Target Spot-Incited Defoliation and Yields of Selected Cotton Cultivars as Influenced by Fungicide Inputs

2018 ◽  
Vol 19 (2) ◽  
pp. 156-162 ◽  
Author(s):  
A. K. Hagan ◽  
K. L. Bowen ◽  
B. Miller ◽  
R. L. Nichols
Keyword(s):  
United States ◽  
Southeastern United States ◽  
The Other ◽  
Corynespora Cassiicola ◽  
Relative Area ◽  
Cotton Yield ◽  
Target Spot ◽  
Study Results ◽  
Yield Gain ◽  
Significant Yield

Target spot, caused by Corynespora cassiicola, prematurely defoliates and occasionally reduces cotton yield across the southeastern United States. Reaction of the cultivars Deltapine 1137 B2RF, Deltapine 1252 B2RF, Fibermax 1944 GLB2, PhytoGen 499 WRF, PhytoGen 575 WRF, and Stoneville 6448 GLB2 to target spot and lint yield as influenced by a full-season Headline + Bravo Ultrex fungicide program was assessed for 3 years in southwest Alabama. Significantly greater final % and relative area under the disease curve (relAUC) season-long defoliation was recorded for PhytoGen 499 WRF than the other cultivars, which had similarly lower defoliation values. A significant yield gain of 92 kg of lint/ha valued at $142/ha across all cultivars was obtained with the fungicide program. In addition, PhytoGen 499 WRF and Fibermax 1944 GLB2 had significantly lower defoliation and greater yield gains (189 and 263 kg of lint/ha, respectively) with the fungicide than no fungicide program. Hardlock incidence was greater in 2016 than in preceding years and did not differ by fungicide program. Open and unopen boll counts were similar across all cultivars and fungicide programs. Study results indicate that partially resistant cultivars may be an effective tool for managing target spot in cotton.

scholarly journals Clonality and geographic structure of host-specialized populations of Corynespora cassiicola causing emerging target spot epidemics in the southeastern United States

PLoS ONE ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. e0205849 ◽  
Author(s):  
Leilani G. Sumabat ◽  
Robert C. Kemerait ◽  
Dong Kyun Kim ◽  
Yeshwant R. Mehta ◽  
Marin T. Brewer
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Corynespora Cassiicola ◽  
Geographic Structure ◽  
Target Spot

scholarly journals Increased Occurrence of Target Spot of Soybean Caused by Corynespora cassiicola in the Southeastern United States

Plant Disease ◽  
2006 ◽  
Vol 90 (7) ◽  
pp. 974-974 ◽  
Author(s):  
S. R. Koenning ◽  
T. C. Creswell ◽  
E. J. Dunphy ◽  
E. J. Sikora ◽  
J. D. Mueller
Keyword(s):  
United States ◽  
North Carolina ◽  
South Carolina ◽  
Microscopic Examination ◽  
Southeastern United States ◽  
Corynespora Cassiicola ◽  
Susceptible Host ◽  
The North ◽  
Target Spot ◽  
Soybean Plants

Target spot of soybean (Glycine max (L.) Merr.) caused by Corynespora cassiicola (Berk. & Curt.), although found in most soybean-growing countries, is considered to be a disease of limited importance (1) and has never been reported to cause soybean yield loss in the southeastern United States (2,3). Soybean plants submitted to the North Carolina Plant Disease and Insect Clinic (NCPDIC) in August 2004 from Beaufort, Robeson, Wilson, and Johnston counties, NC had symptoms consistent with target spot. Symptoms consisted of roughly circular, necrotic leaf lesions from minute to 11 mm in diameter, though typically approximately 4 to 5 mm in diameter, and with a yellow margin. Large lesions occasionally exhibited a zonate pattern often associated with this disease. Microscopic examination of the lesions revealed the presence of spores (conidia) typical of C. cassiicola (1). Conidia were mostly three to five septate with a central hilum at the base and ranged in size from 7 to 22 wide × 39 to 520 μm long. Three commercial soybean fields near Blackville, SC (Barnwell County) were severely affected by this disease and it caused premature defoliation. Nineteen of twenty-seven maturity group VII and VIII genotypes in the 2004 Clemson University soybean variety trial near Blackville, SC had visible symptoms of target spot. Heavy rainfall associated with hurricanes during September 2004 probably enhanced the incidence of this disease, and yield suppression due to target spot was estimated at 20 to 40% in some fields. In 2005, 20 of 161 soybean samples submitted to the NCPDIC or collected in surveys from 16 counties were positive for target spot on the basis of microscopic examination. Target spot also was diagnosed in six counties (Baldwin, DeKalb, Elmore, Fayette, Macon, and Pickens) in Alabama and in four additional counties (Bamberg, Hampton, Orange-burg, and Calhoun) in South Carolina in 2005. Records from the NCPDIC indicate that target spot had not been diagnosed on soybean in North Carolina since 1981. The large increase in incidence of target spot in the southeast may be related to changes in weather patterns, changes in pathogen virulence, and/or the introduction of more susceptible host genotypes. References: (1) J. B. Sinclair. Target spot. Page 27 in: Compendium of Soybean Diseases. G. L. Hartman et al. eds. The American Phytopathological Society, St. Paul, MN, 1999. (2) J. A. Wrather et al. Plant Dis. 79:1076. 1995. (3) J. A. Wrather et al. On-line publication. doi:10.1094/PHP-2003-0325-01-RV. Plant Health Progress, 2003.

