scholarly journals First Report of Neofusicoccum australe, N. luteum, and N. parvum Associated With Avocado Branch Canker in California

Plant Disease ◽  
2009 ◽  
Vol 93 (9) ◽  
pp. 967-967 ◽  
Author(s):  
V. McDonald ◽  
S. Lynch ◽  
A. Eskalen
Keyword(s):  
San Diego ◽  
Transmission Rate ◽  
Vascular Lesion ◽  
Persea Americana ◽  
Santa Barbara ◽  
First Report ◽  
5.8S Rdna ◽  
San Luis ◽  
Mycelial Plug ◽  
Botryosphaeriaceae Species

In 1953, branch cankers on California avocado (Persea americana Mill.) trees were attributed to a Botryosphaeria anamorph, Dothiorella gregaria (teleomorph B. ribis) (2), and the disease was known as Dothiorella canker. Since this time, it has been suggested that this fungus should probably be classified as Fusicoccum aesculi Corda (teleomorph B. dothidea) (3). To our knowledge, B. dothidea is the only reported Botryosphaeriaceae species causing Dothiorella canker on avocado in California. Between the summer of 2008 and the winter of 2009, five trees from each of eight avocado orchards in five counties (San Diego, Riverside, Ventura, Santa Barbara, and San Luis Obispo) were surveyed for Dothiorella canker symptoms to verify the associated Botryosphaeriaceae species. Typical Dothiorella canker symptoms observed included darkened and friable bark with a dried, white, powdery exudate. Underneath the bark, cankers were variable in shape and some penetrated into the heartwood. Small sections of tissue (0.5 cm2) were excised from two to four separate cankers per tree and placed onto potato dextrose agar amended with tetracycline (0.01%) (PDA-tet). The most frequently isolated fungi, based on general growth pattern, speed, and colony color, were in the Botryosphaeriaceae with the following percent recovery by county: Riverside–40 and 100% (site 1 and 2, respectively); San Diego–60% (site 3); Ventura–42 and 53% (site 4 and 5, respectively); Santa Barbara–33% (site 6); and San Luis Obispo–32 and 60% (site 7 and 8, respectively). Pycnidia of Botryosphaeriaceae species were also observed on old diseased avocado tree branches. Sequenced rDNA fragments (ITS1, 5.8S rDNA, ITS2, amplified with ITS4 and ITS5 primers) were compared with sequences deposited in GenBank. Four different Botryosphaeriaceae species were identified and included Neofusicoccum australe, B. dothidea, N. luteum, and N. parvum, with species nomenclature based on the work of Crous et al. (1). Pathogenicity tests were conducted in the greenhouse on 1-year-old avocado seedlings, cv. Hass, with one randomly chosen isolate from each of the Botryosphaeriaceae species noted above. Four replicate seedlings were stem-wound inoculated with a mycelial plug and covered with Parafilm. Sterile PDA plugs were applied to four seedlings as a control. Over a period of 3 to 6 months, seedlings were assessed for disease symptoms that included browning of leaf edges and shoot dieback. Mean vascular lesion lengths on stems were 64, 66, 64, and 18 mm for B. dothidea, N. parvum, N. luteum, and N. australe, respectively. Each fungal isolate was consistently reisolated from inoculated seedlings, thus fulfilling Koch's postulates. To our knowledge, this is the first report of N. australe, N. luteum, and N. parvum recovered from branch cankers on avocado in California. These results are significant because Botryosphaeriaceae canker pathogens are known to enter the host plant through fresh wounds (pruning, frost, and mechanical). With high-density planting becoming more common, which requires intensive pruning, the transmission rate of these pathogens could increase in California avocado groves. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) F. F. Halma and G. A. Zentmyer. Calif. Avocado Soc. Yearb. 38:156, 1953. (3) W. F. T. Hartill and K. R. Everett. N. Z. J. Crop Hortic. Sci. 30:249, 2002.

