Susceptibility of Deciduous Azalea Cultivars to Powdery Mildew Disease

Forty deciduous azalea (Rhododendron sp.) cultivars from commercial sources were evaluated for powdery mildew (Microsphaera sp.) resistance. Plants were established in two duplicate field plantings in Ohio and Minnesota and evaluated in 2002 and 2003. Plants were scored using a disease symptom rating based on the percent of leaf area infected, evaluating both ab- and adaxial leaf surfaces. Highly significant differences were found for cultivar, location, year, cultivar × location and cultivar × year for disease severity. Calendulaceum × speciosum, `Fragrant Star', `Garden Party', `Late Lady', `Millennium', `Parade', and `Popsicle' showed no powdery mildew symptoms in both locations. Another group of plants with only minimal symptoms (<25% leaf area affected) included `Jane Abbott', `Magic', `Northern Hi-Lights' and `Snowbird'. The symptom-free cultivars exhibited glaucous foliage, suggesting a potential, common resistance mechanism. The mean scores for the abaxial and adaxial leaf surfaces were 2.34 and 1.64, respectively, although four cultivars had more disease symptoms on the adaxial surface. `Arneson Gem' showed nearly a two-point difference between abaxial and adaxial scores. Evaluations of azalea powdery mildew susceptibility should consider both leaf surfaces and use the highest score as the best estimate of host resistance.

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First Report of Powdery Mildew (Microsphaera palczewskii) on Siberian Pea Tree (Caragana arborescens) in North America

Plant Disease ◽

10.1094/pdis.2003.87.4.451b ◽

2003 ◽

Vol 87 (4) ◽

pp. 451-451 ◽

Cited By ~ 1

Author(s):

C. Nischwitz ◽

G. Newcombe

Keyword(s):

North America ◽

Powdery Mildew ◽

First Report ◽

Powdery Mildews ◽

Leaf Surfaces ◽

Mean Diameter ◽

Caragana Arborescens ◽

The Mean ◽

Northern United States ◽

The U.S

Caragana arborescens Lam. is an exotic ornamental that can also be somewhat invasive. In July 2002, powdery mildew was observed on C. arborescens along the Idaho-Washington border in Moscow and Pullman, respectively. Leaves were colonized as soon as they emerged, and entire plants were affected. The fungus covered both leaf surfaces, but cleistothecia were more abundant on abaxial surfaces. The mean diameter of the cleistothecia was 91 (± 9.8) μm. Short-stalked asci averaged 67 (± 7.1) μm × 37 (± 5.2) μm, and the ascospores were 21 (± 2.0) μm × 13 (± 0.8) μm. There are records of four species of Microsphaera on C. arborescens in Europe and Asia. The measurements fit the description of Microsphaera palczewskii Jacz. (1), and the identification was confirmed by comparison with specimens of this fungus on C. arborescens from Sweden (U.S. National Fungus Collections: BPI 749057 and 749058). Specimens of M. grossulariae (Wallr. ex Fr.) Lev. on Ribes divaricatum Dougl. from California (BPI 558266) were also examined, but the cleistothecial appendages were distinctly different from those of the Idaho specimens. To our knowledge, this is the first reported occurrence in North America of powdery mildew on C. arborescens and the first report of M. palczewskii. The latter may have been introduced recently into North America because there are areas in southern Canada and the northern United States in which C. arborescens is unaffected by powdery mildew. Interestingly, it is only in recent decades that M. palczewskii has spread from Asia into Europe (2). Now, host and parasite have been reunited in North America as well. Specimens have been deposited in the U.S. National Fungus Collections (BPI). References: (1) U. Braun. A monograph of the Erysiphales (powdery mildews) J. Cramer, Berlin-Stuttgarg, 1987. (2) S. Huhtinen et al. Karstenia 41:31, 2001.

