First Report of Lasiodiplodia crassispora as a Pathogen of Grapevine Trunks in South Africa

In 2003 and 2004, a survey of grapevine (Vitis vinifera L.) trunk pathogens was conducted in 30 vineyards in the Western and Northern Cape and Limpopo provinces of South Africa. In each vineyard, 20 visually healthy plants were sampled randomly by removing the distal part of one cordon arm. Isolations were made onto potato dextrose agar (PDA) from the internal wood decay symptoms observed in the cordon samples. Seven Botryosphaeriaceae spp. were identified, including Lasiodiplodia crassispora (1). Other Botryosphaeriaceae spp. are known grapevine trunk pathogens (2). Species identity was confirmed by DNA sequence data of the partial translation factor 1-α gene (1) and sequences deposited in GenBank (GU233658 and GU233659). The L. crassispora isolates (CBS 125626 and 125627) were associated with brown internal necrosis, a known symptom of grapevine Botryosphaeriaceae spp. infection (3), in the cordon arms of Ruby Cabernet grapevines occurring in two vineyards in the Northern Cape Province. L. crassispora was described from cankered wood of Santalum album in Western Australia and endophytically from Eucalyptus urophylla in Venezuela (1). Its grapevine pathogen status was determined using both isolates in a repeated pathogenicity test that included three isolates each of Botryosphaeria dothidea and Neofusicoccum australe as positive controls (2), Trichoderma harzianum as a nonpathogen treatment, and an uncolonized agar plug as a negative control. The Botryosphaeriaceae spp. and T. harzianum were plated on PDA and incubated at 25°C for 7 days. Lignified, 6-month-old shoots of grapevine cv. Chardonnay were excised from grapevines with internodes 4 to 6 used for inoculations. Before wounding, shoots were disinfected by submersion for 1 min in a 1 ml/liter solution of a quaternary ammonium compound (Sporekill; ICA International Chemicals (Pty) Ltd, Stellenbosch, South Africa). Twelve shoots were used for each isolate or control treatment. Wounds were made 2 mm deep on the fifth internode of the shoots with a 5-mm flame-sterilized cork borer (2,3). Wounds were inoculated with a pathogen colonized agar plug (5 mm in diameter) or an uncolonized agar plug and then covered with Parafilm (2,3). Inoculated shoots were incubated in the dark in moist chambers for 14 days at 25°C. After incubation, the bark of the shoots was peeled from the area around the wound and the lengths of any resultant lesions were measured under sterile conditions. The inoculum effect was assessed by analysis of variance and Student's t-test. Results showed that significantly (P < 0.0001) longer lesions were caused by L. crassispora (13.36 mm) compared with N. australe (9.27 mm) and B. dothidea (5.28 mm) and also significantly longer than lesions caused by the nonpathogen and negative controls (3.23 and 2.90 mm, respectively). To determine if lesions were caused by inoculated fungi, isolations were made from the tissue at the edges of the lesions by aseptically removing five 0.5 × 1 mm pieces of wood and placing them on PDA dishes amended with 0.04 g/liter of streptomycin sulfate. Dishes were incubated under normal fluorescent light at 25°C for 14 days before identifying isolated fungi based on morphological and cultural characteristics (1). To our knowledge, this is the first report of L. crassispora as a grapevine pathogen. References: (1) T. I. Burgess et al. Mycologia 98:423, 2006. (2) J. M. van Niekerk et al. Mycologia 96:781, 2004. (4) J. M. van Niekerk et al. Phytopathol. Mediterr. 45:S43, 2006.

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First Report of Fusarium culmorum and Microdochium bolleyi Causing Root Rot on Triticale in Kazakhstan

Plant Disease ◽

10.1094/pdis-12-20-2659-pdn ◽

2021 ◽

Author(s):

Mehtap Alkan ◽

Göksel Özer ◽

İmren Mustafa ◽

Fatih OZDEMIR ◽

Alexei Morgounov ◽

...

