scholarly journals Spatiotemporal Dynamics of Stemphylium Leaf Blight and Potential Inoculum Sources in New York Onion Fields

2021 ◽  
Author(s):  
Frank Hay ◽  
Daniel Heck ◽  
Audrey Klein ◽  
Sandeep Sharma ◽  
Christy Hoepting ◽  
...  
Keyword(s):  
New York ◽  
Spatial Patterns ◽  
Disease Incidence ◽  
Spatiotemporal Dynamics ◽  
Leaf Blight ◽  
Residue Management ◽  
Lesion Length ◽  
Relative Role ◽  
Inoculum Sources ◽  
Inoculum Source

Stemphylium leaf blight (SLB) caused by Stemphylium vesicarium is the dominant foliar disease affecting large-scale onion production in New York. The disease is managed by fungicides, but control failures are prevalent and recently attributed to fungicide resistance. Little is known of the relative role of inoculum sources in initiation and spread of SLB epidemics. The spatial and spatiotemporal dynamics of SLB epidemics in six onion fields were evaluated along linear transects in 2017 and 2018. Average SLB incidence increased from 0 to 100% throughout the cropping seasons with an average final lesion length of 28.3 cm. Disease progress was typical of a polycyclic epidemic and the logistic model provided the best fit to 83.3% of the datasets. Spatial patterns were better described by the beta-binomial than binomial distribution in half of the datasets and random patterns were more frequently observed by the index of dispersion. Geostatistical analyses of spatial pattern also found a low frequency of datasets with aggregation. Spatiotemporal analysis of epidemics detected that the aggregation was influenced by disease incidence. However, diseased units were not associated with the previous time period according to the spatiotemporal association function of SADIE. Variable spatial patterns suggested mixed inoculum sources dependent upon location, and likely an external inoculum source at the sampling scale used in this study. Plate testing of 28 commercially available organic onion seedlots from 2017 and 2018 did not detect S. vesicarium. This finding suggests that although S. vesicarium has been reported as seed transmitted, this is unlikely to be a significant inoculum source in commercially available organic seed lots and even less so in fungicide-treated seed used to establish conventional fields. A small-plot replicated trial was also conducted in each of two years to quantify the effect of S. vesicarium-infested onion residue on SLB epidemics in a field isolated from other onion fields. SLB incidence was significantly reduced in plots without residue compared to those in which residue remained on the soil surface. Burial of infested residue also significantly reduced epidemic progress in one year. The effect of infested onion residue on SLB epidemics in the subsequent onion crop suggests rotation or residue management may have a substantial effect on epidemics. However, the presence of an inoculum source external to fields in onion production regions as indicated by a lack of spatial aggregation may reduce the efficacy of in-field management techniques.

scholarly journals Spatiotemporal Dynamics of Stemphylium Leaf Blight and Potential Inoculum Sources in New York Onion Fields

Plant Disease ◽  
2021 ◽  
Author(s):  
Frank Hay ◽  
Daniel Winter Heck ◽  
Audrey Klein ◽  
Sandeep Sharma ◽  
Christine Anne Hoepting ◽  
...  
Keyword(s):  
New York ◽  
Spatial Patterns ◽  
Disease Incidence ◽  
Spatiotemporal Dynamics ◽  
Leaf Blight ◽  
Residue Management ◽  
Lesion Length ◽  
Relative Role ◽  
Inoculum Sources ◽  
Inoculum Source

