scholarly journals Variability and Virulence Analysis of Aspergillus niger Isolates Causing Collar Rot of Groundnut

2022 ◽  
Author(s):  
Tejpal Bajaya ◽  
R.P. Ghasolia ◽  
Mamta Bajya ◽  
Manisha Shivran
Keyword(s):  
Aspergillus Niger ◽  
Disease Incidence ◽  
Morphological Variability ◽  
Economic Losses ◽  
Resistance Response ◽  
Collar Rot ◽  
Virulent Isolate ◽  
Resistant Varieties ◽  
Severe Constraint ◽  
Highly Virulent

Background: Collar rot of groundnut (Arachis hypogaea L.) caused by Aspergillus niger is a significant constraint in groundnut cultivation and responsible for huge economic losses in India including Rajasthan. Methods: By surveying of eight major groundnut growing districts of Rajasthan, India, one representative Aspergillus niger isolate from each district was established (ANBK-01= Bikaner, ANCH-02= Churu, ANDA-03= Dausa, ANJP-04= Jaipur, ANJL-05= Jalore, ANJD-06= Jodhpur, ANNG-07= Nagaur and ANSK-08= Sikar) for studying variability in the pathogen as well as to know the response of groundnut varieties to the highly virulent isolate. The colony and spore characteristics were observed for cultural and morphological variability. For resistance response to the disease, ten varieties (M-13, RG-633-9, RG-382, Girnar-2, RG-604, RG-578, Gajraj 10, RG-510, RG-632-1 and RG-644) were evaluated in the field for two consecutive years against a highly virulent Aspergillus niger (ANJP-04) isolate. Result: Our investigations cleared that all the isolates were showed cultural and morphological variability such as shape, colour and size of colony and size of conidia, conidiophores and columella. Isolate (ANJP-04) collected from Khejroli village of Chomu tehsil in Jaipur district showed maximum mycelial growth, conidia diameter, length and diameter of conidiophores and length and diameter of columella, early sporulation and found most virulent as it produced higher disease incidence (54.43%). Ten released varieties of groundnut in the field conditions, revealed that none of the variety was found completely free from the disease whereas RG-644, M-13 and RG-510 were found resistant while RG-604, Girnar-2, Gajraj-10 and RG-632-1 were found moderately resistant and rest were found susceptible to highly susceptible to the disease. Conclusively, it can be finalized that famers may cultivate these resistant varieties in areas where collar rot is a severe constraint. The conclusion of this study can also be utilized to screen varieties/genotypes of groundnut against highly virulent isolate for sustainability of breeding material to the disease effectively.

scholarly journals Factors Influencing Development of Root Rot on Ginseng Caused by Cylindrocarpon destructans

2005 ◽  
Vol 95 (12) ◽  
pp. 1381-1390 ◽  
Author(s):  
Mahfuzur Rahman ◽  
Zamir K. Punja
Keyword(s):  
Soil Moisture ◽  
Root Rot ◽  
Disease Incidence ◽  
Hyphal Growth ◽  
Infested Soil ◽  
Cylindrocarpon Destructans ◽  
Virulent Isolate ◽  
Weakly Virulent ◽  
Highly Virulent

The fungus Cylindrocarpon destructans (Zins) Scholten is the cause of root rot (disappearing root rot) in many ginseng production areas in Canada. A total of 80 isolates of C. destructans were recovered from diseased roots in a survey of ginseng gardens in British Columbia from 2002-2004. Among these isolates, 49% were classified as highly virulent (causing lesions on unwounded mature roots) and 51% were weakly virulent (causing lesions only on previously wounded roots). Pectinase and polyphenoloxidase enzymes were produced in vitro by C. destructans isolates when they were grown on pectin and phenol as a substrate, respectively. However, highly virulent isolates produced significantly (P < 0.001) higher enzyme levels compared with weakly virulent isolates. Histopathological studies of ginseng roots inoculated with a highly virulent isolate revealed direct hyphal penetration through the epidermis, followed by intracellular hyphal growth in the cortex. Subsequent cell disintegration and accumulation of phenolic compounds was observed. Radial growth of highly and weakly virulent isolates on potato dextrose agar was highest at 18 and 21°C, respectively and there was no growth at 35°C. Mycelial mass production was significantly (P ≤ 0.01) lower at pH 7.0 compared with pH 5.0. To study the effects of pH (5.0 and 7.0) and wounding on disease development, ginseng roots were grown hydroponically in Hoagland's solution. Lesions were significantly larger (P < 0.001) at pH 5.0 compared with pH 7.0 and wounding enhanced disease by a highly virulent isolate at both pHs. In artificially infested soil, 2-year-old ginseng roots were most susceptible to Cylindrocarpon root rot among all root ages tested (1 to 4 years) when evaluated using a combined scale of disease incidence and severity. Root rot severity was significantly (P < 0.002) enhanced by increasing the inoculum density from 3.45 × 102 CFU/g of soil to 1.86 × 103 CFU/g of soil. Disease severity was higher at 20°C compared with 15 and 25°C and at -0.02 MPa soil moisture compared with -0.005 and -0.001 MPa. A significant interaction between soil moisture and temperature was observed for root rot severity.