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Optimum Sample Size for Determining Disease Severity and Defoliation Associated with Septoria Leaf Spot of Blueberry

Plant Disease ◽

10.1094/pd-90-1209 ◽

2006 ◽

Vol 90 (9) ◽

pp. 1209-1213 ◽

Cited By ~ 4

Author(s):

P. S. Ojiambo ◽

H. Scherm

Keyword(s):

Sample Size ◽

Leaf Area ◽

Disease Severity ◽

Total Variation ◽

Leaf Spot ◽

Variance Components ◽

Optimum Sample Size ◽

The Mean ◽

Time Required ◽

Optimum Sample

In a 3-year field study, Premier rabbiteye blueberry plants were sampled at three hierarchical levels (leaf, shoot, and bush) to assess severity of Septoria leaf spot (caused by Septoria al-bopunctata) and incidence of defoliation. A positive linear relationship (R 2 = 0.977, P < 0.0001, n = 2127) was observed between the number of spots per leaf and percent necrotic leaf area, both assessed on individual leaves in mid- to late October. For data summarized at the shoot level, percent defoliation increased nonlinearly (R 2 = 0.729, P < 0.0001, n = 224) as disease severity increased, with a rapid rise to an upper limit showing little change in defoliation above 60 spots per leaf. Variance components were calculated for disease severity to partition total variation into variation among leaves per shoot, shoots per bush, and bushes within the field. In all cases, leaves per shoot and shoots per bush accounted for >90% of the total variation. Based on the variance components and linear cost functions (which considered the time required to assess each leaf and select new shoots and bushes for assessment), the optimum sample size for assessing disease severity as number of spots per leaf (with an allowable variation of 20% around the mean) was 75 leaves, one each selected from three shoots per bush on 25 bushes (total time required for assessment: 36.1 min). For disease severity expressed as percent necrotic leaf area, the corresponding values were 144 leaves, two each sampled from three shoots per bush on 24 bushes (total time required: 21.7 min). Thus, given the strong correlation between the two disease variables demonstrated in this study, visual assessment of percent necrotic area was the more efficient method. With an allowable variation of 10% around the mean, a sample of 27 shoots from nine bushes was the optimum sample size for assessing defoliation across the 3 years.

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Nighttime Application of UV-C to Control Cucumber Powdery Mildew

Plant Health Progress ◽

10.1094/php-11-19-0081-rs ◽

2020 ◽

Vol 21 (1) ◽

pp. 40-46 ◽

Cited By ~ 1

Author(s):

Jaimin S. Patel ◽

Leora C. Radetsky ◽

Rohan Nagare ◽

Mark S. Rea

Keyword(s):

Powdery Mildew ◽

Leaf Area ◽

Disease Severity ◽

Uv Radiation ◽

Podosphaera Xanthii ◽

Laboratory Studies ◽

Time Of Application ◽

Cucumber Powdery Mildew ◽

The Impact ◽

Uv C

Nonionizing, ultraviolet (UV) radiation is effective for mitigating powdery mildew associated with a variety of crops including strawberry, grapes, rosemary, tomato, rose, and cucumber. The effectiveness of UV radiation depends upon the dose (irradiance × duration), the frequency of dosing, the time of application, and the sensitivity of the crop to UV radiation. Reported here are the results of two laboratory studies examining the impact of UV-C (254 nm) on cucumber and its obligate powdery-mildew-causing pathogen Podosphaera xanthii. In the first study, doses of UV-C (72 and 144 J m–2) applied every night were more effective at reducing disease severity than dosing every day. However, leaf area was reduced more following nighttime applications than daytime applications, suggesting that both day and night applications of UV-C could compromise yield without necessarily eliminating the disease. The second study showed that a dose of UV-C (7.2 J m–2) applied every night or a higher dose (70 J m–2) applied every fourth night were both effective for eliminating powdery mildew without significantly reducing leaf area. These findings, if confirmed in the field, could provide cucumber growers with additional options for controlling powdery mildew without compromising yield.

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Incidence-Severity Relationships in the Pathosystem Coffea arabica-Hemileia vastatrix

Plant Disease ◽

10.1094/pdis.1999.83.2.186 ◽

1999 ◽

Vol 83 (2) ◽

pp. 186-188 ◽

Cited By ~ 22

Author(s):

R. Silva-Acuña ◽

L. A. Maffia ◽

L. Zambolim ◽

R. D. Berger

Keyword(s):

