scholarly journals First Report of Sclerotinia Rot on Blueberry Caused by Sclerotinia sclerotiorum in Argentina

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 774-774 ◽  
Author(s):  
B. A. Perez ◽  
O. M. Farinon ◽  
M. F. Berretta
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Continuous Light ◽  
Pathogenic Fungi ◽  
Vaccinium Corymbosum ◽  
Universal Primers ◽  
Highbush Blueberry ◽  
Buenos Aires Province ◽  
Laboratory Manual ◽  
First Report ◽  
Sclerotinia Rot

In October 2007, blighted shoots were observed on highbush blueberry (Vaccinium corymbosum L. cv. O'Neal) plants in La Plata, Buenos Aires Province, Argentina. Isolations from surface-disinfested shoots onto carrot agar and Spezieller Nahrstoffarmer Agar (SNA) consistently yielded white colonies that produced black sclerotia, mainly near the edge of the culture plates, after 7 days. Sclerotia were transferred to SNA tubes and kept at 5°C for several months. The germination of sclerotia produced numerous 6 mm long initials, stipitate pale brown cup-shaped apothecia (10 × 6 mm) with eight-spored asci (137 × 7 μm) at 18°C and continuous light conditions. Asci with uniseriate ascospores were cylindrical and narrow at the base. Ascospores (11 to 12 × 4 μm) were hyaline, unicellular, smooth, and ellipsoid. This isolated fungus was morphologically identified as Sclerotinia sclerotiorum (Lib.) de Bary (2,3). The isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 87. Mycelium was cultured in 100 ml of Czapek's-Dox medium, supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins (1), for 3 days and fungal DNA was obtained using a DNA extraction kit. ITS1 and ITS2 of ribosomal genes were amplified by PCR using universal primers (4) and the PCR product was sequenced. A BLAST algorithm search revealed 100% identity of the sequence with 12 GenBank entries for S. sclerotiorum. The nucleotide sequence was deposited in the GenBank with Accession No. JF277567. Pathogenicity testing was achieved by placing detached leaves of cvs. Emerald, Misty, and Start on water agar (WA) plates, inoculating with 9-mm2 mycelial blocks, and incubating at 20°C with 12 h of light. Young shoots of highbush blueberry, Misty and O'Neal, were inoculated by the cut shoot method with micropipette tips filled with mycelium and kept under greenhouse conditions at 24°C and 14 h of light. On control plants, WA blocks or WA-filled micropipette tips were used. Leaf blight was observed after 5 to 6 days and sclerotia appeared after 7 days on inoculated tissues. Shoot blight was recorded on inoculated plants after 5 days. The fungus was reisolated from inoculated tissues, with no symptoms showing on controls. To our knowledge, this is the first report of Sclerotinia rot caused by S. sclerotiorum in blueberry in Argentina. References: (1) J.F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Hoboken, NJ, 2006. (2). J. E. M. Mourde and P. Holliday. No. 513 in: CMI Descriptions of Pathogenic Fungi and Bacteria. Kew, Surrey, UK, 1976. (3) S. Umemoto et al. Gen. Plant Pathol. 73:290, 2007. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Root Rot Caused by Fusarium proliferatum on Blueberry in Argentina

Plant Disease ◽  
2011 ◽  
Vol 95 (11) ◽  
pp. 1478-1478 ◽  
Author(s):  
B. A. Pérez ◽  
M. F. Berretta ◽  
E. Carrión ◽  
E. R. Wright
Keyword(s):  
Root Rot ◽  
Its Region ◽  
Vaccinium Corymbosum ◽  
Fusarium Proliferatum ◽  
Highbush Blueberry ◽  
Buenos Aires Province ◽  
Distilled Water ◽  
First Report ◽  
Potted Plants ◽  
Water Plants