ENCLAVES OF VIOLENCE IN NINETEENTH- CENTURY CALIFORNIA

2004 ◽  
Vol 73 (3) ◽  
pp. 391-424 ◽  
Author(s):  
C. V. MCKANNA
Keyword(s):  
Sense Of Community ◽  
San Diego ◽  
Gold Rush ◽  
Criminal Court ◽  
Ethnic Variation ◽  
Santa Barbara ◽  
Court Records ◽  
Young Males ◽  
San Luis ◽  
Indian Lands

This essay examines homicide data (1,317 cases) collected from newspapers, coroners' inquests, and criminal court records in San Diego, Santa Barbara, San Luis Obispo, Sacramento, San Joaquin, Calaveras, and Tuolumne counties, which were selected because of regional and ethnic variation. The gold rush enticed thousands of young males who spent their leisure hours drinking and gambling in mining camps. Factors such as the boomtown effect and the critical convergence of young men, guns, alcohol, and minor grievances came together to create "enclaves of violence" in these gold camps, in Chinatowns, and in San Diego Indian lands. With the exception of Chinatowns, these enclaves lacked a sense of community. Consequently, they created the image of a violent society and re�ect the reality that parts of California, at certain times and places, were indeed violent.

First report of branch cankers on avocado (Persea americana) caused by Neocosmospora (syn. Fusarium) perseae in Crete (Greece)

2021 ◽  
Author(s):  
Vladimiro Guarnaccia ◽  
Dalia Aiello ◽  
Nikos Papadantonakis ◽  
Giancarlo Polizzi ◽  
M. Lodovica Gullino
Keyword(s):  
Persea Americana ◽  
First Report

scholarly journals Characterization and Pathogenicity of Botryosphaeriaceae Species Obtained from Avocado Trees with Branch Canker and Dieback and from Avocado Fruit with Stem End Rot in Chile

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 996-1005 ◽  
Author(s):  
Ana L. Valencia ◽  
Pilar M. Gil ◽  
Bernardo A. Latorre ◽  
I. Marlene Rosales
Keyword(s):  
Vascular System ◽  
Persea Americana ◽  
Effective Control ◽  
Future Research ◽  
Severe Drought ◽  
Internal Transcribed Spacer Region ◽  
Avocado Fruit ◽  
Hass Avocado ◽  
Botryosphaeriaceae Species ◽  
Branch Canker

Several species of the Botryosphaeriaceae family have been associated with branch canker, dieback, and stem end rot in avocado (Persea americana Mill.). In Chile, the incidence of diseases affecting the avocado tree increased from 2011 to 2016, which coincided with a severe drought that affected avocado production. Moreover, distant countries importing avocados from Chile also reported an increase of stem end rot of ripe avocados. Therefore, the aims of this study were to identify the pathogen species associated with branch canker, dieback, and stem end rot of avocado in Chile and to study their pathogenicity. This study was conducted between 2015 and 2016 in ‘Hass’ avocado orchards located in the main avocado-producing regions in Chile. A diverse collection of fungal species was recovered from both necrotic woody tissue and necrotic tissue on harvested ripe fruit. On the basis of morphology and phylogenetic analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2) and the translation elongation factor 1-α (TEF1-α) gene, eight species in the Botryosphaeriaceae family were identified: Diplodia mutila, D. pseudoseriata, D. seriata, Dothiorella iberica, Lasiodiplodia theobromae, Neofusicoccum australe, N. nonquaesitum, and N. parvum. For each of these species, pathogenicity studies were conducted on 1-year-old healthy Hass avocado plants. All isolates produced brown gum exudate and caused necrosis in the vascular system 3 weeks after inoculation. N. nonquaesitum, N. parvum, and D. pseudoseriata were the most virulent species. Necrotic lesions and cavities with white mycelia near the peduncle union were observed on Hass avocado fruit inoculated postharvest. L. theobromae, N. australe, and N. parvum were significantly more virulent than the other tested species in the Botryosphaeriaceae family. This study identified and characterized the pathogenicity of Botryosphaeriaceae species in Chile, which will prove useful to future research on these pathogens directed at establishing effective control strategies in avocado.

