress curve for different fungicide application schedules and rates were compared with field observations. The model was then used to compare predicted disease severity and area under the disease progress curve (AUDPC) for a calendar spray schedule vs a leafspot advisory program under different weather conditions. Predicted disease severity levels and area under disease progress curves were similar for advisory and calendar spray schedules. Results were insensitive to changes in parameters describing fungicide persistence or efficacy. The model described herein is a good estimator of the combined effects of weather and chlorothalonil treatments on disease progress, effectively ranks treatments or environmental conditions in terms of their effect on leafspot, and provides a basis for comparison of fungicide scheduling strategies. The simulation model predicted AUDPC more accurately than end-of-season disease, and AUDPC is a more reliable indicator of the effect of peanut leafspot disease on yield loss. Simulation experiments will be useful in optimizing fungicide or biocontrol strategies for long-term financial benefit to growers.
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GILLIGAN, C. A. "Comparison of disease progress curves." New Phytologist 115, no. 2 (June 1990): 223–42. http://dx.doi.org/10.1111/j.1469-8137.1990.tb00448.x.
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Godoy, Cláudia V., Lílian Amorim, Armando Bergamin Filho, Herbert P. Silva, Willian J. Silva, and Richard D. Berger. "Temporal progress of southern rust in maize under different environmental conditions." Fitopatologia Brasileira 28, no. 3 (June 2003): 273–78. http://dx.doi.org/10.1590/s0100-41582003000300008.
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The progress of the severity of southern rust in maize (Zea mays) caused by Puccinia polysora was quantified in staggered plantings in different geographical areas in Brazil, from October to May, over two years (1995-1996 and 1996-1997). The logistic model, fitted to the data, better described the disease progress curves than the Gompertz model. Four components of the disease progress curves (maximum disease severity; area under the disease progress curve, AUDPC; area under the disease progress curve around the inflection point, AUDPCi; and epidemic rate) were used to compare the epidemics in different areas and at different times of planting. The AUDPC, AUDPCi, and the epidemic rate were analyzed in relation to the weather (temperature, relative humidity, hours of relative humidity >90%, and rainfall) and recorded during the trials. Disease severity reached levels greater than 30% in Piracicaba and Guaíra in the plantings between December and January. Lower values of AUDPC occurred in later plantings at both locations. The epidemic rate was positively correlated (P < 0.05) with the mean daily temperatures and negatively correlated with hours of relative humidity >90%. The AUDPC was not correlated with any weather variable. The AUDPCi was negatively related to both variables connected to humidity, but not to rain. Long periods (mostly >13 h day-1) of relative humidity >90% (that corresponded to leaf wetness) occurred in Castro. Severity of southern rust in maize has always been low in Castro, thus the negative correlations between disease and the two humidity variables.
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Navas-Cortés, Juan A., Bernhard Hau, and Rafael M. Jiménez-Díaz. "Effect of Sowing Date, Host Cultivar, and Race of Fusarium oxysporum f. sp. ciceris on Development of Fusarium Wilt of Chickpea." Phytopathology® 88, no. 12 (December 1998): 1338–46. http://dx.doi.org/10.1094/phyto.1998.88.12.1338.
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Microplots experiments were carried out at Córdoba, southern Spain, from 1986 to 1989 to determine the effects of sowing date in the management of Fusarium wilt of chickpea as influenced by virulence of the pathogen race and by cultivar susceptibility. A total of 108 epidemics of the disease were described, analyzed, and compared to assess the degree of disease control. The epidemics were characterized by five curve elements: final disease intensity index (DII), standardized area under DII progress curve, time to epidemic onset, time to inflection point (tip), and the DII value at tip, the last two parameters being estimates from the Richards function adjusted by nonlinear regression analysis. The structure of Fusarium wilt epidemics was examined by conducting multivariate principal components and cluster analyses. From these analyses, three factors accounting for 98 to 99% of the total variance characterized the DII progress curves and provided plausible epidemiological interpretations. The first factor included the tip and the time to disease onset and can be interpreted as a positional factor over time. This factor accounted for the largest proportion of the total variance and may, therefore, be considered as the main factor for analysis of Fusarium wilt epidemics. The second factor concerns the standardized area under DII progress curves and the final DII of the epidemics. The third factor identified the uniqueness of the estimated value for the point of inflection of the DII progress curve over time. Our results indicate that for each year of experiment epidemic development was related mainly to the date of sowing. Thus, for chickpea crops in southern Spain, advancing the sowing date from early spring to early winter can slow down the development of Fusarium wilt epidemics, delay the epidemic onset, and minimize the final amount of disease. However, the net effect of this disease management practice may also be influenced, though to a lesser extent, by the susceptibility of the chickpea cultivar and the virulence and inoculum density of the Fusarium oxysporum f. sp. ciceris race.
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MUKHERJEE, A. K., N. K. MOHAPATRA, A. V. SURIYA RAO, and P. NAYAK. "Effect of nitrogen fertilization on the expression of slow-blasting resistance in rice." Journal of Agricultural Science 143, no. 5 (September 30, 2005): 385–93. http://dx.doi.org/10.1017/s0021859605005551.
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The development of rice blast disease in four slow-blasting (SB) genotypes was compared with that in the fast-blasting (FB) genotype Karuna, under natural field epidemics over a period of 3 years at five levels of nitrogen, in order to determine if the application of high doses of nitrogen influenced the expression of disease progress in the SB types. The treatment effects were compared through estimation of nine parameters viz. (i) lesion number (LN); (ii) area under disease progress curve (AUDPC); (iii) relative area under disease progress curve (RAUDPC); (iv) logistic apparent infection rate (r); (v) Gompertz apparent infection rate (k); (vi) logit line intercept (logit-a); (vii) gompit line intercept (gompit-a); (viii) time required for the disease to reach 0·25 severity in logistic (T25r); and (ix) Gompertz (T25k) models. There was a significant increase in LN, AUDPC, RAUDPC, r and k with increased levels of nitrogen application in all genotypes, but the rate of increase in disease severity was much lower in SB genotypes than the FB one and did not lead to breakdown of resistance in the SB genotypes, since severity level was much below the economic injury level. Among the nine derived parameters for evaluation of resistance LN, AUDPC, RAUDPC, r and k were best. The AUDPC and RAUDPC had lower degrees of error variance compared with the other parameters and hence were considered superior measures for characterization of disease progress curves.
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Fernández-Campos, M., C. Góngora-Canul, S. Das, M. R. Kabir, B. Valent, and C. D. Cruz. "Epidemiological Criteria to Support Breeding Tactics Against the Emerging, High-Consequence Wheat Blast Disease." Plant Disease 104, no. 8 (August 2020): 2252–61. http://dx.doi.org/10.1094/pdis-12-19-2672-re.
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Plant disease epidemiology can make a significant contribution for cultivar selection by elucidating the principles of an epidemic under different levels of resistance. For emerging diseases as wheat blast (WB), epidemiological parameters can provide support for better selection of genetic resources. Field experiments were conducted at two locations in Bolivia in 2018–2019 to characterize the temporal dynamics of the disease on 10 cultivars with different levels of reaction to WB. Logistic models best (R2 = 0.70–0.96) fit the disease progress curve in all cultivars followed by Gompertz (R2 = 0.64–0.94), providing additional evidence of a polycyclic disease. Total area under disease progress curve (tAUDPC), final disease severity (Ymax), and logistic apparent infection rates (rL*) were shown to be appropriate epidemiological parameters for describing resistance and cultivar selection. Cultivars that showed a high spike AUDPC (sAUDPC) showed a high leaf AUDPC (lAUDPC). tAUPDC, Ymax, and rL* were positively correlated among them (P < 0.01) and all were negatively correlated with grain weight (P < 0.01). Based on the epidemiological parameters used, cultivars that showed resistance to WB were Urubó, San Pablo, and AN-120, which were previously reported to have effective resistance against the disease under field conditions. The information generated could help breeding programs to make technical decisions about relevant epidemiological parameters to consider prior to cultivar release.