scholarly journals Phylogenetic Diversity and Host Specialization of Corynespora cassiicola Responsible for Emerging Target Spot Disease of Cotton and Other Crops in the Southeastern United States

2018 ◽  
Vol 108 (7) ◽  
pp. 892-901 ◽  
Author(s):  
Leilani G. Sumabat ◽  
Robert C. Kemerait ◽  
Marin Talbot Brewer
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Geographic Location ◽  
The United States ◽  
Plant Diseases ◽  
Host Specialization ◽  
Corynespora Cassiicola ◽  
Target Spot ◽  
Nuclear Loci

Corynespora cassiicola is a ubiquitous fungus causing emerging plant diseases worldwide, including target spot of cotton, soybean, and tomato, which have rapidly increased in incidence and severity throughout the southeastern United States. The objectives of this study were to understand the causes for the emerging target spot epidemics in the United States by comparing phylogenetic relationships of isolates from cotton, tomato, soybean, and other crop plants and ornamental hosts, and through the determination of the host range of isolates from emerging populations. Fifty-three isolates were sampled from plants in the southeastern United States and 1,380 nucleotides from four nuclear loci were sequenced. Additionally, sequences of the same loci from 23 isolates representing each of the distinct lineages of C. cassiicola described from previous studies were included. Isolates clustered based on host of origin, regardless of the geographic location of sampling. There was no genetic diversity detected among isolates from cotton, which were genetically distinct from isolates from other host species. Furthermore, pathogenicity and virulence assays of 40 isolates from various hosts onto cotton, soybean, tomato, and cucumber showed that isolates from cotton were more aggressive to cotton than those from other hosts. Soybean and tomato were most susceptible to isolates that originated from the same host, providing evidence of host specialization. These results suggest that emerging target spot epidemics in the United States are caused by either the introduction of host-specific isolates or the evolution of more aggressive strains on each host.

Growth and Development of Wild Poinsettia (Euphorbia heterophylla) Selections in Peanut (Arachis hypogaea)

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 575-578 ◽  
Author(s):  
Barry J. Brecke ◽  
Piotr Tobola
Keyword(s):  
United States ◽  
Leaf Area ◽  
Growth And Development ◽  
Baton Rouge ◽  
Southeastern United States ◽  
Light Attenuation ◽  
Growing Season ◽  
The Other ◽  
Yield Reduction ◽  
Dry Biomass

Wild poinsettia is a serious weed in several crops, including peanut, grown in the southeastern United States. A study was conducted over 3 yr at Jay, FL, to characterize the growth and development of wild poinsettia grown from seed collected at Plains, GA; Marianna, FL; and Baton Rouge, LA. Seedlings from each selection were transplanted to the field and were grown either alone or in competition with peanut. Observations made throughout the growing season indicated that the Louisiana selection flowered later, grew to a larger size, produced more leaf area and biomass, and caused greater light attenuation and peanut yield reduction than the other two selections. The Georgia selection produced the smallest plants, least leaf area and biomass, and was least competitive with peanut. The Florida selection was intermediate for these parameters. Wild poinsettia dry biomass production was reduced by 78 to 83% when grown with peanut compared with monoculture wild poinsettia.