First Report of Fusarium euwallaceae Causing Necrotic Lesions on Persea americana in South Africa

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1774 ◽  
Author(s):  
N. van den Berg ◽  
M. du Toit ◽  
S. W. Morgan ◽  
G. Fourie ◽  
Z. W. de Beer
Keyword(s):  
South Africa ◽  
Persea Americana ◽  
First Report

scholarly journals First Report of Leptosphaeria biglobosa (Blackleg) on Brassica oleracea (Cabbage) in Mexico

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 791-791 ◽  
Author(s):  
A. Dilmaghani ◽  
M. H. Balesdent ◽  
T. Rouxel ◽  
O. Moreno-Rico
Keyword(s):  
Brassica Oleracea ◽  
Sequence Data ◽  
Leptosphaeria Maculans ◽  
The United States ◽  
Internal Transcribed Spacers ◽  
First Report ◽  
5.8S Rdna ◽  
Single Location ◽  
Leptosphaeria Biglobosa ◽  
Β Tubulin

Broccoli (Brassica oleracea var. italica), cauliflower (B. oleracea var. botrytis), and cabbage (B. oleracea var. capitata) have been grown in central Mexico since 1970, with 21,000 ha cropped in 2001. In contrast, areas grown with oilseed rape (B. napus) are very limited in Mexico (<8,000 ha). Blackleg, a destructive disease of B. napus in most parts of the world, was first observed in Mexico in Zacatecas and Aguascalientes in 1988 on B. oleracea, causing as much as 70% yield loss. A species complex of two closely related Dothideomycete species, Leptosphaeria maculans and L. biglobosa, is associated with this disease of crucifers (1), but leaf symptoms on susceptible plants are different, with L. maculans typically causing >15-mm pale gray lesions with numerous pycnidia, whereas L. biglobosa causes dark and smaller lesions only containing a few pycnidia. Having a similar epidemiology, both species can be present on the same plants at the same time, and symptom confusion can occur as a function of the physiological condition of the plant or expression of plant resistance responses. A total of 209 isolates from symptomatic B. oleracea leaves were collected from three fields in central states of Mexico (58 to 71 isolates per location). All leaves showed similar symptoms, including a 10- to 15-mm tissue collapse with an occasional dark margin. Cotyledons of seven B. napus differentials were inoculated with conidia of all the isolates as described by Dilmaghani et al. (1). Two hundred isolates caused tissue collapse typical of L. maculans. However, nine obtained from white cabbage in a single location in Aguascalientes caused <5-mm dark lesions. When inoculated onto cotyledons of three B. oleracea genotypes commonly grown in Mexico (cvs. Domador, Monaco, and Iron Man), the nine isolates caused a range of symptoms characterized by tissue collapse (maximum 10 to 15 mm), showing the presence of patches of black necrotic spots within the collapse. The occasional presence of a few pycnidia allowed us to reisolate the fungus for molecular identification. ITS1-5.8S-ITS2, (internal transcribed spacers and 5.8S rDNA), actin, and β-tubulin sequences were obtained as described previously (4). Multiple gene genealogies based on these sequence data showed two subclades of L. biglobosa: L. biglobosa ‘occiaustralensis’ (one isolate; ITS [AM410082], actin [AM410084], and β-tubulin [AM410083]) and L. biglobosa ‘canadensis’ (eight isolates; ITS [AJ550868], actin [AY748956], and β-tubulin [AY749004]) (3,4), which were previously described on B. napus in the United States, Canada, and Chile. To our knowledge, this is the first report of L. biglobosa in Mexico. Previously, this species has only been reported once on B. oleracea without discrimination into subclades (2). In the Aguascalientes sampling, 24% of the isolates were L. biglobosa, similar to Canadian locations where this species is still common as compared with L. maculans (1). The large proportion of sampled L. biglobosa ‘canadensis’, highlights the prevalence of this subclade throughout the American continent (1). References: (1) A. Dilmaghani et al. Plant Pathol. 58:1044, 2009. (2) E. Koch et al. Mol. Plant-Microbe Interact. 4:341, 1991. (3) E. Mendes-Pereira et al. Mycol Res. 107:1287, 2003. (4) L. Vincenot et al. Phytopathology 98:321, 2008.

scholarly journals First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Colombia

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 143-143 ◽  
Author(s):  
M. Cadavid ◽  
J. C. Ángel ◽  
J. I. Victoria
Keyword(s):  
Internal Transcribed Spacer ◽  
Pcr Primers ◽  
The United States ◽  
Optical Microscope ◽  
First Report ◽  
5.8S Rdna ◽  
Specific Pcr ◽  
Plant Pathol ◽  
Species Specific ◽  
New Cultivars