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Pereira, Renata C. M., Maria A. Ferreira, Thaissa P. F. Soares, Mario F. C. M. Andrade, Cézar A. L. Filho, Edson A. Pozza, Maria L. M. Avelar, and Lucas A. Melo. "Temporal Progress of Candeia Rust Caused by Puccinia velata in Clonal Candeia Plantation (Eremanthus erythropappus (DC.) McLeisch)." Forests 11, no. 7 (June 29, 2020): 720. http://dx.doi.org/10.3390/f11070720.
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The temporal progress of candeia rust, caused by the fungus Puccinia velata, was monitored in an experimental field at Lavras municipality, Southern Minas Gerais state, Brazil. A plantation with 17 Eremanthus erythropappus clones was set at the site, and the temporal disease progress was analyzed based on visual assessments of disease severity on leaves. The disease was monitored monthly between September 2016 and August 2017. Progress curves based on disease severity were constructed and empirical models were fitted. The area under the disease progress curve (AUDPC) was calculated, and the means test was applied to select clones resistant to the disease. The Pearson coefficient was used to assess correlations between disease severity and environmental variables. The model that best described disease progress over the assessment period was the Gompertz model. The mean AUDPC values were grouped into four groups of resistance levels according to the Scott–Knott test. There was a negative correlation between air temperature and disease severity. Considering that the disease occurred in all clones and that the climatic conditions of Southern Minas Gerais are favorable to the candeia rust, it is important to adopt measures for the selection of clones resistant to this disease.
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Madden, L. V., G. Hughes, and M. E. Irwin. "Coupling Disease-Progress-Curve and Time-of-Infection Functions for Predicting Yield Loss of Crops." Phytopathology® 90, no. 8 (August 2000): 788–800. http://dx.doi.org/10.1094/phyto.2000.90.8.788.
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A general approach was developed to predict the yield loss of crops in relation to infection by systemic diseases. The approach was based on two premises: (i) disease incidence in a population of plants over time can be described by a nonlinear disease progress model, such as the logistic or monomolecular; and (ii) yield of a plant is a function of time of infection (t) that can be represented by the (negative) exponential or similar model (ζ(t)). Yield loss of a population of plants on a proportional scale (L) can be written as the product of the proportion of the plant population newly infected during a very short time interval (X′(t)dt) and ζ(t), integrated over the time duration of the epidemic. L in the model can be expressed in relation to directly interpretable parameters: maximum per-plant yield loss (α, typically occurring at t = 0); the decline in per-plant loss as time of infection is delayed (γ; units of time-1); and the parameters that characterize disease progress over time, namely, initial disease incidence (X0), rate of disease increase (r; units of time-1), and maximum (or asymptotic) value of disease incidence (K). Based on the model formulation, L ranges from αX0 to αK and increases with increasing X0, r, K, α, and γ-1. The exact effects of these parameters on L were determined with numerical solutions of the model. The model was expanded to predict L when there was spatial heterogeneity in disease incidence among sites within a field and when maximum per-plant yield loss occurred at a time other than the beginning of the epidemic (t > 0). However, the latter two situations had a major impact on L only at high values of r. The modeling approach was demonstrated by analyzing data on soybean yield loss in relation to infection by Soybean mosaic virus, a member of the genus Potyvirus. Based on model solutions, strategies to reduce or minimize yield losses from a given disease can be evaluated.
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LAL AHAMED, M., S. S. SINGH, J. B. SHARMA, and R. B. RAM. "Evaluation of inheritance to leaf rust in wheat using area under disease progress curve." Hereditas 141, no. 3 (February 8, 2005): 323–27. http://dx.doi.org/10.1111/j.1601-5223.2004.01794.x.
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Simko, Ivan, and Hans-Peter Piepho. "The Area Under the Disease Progress Stairs: Calculation, Advantage, and Application." Phytopathology® 102, no. 4 (April 2012): 381–89. http://dx.doi.org/10.1094/phyto-07-11-0216.
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The area under the disease progress curve (AUDPC) is frequently used to combine multiple observations of disease progress into a single value. However, our analysis shows that this approach severely underestimates the effect of the first and last observation. To get a better estimate of disease progress, we have developed a new formula termed the area under the disease progress stairs (AUDPS). The AUDPS approach improves the estimation of disease progress by giving a weight closer to optimal to the first and last observations. Analysis of real data indicates that AUDPS outperforms AUDPC in most of the tested trials and may be less precise than AUDPC only when assessments in the first or last observations have a comparatively large variance. We propose using AUDPS and its standardized (sAUDPS) and relative (rAUDPS) forms when combining multiple observations from disease progress experiments into a single value.
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Viriyasuthee, Saksirirat, Saepaisan, Gleason, and Jogloy. "Variability of Alternaria Leaf Spot Resistance in Jerusalem Artichoke (Helianthus Tuberosus L.) Accessions Grown in a Humid Tropical Region." Agronomy 9, no. 6 (May 28, 2019): 268. http://dx.doi.org/10.3390/agronomy9060268.
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Alternaria leaf spot is an emerging disease of Jerusalem artichoke (Helianthus tuberosus L.) in tropical regions. The lack of known resistant germplasm sources is an important constraint to development of Jerusalem artichoke varieties with resistance to Alternaria leaf spot. The objectives of this study were to identify variability of Jerusalem artichoke genotypes for resistance to Alternaria leaf spot under field conditions and to investigate the relationships among resistance characters, yield, and yield components for selection of resistant varieties. Ninety six accessions of Jerusalem artichoke were evaluated in replicated trials under field conditions in early rainy and late rainy seasons in Khon Kaen, Thailand during 2014. Parameters evaluated included disease incidence, disease score, disease severity index, area under disease progress curve of disease incidence, area under disease progress curve of disease severity index, number of tubers/plants, tuber size, and fresh tuber yield. The genotypes HEL 335, HEL 256, HEL 317, HEL 308, and JA 86 were identified as sources of leaf spot resistance in both seasons. These genotypes can be used as sources of leaf spot resistance for Jerusalem artichoke breeding programs. HEL 293 and HEL 246 showed susceptibility to leaf spot disease in both seasons and should be used as standard susceptible checks.
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Pscheidt, Jay W., and Stephanie Heckert. "Progression of Kernel Mold on Hazelnut." Plant Disease 105, no. 5 (May 1, 2021): 1320–27. http://dx.doi.org/10.1094/pdis-05-20-1088-re.
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Hazelnut kernel mold, caused by a number of fungal species, has been a chronic problem in Pacific Northwest hazelnut production areas for many years. Two highly susceptible breeding selections and two commercial cultivars were used to investigate kernel mold development over time and possible correlations with rainfall. Nuts were allowed to naturally fall onto orchard soil, regularly collected, cracked open, and evaluated for kernel mold. Disease progress for each selection or cultivar was evaluated each year with both linear and exponential models. The general progression of kernel mold was similar for the two breeding selections and cultivars Ennis and Lewis, where kernel mold increased slowly during the nut dropping period but more rapidly after normal harvest. An exponential model described disease progress better than a linear model for 8 of the 10 significant disease progress curves examined. Although some years had significantly higher estimated rates of disease increase, this parameter was inversely related to the area under the disease progress curve (AUDPC). The incidence of kernel mold did not significantly increase over time for 8 of the 18 disease progress curves examined, including 6 of 8 curves for commercial cultivars. The relationship between initial kernel mold incidence and AUDPC was described well with a simple linear model indicating that initial disease incidence appeared to be a good predictor of AUDPC. The longer nuts remained on the ground, especially after harvest, the higher the incidence of kernel mold. Kernel mold incidence was not significantly correlated with rainfall totals for any period of time from flowering to harvest. Multiple harvests ending shortly after all nuts have fallen should result in lower incidence of kernel mold for growers.
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Soto-Estrada, Alejandra, and James E. Adaskaveg. "Temporal and Quantitative Analyses of Stem Lesion Development and Foliar Disease Progression of Peach Rust in California." Phytopathology® 94, no. 1 (January 2004): 52–60. http://dx.doi.org/10.1094/phyto.2004.94.1.52.
