Fungicide Resistance in Alternaria alternata from Blueberry in California and Its Impact on Control of Alternaria Rot

Plant Disease ◽  
2021 ◽  
Author(s):  
Fei Wang ◽  
Seiya Saito ◽  
Themis Michailides ◽  
Chang-Lin Xiao
Keyword(s):  
Disease Severity ◽  
Alternaria Alternata ◽  
Fungicide Resistance ◽  
Disease Incidence ◽  
Postharvest Diseases ◽  
Pcr Rflp ◽  
Quinone Outside Inhibitors

Alternaria rot caused by Alternaria alternata is one of the major postharvest diseases affecting blueberries in California. The sensitivity profiles of A. alternata from blueberry field to quinone outside inhibitors (QoIs), boscalid, fluopyram, fludioxonil, cyprodinil and polyoxin D in California were examined in this study. EC50 values of 51 A. alternata isolates for boscalid varied greatly among the isolates, ranging from 0.265 to >100 µg/ml. EC50 values of 51 A. alternata isolates to fluopyram, fludioxonil, cyprodinil, and polyoxin D were 5.188 ± 7.118 µg/ml, 0.078 ± 0.021 µg/ml, 0.465 ± 0.302 µg/ml, and 6.238 ± 7.352 µg/ml, respectively. In total, 143 isolates were screened for resistance at 5 and 10 µg/ml for fludioxonil, cyprodinil, and fluopyram, 10 µg/ml for polyoxin D, and 10 and 50 µg/ml for boscalid. Based on the published discriminatory concentrations for phenotyping resistance, of the 143 isolates, all were considered resistant to boscalid; 32, 69 and 42 were sensitive, low resistant, and resistant to fluopyram, respectively; and all were sensitive to fludioxonil and cyprodinil. In a PCR-RFLP method for phenotyping, 60 out of the 143 isolates were classified as resistant to QoIs. Control tests on detached blueberry fruit inoculated with different Alternaria isolates showed that fludioxonil and cyprodinil significantly reduced disease incidence and severity; however, pyraclostrobin, boscalid, fluopyram and polyoxin D significantly reduced only disease severity. The obtained results will be helpful in making decisions on fungicide programs to control A. alternata isolates with resistance or reduced sensitivities to multiple fungicides.

Baseline Sensitivity of Alternaria alternata and A. arborescens to Natamycin and Control of Alternaria Rot on Stored Mandarin Fruit

Plant Disease ◽  
2021 ◽  
Author(s):  
Fei Wang ◽  
Seiya Saito ◽  
Themis Michailides ◽  
Chang-Lin Xiao
Keyword(s):  
Alternaria Alternata ◽  
Mycelial Growth ◽  
Disease Incidence ◽  
Conidial Germination ◽  
High Rate ◽  
Postharvest Diseases ◽  
Baseline Sensitivity ◽  
Germination Assay ◽  
Growth Assay ◽  
And Control

Alternaria rot caused by Alternaria alternata and A. arborescens is one of the major postharvest diseases on mandarin fruit in California. In this study, natamycin, a newly registered biofungicide, was evaluated for its potential as a postharvest treatment to control Alternaria rot on mandarin fruit. The baseline sensitivities of A. alternata and A. arborescens to natamycin were determined. EC50 values of natamycin for 70 A. alternata isolates ranged from 0.694 to 1.275 µg/ml (mean = 0.921 µg/ml) in a conidial germination assay, and from 2.001 to 3.788 µg/ml (mean = 2.797 µg/ml) for 40 A. alternata isolates in a mycelial growth assay. EC50 values of natamycin for 30 A. arborescens isolates ranged from 0.698 to 1.203 µg/ml (mean = 0.923 µg/ml) in a conidial germination assay, and from 2.035 to 3.368 µg/ml (mean = 2.658 µg/ml) for 20 A. arborescens isolates in a mycelial growth assay. Control tests on detached mandarin fruit showed that natamycin at both low (460 µg/ml) and high recommended rates (920 µg/ml) significantly reduced disease incidence and severity on mandarin fruit inoculated with Alternaria isolates, regardless of species. High rate of natamycin significantly reduced disease incidence and severity compared to the non-treated control even when natamycin treatment was delayed for 6, 12, and 18 hours after inoculation. Our results suggested that natamycin can be an effective postharvest fungicide for control of Alternaria rot on mandarin fruit.

