scholarly journals Verticillium Wilt of Paprika Caused by a Highly Virulent Isolate of Verticillium dahliae

Plant Disease ◽  
1998 ◽  
Vol 82 (4) ◽  
pp. 437-439 ◽  
Author(s):  
Leah Tsror (Lahkim) ◽  
Orly Erlich ◽  
Sarit Amitai ◽  
Marina Hazanovsky
Keyword(s):  
Verticillium Dahliae ◽  
Agar Medium ◽  
Disease Symptoms ◽  
Virulent Isolate ◽  
Pathogenicity Tests ◽  
Potato Isolate ◽  
Dahliae Isolate ◽  
Early Dying ◽  
Pathogen Colonization ◽  
Highly Virulent

Verticillium dahliae caused wilting, stunting and early dying of paprika plants in Israel, resulting in a 22% reduction in yield. A V. dahliae isolate from diseased paprika plants was slower growing on agar medium than V. dahliae isolates from potato, tomato, watermelon, and Dodonaea, but formed microsclerotia earlier. The paprika isolate of V. dahliae was highly virulent to paprika in pathogenicity tests. Disease severity indices obtained from three paprika cultivars ranged from 3.7 to 4.9 (on a scale of 0 to 5). The disease caused height reductions of 43 to 62% in the three inoculated paprika cultivars, and pathogen colonization levels were 10- to 35-fold higher in stems than in leaves. The potato isolate of V. dahliae did not produce symptoms or cause stunting of paprika, and could not be detected in stems or leaves. The tomato, watermelon, and Dodonaea isolates did not cause disease symptoms in paprika, although they colonized the plant tissue. In potato and eggplant, the paprika isolate caused a higher incidence of disease with more severe symptoms and a higher level of tissue colonization than did the potato isolate.

scholarly journals Susceptibility of Weedy Hosts from Pacific Northwest Potato Production Systems to Crop-Aggressive Isolates of Verticillium dahliae

Plant Disease ◽  
2017 ◽  
Vol 101 (8) ◽  
pp. 1500-1506 ◽  
Author(s):  
Z. A. Frederick ◽  
T. F. Cummings ◽  
D. A. Johnson
Keyword(s):  
Pacific Northwest ◽  
Verticillium Dahliae ◽  
Production Systems ◽  
Potato Crop ◽  
Potato Production ◽  
Plant Host ◽  
Term Survival ◽  
Wide Range ◽  
Potato Isolate ◽  
Dahliae Isolate

Verticillium wilt, caused by Verticillium dahliae, is a disease of dicotyledonous crops such as potato and has a wide host range and persistent, long-term survival structures called microsclerotia that can persist in soil for up to 14 years. Some V. dahliae isolates are particularly aggressive on a specific plant host while retaining the ability to infect a wide range of other hosts. Weeds can serve as hosts for V. dahliae but whether they serve as sources of inoculum for aggressive isolates of V. dahliae to crop hosts is unknown. The goal of this research was to quantify V. dahliae microsclerotia obtained from 16 weeds which were grown in the greenhouse. Potting medium was infested with one of eight V. dahliae isolates from potato, mint, sugar beet, sunflower, tomato, and watermelon. The isolates from mint and potato were aggressive on the host from which they were originally isolated. All 16 weeds were infected by at least one V. dahliae isolate, although the number of microsclerotia produced from some infections was relatively low (≤5 microsclerotia/g of dry plant). Black nightshade yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in three of four trials in the greenhouse (second trial false discovery rate, adjusted P ≤ 0.0158; third trial, P ≤ 0.0264; and fourth trial, P ≤ 0.0193). Litchi tomato yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in one of four trials (first trial, P ≤ 0.0149). A V. dahliae isolate from tomato yielded greater numbers of microsclerotia in large crabgrass and wild oat in a second trial (P ≤ 0.0158). Weeds, depending on the species, grown during and between potato crop rotations may increase the number of microsclerotia of the potato-aggressive isolates of V. dahliae.

scholarly journals First Report of Verticillium Wilt of Pistachio Caused by Verticillium dahliae in Spain

Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 382-382
Author(s):  
J. Moral ◽  
F. J. López-Escudero ◽  
L. F. Roca ◽  
M. A. Blanco-López ◽  
A. Trapero
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vascular Tissue ◽  
Agar Medium ◽  
Tap Water ◽  
Conidial Suspension ◽  
First Report ◽  
Soil P ◽  
La Mancha ◽  
Dahliae Isolate

