scholarly journals Epidemiological Criteria to Support Breeding Tactics Against the Emerging, High-Consequence Wheat Blast Disease

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2252-2261 ◽  
Author(s):  
M. Fernández-Campos ◽  
C. Góngora-Canul ◽  
S. Das ◽  
M. R. Kabir ◽  
B. Valent ◽  
...  
Keyword(s):  
Field Experiments ◽  
Temporal Dynamics ◽  
Blast Disease ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Wheat Blast ◽  
Progress Curve ◽  
Cultivar Selection ◽  
Different Levels ◽  
Epidemiological Parameters

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.

Effect of nitrogen fertilization on the expression of slow-blasting resistance in rice

2005 ◽  
Vol 143 (5) ◽  
pp. 385-393 ◽  
Author(s):  
A. K. MUKHERJEE ◽  
N. K. MOHAPATRA ◽  
A. V. SURIYA RAO ◽  
P. NAYAK
Keyword(s):  
Infection Rate ◽  
Error Variance ◽  
Blast Disease ◽  
Economic Injury Level ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Rate Of Increase ◽  
Apparent Infection Rate ◽  
Line Intercept

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.

scholarly journals Yield and resistance of potato cultivars with colour flesh to potato late blight

2017 ◽  
Vol 63 (No. 7) ◽  
pp. 328-333
Author(s):  
Pazderů Kateřina ◽  
Hamouz Karel
Keyword(s):  
Late Blight ◽  
Field Experiments ◽  
Potato Late Blight ◽  
Russet Burbank ◽  
Weak Dependence ◽  
Potato Cultivars ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Better Than

The resistance to potato late blight (as AUDPC – the area under the disease progress curve) and yield were evaluated in precise field experiments with 13 colour-fleshed potato cultivars. Red Emmalie and Blaue Anneliese were the most profitable cultivars of potatoes with coloured flesh, the overall yield did not differ statistically from the control cv. Agria. Cv. Blaue Anneliese resistance to potato late blight was considerably better than both control cultivars, other 2 cultivars HB Red and Red Emmalie were similar to cv. Agria. Surprisingly, cv. Russet Burbank was found to be more resistant than most cultivars tested. A statistically significant weak dependence (r = 0.36) between the percentage of infestation of plants in the T6 evaluation date (6–8 August in individual years) and the yield was detected, the slightly stronger (r = 0.40) was the correlation between AUDPC values and total yields.

scholarly journals Management of Daylily Rust With Different Fungicides and Fungicide Combinations

2017 ◽  
Vol 18 (3) ◽  
pp. 162-165 ◽  
Author(s):  
Robert S. Emmitt ◽  
James W. Buck
Keyword(s):  
United States ◽  
Disease Management ◽  
Disease Severity ◽  
Low Cost ◽  
Single Application ◽  
Southeast United States ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Disease Pressure

Production nurseries and daylily hybridizers in the southeast United States rely on the use of fungicides to manage daylily rust, caused by the fungus Puccinia hemerocallidis. Foliar sprays of pyraclostrobin, flutolanil, tebuconazole, myclobutanil, chlorothalonil, mancozeb, pyraclostrobin + boscalid, flutolanil + tebuconazole, flutolanil + myclobutanil, flutolanil + chlorothalonil, and flutolanil + mancozeb applied on 14-day intervals, and a nontreated control, were evaluated under high disease pressure at three locations in Griffin, GA, in 2015. Tebuconazole or the tebuconazole + flutolanil treatment consistently had the lowest area under the disease progress curve (AUDPC) of the treatments. The addition of flutolanil to chlorothalonil or mancozeb did not improve rust control and no difference in disease severity was observed in any treatment containing contact fungicides on all assessment dates. Single application costs ranged from $10.21 to $95.96 with tebuconazole providing excellent disease management at a relatively low cost per application ($13.90).

scholarly journals Temporal progress of southern rust in maize under different environmental conditions

2003 ◽  
Vol 28 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Cláudia V. Godoy ◽  
Lílian Amorim ◽  
Armando Bergamin Filho ◽  
Herbert P. Silva ◽  
Willian J. Silva ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Disease Severity ◽  
Logistic Model ◽  
Inflection Point ◽  
Gompertz Model ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Puccinia Polysora ◽  
The Mean

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.

scholarly journals Fungicides for Control of Downy Mildew on Pickling Cucumber in Michigan

2019 ◽  
Vol 20 (3) ◽  
pp. 165-169 ◽  
Author(s):  
Katelyn E. Goldenhar ◽  
Mary K. Hausbeck
Keyword(s):  
Downy Mildew ◽  
Untreated Control ◽  
Field Studies ◽  
Pseudoperonospora Cubensis ◽  
Relative Area ◽  
Disease Progress Curve ◽  
Cucurbit Downy Mildew ◽  
Disease Progress ◽  
Pickling Cucumber ◽  
Progress Curve