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The development of rust epidemics caused by Tranzschelia discolor on leaves and stems of cling peach was studied in California orchards. Sporulating stems lesions were only detected from late March until July in 1997 and 1998. When rust was present in the fall, the quadratic equation Y = -82.51 + 1.97JD - 0.01JD2 using Julian day (JD) described the incidence of sporulating lesions on stems of cv. Andross (R2 = 0.73; P ≤ 0.001) in the following spring season. Late-season rust epidemics occurred in 1996 and 1997. Incidence of rust on leaves of cvs. Andross and Ross was <10% from April through July and 80 to 100% by October/November. In 1998, early-season epidemics developed with disease incidence at 28 to 56% by July/August in two cv. Andross orchards. No disease was observed during the 1999 growing season. Using linear regression analysis, logistic and exponential models best described the development of disease in 1996 and 1997, respectively. In contrast, the monomolecular model best described the disease in 1998. In an analysis of variance comparing disease progress curves on cv. Andross from 1996 to 1998, no significant differences in area under the disease progress curve and ρ were observed, whereas ymax was significantly different (P < 0.001). A repeated measures analysis indicated that in a cv. Andross orchard the year of the disease progress curve, time of sampling, and their interaction were highly significant (P < 0.01). This indicated a distinct difference between early- and late-season epidemics. Earlyseason development of rust on leaves occurred in years with ≥117.3 mm of total precipitation and maximum temperatures of ≤30.2°C in April to June.
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Singh, H., and M. V. Rao. "Area Under the Disease Progress Curve: Its Reliability as a Measure of Slow-Rusting Resistance." Plant Breeding 103, no. 4 (December 1989): 319–23. http://dx.doi.org/10.1111/j.1439-0523.1989.tb00392.x.
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Gangwar, Gokil Prasad. "Effect of bioagent formulations on progress of bacterial leaf blight disease of rice under field conditions." Journal of Applied and Natural Science 5, no. 2 (December 1, 2013): 388–93. http://dx.doi.org/10.31018/jans.v5i2.338.
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In the present study, effectiveness of different fungal (Trichoderma harzianum) and bacterial (Pseudomonas fluorescens) bioagent formulations in reducing progress of the bacterial leaf blight disease of rice under field conditions was studied and compared with chemical treatment and untreated check. The results exhibited that after 23 to 30 days after first application, bioagent formulations were more effective then chemical treatment in reducing progress of disease. Bioagent formulations exhibited long lasting effect in reducing progress of disease during Kharif, 2006 and 2007. Application of bioagent formulations resulted in significant reduction (60.5 – 142.8%) in area under disease progress curve (AUDPC) as compared to check during Kharif, 2006 and 2007. Significant increase in grain yield (14.3 - 21.5 %) was observed with the application of bioagent formulations as compared to check during Kharif, 2006 and 2007.
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Jeger, M. J., and S. L. H. Viljanen-Rollinson. "The use of the area under the disease-progress curve (AUDPC) to assess quantitative disease resistance in crop cultivars." Theoretical and Applied Genetics 102, no. 1 (January 2001): 32–40. http://dx.doi.org/10.1007/s001220051615.
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Goldman, J. J., O. D. Smith, C. E. Simpson, and H. A. Melouk. "Progress in Breeding Sclerotinia Blight-Resistant Runner-Type Peanut1." Peanut Science 22, no. 2 (July 1, 1995): 109–13. http://dx.doi.org/10.3146/i0095-3679-22-2-7.
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Abstract Field screening tests were conducted in 1991, 1992, and 1993 to identify Sclerotinia blight-resistant runner-type peanuts. Selections were made from three populations, “backcross to runner,” “backcross to Tamspan 90,” and “single cross.” Runner parents were chosen for agronomic qualities and resistance to other pathogens. Resistant (Spanish) parents used were cultivar Tamspan 90 and TxAG-5 germplasm. Families within populations were planted as single row 3 × 0.9-m plots. Repeated plant-by-plant inspections (PBPI) were made for assessment of sequence of infection and subsequent calculation of an area under the disease progress curve (AUDPC). Most families in the backcross to Tamspan 90 population consistently had a disease reaction close to or lower than Tamspan 90 but also retained undesirable plant forms (i.e., upright). By 1993, the F2:5 backcross to runner population had the highest percentage of runner-type families (88%) and a mean disease reaction close to Tamspan 90. Whole plot evaluation of Sclerotinia blight severity was compared with PBPI for effectiveness on a segregating population containing a total of 298 F4:7 single cross and F2:5 backcross entries. The whole plot system used a scale of 0 = no visible plot infection to 5 ≥80% infection in the plot. Correlation between area under disease progress curve values of both methods was high (>.85). Remnant seed of selections screened for resistance in the greenhouse were planted in the field and evaluated for resistance. Chi-square test for independence indicated a significant (α = .012) relationship between greenhouse and field performance. Field screening and limited greenhouse screening appears to be an effective way to develop resistant runner-type peanut lines.
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Nascimento, Jefferson Fernandes do, João Batista Vida, Dauri José Tessmann, Laércio Zambolim, Rafael Augusto Vieira, and Ricardo Ribeiro de Oliveira. "Progress of Asian soybean rust and airborne urediniospores of Phakopsora pachyrhizi in southern Brazil." Summa Phytopathologica 38, no. 4 (December 2012): 280–87. http://dx.doi.org/10.1590/s0100-54052012000400002.
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Asian soybean rust, caused by the fungus Phakopsora pachyrhizi, was reported at epidemic levels in 2003/2004 and is the main soybean disease in Brazil. The aim of this study was to investigate the spread of Asian soybean rust and to quantify airborne urediniospores in the region of Campo Mourão, Paraná State, Brazil. Three experiments were conducted under field conditions during the 2007/08 and 2008/09 crop seasons. Using the disease gradient method, provided by the application of increasing levels of the fungicide tebuconazole, four Asian soybean rust epidemics at different intensities were obtained in each experiment. To quantify the urediniospores, weathercock-type spore collectors were installed during and between the two crop seasons. Disease progress curves were plotted for each epidemic, and maximum severity was estimated. The curves were fit to the logistic model, which provided higher coefficients of determination and more randomly distributed residuals plotted over time. Analyses of the area under the disease progress curve showed that the largest epidemics occurred in the 2007/2008 crop season and that the progress rates were higher for severity, even among plants protected with the fungicide. The number of urediniospores collected in the air was related to the presence of soybean plants in the cultivated crops. The quantity of urediniospores was also positively correlated to the disease severity and incidence, as well as to cumulative rainfall and favorable days for P. Pachyrhizi infection.
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Mengist, Yigrem, Samuel Sahile, Assefa Sintayehu, and Sanjay Singh. "Evaluation of Chickpea Varieties and Fungicides for the Management of Chickpea Fusarium Wilt Disease (Fusarium oxysporum f.sp. ciceris) at Adet Sick Plot in Northwest Ethiopia." International Journal of Agronomy 2018 (December 18, 2018): 1–7. http://dx.doi.org/10.1155/2018/6015205.
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A 2-year experiment was conducted at wilt sick plot infested with natural occurring Fusarium oxysporum f.sp. ciceris at Adet Agricultural Research Center in northwestern Ethiopia with an aim to evaluate effective chickpea varieties and fungicides for the management of chickpea fusarium wilt in order to integrate chickpea varieties and fungicides. Four varieties, namely, Shasho, Arerti, Marye, and local, two fungicides, namely, Apron Star and mancozeb, and untreated local chickpea were used as treatments. Treatments were arranged in a factorial combination in randomized complete block design in three replications. There were significant differences at p<0.05 in the overall mean of fusarium wilt disease incidence, area under disease progress curve %-day, yield and yield components among varieties and fungicides treatments. Data were analyzed using SAS system version 9.2. The results indicated that the maximum disease incidence and area under disease progress curve values 65.62% and 578.5%-day, respectively, were recorded from untreated local chickpea, while the minimum disease incidence and area under disease progress curve values 23.41% and 147%-day, respectively, were recorded from Shasho variety treated with Apron Star. The maximum biomass and grain yield of 6.71 t/ha and 4.6 t/ha, respectively, were recorded from Shasho variety treated with Apron Star while the minimum biomass and grain yield of 0.62 t/ha and 0.21 t/ha, respectively, were recorded from untreated local chickpea. Thus, the experiment results suggested that the variety of Shasho treated with fungicide Apron Star caused significant reduction in chickpea fusarium wilt incidence leading to a corresponding increase in grain yield of chickpea.
