scholarly journals A Quantifiable Disease Severity Rating Scale for Frogeye Leaf Spot of Soybean

2016 ◽  
Vol 17 (1) ◽  
pp. 27-29 ◽  
Author(s):  
Trey Price ◽  
Myra Purvis ◽  
Hunter Pruitt
Keyword(s):  
Disease Severity ◽  
Leaf Spot ◽  
Rating Scale ◽  
Analysis Software ◽  
Severity Rating ◽  
Image Analysis Software ◽  
Efficacy Trials ◽  
Frogeye Leaf Spot ◽  
Fungicide Efficacy ◽  
Foliar Fungicide

A quantifiable rating scale based on disease severity was developed for frogeye leaf spot (FLS) using image analysis software. The scale may be useful for estimating FLS severity in producer fields, which may aid in management decisions. Other applications of the scale include quantifying FLS severity in cultivar evaluations and foliar fungicide efficacy trials. Accepted for publication 17 February 2016. Published 22 February 2016.

scholarly journals A Quantitative Disease Severity Rating Scale for Northern Corn Leaf Blight

2016 ◽  
Vol 17 (1) ◽  
pp. 49-50 ◽  
Author(s):  
Trey Price ◽  
Myra Purvis ◽  
Hunter Pruitt
Keyword(s):  
United States ◽  
Disease Severity ◽  
Rating Scale ◽  
The United States ◽  
Leaf Blight ◽  
Analysis Software ◽  
Northern Corn Leaf Blight ◽  
Severity Rating ◽  
Corn Leaf Blight

Northern corn leaf blight (NCLB) is an annual issue for corn producers throughout the United States. Consequently, researchers are constantly evaluating hybrids for resistance and fungicides for efficacy. In most cases, NCLB severity is evaluated by visually estimating the percentage of affected foliage. Perceptions of disease severity are variable among stakeholders; therefore, a rating scale was created using photo analysis software that may be used to increase accuracy of disease severity estimations. Accepted for publication 15 March 2016. Published 28 March 2016.

scholarly journals Molecular characterization of leaf spot caused by Alternaria alternata on buttonwood (Conocarpus erectus L.) and determination of pathogenicity by a novel disease rating scale

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251471
Author(s):  
Muhammad Fahim Abbas ◽  
Muhammad Rafiq ◽  
Abdullah M. Al-Sadi ◽  
Saleh Alfarraj ◽  
Sulaiman Ali Alharbi ◽  
...  
Keyword(s):  
Disease Severity ◽  
Alternaria Alternata ◽  
Leaf Spot ◽  
Rating Scale ◽  
Management Strategies ◽  
Alternaria Leaf Spot ◽  
Link Type ◽  
Conocarpus Erectus ◽  
Its Regions ◽  
First Time

The buttonwood (Conocarpus erectus L.) is a mangrove shrub belonging to Combretaceae family. It mostly grows on the shorelines of tropical and subtropical regions in the world. It was introduced to Lasbela University of Water, Agriculture & Marine Sciences (LUWMS), Uthal, Baluchistan as an ornamental plant as it grows well under harsh, temperate and saline conditions. During a routine survey, typical leaf spot symptoms were observed on the leaves of buttonwood plants. A disease severity scale for alternaria leaf spot of buttonwood was developed for the first time through this study. Disease severity according to the scale was 38.97%. The microscopic characterizations was accomplished for the identification of Alternaria alternata and Koch’s postulates were employed to determine the pathogenicity. For molecular identification, 650 bp internal transcribed spacer (ITS) regions (ITS1, 5.8s and ITS2) were amplified from three representative isolates (LUAWMS1, LUAWMS2 and LUAWMS3) through polymerase chain reaction (PCR). The nucleotide sequences from ITS regions of the isolates were submitted to NCBI with GenBank accession numbers MW585375, MW585376 and MW585377, respectively. The phylogenetic tree of 22 A. alternata isolates was computed and representative isolates exhibited 99.98% genetic similarity with mangroves ecosystem isolates. This study reports the incidence of alternaria leaf spot of buttonwood at LUWMS for the first time. It is suspected that the disease may spread further. Therefore, effective management strategies should be opted to halt the further spread of the disease.

scholarly journals Reaction of beet genotypes to the Beet Leaf Spot in the upper Valley of Itajaí, Santa Catarina state, Brazil