Keyword(s):

Root Rot ◽

Disease Incidence ◽

Fusarium Culmorum ◽

Gaeumannomyces Graminis ◽

Control Treatment ◽

Sodium Hypochlorite Solution ◽

Pathogenicity Test ◽

First Report ◽

Agar Plug ◽

Microdochium Bolleyi

Triticale (×Triticosecale Wittmack) is obtained from wheat × rye crossing. It is positioned between wheat and rye in terms of resistance to soilborne pathogens including Gaeumannomyces graminis var. tritici, Fusarium culmorum, F. avenaceum, and Bipolaris sorokiniana (Arseniuk and Góral 2015). In 2019, seven triticale fields were surveyed in Almaty Province, Kazakhstan to examine soil-borne fungal pathogens. A total of 28 symptomatic plants with stunting, rot or discolored root were collected to identify causal agents. The overall disease incidence was approximately 8 to 10% in the fields. Fungi were isolated from 3-5 mm pieces excised from symptomatic tissues. The pieces were exposed to surface disinfection in 1% sodium hypochlorite solution for 2 min, rinsed three times with sterile distilled water, blotted dry, and plated on 1/5 strength potato dextrose agar (PDA) amended with 0.01% streptomycin. Plates were left in the dark at 23°C for 7 days. A total of 34 fungal colonies were isolated of which nineteen isolates, originally from six fields showed the cultural characteristics of B. sorokiniana. This species was previously reported to cause common root rot on triticale in Kazakhstan (Özer et al. 2020). Ten isolates from four fields produced pale orange and cottony mycelium with red pigmentation on the agar, which is typical of Fusarium-like growth. The remaining isolates (n=5) from two fields produced salmon-colored and scarce aerial mycelium with no soluble pigmentation, similar to Microdochium spp. Fusarium isolates produced thick-walled and curved macroconidia with 3-4 septa (n=50, 25.7 to 37.6 × 4.1 to 7.3 μm in size) and notched basal cell on PDA, but microconidia were absent, which matches the description of F. culmorum (Wm.G. Sm.) Sacc. (Leslie and Summerell 2006). Microdochium isolates produced swollen, brown, and thick-walled chlamydospores and hyaline, one-celled, and thin-walled conidia (n=50, 5.4 to 9.3 × 1.5 to 3.0 μm in size) formed on ampullate and cylindrical conidiogenous cells on oatmeal agar (OA). These morphological features are consistent with previous observations for Microdochium bolleyi (R. Sprague) de Hoog & Herm.-Nijh. (Hong et al. 2008). To confirm morphological preliminary identifications, the portion of the translation elongation factor 1-alpha (EF1-α) gene was amplified with EF1/EF2 primers (O’Donnell et al. 1998) for representative Fusarium isolates (n=4) for each field. Additionally, the internal transcribed spacer (ITS) of ribosomal DNA was amplified with ITS1/ITS4 primers (White et al. 1990) for representative Microdochium isolates (n=2) for each field. BLASTn queries against NCBI GenBank revealed that the EF1-α sequences of Fusarium isolates (MW311081-MW311084) shared 100% identity with F. culmorum strain CBS 110262 (KT008433). The ITS sequences of M. bolleyi isolates (MW301448-MW301449) matched that of M. bolleyi strain CBS 137.64 (AM502264) with 100% sequence similarity. Pathogenicity test was conducted on pregerminated seeds of triticale cv. Balausa. A plastic pot (17 cm height, 9 cm in diam) was filled with a sterile mixture of vermiculite, peat, and soil (1:1:1, v/v/v). Mycelial plugs (1 cm in diam) were cut from the margin of a growing culture of representative isolates (Kaz_Fus123 and Kaz_Mb01) and placed onto the mixture in the pot. A sterile agar plug was employed as a control treatment. One pregerminated seed was put on the plug and covered with the mixture. The pots were transferred to a growth chamber set at 23 ± 2°C and a photoperiod of 14 hours. The experiment was performed twice using 5 replication pots per isolate. Four weeks after inoculation, discoloration of the crown was observed on all the inoculated roots, whereas no symptoms were observed on the control plants. Koch’s postulates were fulfilled by reisolating and identifying the pathogen based on the morphology described above. This is the first report of M. bolleyi and F. culmorum causing root rot on triticale in Kazakhstan. Although B. sorokiniana is the most primary pathogen that may limit yield in the production of triticale in Kazakhstan, F. culmorum and M. bolleyi have been found to be less frequent and less aggressive pathogens, respectively. Further studies are needed to better understand the potential distribution and impact of these pathogens on triticale.