scholarly journals Effect of Compost Amendments on Disease Severity and Yield of Tomato in Conventional and Organic Production Systems

Plant Disease ◽  
2002 ◽  
Vol 86 (2) ◽  
pp. 156-161 ◽  
Author(s):  
P. A. Abbasi ◽  
J. Al-Dahmani ◽  
F. Sahin ◽  
H. A. J. Hoitink ◽  
S. A. Miller
Keyword(s):  
Disease Severity ◽  
Production Systems ◽  
Disease Incidence ◽  
Organic Production ◽  
Fruit Rot ◽  
High Rate ◽  
Bacterial Spot ◽  
Marketable Yield ◽  
Tomato Production ◽  
Compost Amendments

Field trials were conducted over 2 years to assess the effects of compost amendments on disease development in organic and conventional processing tomato (Lycopersicon esculentum L.) production systems. The incidence of anthracnose fruit rot was reduced in organic tomato plots amended with a high rate of composted cannery wastes compared with the incidence in nonamended control plots in 1998 when disease incidence was high. Marketable yield was increased by 33% in compost-amended organic plots. Plots amended with a high compost rate had more ripe fruit than the nonamended control. The incidence of anthracnose and of total disease on fruit was less on the cultivar OH 8245 than on Peto 696. Total fruit yield of OH 8245 but not Peto 696 in organic plots was increased by amendment with composted cannery wastes. In conventional tomato production, composted yard wastes increased disease severity on foliage both years but reduced bacterial spot incidence on fruit in 1997, when disease pressure was high. The incidence of anthracnose was not affected by composted yard wastes. Marketable and total fruit yields of Peto 696 were not increased in compost-amended conventional plots. The plant activator Actigard reduced foliar disease severity and the incidence of bacterial spot and anthracnose on fruit, while increasing yield of marketable fruit.

scholarly journals Effect of irrigation frequency and fungicide spray on yield and disease infection of onion

1970 ◽  
Vol 34 (3) ◽  
pp. 417-424
Author(s):  
SK Biswas ◽  
MA Razzaque Akanda ◽  
M Rafi Uddin ◽  
PK Sarker
Keyword(s):  
Disease Severity ◽  
Water Use ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Research Station ◽  
Irrigation Frequency ◽  
Yield Attributes ◽  
Irrigation Water Use ◽  
Use Efficiency ◽  
Bulb Yield

A two-year field experiment was conducted at Regional Agricultural Research Station, Jessore during the rabi seasons of 2002-2003 and 2003-2004 to find out the level of disease incidence under different levels of irrigation and fungicide spray on the bulb yield of onion. Four irrigation levels: no irrigation (I1), irrigation at 10 days interval (I2), 20 days interval (I3), and 30 days interval (14) with 4 spray schedules: no spray (F1), one spray at 40 days after transplanting (DAT) (F2), two sprays each at 40 and 55 DAT (F3) and three sprays each at 40, 55, and 70 DAT (F4) were used. Yield and yield attributes varied significantly (p = 0.05) between sprayed and unsprayed, and irrigated and non-irrigated treatments, respectively. Higher yields were obtained with the higher frequencies of irrigation and spray. Application of fungicide reduced the disease severity significantly, while irrigation had no significant effect on disease infection. But there was a decreasing trend of the disease severity with increasing irrigation frequency. The highest bulb yield of onion (12.45 t/ha) was obtained with a total water use of 245 mm in six applications including an effective rainfall of 16 mm and three sprays. The disease severity between sprayed and unsprayed plots ranged from 1.33 to 3.16 for I1, 1.08 to 2.33 for I2 1.16 to 2.83 for I3, and 1.16 to 3.00 for I4, respectively. Key Words: Onion, disease incidence, irrigation, water use efficiency. DOI: 10.3329/bjar.v34i3.3967 Bangladesh J. Agril. Res. 34(3) : 417-424, September 2009