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Bailey, D. J., and C. A. Gilligan. "Dynamics of Primary and Secondary Infection in Take-All Epidemics." Phytopathology® 89, no. 1 (January 1999): 84–91. http://dx.doi.org/10.1094/phyto.1999.89.1.84.
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Using a combination of experimentation and mathematical modeling, the effects of initial (particulate) inoculum density on the dynamics of disease resulting from primary and secondary infection of wheat by the take-all fungus, Gaeumannomyces graminis var. tritici, were tested. A relatively high inoculum density generated a disease progress curve that rose monotonically toward an asymptote. Reducing the initial inoculum density resulted in a curve that initially was monotonic, rising to a plateau, but which increased sigmoidally to an asymptotic level of disease thereafter. Changes in the infectivity of particulate inoculum over time were examined in a separate experiment. Using a model that incorporated terms for primary and secondary infection, inoculum decay, and host growth, we showed that both disease progress curves were consistent with consecutive phases dominated, respectively, by primary and secondary infection. We examined the spread of disease from a low particulate inoculum density on seminal and adventitious root systems separately. Although seminal roots were affected by consecutive phases of primary and secondary infection, adventitious roots were affected only by secondary infection. We showed that the characteristic features of disease progress in controlled experiments were consistent with field data from crops of winter wheat. We concluded that there is an initial phase of primary infection by G. graminis var. tritici on winter wheat as seminal roots grow through the soil and encounter inoculum, but the rate of primary infection slows progressively as inoculum decays. After the initial phase, there is an acceleration in the rate of secondary infection on both seminal and adventitious roots that is stimulated by the increase in the availability of infected tissue as a source of inoculum and the availability of susceptible tissue for infection.
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Holb, I. J., B. Heijne, J. C. M. Withagen, J. M. Gáll, and M. J. Jeger. "Analysis of Summer Epidemic Progress of Apple Scab at Different Apple Production Systems in the Netherlands and Hungary." Phytopathology® 95, no. 9 (September 2005): 1001–20. http://dx.doi.org/10.1094/phyto-95-1001.
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Two, 4-year studies on summer epidemic progress of apple scab were conducted at Randwijk, the Netherlands, from 1998 until 2001 and at Eperjeske, Hungary, from 2000 until 2003. Disease assessments were made on scab-susceptible cv. Jonagold. A range of nonlinear growth functions were fitted to a total of 96 disease progress curves (3 treatment classes × 2 plant parts × 2 disease measures × 4 years × 2 locations) of apple scab incidence and severity. The three-parameter logistic model gave the most consistent fit across three treatment classes in the experiment (integrated, organic-sprayed, and organic-unsprayed). Parameters estimated or calculated from the three-parameter logistic function were used to analyze disease progress. These were disease incidence and severity on the day of the first assessment (Ys); final disease incidence or upper asymptote for incidence (Yif) or severity (Ysf); fruit incidence and severity on day 40, after which no new lesions on fruits appeared (Y40); leaf incidence and severity on day 75, at which shoot growth stopped (Y 75); relative (β) and “absolute” (θ) rates of disease progress; inflection point (M); and area under the disease progress curve (AUDPCS) standardized by the duration of the total epidemic. Comparisons among disease progress curves were made by correlation and factor analysis followed by Varimax rotation. There were large differences but high positive correlations among the parameters Ys, Yf, θ, and AUDPCS across the three treatment classes. In the factor analysis, two factors accounted for more than 85% of the total variance for both incidence and severity. Factor 1 gave an overall description of epidemic progress of both scab incidence and severity and included the parameters Yf, Y40, Y75, θ, and AUDPCS. Factor 2 identified a relationship between the relative rate parameter (β) and the inflection point (M) for severity and a relationship between disease incidence and severity. For an integrated or an organic orchard, θ, AUDPCS, and one of Yf or Y75 (because of the link with host phenology) can characterize apple scab epidemics during summer. Based on these findings, improved scab management approaches were provided for integrated and organic apple production systems.
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Ascari, João Paulo, Inês Roeder Nogueira Mendes, Vanessa Costa da Silva, and Dejânia Vieira de Araújo. "Ramularia leaf spot severity and effects on cotton leaf area and yield1." Pesquisa Agropecuária Tropical 46, no. 4 (December 2016): 434–41. http://dx.doi.org/10.1590/1983-40632016v4642781.
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ABSTRACT Cotton monoculture favors the development of diseases such as ramularia leaf spot, which causes early defoliation and boll rotting, thus decreasing yield. This study aimed at evaluating the severity of ramularia leaf spot and its effects on cotton leaf area and yield. The experiment was conducted in a triple (4 x 3 x 2) factorial design, consisting of four cultivars (FM940GLT, FM944GL, TMG42WS and TMG43WS), three thirds of the plant (lower, middle and upper) and two management conditions (with and without fungicide application). To the variable area under the disease progress curve, the lowest values were observed in the upper third of the TMG42WS and TMG43WS cultivars, with the lower and middle thirds presenting the highest severity. The condition managed with fungicide and the upper third showed the lowest values for area under the disease progress curve. The leaf area was negatively affected by the ramularia leaf spot. Concerning the seed and fiber yields, the highest averages were observed for the middle third and the condition managed with fungicide. There was no statistical difference for cotton yield loss.
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CATÃO, HUGO CESAR RODRIGUES MOREIRA, NILZA LIMA PEREIRA SALES, JOÃO BATISTA DE CAMPOS MENEZES, FRANCIELE CAIXETA, and CÂNDIDO ALVES COSTA. "PRODUCTIVE POTENTIAL OF THE CHERRY TOMATO GENOTYPE GROUP BEFORE INFECTION BY Alternaria tomatophila." Revista Caatinga 30, no. 2 (June 2017): 296–302. http://dx.doi.org/10.1590/1983-21252017v30n204rc.
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ABSTRACT Early blight (caused by Alternaria tomatophila) is a major disease of tomato with no resistant cultivars. Thus, it is necessary to identify sources of resistance and productive genotypes for the development of new cultivars. Therefore, this study aimed to evaluate the productive potential of cherry tomato genotypes grown in the summer / fall, the severity of early blight on leaves and the incidence of disease in fruits. The treatments consisted of Carolina tomato genotypes, Cereja Vermelho, CH 152 and CLN1561A. The experimental design consisted of randomized blocks with six replications, and the experimental plot had 16 plants. The following characteristics were evaluated: area under the disease progress curve (AUDPC), average number of microinjuries on the fruits (MF), average number of fruits per bunch (NFC), average number of bunches per plant (NCP), average number of fruits per plant (NFP), average yield, number of fruits with incidence of early blight per plant (NFI) and the severity of early blight in leaves (%). The cherry tomato genotype CH152 showed tolerance to early blight with a smaller area under the disease progress curve, lower severity and fruits with incidence of A. tomatophila were not observed in this genotype. The CH152 had the highest number of fruits per bunch, greater number of bunches per plant, higher number of fruits per plant and higher productivity. This line has great potential of being integrated into breeding programs.
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Johnson, C. D., and B. L. Davidson. "Huntington's disease: progress toward effective disease-modifying treatments and a cure." Human Molecular Genetics 19, R1 (April 15, 2010): R98—R102. http://dx.doi.org/10.1093/hmg/ddq148.
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de Oliveira, Mara Elisa Soares, Fabiano Silva Fernandes, Murilo A. Glória Junior, Alvaro Soares de Oliveira, Reginaldo Gonçalves Mafia, and Maria Alves Ferreira. "Temporal Analysis of Bacterial Leaf Blight in Clonal Eucalyptus Plantations in Brazil." Forests 10, no. 10 (September 25, 2019): 839. http://dx.doi.org/10.3390/f10100839.