scholarly journals Studies of alternaria black spot disease of pomegranate caused by Alternaria alternata in Punjab

2017 ◽  
Vol 9 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Adesh Kumar ◽  
Tanjeet Singh Chahal ◽  
Mandeep Hunjan Singh Singh ◽  
Harminder Kaur ◽  
Roomi Rawal
Keyword(s):  
Alternaria Alternata ◽  
Mycelial Growth ◽  
Disease Incidence ◽  
Black Spot ◽  
Economic Losses ◽  
Group Method ◽  
Research Station ◽  
Toxic Reaction ◽  
Pair Group ◽  
Highly Virulent

Alternaria black spot of pomegranate caused by Alternaria alternata pose significant economic losses in India as it reduce the crop yield. Farm survey was undertaken at Punjab Agricultural University, Pomegranate Research Block, Fruit Research Station, Jallowal- Lesriwal Jalandhar during 2015. Among all the five cultivars highest disease incidence (70%) and severity (30%) was registered in cultivar Bhagwa. Twenty two isolates of A. alternata were recovered from infected fruits and clustered using UPGMA (unweighted pair group method with arithmetic averages) on the basis of disease score produced in five cultivars (Ganesh, Ruby, Bhagwa, Jyoti and Mridula). It was revealed that five isolates namely AL14, AL15, AL20, AL21 and AL22 were highly virulent on almost all the pomegranate cultivars. Two cultivars viz. Bhagwa and Mridula were found to be most susceptible as 45.45 % isolates were found to be highly virulent on them.Thein vitro antifungal effects of the six fungicides on mycelial growth were investigated. Based on the inhibition of mycelial growth, all the fungicides showed most toxic reaction with 50% effective concentrations (EC50) of < 1 ppm. However, they varied in EC90 values. 10 ppm cocentration of Tilt (azole group) showed 90% effective concentration (EC90). Folicur also showed approximately same results as Tilt while EC90 value of Natio and SAAF was <25 ppm and > 20 ppm. However, two fungicides namely Dithane Z-78 and Bavistin showed less toxicity against Alternaria alternata as compared to other with EC90 value at concentrations <50 ppm and > 25 ppm. Azole group fungicides (Tilt and Folicur) were found most effective to inhibit the pathogen growth.

scholarly journals Development of Vernonia amygdalina Leaf Extract Emulsion Formulations in Controlling Gray Mold Disease on Tomato (Lycopersicon esculentum Mill.)

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 373
Author(s):  
Siti Fairuz Yusoff ◽  
Farah Farhanah Haron ◽  
Norhayu Asib ◽  
Mahmud Tengku Muda Mohamed ◽  
Siti Izera Ismail
Keyword(s):  
Antifungal Activity ◽  
Leaf Extract ◽  
Fungicidal Activity ◽  
Disease Incidence ◽  
Gray Mold ◽  
Positive Control ◽  
Economic Losses ◽  
Vernonia Amygdalina ◽  
Emulsion Formulation