In 2009, a highbush blueberry (Vaccinium corymbosum L. ‘O'Neal’) field located in Rojas, Buenos Aires Province showed 30% of plants with dry or dead branches. Disinfected root pieces were placed on water agar and incubated at 24°C. A fungal colony was obtained and purified by successive transfers of an individual hyphal tip from a sparsely growing colony. Colony color and growth rate were evaluated in potato dextrose agar where the fungus produced white-to-pale pink colonies and grew 3.5 cm after 5 days. The fungus was studied on Spezieller Nährstoffarmer agar (2), carnation leaf-piece agar, and KCl agar where it produced abundant single-celled hyaline microconidia in moderate-length chains and in false heads originated from monophialides and polyphialides. Microconidia measured 6 to 12 × 2 to 3 μm (average 8 × 2.3 μm). On KCl, chains of microconidia and tan-to-light cream sporodochia with 3- to 5-septate, slender, relatively straight macroconidia were easily observed after 4 and 10 days, respectively. Macroconidia measured 38 to 48 × 3.5 to 4 μm (average 43.9 × 3.9 μm). Chlamydospores and sclerotia were not present. Data coincided with the description for Fusarium proliferatum (Matsush.) Niremberg ex Gerlach & Niremberg. The isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 144. The fungus was cultured in 100 ml of Czapek-Dox supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins for 4 days. Genomic DNA was obtained with a DNA extraction kit, PCR amplified with primers ITS1 and ITS4 for the internal transcribed spacer (ITS) region of ribosomal genes, and sequenced. The nucleotide sequence (Accession No JF913468) was compared with GenBank records. The sequence shared 99% identity with Accession No HQ113948 for F. proliferatum. Pathogenicity was confirmed in 1-year-old ‘O'Neal’ plants. A 10-ml suspension (2.4 × 106 conidia/ml in sterile distilled water) was applied to six potted plants grown in sterilized potting mix. Roots were superficially wounded with a needle. Control plants were treated with sterile distilled water. Plants were incubated at 24°C and a 12-h photoperiod. After 90 days, plants showed root rot, leaf chlorosis, and branch necrosis followed by plant death. Control plants remained healthy. F. proliferatum was reisolated from diseased roots of inoculated plants. This fungus was previously cited in Argentina on asparagus (1), corn (1,3), and oat (4). To our knowledge, this is the first report of F. proliferatum as a root pathogen of highbush blueberry in Argentina. References: (1) G. Lori et al. Plant Dis. 82:1405, 1998. (2) H. I. Nirenberg. Releases Fed. Biol. Res. Ctr. Agric. For. (Berlin-Dahlem) 169:1, 1976. (3) D. A. Sampietro et al. Fung. Biol. 114:74, 2010. (4) S. A. Stenglein et al. Plant Dis. 94:783, 2010.

scholarly journals First Report of Fusarium oxysporum f. sp. lycopersici Race 3 and F. oxysporum f. sp. radicis-lycopersici in Tomatoes in the Azapa Valley of Chile

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1432-1432 ◽  
Author(s):  
G. Sepúlveda-Chavera ◽  
W. Huanca ◽  
R. Salvatierra-Martínez ◽  
B. A. Latorre
Keyword(s):  
Fusarium Oxysporum ◽  
Tap Water ◽  
Universal Primers ◽  
Conidial Suspension ◽  
Laboratory Manual ◽  
First Report ◽  
Solanum Lycopersicum L ◽  
Vascular Discoloration ◽  
Seedling Roots ◽  
Pcr Assays