Stemphylium leaf blight (SLB) caused by Stemphylium vesicarium is the dominant foliar disease affecting large-scale onion production in New York. The disease is managed by fungicides, but control failures are prevalent and recently attributed to fungicide resistance. Little is known of the relative role of inoculum sources in initiation and spread of SLB epidemics. Plate testing of 28 commercially available organic onion seedlots from 2016 and 2017 did not detect S. vesicarium. This finding suggests that although S. vesicarium has been reported as seed transmitted, this is unlikely to be a significant inoculum source in commercially available organic seed lots and even less so in fungicide-treated seed used to establish conventional fields. The spatial and spatiotemporal dynamics of SLB epidemics in six onion fields were evaluated along linear transects in 2017 and 2018. Average SLB incidence increased from 0 to 100% throughout the cropping seasons with an average final lesion length of 28.3 cm. Disease progress was typical of a polycyclic epidemic and the logistic model provided the best fit to 83.3% of the datasets. Spatial patterns were better described by the beta-binomial than binomial distribution in half of the datasets (50%) and random patterns were more frequently observed by the index of dispersion (59%). Geostatistical analyses also found a low frequency of datasets with aggregation (60%). Spatiotemporal analysis of epidemics detected that the aggregation was influenced by disease incidence. However, diseased units were not frequently associated with the previous time period according to the spatiotemporal association function of SADIE. Variable spatial patterns suggested mixed inoculum sources dependent upon location, and likely an external inoculum source at the sampling scale used in this study. A small-plot replicated trial was also conducted in each of two years to quantify the effect of S. vesicarium-infested onion residue on SLB epidemics in a field isolated from other onion fields. SLB incidence was significantly reduced in plots without residue compared to those in which residue remained on the soil surface. Burial of infested residue also significantly reduced epidemic progress in one year. The effect of infested onion residue on SLB epidemics in the subsequent onion crop suggests rotation or residue management may have a substantial effect on epidemics. However, the presence of an inoculum source external to fields in onion production regions as indicated by a lack of spatial aggregation may reduce the efficacy of in-field management techniques.

scholarly journals An IPM Program for Managing Fungal Leaf Blight Diseases of Carrot in New York

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 59-65 ◽  
Author(s):  
B. K. Gugino ◽  
J. E. Carroll ◽  
T. L. Widmer ◽  
P. Chen ◽  
G. S. Abawi
Keyword(s):  
New York ◽  
Disease Severity ◽  
Crop Rotation ◽  
Disease Incidence ◽  
Leaf Blight ◽  
Yield Reduction ◽  
Weather Forecasts ◽  
Alternaria Dauci ◽  
Leaf Blights ◽  
Cultivar Susceptibility

Fungal leaf blight diseases caused by Cercospora carotae and Alternaria dauci occur annually on processing carrot in New York, with growers applying up to eight fungicide sprays to manage these diseases. An integrated pest management (IPM) program involving the use of a 25% disease incidence threshold to prompt the first fungicide application and timing subsequent sprays by monitoring for increases in disease severity and weather forecasts in conjunction with a 10- to 14-day spray interval was evaluated in grower fields in 1997 and 1998. The IPM plots, compared with the grower plots, required two to six fewer fungicide applications but showed no yield reduction. From 1999 to 2004, the IPM program was validated and the effect of crop rotation and carrot cultivar susceptibility also were assessed. Carrot plants growing in fields with 2-year or longer crop rotation intervals reached the 25% disease incidence threshold later in the season and required fewer fungicide applications. The less-susceptible carrot cultivars also reached the 25% disease incidence threshold later, required fewer fungicide applications, and were less severely diseased than more susceptible cultivars. Validation of the IPM program in New York showed that both fungal leaf blights can be managed effectively using a 25% incidence threshold to prompt the first fungicide spray and making the subsequent fungicide applications based on increases in disease severity, weather forecasts, and a 10- to 14-day spray interval.

scholarly journals Hairy Nightshade as a Potential Potato leafroll virus (Luteoviridae: Polerovirus) Inoculum Source in Pacific Northwest Potato Ecosystems

2008 ◽  
Vol 98 (9) ◽  
pp. 985-991 ◽  
Author(s):  
R. Srinivasan ◽  
J. M. Alvarez
Keyword(s):  
Pacific Northwest ◽  
Green Peach Aphid ◽  
Potato Leafroll Virus ◽  
Inoculum Sources ◽  
Inoculum Source ◽  
Hairy Nightshade ◽  
Aphid Density ◽  
Temporal And Spatial ◽  
Green Peach Aphids ◽  
Leafroll Virus