Postharvest fruits including tomatoes are commonly infected by gray mold disease resulting in significant economic losses in the fruit industry. Therefore, this study aimed to develop botanical fungicide derived from Vernonia amygdalina leaf extract to control gray mold on tomato. The emulsion formulation containing surfactant, oil carrier and water was optimized at different non-ionic alkyl polyglucoside surfactants through eleven combinations of oil to surfactant ratio (0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 and 10:0 w/w). From eight selected formulations, two formulations, F5 and F7 showed stable in storage, remarkable thermodynamic stability, smaller particle size (66.44 and 139.63 nm), highly stable in zeta potential (−32.70 and −31.70 mV), low in polydispersity index (0.41 and 0.40 PdI), low in viscosity (4.20 and 4.37 cP) and low in surface tension (27.62 and 26.41 mN/m) as compared to other formulations. In situ antifungal activity on tomato fruits showed F5 formulation had a fungicidal activity against B. cinerea with zero disease incidence and severity, whereas F7 formulation reduced 62.5% disease incidence compared to a positive control with scale 1. Based on these findings, F5 formulation exhibited pronounced antifungal activity and may contribute to the development of new and safe antifungal product against gray mold on tomato.

scholarly journals Pathotypes of Xanthomonas axonopodis pv. dieffenbachiae Isolated from Anthurium andraeanum in China

Pathogens ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 85
Author(s):  
Shuang-Chun Li ◽  
Wei-Da Zeng ◽  
Xing-Wei Li ◽  
Xiao-Yun Zhou ◽  
Qiong-Guang Liu
Keyword(s):  
Population Structure ◽  
Disease Susceptibility ◽  
Foliar Spray ◽  
Disease Index ◽  
Xanthomonas Axonopodis ◽  
Resistant Varieties ◽  
Medium Level ◽  
Anthurium Andraeanum ◽  
Highly Virulent ◽  
Susceptibility Patterns

Anthurium blight, caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad), is one of the most serious diseases of Anthurium andraeanum. However, little is known about variations in virulence between Xad pathotypes. Here, we examined the virulence of 68 Xad strains isolated from 30 anthurium plants from five regions of China against five different anthurium cultivars. Seven bacterial pathotypes were identified based on disease index and incidence analyses following foliar spray or leaf-clip inoculation. The resulting disease susceptibility patterns for pathotypes I–VII were RRRSS, RRSRS, RSRSR, RRSSS, RSSRS, RSSSS, and SSSSS, respectively. Overall, 72% of tested strains belonged to pathotypes VI or VII and were highly virulent. A further 22.1% of strains showed medium-level virulence and were classed as pathotype III, IV, or V, while the remaining 5.9% of strains were pathotype I or II, showing low virulence. Further analysis revealed differences in the virulence of Xad strains from the same anthurium cultivar, with variation also observed in pathovars associated with the same cultivar from different areas. Our results reveal the diversity and complexity of the Xad population structure in China and suggest that investigation of Xad pathotypes provides useful information to guide the identification and use of resistant varieties of A. andraeanum.

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 Management of Black Scurf (Rhizoctonia solani) of Potato through Organic Approaches

2020 ◽  
Author(s):  
Narendra Singh ◽  
Vikee M. Patel
Keyword(s):  
Boric Acid ◽  
Rhizoctonia Solani ◽  
Tuber Yield ◽  
Disease Incidence ◽  
Organic Amendments ◽  
Black Scurf ◽  
Economic Losses ◽  
Research Station ◽  
Diseased Tuber ◽  
Tuber Treatment

Black scurf (Rhizoctonia solani) disease of potato is becoming prominent in many potato growing districts of Gujarat state which reduce quality and market value of the produce, resulting in economic losses. The field experiment was conducted during rabi season of 2014-15 in naturally infested field with scurf pathogen at Potato Research Station, S.D. Agricultural University, Deesa (Gujarat) with the objective to find out suitable management strategies for black scurf through organic approaches (bio-agents and organic amendments). Among different bio-agents (Trichoderma viride, T. harzianum. Pseudomonas fluorescens and Bacillus subtilis) tested against black scurf, the tuber treatment with 2 per cent boric acid spray along with tuber treatment with T. viride @ 10 g/kg seed before sowing recorded the lowest disease incidence (15.33 %) and index (0.38) with highest total tuber yield (324.68 q/ha) with maximum income `2,57,414/ha. When price computed with healthy and diseased tuber yield among treatments, the maximum income variation was (`92,986/ha) recorded by the same treatment followed by the tuber treatment with 3 % boric acid spray before sowing (`68,440/ha). In case of various organic amendments tested, soil application of mustard cake @ 10 q/ha registered minimum disease incidence (37.33 %) and disease index (0.66) as compared to rest of the organic treatment with highest total tuber yield (`327.20 q/ha) with maximum income `2,65,010/ha. When price computed with healthy and diseased tuber yield among treatments, the maximum income variation was (`1,12,990/ha) recorded by the same treatment followed by the neem cake @ 10 q/ha (`56,660/ha). These organic treatments can provide an effective and economical management of black scurf of potato for cultivaters.