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First Report of Powdery Mildew of Cashew Caused by Oidium anacardii in South Africa

Plant Disease ◽

10.1094/pdis.2004.88.11.1284a ◽

2004 ◽

Vol 88 (11) ◽

pp. 1284-1284

Author(s):

W. J. Swart

Keyword(s):

South Africa ◽

Powdery Mildew ◽

Control Treatment ◽

Pathogenicity Test ◽

First Report ◽

Significant Damage ◽

Kwazulu Natal ◽

Young Leaves ◽

Powdery Mildew Fungi ◽

Extensive Growth

The cashew plant (Anacardium occidentale L.) (family Anacardiaceae) is native to Brazil. It was introduced in East Africa by the Portuguese in the 16th century where it is now widely cultivated, especially in Tanzania, Kenya, and Mozambique. The processed kernels are the most important product derived from the plant, although in Brazil and India, juices, jam, and alcoholic and soft drinks are also made from the pear-shaped edible receptacle. The plant is currently being evaluated in South Africa for commercial production. During May 2002, at least 25% of 5-year-old cashew trees grown from seed in the northern KwaZulu-Natal Province of South Africa were infected with powdery mildew. Signs included extensive growth of white, superficial mycelium bearing upright conidiophores on young shoots with tender leaves, inflorescences, and young receptacles. In severely affected trees, approximately 35% of young shoots and 45% of young receptacles displayed signs of powdery mildew. Severely infected young leaves were brown and deformed in contrast to older leaves that were unaffected. Microscopic examination of diseased tissue revealed hyaline, cylindrical-to-slightly doliform, single-celled conidia (10 to 17.5 × 2.5 to 5 μm) borne in chains. The pathogen was subsequently identified as Oidium anacardii Noack on the basis of morphology (1). No other species of powdery mildew fungi have been reported on cashew. A pathogenicity test was conducted by gently pressing a heavily diseased leaf onto two healthy leaves of each of 10 cashew plants maintained in pots on open benches in the glasshouse at 22 to 25°C and mean relative humidity of 65%. Control treatments entailed pressing an asymptomatic leaf onto each of two healthy leaves per plant. The experiment was conducted three times. After 14 days, at least one powdery mildew colony had developed on 80% of inoculated leaves but were absent from all replications of the control treatment. The source of inoculum for this reported outbreak is unknown, although O. anacardii is known to occur in southern Mozambique less than 100 km from the infected site. Cashew powdery mildew was first officially reported in Tanzania in 1979 where significant crop losses, partially attributable to the pathogen, have been recorded since (3). No significant damage to production has been recorded in Brazil (2). To our knowledge, this is the first report of O. anacardii occurring on cashew in South Africa. References: (1) E. Castellani and F. Casulli. Rivista di Agricoltura Subtropicale e Tropicale 75:211, 1981. (2) F. C. O. Freire et al. Crop Prot. 21:489, 2002. (3) P. J. Martin et al. Crop Prot. 16:5, 1996.