Tomato (Solanum lycopersicum L.) is an important crop in the Azapa Valley (18°35′ S, 69°30′ W) in northern Chile, with approximately 600 ha of fresh tomatoes under greenhouses. Cultivars resistant to Fusarium oxysporum f. sp. lycopersici (FOL) races 1 and 2 are mainly used. However, in 2012 and 2013, Fusarium wilt incidence was 2 to 3%. Symptoms appeared unilaterally and consisted of yellowing, leaf wilting of lower leaves, dark brown vascular discoloration, and plant death. The aim of this study was to determine the causal agent of tomato wilt in seven tomato greenhouses in the Azapa Valley. Stem samples (5 × 5 mm) were obtained 10 cm of the stem base from wilted tomatoes ‘Naomi’ (BIOAMERICA S.A., Chile) or from Maxifort tomato rootstock (De Ruiter Seed, USA), both FOL resistant to races 1 and 2. Samples were washed with tap water, surface sterilized with 1% NaClO for 3 min, and incubated on sterile moist paper towels in petri plates for 5 days at 22°C. Mycelial fragments from white colonies, emerging from diseased tissues, were transferred to PDA. Six Fusarium isolates were characterized by the presence of hyaline macroconidia, mostly 3 to 5 septate, slightly curved (19.2 to 32.1 × 2.9 to 4.5 μm) and single-celled, oval to elongated microconidia (3.1 to 8.9 × 2.0 to 4.0 μm). Chlamydospores were single or in pairs. These isolates were identified as F. oxysporum (3). The identity of F. oxysporum was confirmed by PCR assays using genomic DNA of each isolated and the universal primers Uni F and Uni R that generate a 672-bp PCR product. The pathogenic form and races were determined by PCR assays using the specific primers uni, sp13, sp23, and sprl that were able to discriminate all the three FOL races as well as F. oxysporum f. sp. radicis-lycopersici (FORL) isolates (2). The sp13 and sp23 primers amplified DNA bands of 445 and 518 bp, confirming the identity of FOL race 3. However, sprl amplified a fragment of 947 bp corresponding to FORL (2). Pathogenicity tests were conducted on 25-day-old seedlings (10 seedlings per isolate) of tomato ‘Poncho Negro,’ which is susceptible to FOL and FORL. Seedling roots were cut, submerged for 5 min in conidial suspension of 2 × 106 conidia/ml, and transplanted to 250-ml plastic containers with sterile substrate (sand/peat, 1:1). Equally treated non-inoculated seedlings were left as controls. The first symptoms induced by each of the five FOL isolates appeared 8 days after incubation under greenhouse and were characterized by yellowing of older leaves, sometimes affecting one side of the plant, vascular discoloration of the stem, and eventually plant death. In contrast, all seedlings inoculated with a FORL isolate developed a necrotic lesion and vascular discoloration at the base of the stems near the soil line, followed by wilting and plant death. Control plants remained asymptomatic. F. oxysporum was re-isolated only from inoculated plants, completing Koch's postulates. FOL and FORL were reported earlier in other tomato growing areas of Chile (1), located over 1,000 km south of the Azapa Valley. However, this is the first report of FOL race 3 and FORL in the Azapa Valley and FOL race 3 is reported for the first time in Chile. References: (1) S. Acuña. Compendio de Fitopatógenos de Cultivos Agrícolas. Servicio Agrícola y Ganadero. Gobierno de Chile, 2008. (2) Y. Hirano and T. Arie. J. Gen. Plant Pathol. 72:273, 2006. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

scholarly journals First Report of Alternaria Leaf Spot Caused by Alternaria sp. on Highbush Blueberry (Vaccinium corymbosum) in South Korea

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1434-1434
Author(s):  
J.-H. Kwon ◽  
D.-W. Kang ◽  
M.-G. Cheon ◽  
J. Kim
Keyword(s):  
South Korea ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Vaccinium Corymbosum ◽  
Its Rdna ◽  
Universal Primers ◽  
Conidial Suspension ◽  
First Report ◽  
Representative Isolate ◽  
Alternaria Sp