Leaf Area ◽

Disease Severity ◽

Host Resistance ◽

Coffea Arabica ◽

Data Sets ◽

Independent Data ◽

Hemileia Vastatrix ◽

Fungicide Treatment ◽

Coffee Rust

Incidence-severity relationships for coffee rust were studied to determine if the easily assessed incidence could be used to evaluate host resistance and fungicide treatment. At two locations in each of 3 years, the incidence of rust on 300 leaves was compared with two assessments of severity: (i) the average number of sporulating pustules per leaf, and (ii) the estimated leaf area with rust. For nine or 10 assessments in time at one location and pooled over 3 years, the average number of sporulating pustules per leaf (Y sp) was well related with the incidence of leaves with rust (X) as Y sp = 0.02982+ 0.017035X +0.000573X 2; R 2 = 0.87. The leaf area with rust (Y la) was also well related with incidence of leaves with rust as Y la = 0.001 − 0.01076X +0.008376X 2; R 2 = 0.92. For two independent data sets from a second location obtained over two seasons, the above models satisfactorily fit the relationships for the average sporulating pustules per leaf (R 2 = 0.97 and 0.96) and for the estimated leaf area with rust (R 2 = 0.95 and 0.98). Therefore, the readily determined incidence can be used to estimate both measures of disease severity of coffee rust.

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Bacterial Leaf Blight (BLB) Disease Incidence and Severity in Basmati and Non-Basmati Rice Growing Areas of Punjab, Pakistan

International Journal of Phytopathology ◽

10.33687/phytopath.009.03.3417 ◽

2020 ◽

Vol 9 (3) ◽

pp. 157-163

Author(s):

Hafiz M. I. Arshad ◽

Junaid A. Khan ◽

Kamran Saleem ◽

Syed S. Alam ◽

Shahbaz T. Sahi

Keyword(s):

Leaf Area ◽

Disease Severity ◽

Disease Incidence ◽

Management Strategies ◽

Leaf Blight ◽

Bacterial Leaf Blight ◽

Basmati Rice ◽

Rice Varieties ◽

Disease Symptoms ◽

Rice Season

Bacterial leaf blight (BLB) is one of the most damaging diseases of rice in Asia and annually incurring significant yield loss to rice production in Pakistan. Management of disease required the information of BLB incidence and severity in basmati and non-basmati rice areas. The current study presented the observation of BLB disease incidence and severity in 19 major rice growing districts of Punjab. In this study, 9 Basmati growing and 10 non-basmati rice growing districts were surveyed from September to October in 2009, 2010, 2012, and 2013. Rice fields near to roadside, research stations and adjoining farmer fields were preferred for the survey. Each halt was after 10 km on the route depending upon the crop intensity. The general appearance of the field was observed for the absence or presence of BLB disease symptoms. The incidence of BLB was recorded as a percentage of plants infected in a field on a visual basis. For each field, 4 plants were observed at 5 points/hill along the diagonal transect for disease symptoms. The data of severity was recorded as the percentage of leaf area infected out of the total leaf area. Among the districts with basmati rice, the mean incidence of BLB was maximum in Gujranwala, Sheikhupura and Hafizabad followed by Mandi Bahauddin and Gujrat. A similar pattern of disease severity was observed in the basmati rice belt with maximum BLB mean severity in Gujranwala, Sheikhupura and Hafizabad having most of the field with a severity scale of 9. Overall, the disease trend showed that both the incidence and the severity were higher in 2010, 2012 and 2013 in the basmati rice belt. The ten districts, comprising of mostly non-basmati rice varieties showed relatively less BLB incidence and severity compared to basmati rice districts. The maximum mean incidence of 20-25% was observed in Faisalabad, Chiniot and Sahiwal in at least one year of the rice season. None of the field with BLB disease symptoms was observed in districts Okara, Khanewal and Bahawalpur during the 2012 and 2013 rice season. Maximum disease severity of mean value 3 was observed in Sahiwal during 2009 while the rest of the districts showed less than 2 mean severity during all rice growing season. Overall, in non-basmati rice districts, no specific trend of disease incidence and severity was apparent, however, the disease was present in very low magnitude or absent during the surveyed years. The information from this study is helpful in the selection of variety for basmati and non-basmati districts of Punjab and the adoption of appropriate disease management strategies.