Pistachio (Pistacia vera L.) trees in the Castilla La Mancha and Andalusia regions of central and southern Spain are grown close to olive orchards, which are often severely affected by Verticillium dahliae. During the last decade, wilt and death of one or several branches have been observed on pistachio (cv. Kerman) scions grafted on rootstock (P. terebinthus). Discoloration of vascular tissue was occasionally observed. In five surveyed orchards, incidence of affected trees was less than 2%. Wood chips with the bark removed from symptomatic trees were washed in running tap water, surface disinfested in 0.5% sodium hypochlorite for 1 min, and placed onto potato dextrose agar plates incubated at 25°C in the dark. Isolates were identified as V. dahliae on the basis of the characteristics of microsclerotia, conidiophores, and conidia. V. dahliae isolate V117 from olive was used as reference (1). The fungus was also isolated from soil in pistachio orchards using wet sieving and a modified sodium polypectate agar medium (1). Inoculum density varied from 0 to 4.73 microsclerotia per gram of soil. P. terebinthus seedlings were inoculated with two isolates of V. dahliae from pistachio trees by injecting the stems with 50 μl of a conidial suspension (107 conidia per ml) (2). Wilt symptoms of varying severity developed in 12 and 15 seedlings of the 20 pistachio seedlings inoculated with each of two isolates. No symptoms developed on the control seedlings. The pathogen was recovered from stem tissues of inoculated plants. To our knowledge, this is the first report of Verticillium wilt of pistachio in Spain. This study demonstrates the susceptibility of certain rootstocks to V. dahliae and the importance of using resistant rootstocks, such as UCBI (2), in pistachio plantations established on soils infested by V. dahliae. References: (1) F. J. López-Escudero and M. A. Blanco-López. Plant Dis. 91:1372, 2007. (2) D. P. Morgan et al. Plant Dis. 76:310, 1992.

scholarly journals Virulence not linked with vegetative compatibility groups in Australian cotton Verticillium dahliae isolates

2020 ◽  
pp. 633-640 ◽  
Author(s):  
Pearl Dadd Daigle ◽  
Karen Kirkby ◽  
Damian Collins ◽  
Will Cuddy ◽  
Peter Lonergan ◽  
...  
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Group ◽  
Plant Mortality ◽  
Severe Damage ◽  
Disease Symptoms ◽  
Vegetative Compatibility Groups ◽  
Compatibility Group ◽  
Highly Virulent

Verticillium dahliae, the causal agent of Verticillium wilt, is a soil-borne ascomycete that infects numerous agriculturally important crops globally, including cotton. As a billion-dollar industry, cotton is economically important to Australia and the management of disease such as Verticillium wilt is key for the success of the industry. Internationally, defoliating V. dahliae isolates belonging to Vegetative Compatibility Group (VCG) 1A cause severe damage to cotton, while non-defoliating VCG2A isolates result in significantly less disease. However, in Australia, VCG2A is causing more severe damage to crops in the field than the defoliating VCG1A. This study aimed to replicate field observations in controlled greenhouse conditions. We examined and compared disease symptoms on a range of Australian commercial cotton varieties when inoculated with different V. dahliae VCGs. Seedlings were root dipped in conidial suspensions and assessed over seven weeks. The final disease score, disease over time and root length were analysed. Plant mortality resulted from both V. dahliae VCG1A and VCG2A isolates across all cotton varieties used, confirming that there are virulent VCG2A isolates present in Australia. To our knowledge, although virulent on other plant hosts, V. dahliae VCG2A has not previously been reported to be highly virulent in cotton. We infer that virulence cannot be defined solely by VCG in Australian V. dahliae isolates causing disease in cotton.

scholarly journals Considerations for Verticillium Wilt Resistance Evaluation in Potato

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 360-367 ◽  
Author(s):  
K. E. Frost ◽  
D. I. Rouse ◽  
S. H. Jansky
Keyword(s):  
Disease Severity ◽  
Verticillium Wilt ◽  
Yield Loss ◽  
Control Culture ◽  
In Planta ◽  
Disease Symptoms ◽  
Accuracy And Precision ◽  
Population Sizes ◽  
Pathogen Colonization ◽  
Time Accuracy