Cotton Yield Forecasting for the Southeastern United States Using Climate Indices

2012 ◽  
Vol 28 (5) ◽  
pp. 711-723 ◽  
Author(s):  
T. B. Pathak ◽  
J. W. Jones ◽  
C. W. Fraisse
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Climate Indices ◽  
Cotton Yield ◽  
Yield Forecasting

scholarly journals Examination of the Predictability of Nocturnal Tornado Events in the Southeastern United States

2019 ◽  
Vol 34 (2) ◽  
pp. 467-479 ◽  
Author(s):  
Ryan C. Bunker ◽  
Ariel E. Cohen ◽  
John A. Hart ◽  
Alan E. Gerard ◽  
Kim E. Klockow-McClain ◽  
...  
Keyword(s):  
United States ◽  
Predictive Power ◽  
Meteorological Parameters ◽  
Southeastern United States ◽  
Time Frame ◽  
Assessment Model ◽  
The Other ◽  
Risk Assessment Model ◽  
Multiple Parameters ◽  
Effective Layer

Abstract Tornadoes that occur at night pose particularly dangerous societal risks, and these risks are amplified across the southeastern United States. The purpose of this study is to highlight some of the characteristics distinguishing the convective environment accompanying these events. This is accomplished by building upon previous research that assesses the predictive power of meteorological parameters. In particular, this study uses the Statistical Severe Convective Risk Assessment Model (SSCRAM) to determine how well convective parameters explain tornado potential across the Southeast during the months of November–May and during the 0300–1200 UTC (nocturnal) time frame. This study compares conditional tornado probabilities across the Southeast during November–May nocturnal hours to those probabilities for all other November–May environments across the contiguous United States. This study shows that effective bulk shear, effective storm-relative helicity, and effective-layer significant tornado parameter yield the strongest predictability for the November–May nocturnal Southeast regime among investigated parameters. This study demonstrates that November–May southeastern U.S. nocturnal predictability is generally similar to that within other regimes across the contiguous United States. However, selected ranges of multiple parameters are associated with slightly better predictability for the nocturnal Southeast regime. Additionally, this study assesses conditional November–May nocturnal tornado probabilities across a coastal domain embedded within the Southeast. Nocturnal coastal tornado predictability is shown to generally be lower than the other regimes. All of the differences highlight several forecast challenges, which this study analyzes in detail.

scholarly journals Performance of North American Strawberry Cultivars under Conditions Mimicking California Production Systems

1994 ◽  
Vol 119 (5) ◽  
pp. 1034-1038 ◽  
Author(s):  
John M. Rariden ◽  
Douglas V. Shaw
Keyword(s):  
United States ◽  
Variance Components ◽  
Production Systems ◽  
Southeastern United States ◽  
Total Yield ◽  
The Other ◽  
Phenotypic Variance ◽  
Growth Attributes ◽  
Geographic Regions ◽  
Strawberry Cultivars

Runner plants from 16 strawberry (Fragaria ×ananassa Duch.) cultivars were grown using annual Mediterranean production systems to test for differences in productivity, performance traits, and vegetative growth attributes. Genotypes were included from germplasm adapted to four geographic regions: California and northwestern, northeastern, and mid-Atlantic or southeastern United States. The California genotypes were divided further into day-neutral and June-bearing categories. With these treatments, California cultivars had significantly larger plants and grew more rapidly during the fall and winter, had larger fruit, and produced at least twice the quantity of fruit of cultivars from the other regions. Variance components due to region explained 64% and 26% of the phenotypic variance for early and total yield, respectively, whereas differences among cultivars within regions explained 12% and 7% of the variance for these traits. Cultivars from all regions had significantly larger plants and were more productive when treated with 3 weeks of artificial vernalization. However, region × vernalization effects were nonsignificant for all traits, a result suggesting that selection in Mediterranean environments has not adapted germplasm specifically for low vernalization conditions.