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POMICS: A Simulation Disease Model for Timing Fungicide Applications in Management of Powdery Mildew of Cucurbits

Phytopathology ◽

10.1094/phyto-11-16-0413-r ◽

2017 ◽

Vol 107 (9) ◽

pp. 1022-1031 ◽

Cited By ~ 1

Author(s):

Z. Sapak ◽

M. U. Salam ◽

E. J. Minchinton ◽

G. P. V. MacManus ◽

D. C. Joyce ◽

...

Keyword(s):

Powdery Mildew ◽

Disease Severity ◽

Secondary Infection ◽

Natural Infection ◽

Disease Model ◽

Field Studies ◽

Crop Disease ◽

Causal Pathogen ◽

The Mean ◽

Infection Cycles

A weather-based simulation model, called Powdery Mildew of Cucurbits Simulation (POMICS), was constructed to predict fungicide application scheduling to manage powdery mildew of cucurbits. The model was developed on the principle that conditions favorable for Podosphaera xanthii, a causal pathogen of this crop disease, generate a number of infection cycles in a single growing season. The model consists of two components that (i) simulate the disease progression of P. xanthii in secondary infection cycles under natural conditions and (ii) predict the disease severity with application of fungicides at any recurrent disease cycles. The underlying environmental factors associated with P. xanthii infection were quantified from laboratory and field studies, and also gathered from literature. The performance of the POMICS model when validated with two datasets of uncontrolled natural infection was good (the mean difference between simulated and observed disease severity on a scale of 0 to 5 was 0.02 and 0.05). In simulations, POMICS was able to predict high- and low-risk disease alerts. Furthermore, the predicted disease severity was responsive to the number of fungicide applications. Such responsiveness indicates that the model has the potential to be used as a tool to guide the scheduling of judicious fungicide applications.

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Vitamin D levels are not associated with non-alcoholic fatty liver disease severity in a Brazilian population

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000667 ◽

2020 ◽

pp. 1-8

Author(s):

Jeniffer Danielle M. Dutra ◽

Quelson Coelho Lisboa ◽

Silvia Marinho Ferolla ◽

Carolina Martinelli M. L. Carvalho ◽

Camila Costa M. Mendes ◽

...

Keyword(s):

Vitamin D ◽

Liver Disease ◽

Fatty Liver ◽

Disease Severity ◽

Fatty Liver Disease ◽

Hypovitaminosis D ◽

Alcoholic Fatty Liver ◽

Vitamin D Levels ◽

The Mean ◽

Alcoholic Fatty Liver Disease

Abstract. Some epidemiological evidence suggests an inverse correlation between non-alcoholic fatty liver disease (NAFLD) frequency and vitamin D levels. Likewise, a beneficial effect of vitamin D on diabetes mellitus (DM) and insulin resistance has been observed, but this is an unsolved issue. Thus, we aimed to investigate the prevalence of hypovitaminosis D in a NAFLD Brazilian population and its association with disease severity and presence of comorbidities. In a cross-sectional study, the clinical, biochemical and histological parameters of 139 NAFLD patients were evaluated according to two different cut-off points of serum 25-hydroxyvitamin D levels (20 ng/mL and 30 ng/mL). The mean age of the population was 56 ± 16 years, most patients were female (83%), 72% had hypertension, 88% dyslipidemia, 46% DM, 98% central obesity, and 82% metabolic syndrome. Serum vitamin D levels were < 30 ng/mL in 78% of the patients, and < 20 ng/mL in 35%. The mean vitamin D level was 24.3 ± 6.8 ng/mL. The comparison between the clinical, biochemical and histological characteristics of the patients according to the levels of vitamin D showed no significant difference. Most patients with NAFLD had hypovitaminosis D, but low vitamin D levels were not related to disease severity and the presence of comorbidities.

