scholarly journals Analysis of Bacterial Leaf Streak Epidemics on Winter Wheat in Louisiana

Plant Disease ◽  
1999 ◽  
Vol 83 (6) ◽  
pp. 541-548 ◽  
Author(s):  
K. M. Tubajika ◽  
J. S. Russin ◽  
S. A. Harrison
Keyword(s):  
Winter Wheat ◽  
Disease Incidence ◽  
Gompertz Model ◽  
Good Method ◽  
Exponential Model ◽  
Point Sources ◽  
Disease Spread ◽  
Growth Stages ◽  
Bacterial Leaf Streak ◽  
Incidence Data

Studies were conducted to characterize spatial and temporal progress of bacterial leaf streak disease (Xanthomonas translucens pv. translucens) on susceptible (Florida 304) and moderately resistant (Terral 101) winter wheat cultivars. Epidemics were initiated with rifampicin-resistant strain 88–14rif of X. translucens pv. translucens by establishing point sources of inoculum in plot centers. Incidence of bacterial leaf streak was assessed five times in 1995 and three times in 1996, starting from the first observation of leaf streak symptoms. Rainfall, temperature, and wind speed were significantly related to disease incidence, but relative humidity was not. The Gompertz model gave the best statistical fit for the progression of disease incidence over time. Average rates of disease progress (k) obtained from the regression of bacterial leaf streak incidence against time provided a good method of comparing the cultivars Florida 304 and Terral 101 and were consistent across locations. Bacterial leaf streak disease gradients were best described by the negative exponential model. Bacterial leaf streak incidence decreased with distance from inoculum source for both cultivars. Disease incidence on Terral 101 was near 0% at 2 m from the source, and disease incidence close to the source was consistently lower on Terral 101 than on Florida 304 at all growth stages sampled. This was not unexpected because the two cultivars differed in susceptibility. Disease incidence data were more useful than severity data in providing a good estimate of disease spread away from the source.

scholarly journals Identification of Small Grains Genotypes Resistant to Wheat spindle streak mosaic virus

Plant Disease ◽  
2006 ◽  
Vol 90 (8) ◽  
pp. 1045-1050 ◽  
Author(s):  
L. Cadle-Davidson ◽  
M. E. Sorrells ◽  
S. M. Gray ◽  
G. C. Bergstrom
Keyword(s):  
Winter Wheat ◽  
Mosaic Virus ◽  
Control Strategy ◽  
Significant Interaction ◽  
Disease Incidence ◽  
Virus Titer ◽  
Incidence Data ◽  
Small Grains ◽  
Resistant Genotypes

Once Wheat spindle streak mosaic virus (WSSMV) becomes established in a field, the only available control strategy is the planting of resistant genotypes. In this study, we assessed 112 genotypes of winter wheat, rye, triticale, and barley for resistance to WSSMV in a 3-year trial in a field that had been used continuously for WSSMV evaluation for over 20 years. Because resistance to WSSMV reduces the percentage of plants that develop detectable virus titer and symptoms, we collected and analyzed disease incidence data. None of the genotypes was immune to infection. Sixty-two of the regionally adapted genotypes repeatedly expressed resistance to WSSMV, thus providing growers with a choice of cultivars resistant to WSSMV. Because of a significant interaction between genotypes and environment (year), genotypes should be assessed for incidence of symptomatic plants in multiple years, particularly when differentiating intermediate responses from highly susceptible and highly resistant responses.

scholarly journals The Impact of Using Geographic Information Systems Technology on Students’ Understanding of Epidemiology

2018 ◽  
Vol 80 (3) ◽  
pp. 191-197
Author(s):  
Jason A. Rosenzweig ◽  
Maruthi Sridhar Balaji Bhaskar ◽  
Shishir Shishodia
Keyword(s):  
Information Science ◽  
Disease Incidence ◽  
Geographic Information Science ◽  
Geographic Information ◽  
Disease Spread ◽  
Data Mapping ◽  
Laboratory Exercise ◽  
Incidence Data ◽  
Post Infusion ◽  
The Impact

