scholarly journals Erratum: Characterization of Leaf Spot Pathogens from Several Spinach Production Areas in the United States

Plant Disease ◽  
2021 ◽  
Vol 105 (3) ◽  
pp. 719-719
Keyword(s):  
United States ◽  
Leaf Spot ◽  
The United States ◽  
Production Areas

scholarly journals Characterization of Leaf Spot Pathogens from Several Spinach Production Areas in the United States

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1994-2004
Author(s):  
Bo Liu ◽  
Larry Stein ◽  
Kimberly Cochran ◽  
Lindsey J. du Toit ◽  
Chunda Feng ◽  
...  
Keyword(s):  
United States ◽  
South Carolina ◽  
Leaf Spot ◽  
The United States ◽  
Leaf Damage ◽  
Leaf Spots ◽  
Pathogenicity Tests ◽  
Agar Media ◽  
Production Areas

Leaf spot diseases have become a major concern in spinach production in the United States. Determining the causal agents of leaf spots on spinach, their prevalence and pathogenicity, and fungicide efficacy against these pathogens is vital for effective disease management. Spinach leaves with leaf spots were collected from Texas, California, Arizona, and South Carolina from 2016 to 2018, incubated in a moist chamber, and plated on potato dextrose and tryptic soy agar media. Fungal and bacterial colonies recovered were identified based on morphology and sequence analysis of the internal transcribed spacer rDNA and 16S rRNA, respectively. Two predominant genera were isolated: (i) Colletotrichum spp., which were identified to species based on sequences of both introns of the glutamate synthetase (GS-I) and glyceraldehyde-3-phosphate dehydrogenase (gapdh-I) genes; and (ii) Stemphylium spp., identified to species based on sequences of the gapdh and calmodulin (cmdA) genes. Anthracnose (Colletotrichum spinaciae) and Stemphylium leaf spot (Stemphylium vesicarium and S. beticola) were the predominant diseases. Additional fungi recovered at very limited frequencies that were also pathogenic to spinach included Colletotrichum coccodes, C. truncatum, Cercospora beticola, and Myrothecium verrucaria. All of the bacterial isolates were not pathogenic on spinach. Pathogenicity tests showed that C. spinaciae, S. vesicarium, and S. beticola caused significant leaf damage. The fungicides Bravo WeatherStik (chlorothalonil), Dithane F-45 (mancozeb), Cabrio (pyraclostrobin), and Merivon (fluxapyroxad and pyraclostrobin) were highly effective at reducing leaf spot severity caused by an isolate of each of C. spinaciae and S. vesicarium, when inoculated individually and in combination.

scholarly journals Three New Fungal Leaf Spot Diseases of Spinach in the United States and the Evaluation of Fungicide Efficacy for Disease Management

Plant Disease ◽  
2021 ◽  
pp. PDIS-04-20-0918
Author(s):  
Bo Liu ◽  
Larry Stein ◽  
Kimberly Cochran ◽  
Lindsey J. du Toit ◽  
Chunda Feng ◽  
...  
Keyword(s):  
United States ◽  
Sequence Analysis ◽  
Leaf Spot ◽  
The United States ◽  
Leaf Spots ◽  
Fungicide Efficacy ◽  
Windblown Sand ◽  
Pathogenicity Tests ◽  
Spinach Leaf ◽  
Production Areas