scholarly journals Molecular Characterization of Pathogenicity Locus (PaLoc) and tcdC Genetic Diversity Among tcdA+B+ Clostridioides Difficile Clinical Isolates in Tehran, Iran

2020 ◽  
Author(s):  
Mansoor Kodori ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami ◽  
Masoumeh Azimirad ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Molecular Characterization ◽  
Disease Severity ◽  
Genetic Variants ◽  
Rflp Analysis ◽  
Clostridioides Difficile ◽  
Pcr Rflp ◽  
The Common ◽  
Healthcare Associated

Abstract Background: Clostridioides difficile is the main cause of healthcare-associated diarrhea worldwide. It is proposed that certain C. difficile toxinotypes with distinct pathogenicity locus (PaLoc) variants are associated with disease severity and outcomes. Additionally, few studies have described the common C. difficile toxinotypes, and also little is known about the tcdC variants in Iranian isolates. We characterized the toxinotypes and the tcdC genotypes from a collection of Iranian clinical C. difficile tcdA+B+ isolates with known ribotypes (RTs).Methods: Fifty C. difficile isolates with known RTs and carrying the tcdA and tcdB toxin genes were analyzed. Toxinotyping was carried out based on a PCR-RFLP analysis of a 19.6 kb region encompassing the PaLoc. Genetic diversity of the tcdC gene was determined by the sequencing of the gene.Results: Of the 50 C. difficile isolates investigated, five distinct toxinotypes were recognized. Toxinotypes 0 (33/50, 66%) and V (11/50, 22%) were the most frequently found. C. difficile isolates of the toxinotype 0 mostly belonged to RT 001 (12/33, 36.4%), whereas toxinotype V consisted of RT 126 (9/11, 81.8%). The tcdC sequencing showed six variants (35/50, 70%); tcdC-sc3 (24%), tcdC-A (22%), tcdC-sc9 (18%), tcdC-B (2%), tcdC-sc14 (2%), and tcdC-sc15 (2%). The remaining isolates were wild-types (15/50, 30%) in the tcdC gene.Conclusions: The present study demonstrates that the majority of clinical tcdA+B+ isolates of C. difficile frequently harbor tcdC genetic variants. We also found that the RT 001/ toxinotype 0 and the RT 126/ toxinotype V are the most common types among Iranian isolates. Further studies are needed to investigate the putative association of various tcdC genotypes with CDI severity and its recurrence.

scholarly journals Cotton resistance to ramulose and variability of Colletotrichum gossypii f. sp. cephalosporioides

2006 ◽  
Vol 32 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Jefferson Fernandes do Nascimento ◽  
Laércio Zambolim ◽  
Francisco Xavier Ribeiro do Vale ◽  
Paulo Geraldo Berger ◽  
Paulo Roberto Cecon
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Disease Index ◽  
Mato Grosso ◽  
Progress Curve ◽  
Commercial Cultivars ◽  
Resistant Group ◽  
The Relationship ◽  
Highly Virulent ◽  
Susceptible Group