Symptoms of sugarcane orange rust were first observed in July 2010 on sugarcane (interspecific hybrid of Saccharum L. species) cv. CC 01-1884 planted in the La Cabaña Sugar Mill, Puerto Tejada, Colombia. Morphological features of uredinial lesions and urediniospores inspected with an optical microscope and scanning electron microscopy were distinct from common rust of sugarcane caused by Puccinia melanocephala Syd. & P. Syd., revealing spores identical morphologically to those described for the fungus P. kuehnii (Kruger) E. Butler, causal agent of sugarcane orange rust (1,3). Uredinial lesions were orange and distinctly lighter in color than pustules of P. melanocephala. Urediniospores were orange to light cinnamon brown, mostly ovoid to pyriform, variable in size (27.3 to 39.2 × 16.7 to 21.2 μm), with pronounced apical wall and moderately echinulate with spines evenly distributed. Paraphyses, telia, and teliospores were not observed. Species-specific PCR primers designed from the internal transcribed spacer (ITS)1, ITS2, and 5.8S rDNA regions of P. melanocephala and P. kuehnii were used to differentiate the two species (2). The primers Pm1-F and Pm1-R amplified a 480-bp product from P. melanocepahala DNA in leaf samples with symptoms of common rust. By contrast, the primers Pk1-F and Pk1-R generated a 527-bp product from presumed P. kuehnii DNA in leaf samples with signs of orange rust, confirming the identity as P. kuehnii. The Centro de Investigación de la Caña de Azúcar de Colombia (Cenicaña) started a survey of different cultivars in nurseries and experimental and commercial fields in the Cauca River Valley and collected leaf samples for additional analyses. Experimental cvs. CC 01-1884, CC 01-1866, and CC 01-1305 were found to be highly susceptible to orange rust and were eliminated from regional trials, whereas commercial cvs. CC 85-92 and CC 84-75, the most widely grown cultivars, were resistant. With the discovery of orange rust of sugarcane in Colombia, Cenicaña has incorporated orange rust resistance in the selection and development of new cultivars. To our knowledge, this is the first report of P. kuehnii on sugarcane in Colombia. Orange rust has also been reported from the United States, Cuba, Mexico, Guatemala, Nicaragua, El Salvador, Costa Rica, Panama, Ecuador, and Brazil. References: (1) J. C. Comstock et al. Plant Dis. 92:175, 2008. (2) N. C. Glynn et al. Plant Pathol. 59:703, 2010. (3) E. V. Virtudazo et al. Mycoscience 42:167, 2001.

scholarly journals First Report of White Mold Caused by Sclerotinia sclerotiorum on Oreganum vulgare and Taraxacum officinale in Italy

Plant Disease ◽  
2007 ◽  
Vol 91 (10) ◽  
pp. 1360-1360
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Soil Surface ◽  
Taraxacum Officinale ◽  
White Mold ◽  
Economic Losses ◽  
Medicinal Uses ◽  
First Report ◽  
Potted Plants ◽  
Mycelial Plug ◽  
Commercial Farms

Oreganum vulgare (wild marjoram) and Taraxacum officinale (dandelion) plants with culinary and medicinal uses are grown in the field and as potted plants in Liguria in northern Italy. In the spring of 2006, extensive chlorosis was observed on both crops on commercial farms. Economic losses were low. Symptoms included foliar necrosis and a watery decay of the stem at the soil level. Necrotic tissues became covered with a whitish mycelium that produced dark sclerotia. Eventually, affected plants wilted and died. Samples of diseased stem tissue were surface sterilized for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 mg/l of streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary (1) was consistently recovered from diseased stem pieces. Sclerotia from infected O. vulgare plants measured 1.8 to 3.4 × 1.8 to 6.1 (average 2.5 to 3.6) mm. Sclerotia from these isolates measured 1.3 to 4.7 × 1.6 to 6.1 (average 2.7 to 3.4) mm on PDA. Sclerotia from infected T. officinale plants measured 1.8 to 3.4 × 1.8 to 6.1 (average 2.5 to 3.6) mm. Sclerotia from these isolates measured 1.7 to 5.2 × 2.0 to 5.7 (average 3.3 to 3.8) mm on PDA. Pathogenicity of three isolates obtained from O. vulgare and three isolates from T. officinale was confirmed on each host. Inoculum consisted of 1 cm2 of mycelial plugs excised from a 10-day-old PDA culture of each isolate. Plants were inoculated by placing a mycelial plug on the soil surface around the base of each plant. Ten plants were inoculated per isolate and an equal number of noninoculated plants served as controls. Plants were incubated at 10 to 27°C (average 18°C) and watered as needed. Pathogenicity tests were repeated once. All inoculated plants developed chlorosis within 12 to 18 days, followed by the appearance of white mycelium and sclerotia, and eventually wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants of both hosts. To our knowledge, this is the first report of white mold on O. vulgare in Italy as well as worldwide and the first report of white mold on T. officinale in Italy. S. sclerotiorum is a well known pathogen of T. officinale (2) and its use as a mycoherbicide has been proposed (3). References: (1) N. F. Buchwald. Page 75. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949. (2) D. M. McLean. Plant Dis. Rep. 35:162, 1951 (3) G. E. Riddle et al. Weed Sci. 39:109, 1991.