Hairy nightshade, Solanum sarrachoides, is a solanaceous weed found abundantly in Pacific Northwest potato ecosystems. It serves as a reservoir for one of the important potato viruses, Potato leafroll virus (PLRV) (Luteoviridae: Polerovirus), and its most important vector, the green peach aphid, Myzus persicae (Homoptera: Aphididae). Laboratory research indicated an increased green peach aphid settling and performance on S. sarrachoides than on potato. It also revealed that green peach aphids transmitted PLRV more efficiently from S. sarrachoides to potato than from potato to potato. To test the efficiency of S. sarrachoides as an inoculum source in the field, a two season (2004 and 2005) trial was conducted at Kimberly, Idaho. Two inoculum sources, PLRV-infected potato and PLRV-infected S. sarrachoides, were compared in this trial. Green peach aphid density and temporal and spatial PLRV spread were monitored at weekly intervals. Higher densities of green peach aphids were observed on plots with S. sarrachoides and inoculum sources (PLRV-infected S. sarrachoides and potato) than on plots without S. sarrachoides and inoculum sources. PLRV infection in plots with PLRV-infected S. sarrachoides was similar to or slightly higher than in plots with PLRV-infected potato as an inoculum source. Temporal and spatial PLRV spread was similar in plots with either inoculum source. Thus, S. sarrachoides is as efficient as or a better PLRV inoculum source than potato.

scholarly journals Spatial patterns of mercury in biota of Adirondack, New York lakes

Ecotoxicology ◽  
2011 ◽  
Vol 20 (7) ◽  
pp. 1543-1554 ◽  
Author(s):  
Xue Yu ◽  
Charles T. Driscoll ◽  
Mario Montesdeoca ◽  
David Evers ◽  
Melissa Duron ◽  
...  
Keyword(s):  
New York ◽  
Spatial Patterns

Alternaria spp. associated with leaf blight of maize in Heilongjiang Province, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xi Xu ◽  
Li Zhang ◽  
Xilang Yang ◽  
Hanshui Cao ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Population Expansion ◽  
Leaf Blight ◽  
Economic Losses ◽  
Heilongjiang Province ◽  
Maize Leaves ◽  
Alternaria Species ◽  
Alternaria Sp

Maize is a major economic crop worldwide. Maize can be infected by Alternaria species causing leaf blight that can result in significant economic losses. In this study, 168 Alternaria isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multi-locus sequence analyses of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer of ribosomal DNA (rDNA ITS), the RNA polymerase II second largest subunit (RPB2), and histone 3 (HIS3). Maize isolates grouped to four Alternaria species including Alternaria tenuissima, A. alternata, A. burnsii, and Alternaria sp. Notably, A. tenuissima (71.4%) was the most prevalent of the four isolated species, followed by A. alternata (21.5%), Alternaria sp. (4.1%), and A. burnsii (3.0%). Pathogenicity tests showed that all four Alternaria species could produce elliptic to nearly round, or strip lesions on leaves of maize, gray white to dry white in the lesions center and reddish brown in the edge. The average disease incidence (58.47%) and average disease index (63.55) of maize leaves inoculated with A. alternata were significantly higher than levels resulting from A. tenuissima (55.28% and 58.49), Alternaria sp. (55.34% and 58.75), and A. burnsii (56% and 55). Haplotype analyses indicated that there were 14 haplotypes of A. tenuissima and 5 haplotypes of A. alternata in Heilongjiang province and suggested the occurrence of a population expansion. Results of the study showed that Alternaria species associated with maize leaf blight in Heilongjiang province are more diverse than those have been previously reported. This is the first report globally of A. tenuissima, A. burnsii, and an unclassified Alternaria species as causal agents of leaf blight on maize.

PUBLIC HEALTH, NURSING, MEDICAL SOCIAL WORK

PEDIATRICS ◽  
1956 ◽  
Vol 18 (3) ◽  
pp. 506-508
Keyword(s):  
New York ◽  
Disease Incidence ◽  
New York State ◽  
Interesting Case ◽  
Retrolental Fibroplasia ◽  
State Laws ◽  
York State ◽  
Special Programs ◽  
Health Nursing

APPEARANCE of "new diseases" is a phenomenon well known to observing pediatricians. When a new disease is first reported, there is often some doubt as to whether it is a separate entity, then a certain amount of hesitation while the definition and characteristics of the disease are being investigated, and finally a rush of increased diagnoses as the disease becomes more "popular" or is better understood. Very often therapy awaits elucidation of etiology, and, of course, therapy is not always successful. The problem of retrolental fibroplasia has constituted an interesting case in point which, while it has not followed all of the characteristics noted above, has certainly approached them. A recently published analysis of "The Rise and Fall of Retrolental Fibroplasia in New York State—A Preliminary Report" by Yankauer, Jacobziner, and Schneider (New York State J. Med., 56:1474, May 1, 1956), reviews in striking fashion the progress of the disease. In contrast to many reports of disease incidence, the paper from New York State is a model of care and precision. The authors point out that diagnosis and follow-up of this condition in New York State are encouraged by state laws regarding the care of the blind, as well as by the special programs for premature infants, which have been promoted by both the city and the state health departments. Furthermore, the reports on the disease have been carefully investigated and the fact of "popularity" mitigated by studying both the time at which the disease is reported in relation to the age of the child, and the evidence for confirmation of the diagnosis.