Four cultivars and 21 lines of cotton were evaluated for resistance to ramulose (Colletotrichum gossypii f. sp. cephalosporioides) in a field where the disease is endemic. The seeds of each genotype were planted in 5 x 5 m plots with three replications. The lines CNPA 94-101 and 'CNPA Precoce 2'were used as standard susceptible and resistant references, respectively. The disease incidence (DI) was calculated from the proportion of diseased plants in the plot. The disease index (DIn) was calculated from the disease severity using a 1 to 9 scale, and was evaluated at weekly intervals starting 107 days after emergence. The data collected was used to calculate the area under disease progress curve (AUDPC). In general, the DIn increased linearly with time and varied from 20.0 to 57.1 and AUDPC from 567 to 1627 among the genotypes which could be clustered in to two distinct groups. The susceptible group contained two cultivars and nine lines and the resistant group contained one cultivar and 12 lines. The relationship between disease index and evaluation times was linear for the 25 genotypes tested. The line CNPA 94-101, used as susceptible standard, was the most susceptible with an average DI = 83.4, DIn = 57.1 and AUDPC = 1627.7. The line CNPA 96-08 with DI = 37.8, DIn = 20.0 and AUDPC = 567.7 was the most resistant one. Among the commercial cultivars 'IAC 22' was the most susceptible and 'CNPA Precoce 2', used as resistant standard was the most resistant. The variability in virulence of the pathogen was studied by spray inoculating nine genotypes with conidial suspensions (10(5)/mL) of either of the 10 isolates. The disease severity was evaluated 30 days later using a scale of 1 to 5. The virulence of the isolate was expressed by DIn. All the isolates were highly virulent but their virulence avaried for several genotypes and could be clustered in two distinct groups of less and more virulent isolates. The isolate MTRM 14 from Mato Grosso was the least virulent while Minas Gerais was the most virulent, with DIn of 6.36 and 46.47, respectively. In this experiment the line HR 102 and the cultivar 'Antares' were the most resistant ones with DIns of 18.32 and 19.14, respectively.

scholarly journals QTLs for potato tuber resistance toDickeya solaniare located on chromosomes II and IV

2021 ◽  
Author(s):  
Renata Lebecka ◽  
Jadwiga Śliwka ◽  
Anna Grupa-Urbańska ◽  
Katarzyna Szajko ◽  
Waldemar Marczewski
Keyword(s):  
Potato Tuber ◽  
Disease Severity ◽  
Starch Content ◽  
Disease Incidence ◽  
Soft Rot ◽  
Bacterial Disease ◽  
Phenotypic Variance ◽  
Tuber Resistance ◽  
Dickeya Solani ◽  
The Relationship

AbstractSoft rot is a bacterial disease that causes heavy losses in potato production worldwide. The goal of this study was to identify quantitative trait loci (QTLs) for potato tuber resistance to bacteriumDickeya solaniand for tuber starch content to study the relationship between these traits. A highly resistant diploid hybrid of potato was crossed with a susceptible hybrid to generate the F1 mapping population. Tubers that were wound-inoculated with bacteria were evaluated for disease severity expressed as the mean weight of rotted tubers, and disease incidence measured as the proportion of rotten tubers. Diversity array technology (DArTseq™) was used for genetic map construction and QTLs analysis. The most prominent QTLs for disease severity and incidence were identified in overlapping regions on potato chromosome IV and explained 22.4% and 22.9% of the phenotypic variance, respectively. The second QTL for disease severity was mapped to chromosome II and explained 16.5% of the variance. QTLs for starch content were detected on chromosomes III, V, VI, VII, VIII, IX, XI, and XII in regions different than the QTLs for soft rot resistance. Two strong and reproducible QTLs for resistance toDickeya solanion potato chromosomes IV and II might be useful for further study of candidate genes and marker development in potato breeding programs. The relationship between tuber resistance to bacteria and the starch content in potato tubers was not confirmed by QTL mapping, which makes the selection of genotypes highly resistant to soft rot with a desirable starch content feasible.

scholarly journals MANAGEMENT OF APHID BORNE POTATO VIRUS Y (PVY) THROUGH CHEMICAL AND BIO-CHEMICAL METHODS

2017 ◽  
Vol 2 (2) ◽  
pp. 159
Author(s):  
Altaf Hussain ◽  
Muhammad Arif ◽  
Aqleem Abbas
Keyword(s):  
Disease Severity ◽  
Potato Virus Y ◽  
Disease Incidence ◽  
Field Conditions ◽  
Individual State ◽  
Chemical Methods ◽  
Neem Extract ◽  
Severity Level ◽  
Level 1 ◽  
Disease Severity Level