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Bacterial leaf blight is an important disease in Eucalyptus spp. plantations since it can cause defoliation, affecting plant development. A better understanding of the disease epidemiology is important for its control. Thus, the aim of this study was to analyze bacterial leaf blight temporal progress in the initial establishment in the field of different eucalyptus clones. It also targeted to correlate the incidence and area under the disease-progress curve (AUDPC), with variables related to growth and meteorological data. Bacterial leaf blight progress curves were analyzed based on incidence and carried out AUDPC calculation. Pearson’s coefficient was used to verify the correlations between bacterial leaf blight incidence and AUDPC with clone initial growth and meteorological factors. Gompertz or Logistic models were the best adjustment to data, according to the assessed clones. A difference in AUDPC was observed between clones regarding bacterial leaf blight incidence during the assessment period. Clones were divided into three groups with different tolerance levels. A negative correlation was observed between bacterial leaf blight incidence, AUDPC, and growth variables of clones. During the assessment period, average air temperature, rainfall, and air relative humidity favored disease incidence. The clones A469, VM01, and 373 were the most tolerant to the disease.
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Cséplö, M., M. Csösz, M. Gál, O. Veisz, and G. Vida. "Seedling resistance to Stagonospora nodorum blotch in wheat genotypes." Czech Journal of Genetics and Plant Breeding 49, No. 2 (May 16, 2013): 77–85. http://dx.doi.org/10.17221/69/2011-cjgpb.
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In two independent experiments set up in the greenhouse the seedling resistance to Stagonospora nodorum blotch was investigated in 92 varieties, breeding lines and genotypes with a known genetic background. The greatest area under the disease progress curve calculated from lesion type was 37.06, while in the case of the most resistant genotype this value was 0.38. Many of the lines and varieties bred in Martonvásár proved to have excellent resistance in terms of both percentage of infected leaf area and lesion type. Observations indicate that, depending on the aim of the experiment, the efficient selection of breeding lines is possible in the seedling stage either on the basis of the area under the disease progress curve calculated for lesion types, or on the basis of lesion types scored 7, 11 or 14 days after inoculation.
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Viriyasuthee, Wanalai, Suwita Saepaisan, Weerasak Saksirirat, Mark L. Gleason, Ruey Shyang Chen, and Sanun Jogloy. "Effective Plant Ages for Screening for Field Resistance to Alternaria Leaf Spot (Caused by Alternaria spp.) under Natural Infection in Jerusalem artichoke (Helianthus tuberosus L.)." Agronomy 9, no. 11 (November 14, 2019): 754. http://dx.doi.org/10.3390/agronomy9110754.
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Host plant resistance has proven to be effective for controlling Alternaria leaf spot on Jerusalem artichoke (JA), but efficient screening techniques have not been developed yet. The objective of this study is to estimate the relationship between disease resistance parameters of JA as a function of plant age. Six JA varieties and three plant ages at the time of inoculation (20, 40 and 60 days after transplanting) (DAT) are evaluated in a factorial experiment in randomized complete block design (RCBD) with four replications. Disease incidence (DI) and severity (DS) are estimated, from which area under the disease progress curve (AUDPC) was calculated. Disease parameters are positively and significantly correlated for plant ages of 40 and 60 DAT. Based on our results, screening of JA at 40 DAT for resistance to Alternaria leaf spot is recommended. Knowledge of the impact of plant age on resistance to key diseases can help breeders to accelerate breeding programs so superior genotypes can be identified before reproductive growth stages.
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Mengistu, Alemu, J. R. Smith, J. D. Ray, and N. Bellaloui. "Seasonal Progress of Charcoal Rot and Its Impact on Soybean Productivity." Plant Disease 95, no. 9 (September 2011): 1159–66. http://dx.doi.org/10.1094/pdis-02-11-0100.
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The seasonal progress of charcoal rot (caused by Macrophomina phaseolina) was measured over two growing seasons in four separate experiments: irrigated infested, irrigated non-infested, non-irrigated infested, and non-irrigated noninfested. Disease was assessed at V5, R1, R3, R5, R6, and R7 growth stages based on colony forming units (CFU) of M. phaseolina recovered from the lower stem and root tissues and the area under the disease progress curve (AUDPC). The population density of M. phaseolina increased slowly from the V5 to R6 growth stages and then rapidly from the R6 to R7 growth stages for all genotypes in all four experiments. Yield loss due to charcoal rot ranged from 6 to 33% in irrigated environments. The extent of yield loss was affected by severity of charcoal rot, which in turn was affected by year. Yield loss due to charcoal rot was consistently measured in all paired comparisons in irrigated environments, suggesting that charcoal rot can be an important disease in irrigated environments. Disease severity based on CFU accounted for more yield loss variation (42%) than did the AUDPC (36%) when used to assess disease. Growth stage R7 was found to be the optimum stage for assessing disease using CFU. In addition, screening soybean genotypes under irrigation environment may have utility in breeding programs where there is a need for evaluating soybean genotypes for both disease resistance and yield.
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Alves, Daniel Pedrosa, Rafael Simões Tomaz, Bruno Soares Laurindo, Renata Dias Freitas Laurindo, Fabyano Fonseca e. Silva, Cosme Damião Cruz, Carlos Nick, and Derly José Henriques da Silva. "Artificial neural network for prediction of the area under the disease progress curve of tomato late blight." Scientia Agricola 74, no. 1 (February 2017): 51–59. http://dx.doi.org/10.1590/1678-992x-2015-0309.
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Bocianowski, Jan, Anna Tratwal, and Kamila Nowosad. "Genotype by environment interaction for area under the disease-progress curve (AUDPC) value in spring barley using additive main effects and multiplicative interaction model." Australasian Plant Pathology 49, no. 5 (June 9, 2020): 525–29. http://dx.doi.org/10.1007/s13313-020-00723-7.
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Abstract The objective of this study was to assess genotype by environment interaction for area under disease progress curve values in spring barley grown in South-West Poland by the additive main effects and multiplicative interaction model. The study comprised of 25 spring barley genotypes (five cultivars: Basza, Blask, Antek, Skarb and Rubinek as well as all possible 10 two-way mixtures and 10 three-way mixtures combinations), evaluated at two locations in 4 years (eight environments) in a randomized complete block design, with four replicates. Area under disease progress curve (AUDPC) value of the tested genotypes ranged from 75.3 to 614.3, with an average of 175.3. In the AMMI analyses, 13.43% of the AUDPC value variation was explained by environment, 37.85% by differences between genotypes, and 18.20% by genotype by environment interaction. The mixture Basza/Skarb is recommended for further inclusion in the breeding program due to its low average AUDPC value (98.8) and is stable (AMMI stability value = 6.65).
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González-Domínguez, Elisa, Giorgia Fedele, Francesca Salinari, and Vittorio Rossi. "A General Model for the Effect of Crop Management on Plant Disease Epidemics at Different Scales of Complexity." Agronomy 10, no. 4 (March 26, 2020): 462. http://dx.doi.org/10.3390/agronomy10040462.
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A general and flexible model was developed to simulate progress over time of the epidemics caused by a generic polycyclic pathogen on aerial plant parts. The model includes all of the epidemiological parameters involved in the pathogen life cycle: between-season survival, production of primary inoculum, occurrence of primary infections, production and dispersal of secondary inoculum both inside and outside the crop, and concatenation of secondary infection cycles during the host’s growing season. The model was designed to include the effect of the main crop management actions that affect disease levels in the crop. Policy-oriented, strategic, and tactical actions were considered at the different levels of complexity (from the agro-ecosystem to the farming and cropping system). All effects due to disease management actions were translated into variations in the epidemiological components of the model, and the model quantitatively simulates the effect of these actions on epidemic development, expressed as changes in final disease and in the area under the disease progress curve. The model can help researchers, students and policy makers understand how management decisions (especially those commonly recommended as part of Integrated Pest Management programs) will affect plant disease epidemics at different scales of complexity.