Leaf spot diseases of spinach, caused by Colletotrichum spinaciae, has become a major production constraint in several production areas, including Texas, in recent years. Leaf spot symptoms were observed in several fields in Texas in 2016 and 2017, with typical anthracnose-like symptoms and leaves with small, circular, and sunken lesions that appeared similar to injury from windblown sand. The lesions were plated on potato dextrose agar, from which fungal cultures were recovered. The fungi were identified based on morphology and sequence analysis of the introns of glutamate synthetase and glyceraldehyde-3-phosphate dehydrogenase (for isolates determined to be Colletotrichum spp.) and the internal transcribed spacer ribosomal DNA (for isolates determined to be Myrothecium spp.). Based on foliar symptoms, fungal colony and spore morphology, pathogenicity tests of fungal isolates on the spinach cultivar ‘Viroflay’, and DNA sequence analysis of the isolates, the symptoms on spinach leaves for two sets of samples were caused by Colletotrichum coccodes and Colletotrichum truncatum, and leaf spots resembling damage from windblown sand were caused by Myrothecium verrucaria. This is the first report of spinach leaf spot diseases caused by C. coccodes, C. truncatum, and M. verrucaria in the United States. C. coccodes and C. truncatum caused severe symptoms on the spinach cultivar ‘Viroflay’, whereas M. verrucaria caused symptoms of intermediate severity. Fungicide efficacy tests demonstrated that chlorothalonil, mancozeb, pyraclostrobin, fluxapyroxad + pyraclostrobin, and penthiopyrad were completely effective at preventing leaf spots caused by any of these pathogens when applied 24 h before inoculation of ‘Viroflay’ plants in greenhouse trials.

First Report of Curvularia Leaf Spot of Corn, Caused by Curvularia lunata, in the United States

2018 ◽  
Vol 19 (2) ◽  
pp. 140-142 ◽  
Author(s):  
T. Garcia-Aroca ◽  
V. Doyle ◽  
R. Singh ◽  
T. Price ◽  
Keith Collins
Keyword(s):  
United States ◽  
Zea Mays ◽  
Molecular Analysis ◽  
Leaf Spot ◽  
Zea Mays L ◽  
The United States ◽  
Curvularia Lunata ◽  
First Report ◽  
Corn Plants ◽  
Production Areas

During the summer of 2017, corn (Zea mays L.) in production areas throughout Louisiana exhibited symptoms similar to eyespot, caused by Kabatiella zeae (Narita & Y. Hirats). Symptoms included round to oval, light tan to light brown lesions (0.5 to 2.0-mm diameter) with reddish-brown margins often with chlorotic halos in the mid to upper canopy of corn at the brown silk stage. The disease was not severe enough to warrant management; however, it was a concern to corn producers. Symptomatic leaves were obtained from diseased corn, lesion margins were disinfested, and the suspected pathogen was isolated and tentatively identified as Curvularia lunata. Koch’s postulates were completed by inoculating V4 to V5 stage corn plants with a spore suspension and subjecting plants to a 16-h dew period at 25°C, observing symptomology, reisolating the pathogen, and identification via molecular analysis. To our knowledge this is the first report of the disease in Louisiana and the United States.

scholarly journals Characterization of a Peanut Leaf Spot of Unknown Etiology

2010 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Emily G. Cantonwine ◽  
Albert K. Culbreath ◽  
Robert C. Kemerait ◽  
Ronald D. Gitaitis
Keyword(s):  
United States ◽  
Leaf Spot ◽  
Pathogenic Fungi ◽  
The United States ◽  
Unknown Etiology ◽  
Abiotic Factor ◽  
Breeding Line ◽  
Growing Region ◽  
Over Time

Irregular leaf spot (ILS) of peanut was first noticed in Florida during the late 1990s. By 2000, ILS was apparent throughout much of the southeastern peanut growing region of the United States. Experiments were conducted to identify the cause of ILS, characterize ILS development over time, and evaluate the effect of genotype, tillage, and applications of fungicides and bactericides on ILS. Severities of ILS were near maximum levels at 33 to 42 days after planting (DAP) and in decline by 56 DAP. Incidence of ILS was greater in the lower canopy than the upper canopy. In most cases, ILS intensities were greater in strip-tilled plantings than conventional-tilled plantings and in the peanut breeding line UF-99325 than the cultivar Georgia Green. No fungicide or bactericide treatment suppressed ILS intensity. Attempts to isolate pathogenic fungi or bacteria from ILS lesions were unsuccessful. Although a pathogen cannot be totally dismissed as the cause of ILS, it is likely that ILS is caused by an abiotic factor. Accepted for publication 17 May 2010. Published 27 July 2010.

