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.

Identification of a highly virulent strain of Xanthomonas axonopodis pv. malvacearum

2008 ◽  
Vol 122 (4) ◽  
pp. 461-469 ◽  
Author(s):  
Xi Huang ◽  
Jinling Zhai ◽  
Yuehua Luo ◽  
Klaus Rudolph
Keyword(s):  
Virulent Strain ◽  
Xanthomonas Axonopodis ◽  
Highly Virulent

scholarly journals Pyricularia grisea Causing Gray Leaf Spot of Perennial Ryegrass Turf: Population Structure and Host Specificity

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 817-826 ◽  
Author(s):  
G. Viji ◽  
B. Wu ◽  
S. Kang ◽  
W. Uddin ◽  
D. R. Huff
Keyword(s):  
United States ◽  
Population Structure ◽  
Winter Wheat ◽  
Perennial Ryegrass ◽  
Leaf Spot ◽  
Genetic Relationships ◽  
The United States ◽  
Gray Leaf Spot ◽  
Pyricularia Grisea ◽  
Highly Virulent

Gray leaf spot is a serious disease of perennial ryegrass (Lolium perenne) turf in the United States. Isolates of Pyricularia grisea causing the disease in perennial ryegrass were characterized using molecular markers and pathogenicity assays on various gramineous hosts. Genetic relationships among perennial ryegrass isolates were determined using different types of trans-posons as probes. Phylogenetic analysis using Pot2 and MGR586 probes, analyzed with AMOVA (analysis of molecular variance), showed that these isolates from perennial ryegrass consist of three closely related lineages. All the isolates belonged to a single mating type, MAT1-2. Among 20 isolates from 16 host species other than perennial ryegrass, only the isolates from wheat (Triticum aestivum) and triticale (× Triticosecale), showed notable similarity to the perennial ryegrass isolates based on their Pot2 fingerprints. The copy number and fingerprints of Pot2 and MGR586 in isolates of P. grisea from perennial ryegrass indicate that they are genetically distinct from the isolates derived from rice (Oryza sativa) in the United States. The perennial ryegrass isolates also had the same sequence in the internal transcribed spacer (ITS) region of the genes encoding ribosomal RNA as that of the wheat and triticale isolates, and exhibited rice isolate sequence polymorphisms. In pathogenicity assays, all the isolates of P. grisea from Legacy II perennial ryegrass caused characteristic blast symptoms on Marilee soft white winter wheat, Bennett hard red winter wheat, Era soft white spring wheat, and Presto triticale, and they were highly virulent on these hosts. An isolate from wheat and one from triticale (from Brazil) were also highly virulent on perennial ryegrass and Rebel III tall fescue (Festuca arundinacea). None of the isolates from perennial ryegrass caused the disease on Lagrue rice, and vice versa. Understanding the population structure of P. grisea isolates infecting perennial ryegrass and their relatedness to isolates from other gramineous hosts may aid in identifying alternate hosts for this pathogen.

scholarly journals Evaluation of Asparagus officinalis Cultivars for Resistance to Stem Blight by Using a Novel Inoculation Method

HortScience ◽  
1997 ◽  
Vol 32 (6) ◽  
pp. 1085-1086 ◽  
Author(s):  
Takahiro Sonoda ◽  
Atsuko Uragami ◽  
Kazuhiko Kaji
Keyword(s):  
Disease Severity ◽  
High Resistance ◽  
Environmental Conditions ◽  
Disease Susceptibility ◽  
Disease Index ◽  
Asparagus Officinalis ◽  
Stem Blight ◽  
Inoculation Method ◽  
Vinyl Tube ◽  
Phomopsis Asparagi

Asparagus officinalis L. cultivars were evaluated for resistance to asparagus stem blight caused by Phomopsis asparagi (Sacc.) Bubák under controlled environmental conditions. The plants were inoculated with the vinyl tube and cotton inoculation method. Disease severity assessments, based on the percentage of diseased plants and the disease index, were made 4 weeks after inoculation. Estimates of the percentage of diseased plants ranged from 33% to 80%, and the disease index ranged from 28 to 79. None of the cultivars and lines showed high resistance, but there were significant differences in disease susceptibility among the cultivars and lines.

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 Evaluation of Daphne Germplasm for Resistance to Daphne Sudden Death Syndrome Caused by the Soil-borne Pathogen Thielaviopsis basicola

HortScience ◽  
2007 ◽  
Vol 42 (7) ◽  
pp. 1639-1643 ◽  
Author(s):  
David Noshad ◽  
Andrew Riseman ◽  
Zamir Punja
Keyword(s):  
Significant Variation ◽  
Plant Disease ◽  
Disease Susceptibility ◽  
In Vitro Assay ◽  
Disease Index ◽  
Thielaviopsis Basicola ◽  
Vitro Assay ◽  
Disease Free

Many daphne cultivars are susceptible to fungal root pathogens and require frequent fungicide applications during production. To identify taxon differences to disease susceptibility, we evaluated 32 Daphne species and cultivars for resistance to the soil-borne pathogen, Thielaviopsis basicola (Berk. and Broome) Ferr., by both in vitro- and in vivo-based methods. Disease-free plant roots were inoculated with the pathogen through topical application of a spore suspension and observed weekly for disease development/progression. Significant variation for disease severity among the taxa evaluated was determined using a plant disease index. Plant reactions ranged from highly resistant, e.g., D. tangutica and D. retusa, to highly susceptible, e.g., D. cneorum. In addition, a high correlation was found between the in vitro and in vivo techniques for the seven selected species, indicating that they are comparable. However, the in vitro assay provided results in significantly less time than the in vivo assay.