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Grigolli, José Fernando Jurca, Mirian Maristela Kubota, Daniel Pedrosa Alves, Gabriel Belfort Rodrigues, Carine Rezende Cardoso, Derly José Henriques da Silva, and Eduardo Seiti Gomide Mizubuti. "Characterization of tomato accessions for resistance to early blight." Crop Breeding and Applied Biotechnology 11, no. 2 (June 2011): 174–80. http://dx.doi.org/10.1590/s1984-70332011000200010.
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The purpose of this study was to characterize 50 tomato genotypes of the Vegetable Genebank of the Federal University of Viçosa. They were evaluated together with the controls Débora, Fanny and Santa Clara, in a randomized block design with two replications. The experiment was conducted in a research field of the UFV, from February to May 2007. We evaluated the disease severity, which is the percentage of diseased leaf area. The severity values were transformed into area under the disease progress curve (AUDPC), improving the result visualization. The analysis of variance and grouping of AUDPC means by the Scott-Knott test at 5 % significance were performed. The accessions BGH-2081, BGH-2034, BGH-700, BGH-2057, BGH-2035, BGH-2054, BGH-2018, BGH-2065, BGH-2008, and BGH-2032 had a lower mean AUDPC than the controls and are therefore indicated for future breeding programs.
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Liu, Yuting. "Research Progress of Diabetes Mellitus Complicated with Cardiovascular Disease." Journal of Clinical and Nursing Research 5, no. 4 (August 2, 2021): 17–21. http://dx.doi.org/10.26689/jcnr.v5i4.2258.
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Diabetes is a chronic disease recognized by the World Health Organization, which is harmful to human life and health. With the improvement of people’s quality of life, people’s diet structure has changed greatly, and the primary “three high” prevalence rate has risen sharply. The main reason for the impaired life expectancy of a large number of diabetic patients is the threat of a series of cardiovascular complications. According to statistics, the risk of cardiovascular disease in diabetic patients are 2-4 times higher than that in non-diabetic patients. More than 80% of patients with type 2 diabetes die of cardiovascular disease every year, and 75% of them have ischemic heart disease [1]. All kinds of data show that diabetes mellitus complicated with cardiovascular diseases have become a worldwide public health problem. We must try our best to find a cure mechanism and give patients a healthy life. In order to effectively curb the threat of diabetes complicated with cardiovascular disease patients, we should strengthen the research in this field. Through the analysis of the risk factors of diabetic cardiovascular disease, we can let the majority of medical workers understand the superficial and potential risk factors, to formulate scientific and reasonable treatment plan, for further improving the quality of life of patients. In the following, the author first introduces the basic situation of diabetes and cardiovascular complications, then introduces the main risk factors of diabetic cardiovascular disease one by one, hoping that this study can help to improve the cure rate of diabetes complicated with cardiovascular disease.
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Skelsey, P., G. J. T. Kessel, W. A. H. Rossing, and W. van der Werf. "Parameterization and Evaluation of a Spatiotemporal Model of the Potato Late Blight Pathosystem." Phytopathology® 99, no. 3 (March 2009): 290–300. http://dx.doi.org/10.1094/phyto-99-3-0290.
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A spatiotemporal, integrodifference equation model of the potato late blight pathosystem is described. Formerly, the model was used in a theoretical context to analyze and predict epidemic dynamics in spatially heterogeneous mixtures of host genotypes. The model has now been modified to reflect a research interest in interactions between genotype, environment, landscape, and management. New parameter values describing host–pathogen interactions were determined and new environment–pathogen relationships included. A new analytical equation describing lesion expansion and associated necrosis has also been developed. These changes prompted a need to assess the quality of model predictions. Cultivar–isolate-specific interactions were characterized in the model using three quantitative components of resistance: infection efficiency, lesion growth rate, and sporulation intensity. These were measured on detached potato leaflets in the laboratory. Results of a sensitivity analysis illuminate the effect of different quantitative components of resistance and initial conditions on the shape of disease progress curves. Using the resistance components, the epidemic process of lesion expansion was separated from the epidemic process of lesion propagation providing two reference curves for diagnosing observed epidemics. The spatial component of the model was evaluated graphically in order to determine if realistic rates of focal expansion for potato late blight are produced. In accordance with theory, the radius of a predicted focus increased linearly with time and a constant focal velocity was reached that compared well with published experimental data. Validation data for the temporal model came from 20 late blight epidemics observed in field trials conducted in the Netherlands in 2002 and 2004. The field data and model were compared visually using disease progress curves, and numerically through a comparison of predicted and observed t5 and t50 points (time in days until 5 and 50% disease severity is reached, respectively) and relative areas under the disease progress curve values. Temporal model predictions were in close agreement with observational data and the ability of the model to translate measured resistance components, weather data, and initial conditions into realistic disease progress curves without the need for calibration confirms its utility as a tool in the analysis and diagnosis of epidemics.
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SARI, BRUNO GIACOMINI, ALESSANDRO DAL'COL LÚCIO, IVAN FRANCISCO DRESSLER DA COSTA, and ANA LÚCIA DE PAULA RIBEIRO. "SAMPLE SIZE FOR ASSESS THE LEAF BLAST SEVERITY IN EXPERIMENTS WITH IRRIGATED RICE." Revista Caatinga 29, no. 4 (December 2016): 822–31. http://dx.doi.org/10.1590/1983-21252016v29n406rc.
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ABSTRACT The aim of this study was to determine the sample size needed to assess the severity of leaf blast in rice in experiments with different fungicide treatments. The severity and the area under the disease progress curve data of three chemical disease control treatments carried out in Rio Grande do Sul, were used in the study. Analysis of variance was performed to verify whether the severity of the disease differed between treatments. The spread of disease was was also found to be different between treatments and assessments, using the variance/mean ratio and Morisita index. The spatial distribution of the disease among the treatments and during the evaluations is important for the choice of the equation used to calculate the sample size. The spatial distribution of the disease was not the same across the experiments, and it varied between treatments and evaluations. Thus, we decided to use a formula that was not associated with distributions to indicate the spatial distribution (negative binomial or Poisson) of the disease in the field. The sample size to estimate the average of rice leaf blast severity varied between treatments and evaluations. The area under the disease progress curve is necessary to be determined to reduce the number of samples needed. Thus, it is recommended to assess 293 sheets to estimate severity, and 63 to estimate AUDPC at 20% error.
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Meena, Prabhu Dayal, Chirantan Chattopadhyay, Syam Sunder Meena, and Arvind Kumar. "Area under disease progress curve and apparent infection rate of Alternaria blight disease of Indian mustard (Brassica juncea) at different plant age." Archives Of Phytopathology And Plant Protection 44, no. 7 (April 2011): 684–93. http://dx.doi.org/10.1080/03235400903345281.
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Spada, Cecília Aparecida, Marcos Ventura Faria, Marcelo Cruz Mendes, Welton Luiz Zaluski, Emanuel Gava, Carlos Augusto da Silva, Diego Fernando de Marck, and Cacilda Márcia Duarte Rios Faria. "Severity of leaf diseases in maize inbred lines with different kernel hardness in two sowing seasons." Semina: Ciências Agrárias 39, no. 1 (February 16, 2018): 29. http://dx.doi.org/10.5433/1679-0359.2018v39n1p29.
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Resistance of maize inbred lines to major leaf diseases should be characterized for the development of new hybrids in breeding programs. Thus, this study aimed to assess the severity of leaf diseases in maize inbredlines with different kernel hardnessand two sowingseasons. We assessed four inbred lines and one check hybrid with dent kernels and four inbred lines and a check hybrid with flint kernels. Treatments were conducted in two sowing seasons, one in October, and another in December 2013. The symptoms of gray leaf spot (Cercospora zeae-maydis), northern leaf blight (Exserohilum turcicum), and white leaf spot (a complex of Phaeosphaeria maydis and Pantoea ananatis) were assessed every 10 days from flowering. The area under the disease progress curve was also calculated. Severity level of the diseases was higher in inbred lines when compared to the check hybrds (AG8041 PRO and P30R50YH), regardless of kernel hardness. Dent-kernel inbred lines showed a higher severity of northern leaf blight symptoms when compared to flint-kernelones. It is worth mentioning that disease severity increased as sowing was delayed.