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First report of Anthracnose on Peach Fruit Caused by Colletotrichum siamense in Uruguay

Plant Disease ◽

10.1094/pdis-05-21-0950-pdn ◽

2021 ◽

Author(s):

María Julia Carbone ◽

Victoria Moreira ◽

Pedro Mondino ◽

Sandra Alaniz

Keyword(s):

South Carolina ◽

Prunus Persica ◽

Disease Incidence ◽

Management Strategies ◽

Control Treatment ◽

Fluorescent Light ◽

Peach Fruit ◽

First Report ◽

Anthracnose Disease ◽

Equidistant Points

Peach (Prunus persica L.) is an economically important deciduous fruit crop in Uruguay. Anthracnose caused by species of the genus Colletotrichum is one of the major diseases in peach production, originating significant yield losses in United States (Hu et al. 2015), China (Du et al. 2017), Korea (Lee et al. 2018) and Brazil (Moreira et al. 2020). In February 2017, mature peach fruits cv. Pavia Canario with symptoms resembling anthracnose disease were collected from a commercial orchard located in Rincon del Colorado, Canelones, in the Southern region of Uruguay. Symptoms on peach fruit surface were characterized as circular, sunken, brown to dark-brown lesions ranging from 1 to 5 cm in diameter. Lesions were firm to touch with wrinkled concentric rings. All lesions progressed to the fruit core in a V-shaped pattern. The centers of the lesions were covered by orange conidial masses. Monosporic isolates obtained from the advancing margin of anthracnose lesions were grown on PDA at 25ºC and 12h photoperiod under fluorescent light. The representative isolates DzC1, DzC2 and DzC6 were morphologically and molecularly characterized. Upper surface of colonies varied from white or pale-gray to gray and on the reverse dark-gray with white to pale-gray margins. Conidia were cylindrical, with both ends predominantly rounded or one slightly acute, hyaline and aseptate. The length and width of conidia ranged from 9.5 to 18.9 µm (x ̅=14.1) and from 3.8 to 5.8 µm (x ̅=4.6), respectively. The ACT, βTUB2, GAPDH, APN2, APN2/MAT-IGS, and GAP2-IGS gene regions were amplified and sequenced with primers ACT-512F/ACT-783R (Carbone and Kohn, 1999), BT2Fd/BT4R (Woudenberg et al. 2009), GDF1/GDR1 (Guerber et al. 2003), CgDLR1/ColDLF3, CgDLF6/CgMAT1F2 (Rojas et al. 2010) and GAP1041/GAP-IGS2044 (Vieira et al. 2017) respectively and deposited in the GenBank database (MZ097888 to MZ097905). Multilocus phylogenetic analysis revealed that Uruguayan isolates clustered in a separate and well supported clade with sequences of the ex-type (isolate ICMP 18578) and other C. siamense strains (isolates Coll6, 1092, LF139 and CMM 4248). To confirm pathogenicity, mature and apparently healthy peach fruit cv. Pavia Canario were inoculated with the three representative isolates of C. siamense (six fruit per isolate). Fruit were surface disinfested with 70% ethanol and wounded with a sterile needle at two equidistant points (1 mm diameter x 1 mm deep). Then, fruit were inoculated with 5 µl of a spore suspension (1×106 conidia mL-1) in four inoculation points per fruit (two wounded and two unwounded). Six fruit mock-inoculated with 5 µl sterile water were used as controls. Inoculated fruit were placed in moist chamber and incubated at 25°C during 10 days. Anthracnose lesions appeared at 2 and 4 days after inoculation in wounded and unwounded points, respectively. After 7 days, disease incidence was 100% and 67% for wounded and unwounded fruit, respectively. The control treatment remained symptomless. The pathogens were re-isolated from all lesions and re-identified as C. siamense. C. siamense was previously reported in South Carolina causing anthracnose on peach (Hu et al. 2015). To our knowledge, this is the first report of anthracnose disease on peach caused by C. siamense in Uruguay. Effective management strategies should be implemented to control anthracnose and prevent the spread of this disease to other commercial peach orchards.