To enhance/update our microbiology course, we employed a geographic information science and technology (GIST) infusion to improve students’ understanding of epidemiology and disease spread and to encourage students to earn a GIST certificate, making them more marketable in an increasingly competitive workplace. Following a 25-minute introductory GIST infusion lecture during a microbiology class session, a 1.5-hour GIST laboratory exercise was performed in which teams of students evaluated Centers for Disease Control (CDC) chlamydial disease incidence data. In addition to answering three quiz questions addressing the data, students created a map, using ArcGIS software, indicating which Texas counties experienced the highest rates of chlamydia in 2014. To determine the efficacy/value of our infusion, GIST survey data (pre- and post-infusion), GIST lab quiz scores, and answers to four GIST lecture exam questions were evaluated. In conclusion, our study was successful in improving understanding of what GIST is and how it could impact biological fields by improving attitudes about the likelihood of further GIST study leading to a certificate program, and by exposing biology undergraduates to GIST technologies and software, enabling student data mapping. Ultimately, our efforts could promote enhanced vocationalization of our biology program, thereby enhancing and broadening employment opportunities for our graduates.

Spread of Sclerotinia stem rot of soybean from area and point sources of apothecial inoculum

2000 ◽  
Vol 80 (2) ◽  
pp. 389-402 ◽  
Author(s):  
S. N. Wegulo ◽  
P. Sun ◽  
C. A. Martinson ◽  
X. B. Yang
Keyword(s):  
Power Law ◽  
Field Experiments ◽  
Disease Incidence ◽  
Exponential Model ◽  
Point Sources ◽  
Stem Rot ◽  
Power Law Model ◽  
Sclerotinia Stem Rot ◽  
Soybean Field ◽  
Area Source

Field experiments were conducted from 1995 to 1998 to quantify the spread of ascospores of Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot of soybean. Incidence of Sclerotinia stem rot measured in a soybean field adjacent to a corn field naturally infested with S. sclerotiorum (area source) was highest close to the area source and decreased with distance from the area source. Disease gradients in the soybean field were described nearly equally well by the exponential model, power law model, and logit-log model. Disease incidence in transects in non-infested areas of a soybean field increased with distance from the edges of soybean and corn area sources of inoculum, reached a maximum at 10–12 and 18–20 m, respectively, from the edges of the inoculum area sources, then decreased in a manner characteristic of the disease gradient curve between 10–12 and 32 m, and 18–20 and 44 m from the edges of the area sources. In soybean plots, disease incidence decreased with distance from point sources of apothecial inoculum. The results from these studies suggest 1) the potential for field to field dispersal of S. sclerotiorum, and 2) that the majority of ascospores of S. sclerotiorum are deposited close to the source (apothecia). Where a concentrated area or point source of S. sclerotiorum inoculum exists, the general exponential model may provide good fits to Sclerotinia stem rot gradient data. Key words: Apothecial inoculum, disease gradients, logit-log model, power law model, simple exponential model

scholarly journals Growth and Phenology of Vulpia Myuros in Comparison with Apera Spica-Venti, Alopecurus Myosuroides and Lolium Multiflorum in Monoculture and in Winter Wheat

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1495
Author(s):  
Muhammad Javaid Akhter ◽  
Bo Melander ◽  
Solvejg Kopp Mathiassen ◽  
Rodrigo Labouriau ◽  
Svend Vendelbo Nielsen ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Weed Management ◽  
Lolium Multiflorum ◽  
Management Strategies ◽  
Integrated Weed Management ◽  
Growth Stages ◽  
Neighborhood Design ◽  
Alopecurus Myosuroides ◽  
Winter Cereals ◽  
Arable Weed

Vulpia myuros has become an increasing weed problem in winter cereals in Northern Europe. However, the information about V. myuros and its behavior as an arable weed is limited. Field and greenhouse experiments were conducted in 2017/18 and 2018/19, at the Department of Agroecology in Flakkebjerg, Denmark to investigate the emergence, phenological development and growth characteristics of V. myuros in monoculture and in mixture with winter wheat, in comparison to Apera spica-venti, Alopecurus myosuroides and Lolium multiflorum. V. myuros emerged earlier than A. myosuroides and A. spica-venti but later than L. multiflorum. Significant differences in phenological development were recorded among the species. Overall phenology of V. myuros was more similar to that of L. multiflorum than to A. myosuroides and A. spica-venti. V. myuros started seed shedding earlier than A. spica-venti and L. multiflorum but later than A. myosuroides. V. myuros was more sensitive to winter wheat competition in terms of biomass production and fecundity than the other species. Using a target-neighborhood design, responses of V. myuros and A. spica-venti to the increasing density of winter wheat were quantified. At early growth stages “BBCH 26–29”, V. myuros was suppressed less than A. spica-venti by winter wheat, while opposite responses were seen at later growth stages “BBCH 39–47” and “BBCH 81–90”. No significant differences in fecundity characteristics were observed between the two species in response to increasing winter wheat density. The information on the behavior of V. myuros gathered by the current study can support the development of effective integrated weed management strategies for V. myuros.