The aim of this study was the management of potato virus Y (PVY) in potato cv. Desiree through chemical and non-chemical methods. The experiment was carried out at the New Developmental Farm (NDF), The University of Agriculture, Peshawar during spring season, 2014 under field conditions. One of the major objectives of the experiment was to assess the effectiveness of the treatments application in their individual state as well as in combinations under field conditions. The treatments were mineral oil, insecticide, biocide and their combinations. Among various treatments, Diver was effective with disease severity level (1) and % disease incidence (40) in individual state and in combination (Diver + Confidor) and (Diver + Confidor + Neem extract) gave good results with % disease incidence (33.33) and with disease severity level (1). Neem extract was found to be less effective when used individually with % disease incidence (56.66) and with disease severity level (3), whereas Confidor when applied individually was more effective than Neem extract with % disease incidence (50) and with disease severity level (2). Moreover Diver in combination with Neem extract was found to be less effective in management of PVY as compared to Diver in combination with Confidor with % disease incidence (40) and disease severity level (1). Three aphid species were found in the field i.e Myzus persicae (Sulzer), Aphid gossypii (Glover) and Macrosiphum euphorbiae (Thomas). In case of aphid’s population, Confidor was more effective in reducing aphid’s population as compared to Diver and Neem extract. Finally, it can be concluded that Diver alone was more effective in the management of PVY. However in combination, Diver with Confidor significantly managed PVY under field conditions

scholarly journals Quantitative resistance loci to southern rust mapped in a temperate maize diversity panel

2021 ◽  
Author(s):  
Guangchao Sun ◽  
Ravi V. Mural ◽  
Jonathan D. Turkus ◽  
James C. Schnable
Keyword(s):  
Disease Severity ◽  
Quantitative Resistance ◽  
Association Studies ◽  
Disease Incidence ◽  
Genome Wide Association Studies ◽  
Maize Germplasm ◽  
Photosynthetic Productivity ◽  
Maize Diversity ◽  
Puccinia Polysora ◽  
Candidate Loci

Southern rust is a severe foliar disease of maize (Zea mays) resulting from infection with the obligate biotrophic fungus Puccinia polysora. This disease reduces photosynthetic productivity, which in turn reduces yields, with the greatest yield losses (up to 50%) associated with earlier onset infections. P. polysora urediniospores overwinter only in tropical and subtropical regions but cause outbreaks when environmental conditions favor initial infection. Increased temperatures and humidity during the growing season combined with an increased frequency of moderate winters are likely to increase the frequency of severe southern rust outbreaks in the US corn belt. In summer 2020, a severe outbreak of southern rust was observed in eastern Nebraska (NE), USA. We scored a replicated maize association panel planted in Lincoln, NE for disease severity and found that disease incidence and severity showed significant variation among maize genotypes. Genome-wide association studies identified four loci associated with significant quantitative variation in disease severity. These loci were associated with candidate genes with plausible links to quantitative disease resistance. A transcriptome-wide association study identified additional genes associated with disease severity. Together, these results indicate that substantial diversity in resistance to southern rust exists among current temperate-adapted maize germplasm, including several candidate loci that may explain the observed variation in resistance to southern rust.

scholarly journals Salicylic acid and jasmonic acid can suppress green and blue moulds of citrus fruit and induce the activity of polyphenol oxidase and peroxidase

2019 ◽  
Vol 31 (1) ◽  
pp. 195-204 ◽  
Author(s):  
Anam Moosa ◽  
Shahbaz Talib Sahi ◽  
Sajid Aleem Khan ◽  
Aman Ullah Malik
Keyword(s):  
Salicylic Acid ◽  
Jasmonic Acid ◽  
Disease Severity ◽  
Polyphenol Oxidase ◽  
Disease Incidence ◽  
Citrus Fruit ◽  
Disease Development ◽  
Post Harvest ◽  
Blue Mould ◽  
Green Mould

