scholarly journals Screening of Genotypes to Identify the Resistance Source against Major Diseases of Soybean under High Disease Pressure Conditions

2020 ◽  
Vol 9 (5) ◽  
pp. 1739-1745
Author(s):  
Pawan K. Amrate ◽  
M. K. Shrivastava ◽  
Gyanendra Singh
Keyword(s):  
Disease Pressure ◽  
Resistance Source

scholarly journals Identification and Mapping of Eastern Filbert Blight Resistance Quantitative Trait Loci in European Hazelnut Using Double Digestion Restriction Site Associated DNA Sequencing

2019 ◽  
Vol 144 (5) ◽  
pp. 295-304 ◽  
Author(s):  
Josh A. Honig ◽  
Megan F. Muehlbauer ◽  
John M. Capik ◽  
Christine Kubik ◽  
Jennifer N. Vaiciunas ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Quantitative Trait ◽  
Genetic Linkage ◽  
Genetic Linkage Map ◽  
Restriction Site ◽  
Eastern United States ◽  
Double Digestion ◽  
Disease Pressure ◽  
Resistance Source

European hazelnut (Corylus avellana L.) is an economically important edible nut producing species, which ranked sixth in world tree nut production in 2016. European hazelnut production in the United States is primarily limited to the Willamette Valley of Oregon, and currently nonexistent in the eastern United States because of the presence of a devastating endemic disease, eastern filbert blight (EFB) caused by Anisogramma anomala (Peck) E. Muller. The primary commercial means of control of EFB to date is through the development and planting of genetically resistant european hazelnut cultivars, with an R-gene introduced from the obsolete, late-shedding pollinizer ‘Gasaway’. Although the ‘Gasaway’ resistance source provides protection against EFB in the Pacific northwestern United States (PNW), recent reports have shown that it is not effective in parts of the eastern United States. This may be in part because the identification and selection of ‘Gasaway’ and ‘Gasaway’-derived cultivars occurred in an environment (PNW) with limited genetic diversity of A. anomala. The objectives of the current research were to develop a genetic linkage map using double digestion restriction site associated DNA sequencing (ddRADseq) and identify quantitative trait loci (QTL) markers associated with EFB resistance from the resistant selection Rutgers H3R07P25 from southern Russia. A mapping population composed of 119 seedling trees was evaluated in a geographic location (New Jersey) where the EFB fungus is endemic, exhibits high disease pressure, and has a high level of genetic diversity. The completed genetic linkage map included a total of 2217 markers and spanned a total genetic distance of 1383.4 cM, with an average marker spacing of 0.65 cM. A single QTL region associated with EFB resistance from H3R07P25 was located on european hazelnut linkage group (LG) 2 and was responsible for 72.8% of the phenotypic variation observed in the study. Based on its LG placement, origin, and disease response in the field, this resistance source is different from the ‘Gasaway’ source located on LG6. The current results, in combination with results from previous research, indicate that the H3R07P25 source is likely exhibiting resistance to a broader range of naturally occurring A. anomala isolates. As such, H3R07P25 will be important for the development of new european hazelnut germplasm that combines EFB resistance from multiple sources in a gene pyramiding approach. Identification of EFB resistance in high disease pressure environments representing a diversity of A. anomala populations is likely a requirement for identifying plants expressing durable EFB resistance, which is a precursor to the development of a commercially viable european hazelnut industry in the eastern United States.

scholarly journals Yield performance of East African highland banana hybrids on farmers fields under high disease pressure

2016 ◽  
Vol 11 (13) ◽  
pp. 1141-1149 ◽  
Author(s):  
R Erima ◽  
J M Ssebuliba ◽  
C M K Nankinga ◽  
P Ragama ◽  
A Barekye ◽  
...  
Keyword(s):  
East African ◽  
Yield Performance ◽  
Disease Pressure

scholarly journals Sensitivity of Mycosphaerella fijiensis from Banana to Trifloxystrobin

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1264-1270 ◽  
Author(s):  
K. M. Chin ◽  
M. Wirz ◽  
D. Laird
Keyword(s):  
Cross Resistance ◽  
In Vitro Tests ◽  
Mycosphaerella Fijiensis ◽  
In Planta ◽  
Baseline Sensitivity ◽  
Single Spore ◽  
Resistance Factors ◽  
Development Site ◽  
Disease Pressure