Targeting Ascophyllum nodosum (L.) Le Jol. extract application at five growth stages of winter wheat

2021 ◽  
Author(s):  
Stamatis Stamatiadis ◽  
Eleftherios Evangelou ◽  
Frank Jamois ◽  
Jean-Claude Yvin
Keyword(s):  
Winter Wheat ◽  
Ascophyllum Nodosum ◽  
Growth Stages

scholarly journals Development of a Protocol and a Diagrammatic Scale for Quantification of Bacterial Leaf Streak Disease on Young Plants of Maize

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2921-2927
Author(s):  
Renata Rodrigues Robaina ◽  
Talita Vigo Longhi ◽  
Douglas Mariani Zeffa ◽  
Leandro Simões Azeredo Gonçalves ◽  
Rui Pereira Leite
Keyword(s):  
Disease Incidence ◽  
The United States ◽  
Bacterial Suspension ◽  
Bacterial Leaf Streak ◽  
Experimental Conditions ◽  
Maize Production ◽  
Maize Hybrids ◽  
Controlled Conditions ◽  
Maize Plants ◽  
Diagrammatic Scale

Bacterial leaf streak (BLS), caused Xanthomonas vasicola pv. vasculorum (Xvv), has become a major concern for maize production, mainly in the United States and South America. Therefore, this study aimed to establish a protocol for Xvv inoculation in young maize plants under controlled conditions and to develop and validate a diagrammatic scale for evaluation of maize hybrids in regard to BLS resistance. The study was carried out in three steps: the establishment of a protocol for inoculation of Xvv in young maize plants under controlled conditions; the development and validation of a diagrammatic scale for BLS severity evaluation; and the screening for BLS resistance of 45 hybrids using the proposed protocol for bacterial inoculation and the diagrammatic scale developed in this study. Besides reproducing a more natural Xvv infection, the bacterial suspension spraying without injury inoculation method induced higher disease incidence and severity, as well as reproducibility of results under the experimental conditions established in this study. The proposed diagrammatic scale allowed evaluating BLS severity with up to 97.49% of the leaf area affected by the disease. Further, the use of the diagrammatic scale resulted in an increase of accuracy from 0.909 up to 0.992. The reaction of 45 maize hybrids to BLS allowed establishing six major groups of susceptibility to the disease. The most resistant maize hybrids to BLS formed a group of 13 hybrids, with disease severity below 5%.

Estimating Yield Losses Due to Barley Yellow Dwarf on Winter Wheat in Kansas Using Disease Phenotypic Data

2015 ◽  
Vol 16 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Genna M. Gaunce ◽  
William W. Bockus
Keyword(s):  
Winter Wheat ◽  
Yield Loss ◽  
Disease Incidence ◽  
Relative Yield ◽  
Yellow Dwarf ◽  
Wheat Cultivars ◽  
Grain Yields ◽  
Barley Yellow Dwarf ◽  
Winter Wheat Cultivars ◽  
The Impact

Barley yellow dwarf (BYD) is one of the most important wheat diseases in the state of Kansas. Despite the development of cultivars with improved resistance to BYD, little is known about the impact that this resistance has on yield loss from the disease. The intent of this research was to estimate yield loss in winter wheat cultivars in Kansas due to BYD and quantify the reduction in losses associated with resistant cultivars. During seven years, BYD incidence was visually assessed on numerous winter wheat cultivars in replicated field nurseries. When grain yields were regressed against BYD incidence scores, negative linear relationships significantly fit the data for each year and for the combined dataset covering all seven years. The models showed that, depending upon the year, 19–48% (average 33%) of the relative yields was explained by BYD incidence. For the combined dataset, 29% of the relative yield was explained by BYD incidence. The models indicated that cultivars showing the highest disease incidence that year had 25–86% (average 49%) lower yield than a hypothetical cultivar that showed zero incidence. Using the models, the moderate level of resistance in the cultivar Everest was calculated to reduce yield loss from BYD by about 73%. Therefore, utilizing visual BYD symptom evaluations in Kansas coupled with grain yields is useful to estimate yield loss from the disease. Accepted for publication 1 December 2014. Published 9 January 2015.