An approach for breeding varieties of rice resistant to bacterial leaf blight with induced mutations

1975 ◽  
Vol 84 (1) ◽  
pp. 167-172 ◽  
Author(s):  
H. Nakai ◽  
M. Goto
Keyword(s):  
Leaf Blight ◽  
Bacterial Leaf Blight ◽  
Induced Mutations ◽  
Disease Reaction ◽  
Resistant Varieties ◽  
And Control ◽  
Highly Virulent

SUMMARYThe studies were designed for breeding resistant varieties of rice to bacterial leaf blightcaused by Xanlhomonas oryzae (Uyeda et Ishiyama) Dowson with induced mutations. In 1971, seedlings of irradiated lines (X$) originated from treatments of 60Co γ-and X-radiation and control (C6), which were propagated in bulk up to X6(C6) generations after the treatments, were inoculated with highly virulent isolates.The results showed that the variability of disease reaction within the irradiated lines increased in both resistant and susceptible directions from the control mean. It was assumed from these results that the irradiation treatments could induce polygenic mutations to give both germ types more resistant and those more susceptible to bacterial leaf blight, suggesting that such treatments might be an effective approach for breeding varieties resistant to the disease.

scholarly journals Preferensi Wereng Batang Cokelat terhadap Varietas Padi dan Ketahanan Varietas Padi terhadap Virus Kerdil Hampa

2016 ◽  
Vol 35 (1) ◽  
pp. 1
Author(s):  
Suprihanto Suprihanto ◽  
Susamto Somowiyarjo ◽  
Sedyo Hartono ◽  
Y. Andi Trisyono
Keyword(s):  
Control Method ◽  
Brown Planthopper ◽  
Preference Test ◽  
Susceptible Variety ◽  
Disease Index ◽  
Lower Percentage ◽  
Resistant Varieties ◽  
Check Variety ◽  
Moderately Resistant ◽  
Rice Ragged Stunt Virus

<p>Rice ragged stunt virus (RRSV) is transmitted by brown planthopper in the persistent manner. This disease in recent years has become a serious problem in Indonesia and some other countries, such as China, Vietnam, Philippines, and Thailand. Disease control is usually conducted by the vector control using insecticides, so often causes an environmental pollution. An alternative control method is using the environmentally friendly of resistant varieties. The purpose of this study was to determine the level of preference of brown planthopper (BPH) to some varieties and rice germplasms, the resistance of several varieties against rice ragged stunt virus (RRSV) disease and its effectiveness as an inoculum source of virus (RRSV). A total of 15 varieties of rice were used in preference test of BPH and resistance test to RRSV. The test for resistance varieties to RRSV was conducted by transmission of 2nd instar of BPH for 3 days of acquisition feeding period, 10 days incubation period and 24 hours inoculation period with population density of 3 BPH/plant. Disease index was calculated and used to determine the level of plant resistance. Varieties that showed resistant, moderately resistant and susceptible responses were selected and were used as a source of inoculum to be transmitted on to TN1 variety susceptible check variety to know the effectiveness of varieties as source of virus inoculum. The results showed that of the 15 varieties tested, Situ Bagendit, Utri Merah, Mentik Wangi, Mahsuri, and Inpari 1 each was less favored by BPH to settle and to multiply. Mentik Wangi, Tetep, Utri Merah, and Swarnalata each showed resistant response to RRSV. Transmission test to susceptible variety (TN1) showed that the variety of Situ Bagendit, Inpari 13, Mentik Wangi, and Tetep each has a fairly low effectiveness as a source of inoculum as indicated by the lower percentage of infection and disease index on the transmited test plants.</p>

scholarly journals Efficacy of Foliar Spray with Seven Fungicides and a Botanical to Control Scab (Elsinoe fawcettii) and Dieback (Colletotrichum gloeosporioides) Diseases of Lemon

1970 ◽  
Vol 9 (1-2) ◽  
pp. 99-105
Author(s):  
TA Siddiquee ◽  
MR Islam ◽  
FM Aminuzzaman ◽  
AN Faruq ◽  
MM Islam
Keyword(s):  
Disease Severity ◽  
Leaf Extract ◽  
Colletotrichum Gloeosporioides ◽  
Foliar Spray ◽  
Disease Index ◽  
Fruit Yield ◽  
Citrus Limon ◽  
Percent Disease Index ◽  
Relationship Of ◽  
The Relationship

An investigation was conducted in a six year old lemon (Citrus limon) garden during March to September 2007 to find out the effect of foliar spray with seven fungicides and a botanical on the severity of citrus scab (Elsinoe fawcettii) and dieback (Colletotrichum gloeosporioides) of the crop. The tested fungicides were Dinthane M 45 (0.30%), Rovral 50 WP (0.10%), Bavistin 50 WP (0.10%), Champion 77 WP (0.20%), Cupravit 50 WP (0.20%), Tilt 250 EC (0.25%), Proud 250 EC (0.25%) and the botanical allamanda (Allamanda cathartica) leaf extract (1:4). The results showed that the fungicides and allamanda leaf extract are effective to achieve significant reduction in severity of scab and dieback diseases, and to increase fruit yield of lemon. The reduction of Percent Disease Index (PDI) of scab on leaf and fruit, and that of dieback ranged 26.45-83.87, 49.01-60.20 and 35.22- 58.01%, respectively after six months of first spray. The relationship of increase in fruit yield was directly and linearly correlated with percentage of reduction in severity of dieback diseases. Based on reduction of disease severity and increase of fruit yield, Allamanda leaf extract was noted as most effective material followed by Bavistin 50 WP, Tilt 250 EC, Cupravit 50 WP and Dithane M-45. Keywords: Citrus; scab; dieback; lemon; fungicide; botanical; control DOI: http://dx.doi.org/10.3329/agric.v9i1-2.9484 The Agriculturists 2011; 9(1&2): 99-105

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