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First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Agastache rugosa in Korea

Plant Disease ◽

10.1094/pdis-03-14-0298-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1278-1278 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. H. Hong ◽

I. Y. Choi ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Severe Disease ◽

Morphological Characteristics ◽

Control Measures ◽

Control Treatment ◽

Width Ratio ◽

Korean Isolate ◽

Pathogenicity Test ◽

Agastache Rugosa ◽

First Report

Agastache rugosa (Fisch. & C.A. Mey.) Kuntze, known as Korean mint, is an aromatic plant in the Lamiaceae. It is widely distributed in East Asian countries and is used as a Chinese traditional medicine. In Korea, fresh leaves are commonly added to fish soups and stews (3). In November 2008, several dozen Korean mints plants growing outdoors in Gimhae City, Korea, were found to be severely infected with a powdery mildew. The same symptoms had been observed in Korean mint plots in Busan and Miryang cities from 2008 to 2013. Symptoms first appeared as thin white colonies, which subsequently developed into abundant hyphal growth on stems and both sides of the leaves. Severe disease pressure caused withering and senescence of the leaves. Voucher specimens (n = 5) were deposited in the Korea University Herbarium (KUS). Appressoria on the mycelium were nipple-shaped or nearly absent. Conidiophores were 105 to 188 × 10 to 13 μm and produced 2 to 4 immature conidia in chains with a sinuate outline, followed by 2 to 3 cells. Foot-cells of the conidiophores were straight, cylindrical, slightly constricted at the base, and 37 to 58 μm long. Conidia were hyaline, ellipsoid to barrel-shaped, measured 25 to 40 × 15 to 23 μm (length/width ratio = 1.4 to 2.1), lacked distinct fibrosin bodies, and showed reticulate wrinkling of the outer walls. Primary conidia were obconically rounded at the apex and subtruncate at the base. Germ tubes were produced at the perihilar position of conidia. No chasmothecia were observed. The structures described above were typical of the Oidium subgenus Reticuloidium anamorph of the genus Golovinomyces. The measurements and morphological characteristics were compatible with those of G. biocellatus (Ehrenb.) V.P. Heluta (1). To confirm the identification, molecular analysis of the sequence of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of isolate KUS-F27200 was conducted. The complete ITS rDNA sequence was amplified using primers ITS5 and P3 (4). The resulting 514-bp sequence was deposited in GenBank (Accession No. KJ585415). A GenBank BLAST search of the Korean isolate sequence showed >99% similarity with the ITS sequence of many G. biocellatus isolates on plants in the Lamiaceae (e.g., Accession Nos. AB307669, AB769437, and JQ340358). Pathogenicity was confirmed by gently pressing diseased leaf onto leaves of five healthy, potted Korean mint plants. Five non-inoculated plants served as a control treatment. Inoculated plants developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on inoculated plants was identical morphologically to that observed on the original diseased plants. The pathogenicity test was repeated with identical results. A powdery mildew on A. rugosa caused by G. biocellatus was reported from Romania (2). To our knowledge, this is the first report of powdery mildew caused by G. biocellatus on A. rugosa in Korea. The plant is mostly grown using organic farming methods with limited chemical control options. Therefore, alternative control measures should be considered. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., online publication, USDA ARS, retrieved 17 February 2014. (3) T. H. Kim et al. J. Sci. Food Agric. 81:569, 2001. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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First Report of Root Rot Caused by Sclerotium rolfsii on Daucus carota var. sativa in Southern Korea

Plant Disease ◽

10.1094/pdis-03-11-0233 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1585-1585

Author(s):

J.-H. Kwon ◽

Y. H. Lee ◽

H.-S. Shim ◽

J. Kim

Keyword(s):