Tillage and farming system affect AM fungus populations, mycorrhizal formation, and nutrient uptake by winter wheat in a high-P soil

2001 ◽  
Vol 16 (4) ◽  
pp. 152-160 ◽  
Author(s):  
Larisa Galvez ◽  
David D. Douds ◽  
Peggy Wagoner
Keyword(s):  
Winter Wheat ◽  
Plant Biomass ◽  
Nutrient Use Efficiency ◽  
Mycorrhizal Fungus ◽  
Am Fungi ◽  
Farming System ◽  
Growth Stages ◽  
Wheat Roots ◽  
Conventional Agriculture ◽  
Low Input

AbstractWe conducted a field study at the Rodale Institute Experimental Farm, Kutztown, Pennsylvania, in a high-P soil to examine the interaction of farming system and tillage on the potential functioning of arbuscular mycorrhizal (AM) fungi. Plots under conventional and low-input systems were either chisel-disked or no-tilled. Winter wheat was planted following the harvest of soybean, and shoots and roots were collected at tillering, jointing, heading, and ripening. Spores of AM fungi were isolated from soil collected at the beginning and end of the growing season. Spore populations and colonization of winter wheat roots by AM fungi were higher under low-input than conventional agriculture. Mycorrhizal fungus colonization occurred at low levels in the tillering stage and increased with plant development. Colonization during the jointing stage was higher in the low-input, no-tilled than in low-input, chisel-disked plots. Spore populations of theGlomus occultum-type group were more numerous in no-tilled than in tilled soil. The nutrient-use efficiency (g of plant biomass per g of plant N or P) of winter wheat depended on plant developmental stage, with a tendency for higher efficiency of the low-input plants at early growth stages, and of conventionally managed plants at more mature stages. Overall, plants grown in chisel-disked plots had higher N and P utilization efficiencies than plants grown in no-tilled plots. Final yield of grain was significantly greater in conventional than low-input plots, especially for no-till, despite the larger population of AM fungi.

scholarly journals Use of an Active Canopy Sensor Mounted on an Unmanned Aerial Vehicle to Monitor the Growth and Nitrogen Status of Winter Wheat

2020 ◽  
Vol 12 (22) ◽  
pp. 3684
Author(s):  
Jie Jiang ◽  
Zeyu Zhang ◽  
Qiang Cao ◽  
Yan Liang ◽  
Brian Krienke ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Dry Matter ◽  
Vegetation Index ◽  
Nutrition Status ◽  
Growth Stages ◽  
Growth Indices ◽  
N Accumulation ◽  
N Nutrition ◽  
Red Edge ◽  
Aerial Vehicle

Using remote sensing to rapidly acquire large-area crop growth information (e.g., shoot biomass, nitrogen status) is an urgent demand for modern crop production; unmanned aerial vehicle (UAV) acts as an effective monitoring platform. In order to improve the practicability and efficiency of UAV based monitoring technique, four field experiments involving different nitrogen (N) rates (0–360 kg N ha−1) and seven winter wheat (Triticum aestivum L.) varieties were conducted at different eco-sites (Sihong, Rugao, and Xinghua) during 2015–2019. A multispectral active canopy sensor (RapidSCAN CS-45; Holland Scientific Inc., Lincoln, NE, USA) mounted on a multirotor UAV platform was used to collect the canopy spectral reflectance data of winter wheat at key growth stages, three growth parameters (leaf area index (LAI), leaf dry matter (LDM), plant dry matter (PDM)) and three N indicators (leaf N accumulation (LNA), plant N accumulation (PNA) and N nutrition index (NNI)) were measured synchronously. The quantitative linear relationships between spectral data and six growth indices were systematically analyzed. For monitoring growth and N nutrition status at Feekes stages 6.0–10.0, 10.3–11.1 or entire growth stages, red edge ratio vegetation index (RERVI), red edge chlorophyll index (CIRE) and difference vegetation index (DVI) performed the best among the red edge band-based and red-based vegetation indices, respectively. Across all growth stages, DVI was highly correlated with LAI (R2 = 0.78), LDM (R2 = 0.61), PDM (R2 = 0.63), LNA (R2 = 0.65) and PNA (R2 = 0.73), whereas the relationships between RERVI (R2 = 0.62), CIRE (R2 = 0.62) and NNI had high coefficients of determination. The developed models performed better in monitoring growth indices and N status at Feekes stages 10.3–11.1 than Feekes stages 6.0–10.0. To sum it up, the UAV-mounted active sensor system is able to rapidly monitor the growth and N nutrition status of winter wheat and can be deployed for UAV-based remote-sensing of crops.

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