In South Korea, the culture, production, and consumption of blueberry (Vaccinium corymbosum) have increased rapidly over the past 10 years. In June and July 2012, blueberry plants with leaf spots (~10% of disease incidence) were sampled from a blueberry orchard in Jinju, South Korea. Leaf symptoms included small (1 to 5 mm in diameter) brown spots that were circular to irregular in shape. The spots expanded and fused into irregularly shaped, large lesions with distinct dark, brownish-red borders. The leaves with severe infection dropped early. A fungus was recovered consistently from sections of surface-disinfested (1% NaOCl) symptomatic leaf tissue after transfer onto water agar and sub-culture on PDA at 25°C. Fungal colonies were dark olive and produced loose, aerial hyphae on the culture surfaces. Conidia, which had 3 to 6 transverse septa, 1 to 2 longitudinal septa, and sometimes also a few oblique septa, were pale brown to golden brown, ellipsoid to ovoid, obclavate to obpyriform, and 16 to 42 × 7 to 16 μm (n = 50). Conidiophores were pale to mid-brown, solitary or fasciculate, and 28 to 116 × 3 to 5 μm (n = 50). The species was placed in the Alternaria alternata group (1). To confirm the identity of the fungus, the complete internal transcribed spacer (ITS) rDNA region of a representative isolate, AAVC-01, was amplified using ITS1 and ITS4 primers (2). The DNA products were cloned into the pGEM-T Easy vector (Promega, Madison, WI) and the resulting pOR13 plasmid was sequenced using universal primers. The resulting 570-bp sequence was deposited in GenBank (Accession No. KJ636460). Comparison of ITS rDNA sequences with other Alternaria spp. using ClustalX showed ≥99% similarity with the sequences of A. alternata causing blight on Jatropha curcas (JQ660842) from Mexico and Cajannus cajan (JQ074093) from India, citrus black rot (AF404664) from South Africa, and other Alternaria species, including A. tenuissima (WAC13639) (3), A. lini (Y17071), and A. longipes (AF267137). Two base substitutions, C to T at positions 345 and 426, were found in the 570-bp amplicon. Phylogenetic analysis revealed that the present Alternaria sp. infecting blueberry grouped separately from A. tenuissima and A. alternata reported from other hosts. A representative isolate of the pathogen was used to inoculate V. corymbosum Northland leaves for pathogenicity testing. A conidial suspension (2 × 104 conidia/ml) from a single spore culture and 0.025% Tween was spot inoculated onto 30 leaves, ranging from recently emerged to oldest, of 2-year-old V. corymbosum Northland plants. Ten leaves were treated with sterilized distilled water and 0.025% Tween as a control. The plants were kept in a moist chamber with >90% relative humidity at 25°C for 48 h and then moved to a greenhouse. After 15 days, leaf spot symptoms similar to those observed in the field developed on the inoculated leaves, whereas the control plants remained asymptomatic. The causal fungus was re-isolated from the lesions of the inoculated plants to fulfill Koch's postulates. To our knowledge, this is the first report of Alternaria sp. on V. corymbosum in South Korea. References: (1) E. G. Simmons. Page 1797 in: Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (3) M. P. You et al. Plant Dis. 98:423, 2014.

scholarly journals First report of Armillaria gallica on highbush blueberry (Vaccinium corymbosum) in Italy

2006 ◽  
Vol 55 (4) ◽  
pp. 583-583 ◽  
Author(s):  
D. Prodorutti ◽  
L. Palmieri ◽  
D. Gobbin ◽  
I. Pertot
Keyword(s):  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
First Report ◽  
Armillaria Gallica

scholarly journals First Report of Diaporthe australafricana Associated with Stem Canker on Blueberry in Chile

Plant Disease ◽  
2012 ◽  
Vol 96 (5) ◽  
pp. 768-768 ◽  
Author(s):  
B. A. Latorre ◽  
K. Elfar ◽  
J. G. Espinoza ◽  
R. Torres ◽  
G. A. Díaz
Keyword(s):  
Vitis Vinifera ◽  
Vascular Tissue ◽  
Its Region ◽  
Pathogenic Fungi ◽  
Stem Canker ◽  
Vaccinium Corymbosum ◽  
Academic Press ◽  
First Report ◽  
Potted Plants ◽  
Blastn Analysis