scholarly journals Differential Spread of Grapevine Red Blotch Virus in California and New York Vineyards

2019 ◽  
Vol 3 (3) ◽  
pp. 203-211 ◽  
Author(s):  
Elizabeth Cieniewicz ◽  
Madison Flasco ◽  
Melina Brunelli ◽  
Anuli Onwumelu ◽  
Alice Wise ◽  
...  
Keyword(s):  
New York ◽  
Disease Incidence ◽  
Primary Source ◽  
Cabernet Sauvignon ◽  
Limited Information ◽  
Initial Inoculum ◽  
Cabernet Franc ◽  
Disease Progress ◽  
Spread Dynamics ◽  
Initial Source

Limited information is available on the spread dynamics of grapevine red blotch virus (GRBV, genus Grablovirus, family Geminiviridae) in vineyards. In this study, we investigated red blotch disease progress in three vineyards with a disparate initial inoculum prevalence. Secondary spread was documented in Cabernet Sauvignon and Cabernet franc vineyards in California, but not in a Merlot vineyard in New York. Increase in annual disease incidence (4.8, 0.13, and 0%) was unrelated to the estimated initial source of inoculum at planting (1, 40, and 40%) in the Cabernet franc, Cabernet Sauvignon, and Merlot vineyards, respectively. Limited genetic diversity of GRBV populations in newly infected vines supported localized spread in California vineyards, and suggested the planting material as the primary source of inoculum. Among the community of hemipteran insects visiting two of the three study vineyards, populations of Spissistilus festinus, the vector of GRBV, were absent in the Merlot vineyard and low in the Cabernet Sauvignon vineyard. Furthermore, all cover crop samples collected from GRBV-infected California vineyards each spring of 2016 to 2018, particularly legume species which are preferred hosts of S. festinus, tested negative for GRBV, suggesting a minimal role, if any, in GRBV spread as inoculum reservoirs. Together our findings illustrate differential disease progress in distinct vineyard ecosystems, and support the elimination of virus inoculum sources as an actionable disease management strategy across vineyards.

scholarly journals First report of Alternaria alternata causing leaf blight on little millet (Panicum sumatrense) in India.

Plant Disease ◽  
2020 ◽  
Author(s):  
Boda Praveen ◽  
A. Nagaraja ◽  
M. K. Prasanna Kumar ◽  
Devanna Pramesh ◽  
K. B. Palanna ◽  
...  
Keyword(s):  
Crop Yields ◽  
Disease Incidence ◽  
Leaf Blight ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Pcr Assay ◽  
Causal Organism ◽  
First Report ◽  
Little Millet