2015 ◽  
Vol 33 (1) ◽  
pp. 106-109
Author(s):  
Leandro L Marcuzzo ◽  
Tatiana S Duarte ◽  
Patrícia C Hilleshein ◽  
Bruno T Scheidt
Keyword(s):  
Disease Severity ◽  
Leaf Spot ◽  
Rating Scale ◽  
Santa Catarina ◽  
Yield Data ◽  
Local Conditions ◽  
Family Farmers ◽  
Progress Curve ◽  
Sowing Dates ◽  
Santa Catarina State

In the region of the Upper Valley of Itajaí, Santa Catarina state, Brazil, family farmers cultivate beet (Beta vulgaris) along with other products such as, onion. However, some diseases, including the Beet Leaf Spot (Cercospora beticola), have compromised the success of the beet crop due to severe leaf incidence. The objective of this study was to evaluate the reaction to the Beet Leaf Spot, under local conditions, in the spring-summer season, of the beet cultivars most frequently used by farmers in the region, namely All Green, Stays Green, Early Wonder, Cabernet, Boro, Modana and Itapuã. Two experiments, with a 30-day interval between sowings were carried out in EPAGRI, Experimental Station of Ituporanga. The experimental design was of randomized complete blocks with four replications and 2,25 m² plots. Disease severity was assessed weekly, using a diagrammatic rating scale, in ten plants taken at random and previously labelled. Disease severity data were used to calculate the area under the disease progress curve (AUDPC) for each cultivar. Same plants were used to estimate yield. AUDPC and yield data were submitted to analysis of variance (F-test, 5% probability), and means were studied by the Scott-Knott test (5% probability). There were no significant differences between cultivars, nor for reaction to the disease, neither for yield, in any of the two sowing dates. In both experiments, cultivar All Green scored the highest severity value in the last assessments, 18.46 and 19.84% respectively in the first and second sowing dates, while hybrid Boro (17.79%) in the first experiment, and Stays Green and Cabernet (18.04%) in the second, recorded the lowest values. We concluded that all cultivars were susceptible to the Beet Leaf Spot in spring-summer conditions in the Upper Valley of Itajaí.

scholarly journals Evaluation of Detached Strawberry Leaves for Anthracnose Disease Severity Using Image Analysis and Visual Ratings

HortScience ◽  
2019 ◽  
Vol 54 (12) ◽  
pp. 2111-2117
Author(s):  
Melinda A. Miller-Butler ◽  
Barbara J. Smith ◽  
Kenneth J. Curry ◽  
Eugene K. Blythe
Keyword(s):  
Image Analysis ◽  
Disease Severity ◽  
Rating Scale ◽  
Visual Assessment ◽  
Nondestructive Method ◽  
Strong Positive Correlation ◽  
Lesion Area ◽  
Breeding Lines ◽  
Anthracnose Disease ◽  
Severity Rating

Inoculation of detached strawberry leaves with Colletotrichum species may provide an accurate, rapid, nondestructive method of identifying anthracnose-resistant germplasm. The purpose of this study was to statistically compare two methods (visual and image analysis) of evaluating disease severity of strawberry germplasm screened for anthracnose resistance. Detached leaves of 77 susceptible and resistant strawberry clones were inoculated with one Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. and two C. fragariae A. N. Brooks isolates. Anthracnose disease symptoms on each leaf were assessed quantitatively via computer-based image analysis to determine percentage lesion area and qualitatively by two independent raters using a visual disease severity rating scale (0 = no symptoms to 5 = entire leaf dead). The two visual raters’ average disease severity ratings (n = 3413) were in substantial agreement with a weighted Cohen’s kappa coefficient (k) of 0.80 [95% confidence interval (CI) 0.79–0.82]. There was a strong positive correlation between percent lesion area determined by image analysis and the visual disease scores of the two raters (rp = 0.79). Image analysis provided a precise measurement of percent lesion area of infected leaves while visual assessment provided more rapid results. Our results indicate that detached leaf inoculations can be used as a rapid preliminary screen to separate anthracnose-susceptible from -resistant germplasm in large populations within breeding programs. It also may be used for assessing the resistance/susceptibility of parental breeding lines to various Colletotrichum species and isolates, for mapping germplasm for resistance genes, and in pesticide development studies.