Stem cankers of blueberry (Vaccinium corymbosum L.) have been observed on as much as 15% of the plants in plantations in central and southern Chile since 2006. Symptoms consisted of apical necrosis of the shoots and brown-to-reddish necrotic lesions on the stems. Internally, a brown-to-reddish discoloration of the vascular tissue can be observed. Twenty, single-plant samples were collected in 12 blueberry plantings (approximately 33°27′ to 40°53′S). Isolations from the margins of the necrotic lesions on the stems were made by plating small pieces (5 mm) on potato dextrose agar acidified with 0.5 μl/ml of 92% lactic acid (APDA). The plates were incubated at 20°C for 5 to 7 days, and hyphal tips of white colonies with septate and hyaline mycelium were transferred to APDA. Colonies were then transferred to autoclaved Pinus radiata needles on 2% water agar and incubated for 20 days at 20°C. Twelve isolates producing black pycnidia and alpha conidia were tentatively identified as a Phomopsis sp. (teleomoph Diaporthe Nitschke). Other fungi, including Botryosphaeriaceae spp. and Pestalotiopsis spp., were also isolated. Alpha conidia were smooth, unicellular, hyaline, fusoid, biguttulate, and 6.4 to 7.9 × 2.3 to 3.3 μm (n = 20). Beta conidia were not observed. The internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1 and ITS2 (4) and sequenced. BLASTn analysis of the 473-bp fragment (GenBank Accession No. JQ045712) showed 100% identity to Diaporthe australafricana Crous & J.M. van Niekerk from Vitis vinifera (3). The pathogenicity of D. australafricana was studied on blueberry cv. O'Neal using detached stems (n = 4) in the laboratory, on 2-year-old potted plants (n = 4) in a greenhouse, and on attached stems of mature plants (n = 4) established in the ground. Inoculations were done by placing mycelial plugs taken from 7-day-old APDA cultures in a 7-mm long incision made on the stems. Inoculations with sterile mycelium plugs served as negative controls. Inoculation sites were wrapped with Parafilm to avoid rapid dehydration. Dark brown, necrotic lesions on the internal tissues were obtained on all inoculated stems 15 days after inoculation. Mean lesion lengths were 18.0 ± 7.4 mm on detached stems, 7.8 ± 6.9 mm on stems of 2-year-old plants, and 7.3 ± 2.5 mm on mature plants in the field. No symptoms developed on control stems. Reisolations were successful in 100% of the inoculated stems and D. australafricana was confirmed by the presence of pycnidia and alpha conidia. To our knowledge, this is the first report of D. australafricana causing stem canker in V. corymbosum. Previously, this pathogen has been reported to be affecting Vitis vinifera in Australia and South Africa (3). These results do not exclude that other plant-pathogenic fungi may be involved in this syndrome (1,2). References: (1) J. G. Espinoza et al. Plant Dis 92:1407, 2008. (2) J. G. Espinoza et al. Plant Dis. 93:1187, 2009. (3) J. M. van Niekerk et al. Australas. Plant Pathol. 34:27, 2005. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, NY, 1990.

scholarly journals First Report of Sclerotinia sclerotiorum on Common Ragweed (Ambrosia artemisiifolia) in Europe

Plant Disease ◽  
1999 ◽  
Vol 83 (3) ◽  
pp. 302-302 ◽  
Author(s):  
Gy. Bohár ◽  
L. Kiss
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Aerial Mycelium ◽  
The United States ◽  
Ambrosia Artemisiifolia ◽  
American Phytopathological Society ◽  
Common Ragweed ◽  
First Report ◽  
Sclerotinia Rot ◽  
Stem Lesions ◽  
Test Plants

Common ragweed (Ambrosia artemisiifolia L.) is reported as a host of Sclerotinia sclerotiorum (Lib.) de Bary in North America (2,4), but not in Europe. A Hungarian survey of fungal diseases of ragweed in 1994 did not find sclerotinia rot of common ragweed (A. artemisiifolia var. elatior (L.) Descourt.) (1). In autumn 1998, mature ragweed plants, 1 to 1.5 m tall, were collected from the borders of four sunflower (Helianthus annuus L.) fields in which sclerotinia rot of sunflower was frequently observed during the season, and also from six other roadside sites in Hungary. Ragweed plants exhibiting symptoms characteristic of sclerotinia rot, i.e., wilting foliage and light brown, dry lesions on the stems, were found only near two sunflower fields. Black, round to irregular or oblong sclerotia were also observed on the infected ragweed plants both externally on the stem lesions and internally, in the pith cavity. Sclerotia measured up to 5 mm in diameter and were 5 to 14 mm long. After isolation on potato dextrose agar, the pathogen produced abundant aerial mycelium and large sclerotia characteristic of S. sclerotiorum. To confirm pathogenicity, potted seedlings and mature plants of ragweed were inoculated in the greenhouse with autoclaved wheat grains colonized with mycelia of S. sclerotiorum placed 0.5 to 1 cm from the collar of the test plants. Seedlings were killed in 2 to 3 days while mature plants wilted after 5 to 6 days. In a field test, six mature plants were inoculated by attaching mycelial disks to their stems with Parafilm. These plants wilted 12 to 14 days after inoculation. The pathogen was reisolated from all diseased plants. This is the first report of S. sclerotiorum on common ragweed in Europe. Nonsclerotial mutants of the fungus (3) are being produced to be tested as potential biocontrol agents of common ragweed, which has become not only the most widespread, but also the most important allergenic plant species in Hungary since the early 1990s. References: (1) Gy. Bohár and L. Vajna. Nōvényvédelem 32:527, 1996. (2) G. J. Boland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (3) G. J. Boland and E. A. Smith. Phytopathology 81:766, 1991.(4) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