Verticillium wilt (Vw), caused by the soilborne fungi Verticillium dahliae and V. albo-atrum, is an important disease of potato (Solanum tuberosum). Host plant resistance is a promising method of Vw control. Culture-based methods that quantify the pathogen in host tissue often are used for Vw resistance screening. To evaluate the processing time, accuracy, and precision of these methods, 46 clones were planted in a field naturally infested with V. dahliae to collect data on visual disease symptoms, pathogen colonization, and yield. In 2002, disease severity explained 4.34% of the variability of yield loss, but the linear relationship between stem colonization and yield loss was not significant. In 2003, stem colonization explained 57.5% of the variability of yield loss, whereas disease severity explained 1.7% of the variability of yield loss. Correlations comparing clone ranks from repeated pathogen measurements indicated that culturing sap from individual stems or bulked stems generated more repeatable clone rankings than culturing dried stems. Clone rankings were more repeatable between years if pathogen measurements were made earlier in the growing season. The results indicate a need to characterize the effect of the environment on the relationship among pathogen population sizes in planta, disease symptoms, and yield loss.

Key Insights and Research Prospects at the Dawn of the Population Genomics Era for Verticillium dahliae

2021 ◽  
Vol 59 (1) ◽  
Author(s):  
Jie-Yin Chen ◽  
Steven J. Klosterman ◽  
Xiao-Ping Hu ◽  
Xiao-Feng Dai ◽  
Krishna V. Subbarao
Keyword(s):  
Population Structure ◽  
Verticillium Dahliae ◽  
Plant Pathogens ◽  
Population Genomics ◽  
Population Divergence ◽  
Annual Review ◽  
Publication Date ◽  
Disease Symptoms ◽  
Historical Perspectives ◽  
Characteristic Features

The genomics era has ushered in exciting possibilities to examine the genetic bases that undergird the characteristic features of Verticillium dahliae and other plant pathogens. In this review, we provide historical perspectives on some of the salient biological characteristics of V. dahliae, including its morphology, microsclerotia formation, host range, disease symptoms, vascular niche, reproduction, and population structure. The kaleidoscopic population structure of this pathogen is summarized, including different races of the pathogen, defoliating and nondefoliating phenotypes, vegetative compatibility groupings, and clonal populations. Where possible, we place the characteristic differences in the context of comparative and functional genomics analyses that have offered insights into population divergence within V. dahliae and the related species. Current challenges are highlighted along with some suggested future population genomics studies that will contribute to advancing our understanding of the population divergence in V. dahliae. Expected final online publication date for the Annual Review of Phytopathology, Volume 59 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Characterization and Pathogenicity of Botryosphaeriaceae Species Collected from Olive and Other Hosts in Spain and California

2010 ◽  
Vol 100 (12) ◽  
pp. 1340-1351 ◽  
Author(s):  
Juan Moral ◽  
Concepción Muñoz-Díez ◽  
Nazaret González ◽  
Antonio Trapero ◽  
Themis J. Michailides
Keyword(s):  
Sequence Data ◽  
Close Association ◽  
Elongation Factor ◽  
Fruit Rot ◽  
Disease Symptoms ◽  
Dna Sequence Data ◽  
Olive Fly ◽  
The Family ◽  
Pathogenicity Tests ◽  
Olive Trees

Species in the family Botryosphaeriaceae are common pathogens causing fruit rot and dieback of many woody plants. In this study, 150 Botryosphaeriaceae isolates were collected from olive and other hosts in Spain and California. Representative isolates of each type were characterized based on morphological features and comparisons of DNA sequence data of three regions: internal transcribed spacer 5.8S, β-tubulin, and elongation factor. Three main species were identified as Neofusicoccum mediterraneum, causing dieback of branches of olive and pistachio; Diplodia seriata, causing decay of ripe fruit and dieback of olive branches; and Botryosphaeria dothidea, causing dalmatian disease on unripe olive fruit in Spain. Moreover, the sexual stage of this last species was also found attacking olive branches in California. In pathogenicity tests using unripe fruit and branches of olive, D. seriata isolates were the least aggressive on the fruit and branches while N. mediterraneum isolates were the most aggressive on both tissues. Isolates of B. dothidea which cause dalmatian disease on fruit were not pathogenic on branches and only weakly aggressive on fruit. These results, together with the close association between the presence of dalmatian disease symptoms and the wound created by the olive fly (Bactrocera oleae), suggest that the fly is essential for the initiation of the disease on fruit. Isolates recovered from dalmatian disease symptoms had an optimum of 26°C for mycelial growth and 30°C for conidial germination, suggesting that the pathogen is well adapted to high summer temperatures. In contrast, the range of water activity in the medium for growth of dalmatian isolates was 0.93 to 1 MPa, which was similar to that for the majority of fungi. This study resolved long-standing questions of identity and pathogenicity of species within the family Botryosphaeriaceae attacking olive trees in Spain and California.