An ascospore germination method was developed and validated to assess the sensitivity of bulk samples of Mycosphaerella fijiensis to trifloxystrobin. Using this method, the sensitivity of 142 ascospore samples from banana plantations not treated with strobilurins was analyzed to establish a baseline of pathogen sensitivity. A bulk method was utilized for monitoring purposes because it avoids potential complications due to the isolation and propagation of single-spore isolates and enables the testing of larger samples. Following intensive use of strobilurins (6 to 11 applications per year) over 4 years, under conditions of high disease pressure and the absence of sanitary measures at a development site in Costa Rica, bulk samples with 50% effective concentration (EC50) resistance factors (RFs) in excess of 500 compared with the mean baseline sensitivity were detected. Single-ascospore isolates derived from spores germinating at the discriminatory dose of 3 μg/ml were also resistant, suggesting that the frequency of resistant individuals in bulk samples could be estimated from the relative numbers of ascospores growing at this dose. The resistance of selected isolates was confirmed in planta. In vitro tests with four resistant and two sensitive single-ascospore isolates collected from different locations and times indicated possible cross-resistance of trifloxystrobin to azoxystrobin, famoxadone, and fenamidone, but not to propiconazole.

Chemical manipulation of Leptosphaeria maculans (blackleg disease) pseudothecial development and timing of ascospore discharge from canola (Brassica napus) residues

2003 ◽  
Vol 54 (9) ◽  
pp. 837 ◽  
Author(s):  
A. D. Wherrett ◽  
K. Sivasithamparam ◽  
M. J. Barbetti
Keyword(s):  
Developmental Stages ◽  
Severe Disease ◽  
Leptosphaeria Maculans ◽  
Potential Method ◽  
Chemical Treatments ◽  
Ascospore Discharge ◽  
Significant Difference ◽  
Significant Efficacy ◽  
Early Seedling ◽  
Disease Pressure

A study was carried out to establish key developmental stages of Leptosphaeria maculans on canola residues leading up to ascospore discharge and how these stages could be affected by chemicals. The residues were dipped in a range of chemicals, including fungicides, herbicides, and surfactants, to determine possible manipulative effects of the chemicals on the development of the fungus including ascospore discharge. Treated residues were placed in the field during the growing season. Ascospore discharge was found to be closely related to pseudothecial maturity and density. There was no significant difference between pseudothecial maturation on the crown component compared with the stem component. A high correlation between rainfall and pseudothecial density suggested that rainfall was a good complimentary indicator for timing of ascospore discharge. These results may provide the canola industry with a potential method of monitoring pseudothecial development for estimating disease hazards. This would allow manipulation of sowing times so as to minimise or avoid heavy ascospore showers coinciding with the early seedling phase. Twenty chemical treatments showed significant efficacy in decreasing ascospore numbers early in the season, most often by delaying the development of the pseudothecia on the residues. Two scenarios were formulated giving growers the potential to manipulate pseudothecial development and/or ascospore discharge. Firstly, a number of chemicals, such as fluquinconazole, technical grade flutriafol, and gluphosinate-ammonium, were able to delay pseudothecial development and subsequent ascospore discharge was decreased by 100%, 99%, and 96%, respectively. This scenario gives growers the potential to minimise synchronisation of ascospore discharge with early crop establishment. Secondly, a situation where pseudothecial development is not delayed, but number of ascospores discharged is reduced (e.g. ziram by 45%) would only be effective if the reduction resulted in a less severe disease epidemic. There is significant potential for development of commercial chemical treatments of residues to reduce disease pressure on seedlings.

scholarly journals Control of Mucosal Candidiasis in the Zebrafish Swim Bladder Depends on Neutrophils That Block Filament Invasion and Drive Extracellular-Trap Production

2017 ◽  
Vol 85 (9) ◽  
Author(s):  
Remi L. Gratacap ◽  
Allison K. Scherer ◽  
Brittany G. Seman ◽  
Robert T. Wheeler
Keyword(s):  
Invasive Disease ◽  
Extracellular Dna ◽  
Epithelial Barrier ◽  
Infection Model ◽  
Swim Bladder ◽  
Spatiotemporal Resolution ◽  
Zebrafish Model ◽  
Content Type ◽  
Mucosal Candidiasis ◽  
Disease Pressure