scholarly journals First Report of Sclerotinia Rot in Sword Bean Caused by Sclerotinia sclerotiorum in South Korea

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 988-988
Author(s):  
I. Han ◽  
K. Park ◽  
H. Lee ◽  
S.-M. Lee ◽  
J. Shin ◽  
...  
Keyword(s):  
South Korea ◽  
Sclerotinia Sclerotiorum ◽  
First Report ◽  
Sclerotinia Rot

scholarly journals First Report of Blueberry Leaf Rust Caused by Thekopsora minima on Vaccinium corymbosum in Michigan

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 768-768 ◽  
Author(s):  
A. M. C. Schilder ◽  
T. D. Miles
Keyword(s):  
South Africa ◽  
New York ◽  
Leaf Rust ◽  
Vaccinium Corymbosum ◽  
Economic Losses ◽  
Its2 Region ◽  
Highbush Blueberry ◽  
Alternate Host ◽  
First Report ◽  
Growing Seasons

Leaf rust symptoms have been noticed sporadically on northern highbush blueberry plants (Vaccinium corymbosum L.) in Michigan for the past 8 years. In 2009, leaf rust was seen in several cultivated blueberry fields and on greenhouse-grown blueberry plants in southwest Michigan. In 2010, leaf rust was widespread throughout western Michigan and particularly evident in the fall, sometimes resulting in premature defoliation. Cultivars Rubel, Jersey, Elliott, Liberty, and Brigitta were most commonly affected. Both the 2009 and 2010 growing seasons were characterized by above-average precipitation in early to mid-summer. Early symptoms on the adaxial leaf surface consisted of roughly circular yellow spots that later developed brown, necrotic centers. Older lesions were more angular and sometimes surrounded by a purplish border. In the fall, a “green island” effect was sometimes apparent around the lesions. On the abaxial side, numerous yellow-to-orange rust pustules (uredinia) were visible. Uredinia were dome shaped, erumpent, 100 to 400 μm in diameter, clustered, and sometimes coalescing. Urediniospores were broadly obovate with dark yellowish content and measured 19 to 25 × 16 to 20 μm (average 22 × 18 μm, n = 30). Spore walls were hyaline, echinulate, and 1.0 to 1.5 μm thick with obscure germ pores. Uredinia were examined with light and scanning electron microscopy for the presence of conspicuous ostiolar cells characteristic of Naohidemyces vaccinii (Wint.) Sato, Katsuya et Y. Hiratsuka, but none were observed. No telia or teliospores were observed. On the basis of morphology, the pathogen was identified as Thekopsora minima P. Syd. & Syd. (3,4) and a sample was deposited in the U.S. National Fungus Collection (BPI 881107). Genomic DNA was extracted from urediniospores of rust isolates from six different locations, and a 267-bp fragment of the ITS2 region was amplified and sequenced using the primers ITS3 and ITS4 (GenBank Accession No. HQ661383). All sequences were identical to each other and shared 99% identity (232 of 234 bp) with a T. minima isolate from South Africa (GenBank Accession No. GU355675). The alternate host, hemlock (mostly Tsuga canadensis L.) is a common and valuable conifer in the Michigan landscape. Hemlock trees were not examined for the presence of aecia but are assumed to play a role in the epidemiology of the disease in Michigan because leaf rust tends to be more severe near hemlock trees. Pucciniastrum vaccinii (G. Wint.) Jorst. was considered the causal agent of blueberry leaf rust until Sato et al. (1,4) identified three unique species. While T. minima has been reported on black huckleberry (Gaylussacia baccata [Wangenh.] K. Koch) in Michigan (4), to our knowledge, this is the first report of T. minima on highbush blueberry in the state. T. minima has been reported on highbush blueberry in Delaware and New York (4), Japan (2), and South Africa (3). The severity of the outbreak in 2010 warrants further research into economic losses, epidemiology, and management of the disease. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Botany and Mycology Laboratory, ARS, UDSA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 2010. (2) T. Kobayashi. Page 1227 in: Index of Fungi Inhabiting Woody Plants in Japan. Host, Distribution and Literature. Zenkoku-Noson-Kyoiku Kyokai Publishing Co., Tokyo, 2007. (3) L. Mostert et al. Plant Dis. 94:478, 2010. (4) S. Sato et al. Trans. Mycol. Soc. Jpn. 34:47, 1993.