scholarly journals Coccinonectria pachysandricola, Causal Agent of a New Foliar Blight Disease of Sarcococca hookeriana

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1337-1346 ◽  
Author(s):  
Catalina Salgado-Salazar ◽  
Nina Shiskoff ◽  
Nicholas LeBlanc ◽  
Adnan A. Ismaiel ◽  
Maxton Collins ◽  
...  
Keyword(s):  
Woody Plants ◽  
Causal Agent ◽  
Washington Dc ◽  
Disease Symptoms ◽  
Foliar Blight ◽  
Pathogenicity Tests ◽  
Artificial Inoculations ◽  
Blight Disease ◽  
Genome Assemblies ◽  
Severe Leaf

Woody plants of the Buxaceae, including species of Buxus, Pachysandra, and Sarcococca, are widely grown evergreen shrubs and groundcovers. Severe leaf spot symptoms were observed on S. hookeriana at the U.S. National Arboretum in Washington, DC, in 2016. Affected plants were growing adjacent to P. terminalis exhibiting Volutella blight symptoms. Fungi isolated from both hosts were identical based on morphology and multilocus phylogenetic analysis and were identified as Coccinonectria pachysandricola (Nectriaceae, Hypocreales), causal agent of Volutella blight of Pachysandra species. Pathogenicity tests established that Co. pachysandricola isolated from both hosts caused disease symptoms on P. terminalis and S. hookeriana, but not on B. sempervirens. Artificial inoculations with Pseudonectria foliicola, causal agent of Volutella blight of B. sempervirens, did not result in disease on P. terminalis or S. hookeriana. Wounding enhanced infection by Co. pachysandricola and Ps. foliicola on all hosts tested but was not required for disease development. Genome assemblies were generated for the Buxaceae pathogens that cause Volutella diseases: Co. pachysandricola, Ps. buxi, and Ps. foliicola; these ranged in size from 25.7 to 28.5 Mb. To our knowledge, this foliar blight of S. hookeriana represents a new disease for this host and is capable of causing considerable damage to infected plants.

scholarly journals First Report of Occurrence of Eggplant Wilt Caused by Verticillium dahliae in Korea

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1152-1152
Author(s):  
S. K. Kim ◽  
S. S. Hong ◽  
K. W. Kim ◽  
E. W. Park
Keyword(s):  
Verticillium Dahliae ◽  
Solanum Melongena ◽  
Morphological Characteristics ◽  
Wilt Disease ◽  
Potato Dextrose Agar ◽  
First Report ◽  
Vascular Tissues ◽  
Fungal Isolates ◽  
Pathogenicity Tests ◽  
Root Cutting

A wilt disease occurred on greenhouse-grown eggplants (Solanum melongena L.) at Hanam and Yeojoo, Korea, in 1997. Lower leaves on the 2-month-old wilted eggplants exhibited gradual yellowing, interveinal necrosis, and marginal crinkling and dropped prematurely. Vascular tissues of diseased stems were discolored and turned black. Vertical sections of the stems revealed that the pith had been colonized by the fungus. The disease progressed from lower parts of the plants upward. Incidence of diseased eggplants in greenhouses was 5% on 23 May 1997. Although the incidence increased to 10% on 13 June, it remained constant through early July. Fungal isolates from discolored vascular tissues were initially whitish to cream color on potato-dextrose agar, which turned black due to the formation of microsclerotia. The fungus also produced abundant verticillate conidiophores with phialides and conidia. Based on these cultural and morphological characteristics, the fungus was identified as Verticillium dahliae Klebahn. Pathogenicity tests by root cutting, root dipping, or soil drenching resulted in similar symptoms observed in the naturally infected eggplants. Symptoms were first observed on lower leaves of each eggplant 3 weeks after inoculation. Isolation from symptomatic leaves of the inoculated eggplants yielded V. dahliae. This is the first report of occurrence of Verticillium wilt of eggplant in Korea.