Scanning electron microscopy of three types of ectomycorrhizae formed on Eucalyptus nova-anglica in the southeastern United States

1981 ◽  
Vol 59 (5) ◽  
pp. 683-688 ◽  
Author(s):  
R. W. Rose Jr. ◽  
C. Gerald Van Dyke ◽  
C. B. Davey
Keyword(s):  
Electron Microscopy ◽  
United States ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Southeastern United States ◽  
The Other ◽  
Cenococcum Geophilum ◽  
Different Types ◽  
Scanning Electron

Three different types of ectomycorrhizae found in the Southeastern United States on Eucalyptus nova-anglica and identified as being formed by Cenococcum geophilum, Pisolithus tinctorius, and Scleroderma geaster were examined with a scanning electron microscope (SEM). In overall appearance the three types of mycorrhizae could be distinguished easily from each other, particularly C. geophilum, which had a relatively smooth, undulate surface in comparison with the other two types. Detailed descriptions and comparisons of these ectomycorrhizae are given and the value of SEM in characterizing ectomycorrhizae is discussed

scholarly journals Epidemics and Yield Losses due to Corynespora cassiicola on Cotton

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2494-2499 ◽  
Author(s):  
Kira L. Bowen ◽  
Austin K. Hagan ◽  
Malcolm Pegues ◽  
Jarrod Jones ◽  
H. Brad Miller
Keyword(s):  
Disease Onset ◽  
Yield Response ◽  
Corynespora Cassiicola ◽  
Yield Losses ◽  
Fungicide Application ◽  
Target Spot ◽  
Significant Yield ◽  
Epidemic Development ◽  
Gompertz Growth Model ◽  
Better Than

Target spot, caused by Corynespora cassiicola, has recently emerged as a problematic foliar disease of cotton. This pathogen causes premature defoliation during boll set and maturation that can subsequently impact yield, and on certain cotton cultivars loss can be substantial. This study sought to better understand target spot epidemics and disease-incited yield losses on cotton. In order to establish a range of disease, varying numbers of fungicide applications were made to each of two cotton cultivars in each of four site-years. Target spot intensity was rated over several dates beginning in late July or early August and continuing into September. Yield of seed plus lint (seed cotton) was recorded at harvest. When analyzed across cultivars, a second or third fungicide application increased yield compared with no treatment. Lack of significant yield response with a single fungicide application may have been due to timing of that application which preceded disease onset. The cultivar PhytoGen 499 WRF had consistently greater defoliation than any of the three Deltapine cultivars grown in each site-year. However, yields of both cultivars responded similarly to the fungicide regimes. Yield loss models based on late August defoliation were only predictive at site-years where conditions favored target spot development, i.e., abundant rain and moderate temperatures. Epidemic development fit the Gompertz growth model better than it did a logistic model. Knowledge of the underlying mathematical character of the epidemiology of target spot will prove useful for development of a predictive model for the disease.

scholarly journals Reduced Midseason Pesticide Program for Control of Scab and Plum Curculio in Peach

Plant Disease ◽  
2003 ◽  
Vol 87 (6) ◽  
pp. 699-706 ◽  
Author(s):  
Z. Lan ◽  
H. Scherm ◽  
D. L. Horton
Keyword(s):  
United States ◽  
Southeastern United States ◽  
The Other ◽  
Application Time ◽  
Conotrachelus Nenuphar ◽  
Plum Curculio ◽  
Nontarget Effects ◽  
And Control ◽  
Preharvest Interval ◽  
Environmental Impact Quotient

Risks to peach production from scab (caused by Cladosporium carpophilum) and plum curculio (Conotrachelus nenuphar), two key pests in the southeastern United States, are high until 2 months past petal fall and then decreases during midseason. This suggests that reduced-input pesticide strategies may effectively control both pests during the latter period. In this study, we evaluated midseason pesticide applications according to an alternate-row middle (ARM) spray program in which sprays were applied only to every other tree row while reducing tractor speed and keeping application intervals unchanged relative to conventional spraying of both sides of the trees. In a 2-year trial in a research orchard, conventional sprays of fungicide (primarily sulfur) and insecticide (primarily phosmet) were applied at 10- to 14-day intervals until first cover, followed by continued conventional sprays of fungicide and insecticide (standard), conventional sprays of one pesticide together with ARM sprays of the other pesticide, or combined ARM sprays of both pesticides. Schedules with midseason ARM sprays of both pesticides also were evaluated in two commercial orchards in 2 years. In all experiments, plots receiving combined ARM sprays were equivalent to the standard in fruit quality and control of scab and plum curculio. Combined ARM spraying resulted in lower environmental nontarget effects (as estimated by the Environmental Impact Quotient) and reduced application time by 25 to 33% for each midseason spray and 12.5 to 18.5% for the entire period from petal fall to the preharvest interval.

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