Daucus Carota ◽

Root Rot ◽

Pathogenic Fungus ◽

Sclerotium Rolfsii ◽

Agricultural Science ◽

Control Treatment ◽

Pathogenicity Test ◽

Optimum Temperature ◽

First Report ◽

Causal Fungus

Carrot (Daucus carota var. sativa DC.), an important root vegetable, is cultivated widely because of its dietary fiber and beta carotene. In June 2009 and June 2010, a disease suspected as root rot of carrot caused by Sclerotium rolfsii occurred in a 5-ha field in Jinju, Korea. Early symptoms consisted of water-soaked lesions on root and lower stem tissue near the soil line. Infected plants gradually withered and white mycelial mats appeared on the surface of roots. Numerous sclerotia were often produced on stem and root surfaces in contact with the soil. The heavily infected carrots became rotted and blighted and the whole plant eventually died. The freshly isolated pathogenic fungus was grown on potato dextrose agar (PDA) and examined microscopically. Optimum temperature for mycelia growth or sclerotia formation was 25 to 30°C. Numerous globoid sclerotia formed on the PDA after 18 days of mycelial growth. The sclerotia (1 to 3 mm in diameter) were white at first and then gradually turned dark brown. Aerial mycelia usually formed, consisting of many narrow hyphal strands 3 to 9 μm wide. The white mycelium formed a typical clamp connection after 5 days of growth at optimum temperature. To fulfill Koch's postulates, 10 carrot seedlings were inoculated with colonized agar discs (6 mm in diameter) of the causal fungus directly on the root and incubated in a humid chamber at 25°C for 24 h. Ten carrot seedlings were inoculated similarly with agar discs as the control treatment. After this period, the inoculated and noninoculated plants were maintained in a greenhouse. Eight days after inoculation, the disease symptoms seen in the field were reproduced and the fungus was reisolated from the artificially inoculated plants. To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA region of the causal fungus was amplified using the primers ITS1 and ITS4 (2) and sequenced. The resulting sequence of 684 bp was deposited in GenBank (Accession No. JF342557). The sequence was 99% similar to sequences of Athelia rolfsii (Sclerotium rolfsii) in GenBank. Cultures of S. rolfsii have been deposited with the Korean Agricultural Culture Collection (KACC 45154), National Academy of Agricultural Science, Korea. On the basis of symptoms, fungal colonies, the ITS sequence, and the pathogenicity test on the host plant, this fungus was identified as S. rolfsii Saccardo (1). To our knowledge, this is the first report of root rot of carrot caused by S. rolfsii in Korea. This disease is highly dependent upon environmental conditions, including warm weather and high humidity. Recent occurrence of the disease suggests that S. rolfsii could spread widely. References: (1) J. E. M. Mordue. CMI Descriptions of Pathogenic Fungi and Bacteria. No. 410, 1974. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990.

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First Report of a New Postharvest Fruit Rot on Apple Caused by Sphaeropsis pyriputrescens

Plant Disease ◽

10.1094/pdis.2004.88.2.223a ◽

2004 ◽

Vol 88 (2) ◽

pp. 223-223 ◽

Cited By ~ 14

Author(s):

C. L. Xiao ◽

J. D. Rogers ◽

R. J. Boal

Keyword(s):