scholarly journals Alternaria alternata Causing Flower Stem Blight of Lupinus havardii

Plant Disease ◽  
2001 ◽  
Vol 85 (2) ◽  
pp. 231-231
Author(s):  
P. F. Colbaugh ◽  
W. A. Mackay ◽  
T. D. Davis
Keyword(s):  
El Paso ◽  
Commonwealth Mycological Institute ◽  
Blue Color ◽  
Cut Flowers ◽  
Disease Symptoms ◽  
Breeding Lines ◽  
Flower Stem ◽  
Pathogenicity Tests ◽  
Alternaria Sp ◽  
Growing Conditions

Lupinus havardii Wats., commonly known as Big Bend or Chisos bluebonnet, is a showy winter annual that can reach 1.0 to 1.5 m in height and produces blue, fragrant inflorescence (racemes). L. havardii is native to a narrow geographic range along the Mexican border in southwest Texas. The inflorescence of L. havardii has considerable potential in the cut flower industry where there is a need for high-quality, durable flowers with a blue color (1). Several crops have been produced in the greenhouse to determine production and post-harvest characteristics of the cut inflorescence. Under greenhouse growing conditions during March through June 1999, numerous plants of L. havardii cv. Texas Sapphire grown in raised beds and in containers in both Dallas and El Paso, TX, were observed with blighted flower racemes with light brown to gray lesions ranging from 1 to 5 cm in length. The racemes were attacked at varying ages and eventually assumed a hooked appearance where the terminal 15 cm of the raceme was bent downward. Isolations from symptomatic lesions removed from L. havardii flower stalks consistently yielded cultures of an Alternaria sp. on potato-dextrose agar. Typical conidia measured 27 μm length and 11 μm width with 3 to 5 transverse septa. The fungus was identified as A. alternata (Fries) Keissler consistent with the description in Ellis (2). Pathogenicity tests were conducted in the laboratory by inoculating cut inflorescences with agar disks containing the fungus. Inoculations produced light brown lesions on the racemes that were typical of disease symptoms observed on greenhouse crops. In addition to the blue-flowered Texas Sapphire cultivar, we also observed the disease symptoms on pink and white flowered breeding lines of L. havardii. This disease is important as a flower stem blighting pathogen and could severely restrict production of cut flowers during the growing season. This is the first report of Alternaria sp. attacking L. havardii. References: (1) T. D. Davis. HortScience 29:1110, 1994. (2) M. B. Ellis. 1971. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute Kew, England.

scholarly journals Co-Occurrence of Defoliating and Non-Defoliating Pathotypes of Verticillium Dahliae in Field-Grown Cotton Plants in New South Wales, Australia

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 750
Author(s):  
Duy P. Le ◽  
Aphrika Gregson ◽  
Thao T. Tran ◽  
Rodney Jackson
Keyword(s):  
Verticillium Dahliae ◽  
New South ◽  
New South Wales ◽  
Cotton Production ◽  
Major Constraint ◽  
South Wales ◽  
Cotton Plants ◽  
Pot Trials ◽  
Germination Traits ◽  
Highly Virulent

Verticillium wilt (VW) is a major constraint to cotton production in Australia and worldwide. The disease is caused by a soilborne fungus, Verticillium dahliae, a highly virulent pathogen on cotton. Commonly, V. dahliae is designated into two pathotypes: defoliating (D) and non-defoliating (ND), based on induced symptoms. In the previous two survey seasons between 2017 and 2019, stems with suspected VW were sampled for the confirmation of presence and distribution of D and ND pathotypes across New South Wales (NSW), Australia. A total of 151 and 84 VW-suspected stems sampled from the 2017/18 and 2018/19 seasons, respectively, were subjected to pathogen isolation. Of these, 94 and 57 stems were positive for V. dahliae; and 18 and 20 stems sampled respectively from the two seasons yielded the D pathotype isolates. Two stems from the 2017/18 season and one stem from 2018/19 season yielded both D and ND pathotype isolates. We also successfully demonstrated the co-infection of both pathotypes in pot trials, which was driven predominantly by either of the pathotypes, and appeared independent on vegetative growth, fecundity and spore germination traits. Our study is the first report of the natural co-occurrence of both D and ND pathotypes in same field-grown cotton plants in NSW, to which a challenge to the disease management will be discussed.

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