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McRae, K. B. "An Index for Cultivar Resistance Based on Disease Progress Curves." Phytopathology 77, no. 8 (1987): 1181. http://dx.doi.org/10.1094/phyto-77-1181.
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SWEETMORE, A., S. A. SIMONS, and M. KENWARD. "Comparison of disease progress curves for yam anthracnose (Colletotrichum gloeosporioides)." Plant Pathology 43, no. 1 (February 1994): 206–15. http://dx.doi.org/10.1111/j.1365-3059.1994.tb00572.x.
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Heck, Daniel W., Miguel Dita, Emerson M. Del Ponte, and Eduardo S. G. Mizubuti. "Incidence, Spatial Pattern and Temporal Progress of Fusarium Wilt of Bananas." Journal of Fungi 7, no. 8 (August 8, 2021): 646. http://dx.doi.org/10.3390/jof7080646.
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The effective management of Fusarium wilt of bananas (FWB) depends on the knowledge of the disease dynamics in time and space. The objectives of this work were: to estimate disease intensity and impact, and to investigate the spatial and temporal dynamics of FWB. Fields planted with Silk (n = 10), Pome (n = 17), or Cavendish (n = 3) banana subgroups were surveyed in Brazil, totaling 95 ha. In each field, all plants were visually assessed, and diseased plants were georeferenced. The incidence of FWB and the impact of the disease on the yield on a regional scale were estimated. Spatial patterns were analyzed using quadrat- and distance-based methods. FWB incidence ranged from 0.09% to 41.42%, being higher in Silk fields (median = 14.26%). Impacts of epidemics on yield ranged from 18.4 to 8192.5 kg ha−1 year−1, with an average of 1856.7 kg ha−1 year−1. The higher economic impact of the disease was observed on Silk cultivar with an average loss of USD 1974.2 ha−1 year−1. Overall, estimated losses increased on average by USD 109.8 ha−1 year−1 at each 1% of incidence. Aggregation of FWB was detected by all analytical methods in 13 fields (1 of Cavendish, 11 of Pome, and 1 of Silk). In the other 17 fields, at least one analytical method did not reject the null hypothesis of randomness. One field (5 ha), composed of six plots, was selected for spatial and temporal studies during two years with bi-monthly assessments. A sigmoidal curve represented the FWB progress and the Gompertz model best-fitted disease progress. The level of aggregation varied over time, and evidence of secondary infection to neighboring and distant plants was detected. FWB is a widespread problem in Brazil and yield losses can be of high magnitude. Epidemiology-based management strategies can now be better established.
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López-Escudero, F. J., and M. A. Blanco-López. "Relationship Between the Inoculum Density of Verticillium dahliae and the Progress of Verticillium Wilt of Olive." Plant Disease 91, no. 11 (November 2007): 1372–78. http://dx.doi.org/10.1094/pdis-91-11-1372.
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An experiment was conducted in microplots which were artificially infested with a defoliating isolate of Verticillium dahliae using seven different treatments of inoculum densities ranging from 0 to 10 microsclerotia per gram of soil (ppg). The experiment was conducted in Andalucía (southern Spain), and the susceptible Spanish olive cv. Picual was used to determine the relationship between pathogen inoculum density and the progress of Verticillium wilt of olive (VWO). The inoculum, produced on a sodium pectate cellophane medium, was found to efficiently infect olive trees. Symptoms first appeared 30 weeks after the trees were transplanted into infested soil. Periods of increasing disease incidence in the following seasons and years were mainly during spring and autumn, particularly in the second year after planting. Olive trees exhibited a high susceptibility to the defoliating pathotype of the pathogen, even at very low inoculum levels; in fact, diseased plants were encountered throughout the experiment regardless of the inoculum density treatment. Inoculum densities greater than 3 ppg in the soil resulted in final disease incidence greater than 50% for the trees after 2.5 years. Therefore, these inoculum densities must be considered very high for olive trees. There were no differences in final disease incidence, mean symptom severity, or area under the disease progress curve between plots infested with 10 or 3.33 ppg, whereas other treatments exhibited lower values for each of these disease parameters. The temporal variations of disease incidence and severity were highly correlated for the higher inoculum density treatments, with r2 values ranging from 0.92 to 0.84 for disease incidence and from 0.93 to 0.88 for severity. However, r2 was slightly lower for the treatments involving lower inoculum densities of the pathogen in microplots. The slopes of the linear regression curves were statistically different for nearly all the inoculum density treatments. Positive correlation was found between the initial inoculum density and final disease incidence values after the study period that was accurately explained by mathematical models. The results suggest that susceptible olive cultivars should not be planted in soils infested with virulent defoliating pathotypes of V. dahliae. Results also clarify that inoculum density levels obtained from field soil analyses can be used for establishing a risk prediction system with a view to controlling VWO in olive tree plantations.
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Marhadour, Sylvie, Roland Pellé, Jean-Marc Abiven, Frédérique Aurousseau, Hervé Dubreuil, Yves Le Hingrat, and Jean-Eric Chauvin. "Disease Progress Curve Parameters Help to Characterise the Types of Resistance to Late Blight Segregating in Cultivated Potato." Potato Research 56, no. 2 (April 9, 2013): 99–114. http://dx.doi.org/10.1007/s11540-013-9233-1.
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Haynes, Kathleen G., and D. Peter Weingartner. "The use of area under the disease progress curve to assess resistance to late blight in potato germplasm." American Journal of Potato Research 81, no. 2 (March 2004): 137–41. http://dx.doi.org/10.1007/bf02853611.
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Nemesia C. San Juan, Bachiller, and Reynaldo G. Abad. "Distribution and progression of stem bleeding disease of coconut (Cocos nucifera L.) in some areas of the Philippines." CORD 20, no. 02 (December 1, 2004): 34. http://dx.doi.org/10.37833/cord.v20i02.386.
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Records of disease occurrence in surveyed provinces show Davao del Sur having the highest disease incidence of stem bleeding caused by Thielaviopsis paradoxa (de Seynes) von Hohnel. Disease incidence in Malayan Yellow Dwarf x West African Tall (MYD x WAT) hybrid at the PCA’s Zamboanga Research Center was relatively lower than the other areas observed. Tall genotypes are less susceptible to the disease as shown in the province of Quezon where the cultivar Laguna Tall is predominantly grown. The incidence of stem bleeding was found to be related with palms age. More incidence of the disease was noted in palms between 11-15 years old.
Study on the spatial distribution of the disease from l991 to l995 show that the disease initially occurred in random foci, and, subsequently infected adjacent palms.
The disease progress curves suggest that stem bleeding follows a sigmoid curve. It follows that the progress of the disease at any given time is a function of the initial inoculums and the number of effective contact points between susceptible host and inoculums per unit time. Analysis of the infection rates using logistic growth model showed that the rate of disease increase ranged from 0.029 to 0.218 per unit per year and 0.227 per unit per year in all the six experimental areas.
Increase in disease incidence is directly related to high amount of rainfall.
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Turechek, William W., Pamela D. Roberts, Philip A. Stansly, Craig G. Webster, Chandrasekar S. Kousik, and Scott Adkins. "Spatial and Temporal Analysis of Squash vein yellowing virus Infections in Watermelon." Plant Disease 98, no. 12 (December 2014): 1671–80. http://dx.doi.org/10.1094/pdis-10-13-1094-re.