Leading Edge ◽

Preliminary Evidence ◽

Apple Fruit ◽

Causal Agent ◽

Fruit Rot ◽

Postharvest Disease ◽

Fluorescent Light ◽

Pathogenicity Test ◽

First Report ◽

Golden Delicious

During March to July 2003, a postharvest fruit rot was observed on ‘Golden Delicious’, ‘Granny Smith’, and ‘Red Delicious’ apples (Malus × domestica Borkh.) sampled from commercial packinghouses in Washington State. Losses as high as 24% in storage bins were observed in July on ‘Red Delicious’. The disease started at the stem bowl area or the calyx end of the fruit. Decayed fruit was apparently not wounded. Decayed areas were brown and firm. Internal decayed flesh appeared yellowish brown. On ‘Red Delicious’ apples, decayed fruit was apparently discolored from red to brown. As the disease advanced, pycnidia of a fungus might form on the stem, sepals, or the surface of decayed fruit. Pycnidia were 0.3 to 0.7 mm in diameter, black, and partially immersed in decayed tissues. To isolate the causal agent, decayed fruit was lightly sprayed with 70% ethanol and air dried. Fragments of diseased tissue were removed from the margin of diseased and healthy tissue and plated on acidified potato dextrose agar (PDA). A fungus was consistently isolated from decayed fruit with the symptoms described above. On PDA, the colonies of the fungus first appeared with dense hyaline mycelium and later turned light yellow to yellow. Black pycnidia of the fungus formed on 2- to 3-week-old oatmeal agar cultures at 20°C under 12-h alternating cycles of fluorescent light and dark. The fungus was identified as Sphaeropsis pyriputrescens Xiao & J. D. Rogers, based on the description of the fungus (1). Voucher specimens were deposited at the WSU Mycological Herbarium. Two isolates of the fungus recovered from decayed apples were tested for pathogenicity on apple. Fruit of ‘Golden Delicious’ and ‘Gala’ were surface-disinfested for 5 min in 0.5% NaOCl, rinsed, and air dried. Fruit was wounded with a sterile 4-mm-diameter nail head. A 4-mm-diameter plug from the leading edge of a 3-day-old PDA culture or plain PDA (control) was placed in the wound of each of 10 replicate fruit for each isolate or control. Fruit was tray packed with polyethylene liners and stored in cardboard boxes in air at 3°C, and decay was evaluated 2 weeks after inoculation. Five decayed fruits from each treatment were selected for reisolation of the causal agent. The experiment was conducted twice. In a separate pathogenicity test, two isolates (one each from apple and pear) were included in the test. Fruit of ‘Red Delicious’ apple was prepared and inoculated as the same manner described above, but fruit was stored in air at 0°C. The experiment was conducted twice. All fruit that were inoculated with the fungus developed decay symptoms. No decay developed on fruit in the controls. The same fungus was reisolated from decayed fruit. This indicates that isolates from apple and pear were pathogenic to apple. S. pyriputrescens is the causal agent of a newly reported postharvest disease on ‘d'Anjou’ pears (1). To our knowledge, this is the first report of this fungus causing postharvest fruit rot on apple. We propose ‘Sphaeropsis rot’ as the name of this new disease on apple and pear. Preliminary evidence suggests that infection of fruit by this fungus occurred in the orchard prior to storage. Reference: (1) C. L. Xiao and J. D. Rogers. Plant Dis. 88:114, 2004.

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First Report of Leaf Spot of Lettuce (Lactuca sativa L.) Caused by Phoma tropica in Italy

Plant Disease ◽

10.1094/pdis-04-12-0394-pdn ◽

2012 ◽

Vol 96 (9) ◽

pp. 1380-1380 ◽

Cited By ~ 4

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

G. Ortu ◽

M. L. Gullino

Keyword(s):