AbstractThe ability of salicylic acid and jasmonic acid to suppress post-harvest infection with green mould Penicillium digitatum and blue mould P. italicum on three citrus species Citrus reticulata ‘Kinnow’, C. limon ‘Meyer Lemon’, and C. limetta ‘Mosambi’ was evaluated in a dose-response study. Salicylic acid (SA) and jasmonic acid (JA) were applied to the fruits as a post-harvest dip treatment followed by wound inoculation with the pathogens. Both resistance inducers caused a significantly lower disease severity compared with the infected but non-treated control, whereas disease incidence was not significantly lower than in the control. The efficacy of both SA and JA in reducing disease severity was concentration-dependent; the use of higher concentrations resulted in a greater degree of suppression. All the Citrus species tested in this study showed different responses in terms of disease development. C. limon ‘Meyer Lemon’ showed the highest disease development, and C. limetta ‘Mosambi’ the lowest. To get an insight into the mechanisms underlying the increase in resistance, the activity of defence-related enzymes – peroxidase (POD) and polyphenol oxidase (PPO) – was recorded in SA- and JA-treated fruit peelings. The activity of both enzymes was directly proportional to the concentration of the SA and JA applications. The highest activity of PPO and POD was observed in C. reticulata ‘Kinnow’ and the lowest in C. limon ‘Meyer Lemon’ fruits. This study is the first to document an increase in the activity of PPO and POD in SA- and JA-treated Citrus species in the presence of blue mould and green mould pathogens.

scholarly journals Effects of Tomato Leaf Curl Virus on Growth and Yield Parameters of Tomato Crop

2021 ◽  
Vol 39 (1) ◽  
pp. 79-83
Author(s):  
Yasir Iftikhar ◽  
◽  
Mustansar Mubeen ◽  
Ashara Sajid ◽  
Mohamed Ahmad Zeshan ◽  
...  
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Tomato Leaf ◽  
Growth And Yield ◽  
Tomato Crop ◽  
Tomato Leaf Curl Virus ◽  
Yield Parameters ◽  
Tomato Leaf Curl ◽  
Leaf Curl Virus ◽  
Leaf Curl

Iftikhar, Y., M. Mubeen, A. Sajid, M.A. Zeshan, Q. Shakeel, A. Abbas, S. Bashir, M. Kamran and H. Anwaar. 2021. Effects of Tomato Leaf Curl Virus on Growth and Yield Parameters of Tomato Crop. Arab Journal of Plant Protection, 39(1): 79-83. Tomato is an important vegetable crop, belongs to the family Solanaceae and is the second most consumed vegetable following potatoes. The tomato crop is grown all over the world in both summer and winter seasons, and plant viruses are a major threat to tomato production. Among these viruses, tomato leaf curl virus (TLCV) causes considerable yield loss to tomato crop. This virus is transmitted by a whitefly (Bemisia tabaci) vector. In this study, the effect of TLCV infection, on the following tomato growth and yield parameters, was evaluated: plant leaf number and area, plant biomass, plant height, root length, and plant stem diameter and yield. Tomato plants were transplanted in wellprepared plots with 4 replications. The control group was covered with polyethene bag to avoid whitefly infestation. Plants were scored on the 15th and 30th day after inoculation and TLCV disease severity was recorded. Analysis of variance (ANOVA) showed the significant differences between the healthy and infected tomato plants. Moreover, growth and yield parameters were reduced with the increase in disease incidence, disease severity and whitefly infestation. Disease severity was increased with the increase in temperature during the growing season. It can be concluded from this study that TLCV significantly affects growth and yield of the tomato crop. Keywords: Tomato, Tomato leaf curl virus, TLCV, disease incidence, disease severity.

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