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.

scholarly journals Characterization of Botrytis cinerea From Commercial Cut Flower Roses

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1577-1583 ◽  
Author(s):  
M. Muñoz ◽  
J. E. Faust ◽  
G. Schnabel
Keyword(s):  
Botrytis Cinerea ◽  
Fungicide Resistance ◽  
Management Practices ◽  
Cultural Practices ◽  
Disease Incidence ◽  
Resistance Management ◽  
Gray Mold ◽  
Economic Losses ◽  
Cut Flower ◽  
Aspergillus Brasiliensis

Botrytis cinerea Pers. infects cut flower roses (Rosa × hybrida L.) during greenhouse production and gray mold symptoms are often expressed in the postharvest environment, resulting in significant economic losses. Disease management is based on cultural practices and preventative chemical treatments; however, gray mold outbreaks continue to occur. Rose tissues from six commercial shipments from two greenhouses in Colombia were evaluated to determine the Botrytis species composition as well as identify other pathogens present, gray mold incidence and severity, and fungicide resistance profiles. Botrytis isolates (49 total) were grouped into six morphological phenotypes, and all were identified to be B. cinerea sensu stricto. Disease incidence was higher in the petals than in the stem, stamen, ovary, sepal, or leaf tissues. Other fungi were isolated infrequently and included Alternaria alternata, Cladosporium cladosporioides, Epicoccum nigrum, Penicillium citrinum, Aspergillus brasiliensis, and Diplodia sp. Fungicide resistance profiles were determined using previously established discriminatory doses. Isolates resistant to thiophanate-methyl, iprodione, boscalid, and cyprodinil were found frequently in all shipments and in both greenhouses. The frequency of resistance to penthiopyrad, fenhexamid, fluopyram, isofetamid, and fludioxonil varied between shipments and greenhouses. No resistance to pydiflumetofen was observed at the discriminatory doses tested. Isolates with resistance to multiple chemical classes were commonly found. These results indicate that fungicide resistance management practices may improve preharvest and postharvest gray mold control of cut flower roses.

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.

scholarly journals Investigation of the Role of the Spike Protein in Reversing the Virulence of the Highly Virulent Taiwan Porcine Epidemic Diarrhea Virus Pintung 52 Strains and Its Attenuated Counterpart

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 41 ◽  
Author(s):  
Chi-Fei Kao ◽  
Hui-Wen Chang
Keyword(s):  
Mortality Rate ◽  
Porcine Epidemic Diarrhea Virus ◽  
Rational Design ◽  
Economic Losses ◽  
Diarrhea Virus ◽  
Viral Shedding ◽  
S Gene ◽  
Porcine Epidemic Diarrhea ◽  
Highly Virulent

Porcine epidemic diarrhea virus (PEDV) has continuously caused severe economic losses to the global swine industries; however, no successful vaccine against PEDV has been developed. In this study, we generated four autologous recombinant viruses, including the highly virulent iPEDVPT-P5, attenuated iPEDVPT-P96, and two chimeric viruses (iPEDVPT-P5-96S and iPEDVPT-P96-5S) with the reciprocally exchanged spike (S) gene, to study the role of the S gene in PEDV pathogenesis. A deeper understanding of PEDV attenuation will aid in the rational design of a live attenuated vaccine (LAV) using reverse genetics system. Our results showed that replacing the S gene from the highly virulent iPEDVPT-P5 led to complete restoration of virulence of the attenuated iPEDVPT-P96, with nearly identical viral shedding, diarrhea pattern, and mortality rate as the parental iPEDVPT-P5. In contrast, substitution of the S gene with that from the attenuated iPEDVPT-P96 resulted in partial attenuation of iPEDVPT-P5, exhibiting similar viral shedding and diarrhea patterns as the parental iPEDVPT-P96 with slightly severe histological lesions and higher mortality rate. Collectively, our data confirmed that the attenuation of the PEDVPT-P96 virus is primarily attributed to mutations in the S gene. However, mutation in S gene alone could not fully attenuate the virulence of iPEDVPT-P5. Gene (s) other than S gene might also play a role in determining virulence.

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