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Influence of sowing dates on the incidence of powdery mildew of chilli

Journal of AgriSearch ◽

10.21921/jas.v4i2.7784 ◽

2017 ◽

Vol 4 (2) ◽

Author(s):

SUDHEENDRA A. ASHTAPUTRE

Keyword(s):

Powdery Mildew ◽

Field Experiment ◽

Disease Severity ◽

Agricultural Research ◽

Time Interval ◽

Research Station ◽

Inoculum Potential ◽

Weather Factors ◽

Agricultural Research Station ◽

Sowing Dates

A field experiment was conducted during kharif, 2005 at Agricultural Research station, Devihosur, Haveri, Karnataka to assess the progress of powdery mildew at different time interval of sowing dates. Totally 20 different dates of sowings were imposed in the experiment at an interval of 10 days. The crop sown on last week of May to mid of June recorded minimum disease severity compared to rest of the date of sowings. This clearly indicated that crop sown during this period suffers less, which may be due to low inoculum potential, whereas late sown crop suffers more because of the readily available inoculum in the early sown crops. Low disease severity in last week of May to mid of June sowing may be attributed to the non-congenial weather factors for the development of the disease.

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Variety resistance of winter barley to powdery mildew in the field in 1976−2005

Czech Journal of Genetics and Plant Breeding ◽

10.17221/2067-cjgpb ◽

2008 ◽

Vol 43 (No. 3) ◽

pp. 87-96 ◽

Cited By ~ 5

Author(s):

A. Dreiseitl

Keyword(s):

Powdery Mildew ◽

Disease Severity ◽

Powdery Mildew Resistance ◽

Specific Resistance ◽

Winter Barley ◽

Mildew Resistance ◽

Average Resistance ◽

The Difference ◽

The Given ◽

Resistance Of Varieties

The results of evaluation of powdery mildew resistance in winter barley varieties in 285 Czech Official Trials conducted at 20 locations were analysed. Over the period, the number of varieties tested per year increased from four to seven in 1976−1985 to 53−61 in 2002−2005. To assess the resistance of varieties, only trials with sufficient disease severity were used. In 1976−2000, six varieties (1.7% of the varieties tested in the given years) ranked among resistant (average resistance of a variety in a year > 7.5) including NR-468 possessing the gene Mla13, KM-2099 with mlo and Marinka with the genes Mla7, MlaMu2. In 2001−2005, already 33 varieties (16.9%) ranked among resistant, of which Traminer possessing the genes Ml(St) and Ml(IM9 dominated. The proportion of susceptible varieties (average resistance ≤ 5.5) did not change in the two mentioned periods. Two-rowed varieties began to be tested as late as in 1990 (the first variety was Danilo), however, no difference was found in the resistance of two- and six-rowed varieties. Using an example of two pairs of varieties (Dura-Miraj and Marinka-Tiffany) with identical genes for specific resistance but with different resistance in the field, the efficiency of non-specific resistance is discussed. The resistance of domestic and foreign varieties was similar in 1994−2000; however, in 2001−2005 the difference was 0.75 point to disadvantage of domestic ones.

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E-Triage Systems for COVID-19 Outbreak: Review and Recommendations

Sensors ◽

10.3390/s21082845 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2845

Author(s):

Fahd Alhaidari ◽

Abdullah Almuhaideb ◽

Shikah Alsunaidi ◽

Nehad Ibrahim ◽

Nida Aslam ◽

...

Keyword(s):

Population Growth ◽

Disease Severity ◽

Waiting Time ◽

Transmission Rate ◽

Waiting Times ◽

Triage System ◽

Disease Symptoms ◽

Comprehensive Review ◽

Severity Levels ◽

Growth And Aging

With population growth and aging, the emergence of new diseases and immunodeficiency, the demand for emergency departments (EDs) increases, making overcrowding in these departments a global problem. Due to the disease severity and transmission rate of COVID-19, it is necessary to provide an accurate and automated triage system to classify and isolate the suspected cases. Different triage methods for COVID-19 patients have been proposed as disease symptoms vary by country. Still, several problems with triage systems remain unresolved, most notably overcrowding in EDs, lengthy waiting times and difficulty adjusting static triage systems when the nature and symptoms of a disease changes. In this paper, we conduct a comprehensive review of general ED triage systems as well as COVID-19 triage systems. We identified important parameters that we recommend considering when designing an e-Triage (electronic triage) system for EDs, namely waiting time, simplicity, reliability, validity, scalability, and adaptability. Moreover, the study proposes a scoring-based e-Triage system for COVID-19 along with several recommended solutions to enhance the overall outcome of e-Triage systems during the outbreak. The recommended solutions aim to reduce overcrowding and overheads in EDs by remotely assessing patients’ conditions and identifying their severity levels.

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