Little millet (LM) is a minor cereal crop grown in the Indian sub-continent. During October 2018, dark brown, circular to oval necrotic spots surrounded by concentric rings were observed on the upper leaf surface of the LM (cv. VS-13) grown in the fields of the University of Agricultural Sciences, Bengaluru, India (13.0784oN, 77.5793oE). As the disease progressed, infected leaves became blighted. Disease incidence up to 53% was recorded in 3 fields of 0.4-hectare area each. Thirty symptomatic leaves were collected to isolate the associated causal organism. The margins of diseased tissue were cut into 5 × 5-mm pieces, surface-sterilized in 75% ethanol for 45 seconds followed by 1% sodium hypochlorite for 1 min, finally rinsed in sterile distilled water five times and placed on PDA. After 7 days of incubation at 25°C, greyish fungal colonies appeared on PDA. Single-spore isolations were performed to obtain ten isolates. Pure cultures of the fungus initially produced light gray aerial mycelia that later turned to dark grey. All isolates formed obclavate to pyriform conidia measured 22.66-48.97μm long and 6.55-13.79µm wide with 1-3 longitudinal and 2-7 transverse septa with a short beak (2.55-13.26µm) (n=50). Based on the conidial morphology, the fungus was identified as Alternaria sp. Further, the taxonomic identity of all ten isolates was confirmed as A. alternata using species-specific primers (AAF2/AAR3, Konstantinova et al. 2002) in a PCR assay. Later, one of the isolate UASB1 was selected, and its internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), major allergen Alt a 1 (Alt a 1), major endo-polygalacturonase (endoPG), OPA10-2, and KOG1058 genes were amplified in PCR (White et al. 1990; Berbee et al. 1999; Woudenberg et al. 2015), and the resultant products were sequenced and deposited in the NCBI GenBank (ITS, MN919390; gapdh, MT637185; Alt a 1, MT882339; endoPG, MT882340; OPA10-2, MT882341; KOG1058, MT882342). Blastn analysis of ITS, gapdh, Alt a 1, endoPG, OPA10-2, KOG1058 gene sequences showed 99.62% (with AF347031), 97.36% (with AY278808), 99.58% (with AY563301), 99.10% (with JQ811978), 99.05% (with KP124632) and 99.23% (with KP125233) respectively, identity with reference strain CBS916.96 of A. alternata, confirming UASB1 isolate to be A. alternata. For pathogenicity assay, conidial suspension of UASB1 isolate was spray inoculated to ten healthy LM (cv. VS-13) plants (45 days old) maintained under protected conditions. The spore suspension was sprayed until runoff on healthy leaves, and ten healthy plants sprayed with sterile water served as controls. Later, all inoculated and control plants were covered with transparent polyethylene bags and were maintained in a greenhouse at 28±2 ◦C and 90% RH. The pathogenicity test was repeated three times. After 8 days post-inoculation, inoculated plants showed leaf blight symptoms as observed in the field, whereas no disease symptoms were observed on non-inoculated plants. Re-isolations were performed from inoculated plants, and the re-isolated pathogen was confirmed as A. alternata based on morphological and PCR assay (Konstantinova et al. 2002). No pathogens were isolated from control plants. There is an increasing acreage of LM crop in India, and this first report indicates the need for further studies on leaf blight management and the disease impacts on crop yields.

Morphological and Molecular Characterization of Alternaria Species Causing Leaf Blight on Watermelon in China

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Guoping Ma ◽  
Shuwen Bao ◽  
Juan Zhao ◽  
Yuan Sui ◽  
Xuehong Wu
Keyword(s):  
Rna Polymerase Ii ◽  
Disease Incidence ◽  
Disease Index ◽  
Leaf Blight ◽  
Economic Losses ◽  
Rdna Its ◽  
Detached Leaves ◽  
Alternaria Species ◽  
Alternaria Sp ◽  
The One

Watermelon is an economically important crop in China and is commonly affected by Alternaria-like leaf blight that can result in significant economic losses. In this study, 830 Alternaria isolates, recovered from symptomatic watermelon leaves, were identified based on morphological traits, pathogenicity, and multilocus sequence analyses of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone 3 (HIS3), the internal transcribed spacer of ribosomal DNA (rDNA ITS), and the RNA polymerase II second largest subunit (RPB2). Watermelon isolates grouped to five Alternaria species and one unclassified Alternaria species. They were A. tenuissima, A. alternata, A. cucumerina, A. infectoria, A. gaisen, and Alternaria sp. Notably, A. tenuissima was the most prevalent (73.5%) of the six isolated species, followed by A. alternata (25.0%), A. cucumerina (1.1%), Alternaria sp. (0.2%), A. infectoria (0.1%), and A. gaisen (0.1%). Pathogenicity tests demonstrated that all six Alternaria species could produce brown necrotic lesions on detached leaves of watermelon. The average disease incidence (75.1%) and average disease index (60.8) of watermelon resulting from inoculation of leaves with A. cucumerina were significantly higher than levels resulting from A. alternata (52.9% and 37.2) and A. tenuissima (47.5% and 30.8). Inoculation with Alternaria sp. resulted in a disease incidence (70.0%) and disease index (51.5), which were lower than those of A. cucumerina. The disease incidence and disease index in watermelon leaves inoculated with the one isolate of A. infectoria and the one isolate of A. gaisen present in the inoculated leaves were 28.9% and 16.4, and 48.9% and 31.4, respectively. Results of the study indicate that Alternaria species associated with watermelon leaf blight in China are more diverse than that has been previously reported. This is the first report globally of A. infectoria, A. gaisen, and an unclassified Alternaria species as causal agents of leaf blight on watermelon.

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