Expansion of Groundnut ringspot virus Host and Geographic Ranges in Solanaceous Vegetables in Peninsular Florida

2011 ◽  
Vol 12 (1) ◽  
pp. 34 ◽  
Author(s):  
Craig G. Webster ◽  
William W. Turechek ◽  
H. Charles Mellinger ◽  
Galen Frantz ◽  
Nancy Roe ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Vegetable Production ◽  
Viral Pathogen ◽  
Geographic Ranges ◽  
First Report ◽  
Geographic Spread ◽  
Wide Range ◽  
Production Areas ◽  
Solanaceous Plants

To the best of our knowledge, this is the first report of GRSV infecting tomatillo and eggplant, and it is the first report of GRSV infecting pepper in the United States. This first identification of GRSV-infected crop plants in commercial fields in Palm Beach and Manatee Counties demonstrates the continuing geographic spread of the virus into additional vegetable production areas of Florida. This information indicates that a wide range of solanaceous plants is likely to be infected by this emerging viral pathogen in Florida and beyond. Accepted for publication 27 June 2011. Published 25 July 2011.

scholarly journals Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 263-268 ◽  
Author(s):  
S. K. Gremillion ◽  
A. K. Culbreath ◽  
D. W. Gorbet ◽  
B. G. Mullinix ◽  
R. N. Pittman ◽  
...  
Keyword(s):  
United States ◽  
Disease Resistance ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
The United States ◽  
Yield Potential ◽  
Cercospora Arachidicola ◽  
Breeding Lines ◽  
Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

Phylogenetic and phenotypic characterization of Fomes fasciatus and Fomes fomentarius in the United States

Mycologia ◽  
2013 ◽  
Vol 105 (6) ◽  
pp. 1524-1534 ◽  
Author(s):  
Meghan A. McCormick ◽  
Larry F. Grand ◽  
Justin B. Post ◽  
Marc A. Cubeta
Keyword(s):  
United States ◽  
The United States ◽  
Phenotypic Characterization ◽  
Fomes Fomentarius

scholarly journals Phenotypic Characterization of Recent Clonal Lineages of Phytophthora infestans in the United States

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 873-881 ◽  
Author(s):  
G. Danies ◽  
I. M. Small ◽  
K. Myers ◽  
R. Childers ◽  
W. E. Fry
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
The United States ◽  
Phenotypic Characterization ◽  
Phenotypic Traits ◽  
Mating Types ◽  
Late Blight Disease ◽  
Blight Disease

Phytophthora infestans, the causal agent of late blight disease, has been reported in the United States and Canada since the mid-nineteenth century. Due to the lack of or very limited sexual reproduction, the populations of P. infestans in the United States are primarily reproducing asexually and, thus, show a simple genetic structure. The emergence of new clonal lineages of P. infestans (US-22, US-23, and US-24) responsible for the late blight epidemics in the northeastern region of the United States in the summers of 2009 and 2010 stimulated an investigation into phenotypic traits associated with these genotypes. Mating type, differences in sensitivity to mefenoxam, differences in pathogenicity on potato and tomato, and differences in rate of germination were studied for clonal lineages US-8, US-22, US-23, and US-24. Both A1 and A2 mating types were detected. Lineages US-22, US-23, and US-24 were generally sensitive to mefenoxam while US-8 was resistant. US-8 and US-24 were primarily pathogenic on potato while US-22 and US-23 were pathogenic on both potato and tomato. Indirect germination was favored at lower temperatures (5 and 10°C) whereas direct germination, though uncommon, was favored at higher temperatures (20 and 25°C). Sporangia of US-24 released zoospores more rapidly than did sporangia of US-22 and US-23. The association of characteristic phenotypic traits with genotype enables the prediction of phenotypic traits from rapid genotypic analyses for improved disease management.

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