Effects of Foliar Fungicide and Insecticide Applications on Soybean in Ohio

2010 ◽  
Vol 11 (1) ◽  
pp. 31 ◽  
Author(s):  
A. E. Dorrance ◽  
C. Cruz ◽  
D. Mills ◽  
R. Bender ◽  
M. Koenig ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Growth Stage ◽  
Yield Loss ◽  
Disease Incidence ◽  
Brown Spot ◽  
Single Application ◽  
Soybean Aphids ◽  
Frogeye Leaf Spot ◽  
Farm Scale ◽  
Foliar Fungicide

Mid-season applications of Quadris with and without Warrior insecticide were evaluated in 2004 and 2005, and Headline, Folicur, Domark, or Headline plus Folicur were evaluated in 2006, 2007, and 2008 in 37 farm scale studies in Ohio. Producer cooperators selected fields, applied treatments at growth stage R3 and harvested fields. Each trial was rated at growth stage R5 or R6 for incidence and severity of brown spot and frogeye leaf spot. Aphids and foliar disease incidence was low in 2004. Soybean aphids were counted at stage R5 in 2005. Brown spot severity was reduced significantly by Headline in seven of the 13 locations. In the absence of soybean aphid, a single application of fungicide(s) increased yield significantly in only six of the 28 locations, of which only three had yield increases greater than 4.2 bu/acre. Populations of soybean aphids were high during 2005 at nine locations, and an insecticide application increased yield significantly at eight locations. These data indicated that foliar diseases and aphids contribute to yield loss in soybeans. However, more studies are required to determine action thresholds for brown spot and frogeye leaf spot. Accepted for publication 14 October 2010. Published 22 January 2010.

scholarly journals Outbreaks of Soybean Frogeye Leaf Spot in Iowa

Plant Disease ◽  
2001 ◽  
Vol 85 (4) ◽  
pp. 443-443 ◽  
Author(s):  
X. B. Yang ◽  
M. D. Uphoff ◽  
S. Sanogo
Keyword(s):  
Disease Severity ◽  
Leaf Spot ◽  
Performance Test ◽  
Disease Incidence ◽  
Central City ◽  
Cercospora Sojina ◽  
East Central ◽  
Production Region ◽  
Frogeye Leaf Spot ◽  
Winter Temperatures

Frogeye leaf spot of soybean, caused by Cercospora sojina, is typically a disease of warm and humid regions (2). Although the disease was reported in the Midwest in the 1920s (1), no outbreaks have been recorded in Iowa. Outbreaks of frogeye leaf spot occurred during 1999 in soybean fields in Ames and Grand Junction in central Iowa. During the 2000 growing season, the disease occurred in southwestern, southcentral, central, southeastern, and east-central Iowa. Occurrences of the disease with severity (reduction of green leaf area) greater than 50% were observed in production soybean fields at Grand Junction in central Iowa and Central City in eastern Iowa. In a 12-ha no-till field planted with cv. Asgrow 2501, the disease was noticeable and uniformly distributed in the entire field in mid July. Disease severity in this field was greater than 70% by the end of August. Disease incidence, however, was less than 10% in three adjacent soybean fields. In a soybean performance test at a central Iowa location where the disease occurred in 1999 and 2000, the disease was observed on all 80 varieties, with four having a severity equal to or greater than 40%. Fourteen entries had less than a 10% disease severity and 19 entries had a disease severity equal to or greater than 30%. Infected leaves in these locations had typical lesions of frogeye leaf spot, which appeared as reddish brown margins surrounding light brown or ash gray centers. On the infected tissues, hyaline, straight, and multiseptate conidia from clustered conidiophores were found, isolated, and identified to C. sojina. The relatively warm winter temperatures in 1998 to 1999 and 1999 to 2000 were associated with frogeye leaf spot epidemics. Because of the seedborne nature of C. sojina, efforts are warranted to monitor and survey the occurrence of frogeye leaf spot in Iowa, an important seed production state in the northern soybean production region. References: (1) K. Athow and A. H. Probst. Phytopathology 42:660–662, 1952. (2) D. V. Phillips. 1999. Pages 20–21 in: Soybean Disease Compendium. Hartman et al. eds, American Phytopathological Society. St. Paul, MN.