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Squash vein yellowing virus (SqVYV) is a whitefly-transmitted ipomovirus infecting watermelon and other cucurbits that was recently introduced to Florida. Effects on watermelon are devastating, with total vine collapse, often near harvest, and fruit rendered unmarketable by brown, discolored flesh. The epidemiology of SqVYV was studied in a 1-ha field of ‘Fiesta’ watermelon over six growing seasons (I to VI) to characterize the spatial patterning of disease and temporal rate of disease progress, as well as its association with Cucurbit leaf crumple virus (CuLCrV) and Cucurbit yellow stunting disorder virus (CYSDV), two additional whitefly-transmitted viruses that often occur with SqVYV. The field was scouted at regular intervals for the length of the season for incidence of virus and number of whiteflies. Incidence of SqVYV reached 100% during seasons I, II, and V and 20% during season III. SqVYV did not occur during seasons IV and VI. SqVYV progressed in a characteristic logistic fashion in seasons I, II, and V but less so in season III. The rate of disease progress was similar for the three seasons with high disease incidence, with an average value of 0.18. A positive correlation between the area under the disease progress curve and whitefly-days was found, where both progress curves were calculated as a function of thermal time (degree days, base 0°C). SqVYV displayed significant but variable levels of aggregation, as indicated by its fit to the β-binomial distribution, the binary power law, and ordinary runs analysis. Association analysis indicated that the viruses were largely transmitted independently. Results of this study provide epidemiological information that will be useful in the development of management strategies for SqVYV-induced vine decline, and provide new information for CuLCrV and CYSDV.
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Caldwell, P. M., J. M. J. Ward, N. Miles, and M. D. Laing. "Assessment of the Effects of Fertilizer Applications on Gray Leaf Spot and Yield in Maize." Plant Disease 86, no. 8 (August 2002): 859–66. http://dx.doi.org/10.1094/pdis.2002.86.8.859.
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The effects of the application of 0, 60, and 120 kg N ha-1 and of 0, 25, 50, and 150 kg K ha-1 on final disease severity, standardized area under disease progress curve, and grain yield were investigated at Cedara, South Africa, on a maize (Zea mays) hybrid susceptible to gray leaf spot (GLS), caused by Cercospora zeae-maydis. The trial was a randomized 3 × 4 factor design, split for fungicide treatments, and replicated three times. With increased N and K levels, final percent leaf blighting and the standardized area under disease progress curve were higher. In fungicide-treated maize, grain yields increased with increasing levels of N and K, as expected. In non-fungicide-treated maize, grain yield increased significantly with increased levels of N, despite increased disease severity. This was in contrast to small increases in grain yields from non-fungicide-treated maize with increased K levels, which were not significant. This was probably because grain yield response, which should have occurred at higher K applications, was reduced by increased disease severity. The effect of N, P, and K on GLS wasinvestigated at Ahrens. Maize was grown in a 4 × 4 × 4 N-P-K factorial, in a randomized complete block design. Fertilizer was applied at 0, 60, 120, and 180 kg N ha-1, 0, 30, 60, and 120 kg P ha-1, and 0, 50, 100, and 150 kg K ha-1. No fungicides were applied. A single disease assessment at physiological maturity showed that final disease severity increased with increasing levels of N, P, and K. These results have implications for small-scale farmers who are encouraged to fertilize for increased grain yields but may not have the resources to apply fungicide sprays to control fungal diseases.
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Hess, D. E., R. Bandyopadhyay, and I. Sissoko. "Pattern Analysis of Sorghum Genotype × Environment Interaction for Leaf, Panicle, and Grain Anthracnose in Mali." Plant Disease 86, no. 12 (December 2002): 1374–82. http://dx.doi.org/10.1094/pdis.2002.86.12.1374.
Full textAbstract:
Resistance to anthracnose, caused by Colletotrichum graminicola, in sorghum was identified through field screening at two locations (Samanko and Longorola) in Mali. The occurrence and progress of anthracnose were monitored on 19 sorghum lines plus resistant and susceptible checks in the 1996 to 1998 rainy seasons. Foliar anthracnose severity was assessed at regular intervals throughout the season. Area under the disease progress curve (AUDPC) was calculated for each genotype. Anthracnose severity was also evaluated on the peduncle, rachis and glumes, panicle, and grain. For the characters under study, the site × year and site × year × line interactions accounted for the genotype × environment interactions. Pattern analysis was applied to the environment-standardized matrix of genotype × environment means to analyze these interactions and elucidate genotypic adaptation. None of the lines was completely (hypersensitive) resistant to the disease, but 12 showed high levels of stable resistance to both foliar and panicle anthracnose. Only one was moderately susceptible to both forms of the disease. In addition to identifying varieties that can be grown in zones to which they are adapted, additional genotypes were identified that can serve as sources of resistance in regional breeding programs.
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Tredway, L. P., K. L. Stevenson, and L. L. Burpee. "Components of Resistance to Magnaporthe grisea in ‘Coyote’ and ‘Coronado’ Tall Fescue." Plant Disease 87, no. 8 (August 2003): 906–12. http://dx.doi.org/10.1094/pdis.2003.87.8.906.
Full textAbstract:
The components of resistance in tall fescue to Magnaporthe grisea, the causal agent of gray leaf spot, were measured in growth chamber experiments. Cultivars ranging in susceptibility to M. grisea were selected: ‘Kentucky 31’ (susceptible), ‘Rebel III’ (moderately susceptible), ‘Coronado’ (resistant), and ‘Coyote’ (resistant). Plants were inoculated with nine M. grisea isolates representing five clonal lineages associated with tall fescue in Georgia. Compared to Kentucky 31, Coronado and Coyote exhibited longer incubation and latent periods, reduced rates of disease progress and lesion expansion, and lower final disease incidence, final foliar blight incidence, final mean lesion length, area under the lesion expansion curve, and area under the disease progress curve. No evidence of hypersensitive response was observed, all M. grisea isolates completed the disease cycle by producing secondary inoculum, and no differential response to isolates from different clonal lineages was detected in Coronado and Coyote. These results indicate that Coronado and Coyote have partial resistance to M. grisea. Measurement of resistance components using primary parameters and derived parameters yielded similar results. Foliar blight incidence data exhibited increased variation relative to other parameters and was less powerful for detection of M. grisea resistance. Measurements of incubation period, latent period, final disease incidence, and final mean lesion length were the most effective and efficient methods for detecting M. grisea resistance in tall fescue.
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Li, Yonghao, and David O. TeBeest. "Temporal and Spatial Development of Sorghum Anthracnose in Arkansas." Plant Disease 93, no. 3 (March 2009): 287–92. http://dx.doi.org/10.1094/pdis-93-3-0287.
Full textAbstract:
Development of sorghum anthracnose in time and space on susceptible (‘BTx623’ and ‘Pioneer 8313’) and resistant (‘Cargill 888Y’) sorghum (Sorghum bicolor) cultivars was investigated in field plots inoculated with a mixture of three strains (T430-SW, Ar54-SW, and ArSS-1SW) of Colletotrichum sublineolum in 2001 and 2002. After slow development during early growth stages, sorghum anthracnose developed rapidly after flowering. The logistic model provided a good statistical fit for disease progress curves for sorghum anthracnose in Arkansas. Compared to susceptible cultivars, the resistant cultivar had significantly lower values for the standard area under the disease progress curve, a lower upper asymptote, and delayed epidemic onset. However, there were no significant differences in infection rate and the time of the inflection points, the times at which the disease proportion equaled values of one-half of upper asymptotes, among the three cultivars. The negative exponential model more closely described disease gradients of sorghum anthracnose than the inverse power law model. There were significant differences in intercepts but not in slopes and half-distance between the resistant and susceptible cultivars. The slopes of disease gradients were significantly lower at 78 days after inoculation (DAI) than at 57 DAI on the three cultivars. The results could provide epidemiological components of sorghum anthracnose to help evaluate sorghum cultivars and breeding lines under field conditions.
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Kapitsa, L. M. "Natural Resources and Socio-Economic Progress." MGIMO Review of International Relations, no. 4(37) (August 28, 2014): 168–86. http://dx.doi.org/10.24833/2071-8160-2014-4-37-168-186.
Full textAbstract:
The article reviews international debates on development problems of the resource-based economies. It draws atten tion to causes and mechanisms of the so-called "resource curse" and symptoms of systemic breakdowns and stagnant phenomena in resource-based economies named "Dutch disease". Specific attention is given to the role of national elites and institutions in the emergence of "Dutch disease", preservation of economic backwardness and/or de-industrialization of resource-rich countries. The author also considers new approaches to resolving the problem of'resource-curse", in particular, return to traditional instruments of economic diversification as industrialization and protectionism.