Michigan growers rely on fungicides to limit cucurbit downy mildew (CDM), incited by Pseudoperonospora cubensis; resistance of the pathogen to fungicides is a concern. We evaluated fungicides against CDM in Michigan field studies from 2015 to 2017. According to the relative area under the disease progress curve (rAUDPC), in 2015, mandipropamid, propamocarb, fluxapyroxad/pyraclostrobin, copper octanoate, and dimethomorph resulted in disease levels similar to the control. These treatments, along with cymoxanil, were similar to the control in 2016. Fungicides that were ineffective during 2015 and 2016 did not limit CDM in 2017. Famoxadone/cymoxanil and fluopicolide did not limit CDM in 2017. Each year, the following treatments were similar for disease based on rAUDPC data: oxathiapiprolin applied alone or premixed with chlorothalonil or mandipropamid, ametoctradin/dimethomorph, fluazinam, mancozeb/zoxamide, cyazofamid, and ethaboxam. An exception occurred in 2017, when ethaboxam was less effective than fluazinam, oxathiapiprolin/chlorothalonil, and oxathiapiprolin/mandipropamid. Mancozeb and chlorothalonil treatments were similar in 2015 and 2017, according to rAUDPC data. In 2017, yields were increased for oxathiapiprolin/chlorothalonil, oxathiapiprolin/mandipropamid, mancozeb, ametoctradin/dimethomorph, mancozeb/zoxamide, ethaboxam, cyazofamid, chlorothalonil, and fluazinam compared with the untreated control.

scholarly journals Stability of Slow-Rusting Resistance to Puccinia asparagi and Managing Rust in Asparagus

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 997-1000 ◽  
Author(s):  
Dennis A. Johnson
Keyword(s):  
Irrigation Management ◽  
Field Trials ◽  
Disease Progress Curve ◽  
Resistant Cultivars ◽  
Disease Progress ◽  
Slow Rusting ◽  
South Central ◽  
Progress Curve ◽  
The Stability

The stability of slow-rusting resistance to Puccinia asparagi in several asparagus cultivars was evaluated in two replicated field trials. Rust epidemics were monitored in each trial for 8 years spanning a period of 13 years (1983–1990 and 1987–1995). Inoculum of P. asparagi, an autoecious macrocyclic rust, originated each year as teliospores. In the first trial, the cultivars Jersey Titan, Jersey Centennial, Jersey Giant, Delmonte-361, and UC-157 had consistently lower area under the disease progress curve (AUDPC) values than Wash T2 and WSU-1. Cultivar Mary Washington was intermediate between the two groups of resistant and susceptible cultivars in 6 of 8 years. Jersey Titan consistently ranked number 1 for resistance with the lowest AUDPC values all 8 years. In the second trial, Jersey Giant, Delmonte-361, and UC-157 had consistently lower AUDPC values than Larac, Gynlim, Cito, Largo 17-3, and Franklim in each of 8 years. Jersey Giant, Delmonte-361, and UC-157 always ranked low (1, 2, or 3) for AUDPC. A shift from rust-susceptible to rust-resistant asparagus cultivars began in central Washington around 1996. In 2011, resistant cultivars made up nearly 96% of the asparagus plantings. From 1996 to 2011, rust was not considered a problem in commercial fields with slow-rusting resistant cultivars. Use of durable, slow-rusting cultivars, along with sanitation practices that reduced levels of aecia in nonharvested nurseries and on volunteer asparagus plants and judicious irrigation management, has effectively managed asparagus rust in commercial fields for at least 29 years in south-central Washington.

scholarly journals SAMPLE SIZE FOR ASSESS THE LEAF BLAST SEVERITY IN EXPERIMENTS WITH IRRIGATED RICE

2016 ◽  
Vol 29 (4) ◽  
pp. 822-831 ◽  
Author(s):  
BRUNO GIACOMINI SARI ◽  
ALESSANDRO DAL'COL LÚCIO ◽  
IVAN FRANCISCO DRESSLER DA COSTA ◽  
ANA LÚCIA DE PAULA RIBEIRO
Keyword(s):  
Spatial Distribution ◽  
Sample Size ◽  
Negative Binomial ◽  
Leaf Blast ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Morisita Index ◽  
Rice Leaf Blast ◽  
Severity Of The Disease

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.

scholarly journals The Area Under the Disease Progress Stairs: Calculation, Advantage, and Application

2012 ◽  
Vol 102 (4) ◽  
pp. 381-389 ◽  
Author(s):  
Ivan Simko ◽  
Hans-Peter Piepho
Keyword(s):  
Real Data ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Multiple Observations ◽  
Progress Curve ◽  
New Formula

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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