ABSTRACT Candida albicans is a ubiquitous mucosal commensal that is normally prevented from causing acute or chronic invasive disease. Neutrophils contribute to protection in oral infection but exacerbate vulvovaginal candidiasis. To dissect the role of neutrophils during mucosal candidiasis, we took advantage of a new, transparent zebrafish swim bladder infection model. Intravital microscopic tracking of individual animals revealed that the blocking of neutrophil recruitment leads to rapid mortality in this model through faster disease progression. Conversely, artificial recruitment of neutrophils during early infection reduces disease pressure. Noninvasive longitudinal tracking showed that mortality is a consequence of C. albicans breaching the epithelial barrier and invading surrounding tissues. Accordingly, we found that a hyperfilamentous C. albicans strain breaches the epithelial barrier more frequently and causes mortality in immunocompetent zebrafish. A lack of neutrophils at the infection site is associated with less fungus-associated extracellular DNA and less damage to fungal filaments, suggesting that neutrophil extracellular traps help to protect the epithelial barrier from C. albicans breach. We propose a homeostatic model where C. albicans disease pressure is balanced by neutrophil-mediated damage of fungi, maintaining this organism as a commensal while minimizing the risk of damage to host tissue. The unequaled ability to dissect infection dynamics at a high spatiotemporal resolution makes this zebrafish model a unique tool for understanding mucosal host-pathogen interactions.

Management strategies to reduce losses caused by fusarium seedling blight of field pea

2013 ◽  
Vol 93 (4) ◽  
pp. 619-625 ◽  
Author(s):  
K. F. Chang ◽  
S. F. Hwang ◽  
H. U. Ahmed ◽  
B. D. Gossen ◽  
G. D. Turnbull ◽  
...  
Keyword(s):  
Root Rot ◽  
Field Experiments ◽  
Management Strategies ◽  
Stand Density ◽  
Field Trials ◽  
Field Pea ◽  
Seedling Blight ◽  
Inoculum Level ◽  
Fusarium Seedling Blight ◽  
Disease Pressure

Chang, K. F., Hwang, S. F., Ahmed, H. U., Gossen, B. D., Turnbull, G. D. and Strelkov, S. E. 2013. Management strategies to reduce losses caused by fusarium seedling blight of field pea. Can. J. Plant Sci. 93: 619–625. Fusarium seedling blight can cause substantial reductions in the stand density of field pea in western Canada. In greenhouse experiments, emergence decreased and root rot severity rose with increasing inoculum density. In field trials in 2007 and 2008 near Edmonton, AB, seeding at different depths and seeding dates did not consistently affect emergence or yield in Fusarium-infested soils. In field experiments, emergence declined significantly with each increase in inoculum level. Also, seed yield were reduced at high levels of disease pressure. Treatment of seed with Apron Maxx improved emergence, nodulation and yield of treatments challenged with inoculum of F. avenaceum in both greenhouse and field experiments. This research demonstrates the need to prevent seedling blight and root rot through proper seed treatment.

scholarly journals Management of Daylily Rust With Different Fungicides and Fungicide Combinations

2017 ◽  
Vol 18 (3) ◽  
pp. 162-165 ◽  
Author(s):  
Robert S. Emmitt ◽  
James W. Buck
Keyword(s):  
United States ◽  
Disease Management ◽  
Disease Severity ◽  
Low Cost ◽  
Single Application ◽  
Southeast United States ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Disease Pressure

Production nurseries and daylily hybridizers in the southeast United States rely on the use of fungicides to manage daylily rust, caused by the fungus Puccinia hemerocallidis. Foliar sprays of pyraclostrobin, flutolanil, tebuconazole, myclobutanil, chlorothalonil, mancozeb, pyraclostrobin + boscalid, flutolanil + tebuconazole, flutolanil + myclobutanil, flutolanil + chlorothalonil, and flutolanil + mancozeb applied on 14-day intervals, and a nontreated control, were evaluated under high disease pressure at three locations in Griffin, GA, in 2015. Tebuconazole or the tebuconazole + flutolanil treatment consistently had the lowest area under the disease progress curve (AUDPC) of the treatments. The addition of flutolanil to chlorothalonil or mancozeb did not improve rust control and no difference in disease severity was observed in any treatment containing contact fungicides on all assessment dates. Single application costs ranged from $10.21 to $95.96 with tebuconazole providing excellent disease management at a relatively low cost per application ($13.90).

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