scholarly journals First Report of Black Spots on Avocado Fruit Caused by Neofusicoccum parvum in Mexico

Plant Disease ◽  
2012 ◽  
Vol 96 (2) ◽  
pp. 287-287 ◽  
Author(s):  
E. Molina-Gayosso ◽  
H. V. Silva-Rojas ◽  
S. García-Morales ◽  
G. Avila-Quezada
Keyword(s):  
Average Length ◽  
Black Spot ◽  
Persea Americana ◽  
Universal Primers ◽  
Internal Transcribed Spacer Region ◽  
Pathogenic Potential ◽  
Neofusicoccum Parvum ◽  
First Report ◽  
Black Spots ◽  
Avocado Fruit

Avocado (Persea americana L.) production for export markets has increased in Mexico during the past 10 years. The production system, however, is affected by several sanitation factors, including diseases. During the spring of 2009, smooth, black, circular spots were noted on the surface of avocado fruit. A study was conducted during the winter of 2010 to ascertain the etiology and identify the fungus associated with black spot symptoms on avocado fruit in orchards of Nuevo Parangaricutiro County (19°25′00″ and 102°07′43″) in Michoacan, Mexico. Several fungal isolates were obtained on potato dextrose agar (PDA) from the margin of lesions on immature fruit. The internal transcribed spacer region (ITS) of the rDNA from representative isolates was sequenced with universal primers ITS5 and ITS4 (2). BLAST searches in GenBank showed 100% similarity of the nucleotide sequences with Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, GenBank Accession Nos. GU188001 to GU188007 and GU187985 to GU187987. A representative nucleotide sequence of this region was deposited in GenBank under the Accession No. JN203129. Strains of N. parvum produced aerial and compact mycelium on acidified PDA, the anamorph state of Botryosphaeria parva. Mycelium was initially white, turning gradually gray to black. Conidia were one celled, hyaline, ellipsoidal to fusiform, externally smooth, thin walled, nonseptate, with one or two septa with age, and an average length and width of 14.5 (9.5 to 19) × 5.8 (4.0 to 7.2) μm (n = 100). Pathogenicity tests were conducted with six avocado fruit cv. Hass. Fruit were inoculated at three evenly spaced locations on the fruit surface, either by wounding the tissue with a needle that had been dipped in a conidial mass from an 8-day-old monoconidial culture of N. parvum strain CIAD-021-11 or by placing 5 μl of 1 × 106 conidia ml–1 suspension on each inoculation site. Inoculated fruit were maintained in a moist chamber at 25°C for 2 weeks. Black lesions appeared on all wounded sites 2 days postinoculation (dpi) and on unwounded sites 4 dpi. The delay of symptom development was likely due to penetration through the lenticels, which took longer to initiate infection. No symptoms were observed in the control fruit. The pathogen was reisolated from the lesions of all inoculated fruit, thus fulfilling Koch's postulates. The results confirmed the pathogenic potential of this fungus and indicated its possible involvement in the etiology of black spot on avocado fruit. N. parvum is a cosmopolitan, plurivorous pathogen causing disease in several hosts of economic importance, such as grapes and kiwi, as well as causing stem-end rot of avocado fruit in New Zealand (1) and avocado twigs in Spain (3). To our knowledge, this is the first report of N. parvum causing black spots on avocado fruit in Mexico. References: (1) W. F. T. Hartill et al. N.Z.J. Crop Hortic. Sci. 30:249. 2002. (2) T. J. White et al. Page: 315 in: PCR Protocols: A Guide to Methods and Application. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990. (3) T. Zea-Bonilla et al. Plant Dis. 91:1052, 2007.

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