Development of a disease severity rating scale for plane tree anthracnose

2005 ◽  
Vol 3 (2) ◽  
pp. 93-101 ◽  
Author(s):  
María-Luisa Tello ◽  
Cristina Redondo ◽  
Laura Gaforio ◽  
Silvina Pastor ◽  
Eloy Mateo-Sagasta
Keyword(s):  
Disease Severity ◽  
Rating Scale ◽  
Plane Tree ◽  
Severity Rating

scholarly journals First Report of Gray Leaf Spot Caused by Pyricularia grisea on Lolium perenne in Illinois

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1151-1151 ◽  
Author(s):  
D. K. Pedersen ◽  
R. T. Kane ◽  
H. T. Wilkinson
Keyword(s):  
Disease Severity ◽  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Leaf Spot ◽  
Gray Leaf Spot ◽  
Pyricularia Grisea ◽  
Conidial Suspension ◽  
First Report ◽  
Severity Rating ◽  
Plastic Bags

Each year from 1991 to 1999, a disease matching the description of gray leaf spot (1) was observed in the central and north central regions of Illinois. Disease severity was low (<10% blight) from 1991 to 1994 and 1999 and was severe (>50% blight in some areas) from 1995 to 1998. The disease was observed on Lolium perenne (perennial ryegrass) golf course fairways and sports fields. Isolations of Pyricularia grisea were made from L. perenne collected from golf courses in Bloomington, Decatur, Kankakee, Pekin, Urbana, and Moline, IL. All isolates were collected from surface-sterilized, symptomatic leaves. Cultures were maintained on one-fifth strength potato-dextrose agar (PDA) and induced to sporulate on full-strength oatmeal agar. All isolates in culture displayed vegetative and conidial characteristics similar to those previously described for P. grisea (1). Twenty-five different L. perenne germ plasms were inoculated with isolate WF9826 (Kankakee) using a suspension of 1 × 105 conidia per milliliter. The 4-week-old lawns (100 plants per 3-cm-diameter cone-tainer) of each ryegrass germ plasm were inoculated by spraying foliage with the conidial suspension until runoff. Inoculated and uninoculated lawns were enclosed in plastic bags and placed in an incubator (16 h light; 28°C) for 7 days. Disease severity was rated using a scale of 0 to 10 (10 = 100% blight). Each treatment was replicated three times, and all experiments were repeated four times. Small blue-gray, water-soaked lesions with dark brown borders were observed on leaves of all inoculated ryegrass germ plasms. Advanced symptoms included blighting of much of the leaves. The mean disease severity rating was 3.8 (range 2 to 7) for all experimental units and all 25 germ plasms. P. grisea was isolated from leaves that were inoculated with WF9826. This is the first report of gray leaf spot of perennial ryegrass caused by P. grisea in Illinois. Reference: (1) P. J. Landschoot et al. Plant Dis. 76:1280, 1992.

scholarly journals Tillage, Fungicide, and Cultivar Effects on Frogeye Leaf Spot Severity and Yield in Soybean

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1476-1484 ◽  
Author(s):  
Alemu Mengistu ◽  
Heather M. Kelly ◽  
Nacer Bellaloui ◽  
Prakash R. Arelli ◽  
Krishna N. Reddy ◽  
...  
Keyword(s):  
United States ◽  
Disease Severity ◽  
Leaf Spot ◽  
Growth Stages ◽  
University Of Tennessee ◽  
No Till ◽  
Frogeye Leaf Spot ◽  
Progress Curve ◽  
Significant Difference ◽  
Northern United States

Frogeye leaf spot (FLS) of soybean, caused by Cercospora sojina, has been a problem in the southern United States for many years but has become an increasing problem in the northern United States more recently, causing significant yield losses. This increase in disease severity in the northern United States has been attributed to increased utilization of no-till planting and changes in climate. A field study was conducted at the University of Tennessee, Research and Education Center in Milan, TN from 2007 to 2010 to determine severity in tilled and no-till plots treated with or without fungicide at R3 and R5 growth stages. Three FLS-susceptible cultivars, one each in Maturity Groups III, IV, and V, were treated with pyraclostrobin (Headline) fungicide. Analysis of variance using the area under the disease progress curve (AUDPC) indicated no significant difference (P ≤ 0.05) in disease severity between tilled and no-till plots without fungicide. Fungicide did not significantly reduce disease under no-till, but did under tilled plots. This is the first study showing that no-till plots did not reduce or enhance the severity of FLS when no fungicide was applied. Fungicide application significantly reduced (P ≤ 0.05) disease severity and AUDPC and increased yield in tilled plots. The yield gains in tilled, fungicide-treated plots ranged from 1 to 17%. When fungicide was applied, disease severity was not reduced as significantly in no-till as in treated tilled plots, suggesting that fungicide programs under a no-till system may require further study to minimize the risk of FLS severity.

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