scholarly journals First Report of Ascochyta rabiei Causing Ascochyta Blight of Chickpea in Argentina

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1375-1375 ◽  
Author(s):  
G. Viotti ◽  
M. A. Carmona ◽  
M. Scandiani ◽  
A. N. Formento ◽  
A. Luque
Keyword(s):  
Disease Incidence ◽  
Ascochyta Blight ◽  
Morphological Characteristics ◽  
Pathogenic Fungi ◽  
Ascochyta Rabiei ◽  
Infected Leaf ◽  
Buenos Aires Province ◽  
Conidial Suspension ◽  
First Report ◽  
Plastic Bags

In November 2011, lesions similar to those reported for Ascochyta blight (1) were observed on Cicer arietinum L. (chickpea) plants growing in three commercial fields located at Río Primero and Río Segundo (Cordoba Province) and Lobería (Buenos Aires Province), Argentina. Disease incidence (percentage of plants affected) was 100% in all fields surveyed. Plants showed leaves, petioles, stems, and pods with brown lesions. Symptoms on leaves and pods were circular to oval (2 to 14 mm) while in the stems the lesions were elongated (2 to 30 mm). Seeds appeared small and shriveled with brown discoloration. Morphology of the fungi was examined on infected tissues. Numerous black pycnidia measuring 94.6 to 217.9 μm (145.9 ± 28.8 μm), arranged in concentric rings, were observed within of all the lesions. Conidia were predominantly aseptate, straight, hyaline with blunt ends, and measured 9.3 to 12.9 (11.3 ± 1.12) × 3.3 to 5.0 μm (4.2 ± 0.51). Morphological characteristics of the pathogen were similar to those described for Ascochyta rabiei (Pass.) Labrousse (teleomorph Didymella rabiei (Kovacheski) v. Arx (= Mycosphaerella rabiei Kovacheski)) (2). Fungus from infected leaf tissues was isolated on potato dextrose agar. Pathogenicity tests were conducted on seedlings of the susceptible cultivar by spraying leaves of each of 100 seedling plants with 10 ml of a conidial suspension (2 × 104 conidia/ml) of the isolated pathogen with a handheld atomizer. Plants were covered with plastic bags and placed in a growing chamber at 20 to 25°C for 3 days. The plastic bags were removed and the plants were maintained in high humidity at the same temperature. Noninoculated plants were used as controls. After 5 days, all inoculated plants showed typical symptoms. Foliar and stem lesions symptoms were similar to those originally observed in the field. Control plants remained healthy. Koch's postulates were fulfilled by isolating A. rabiei from inoculated plants. The colonies and the morphology of conidia were the same as those of the original isolates. To our knowledge, this is the first report of A. rabiei infecting chickpeas in Argentina. The outbreak of Ascochyta blight in Argentina is of concern because of its severity and the possibility that the pathogen was introduced on seed. This report underscores the need for further research on effective management programs for Ascochyta blight. References: (1) B. Bayaa and W. Chen. Compendium of Chickpea and Lentil Diseases and Pests The American Phytopathological Society, St. Paul, MN, 2011. (2) E. Punithalingam and P. Holliday. Page 337 in: CMI Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1972.

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