Relative Humidity ◽

Lactuca Sativa ◽

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Fluorescent Light ◽

Malt Extract ◽

Pathogenicity Test ◽

First Report ◽

Lactuca Sativa L

Lettuce (Lactuca sativa L.) is widely grown in Italy, with the production for the preparation of ready-to-eat salads becoming increasingly important. During the spring of 2011, a previously unknown leaf spot was observed on L. sativa plants, cv Rubia, grown in several plastic tunnels in Lumbardy (northern Italy), 20 to 25 days after sowing. Thirty to forty per cent of leaves of the plants growing in the part of the tunnel with the highest relative humidity were affected. Leaves of infected plants showed extensive, irregular, dark brown, necrotic lesions with a chlorotic halo. Lesions initially ranged from 0.5 to 3 mm, then eventually coalesced, reaching 2 to 3 cm, showing a well-defined, dark brown border. Affected leaves senesced and withered. The crown was not affected by the disease. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 60 s, rinsed in water, then cultured on potato dextrose agar (PDA), amended with 25 mg/l of streptomycin sulphate. After 5 days, a fungus developed, producing a greenish grey mycelium with a white border when incubated under 12 h/day of fluorescent light at 21 to 23°C. In order to favor the production of conidia, the fungus was transferred on malt extract agar (MA) and maintained under 12 h/day of fluorescent light at 22°C. After 15 days, black pycnidia, 175 to 225 μm, developed, with hyaline, elliptical, unicellular conidia, measuring 3.21 to 6.7 × 1.08 to 3.2 (average 5.5 × 1.9) μm. On the basis of these morphological characteristics, the fungal causal agent of the disease could be related to the genus Phoma (2). The internal transcribed spacer (ITS) region of rDNA of the isolate PHT30 was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 466-bp segment showed a 99% similarity with the sequence of Phoma tropica (GenBank Accession No. JF923820.1). The nucleotide sequence has been assigned the GenBank Accession No. JQ954396. Pathogenicity tests were performed by spraying healthy 20-day-old lettuce plants, cv Rubia, with a spore suspension (1 × 105 conidia/ml) prepared from 14-day-old colonies of the strain PHT30 grown on MA cultures. Plants inoculated with water alone served as controls. Ten plants per isolate were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a growth chamber at 20°C and 80% relative humidity. The first foliar lesions, similar to those occurring on the naturally infected plants, developed on leaves 12 days after inoculation. Control plants remained healthy. The pathogen was consistently reisolated from leaf lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of P. tropica on lettuce in Italy as well as worldwide. In the United States, the presence of P. exigua was reported in 2006 (3). The economic importance of the disease at present is limited, probably also because symptoms can be confused with those caused by Botrytis cinerea. However, P. tropica could become a more significant problem because of the importance of the crop. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema. Trans. Br. Mycol. Soc. 67:289, 1976. (3) S. Y. Koike. Plant Dis. 90:1268, 2006.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Platycodon grandiflorum in Italy

Plant Disease ◽

10.1094/pdis-93-9-0969b ◽

2009 ◽

Vol 93 (9) ◽

pp. 969-969

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Botrytis Cinerea ◽

Its Region ◽

The United States ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Platycodon Grandiflorum ◽

First Report ◽

Bedding Plant

Platycodon grandiflorum (balloon flower), a perennial plant belonging to the Campanulaceae family, is widely grown as a bedding plant in temperate gardens. This species is characterized by the ability to bloom profusely throughout the summer into early fall and for its white to blue and pink flowers. In September 2008, symptoms of a previously unknown blight were observed in six gardens located in the Biella Province of northern Italy. When the disease developed, temperatures ranged between 15 and 22°C with frequent rains (149.8 mm of rainfall registered in September 2008 by the meteorological station of Oropa, located in the same area in which the disease appeared). Initially, leaves and petioles appeared chlorotic. Subsequently, lesions developed on the stems and flowers were sometimes affected. In each garden examined, approximately 50% of the plants were affected by the disease. A soft, gray mycelium was observed on symptomatic tissues, especially the stems. Severely infected leaves and stems eventually became completely rotted and later desiccated. Diseased tissue was excised from affected leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. A fungus developed that produced abundant mycelium on PDA medium when incubated under constant fluorescent light at 22 ± 1°C. Numerous sclerotia were produced on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, irregular, and measured 1 to 3.5 × 0.9 to 2.5 (average 2.1 × 1.5) mm. Conidia were smooth, ash colored, unicellular, ovoid, and measured 11 to 19 × 7 to 13 (average 15 × 11) μm. These morphological features were typical of those described for Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 539-bp segment showed 100% similarity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned the GenBank Accession No. GQ149480. Pathogenicity tests were performed by placing 1-cm2 fragments removed from PDA cultures of B. cinerea isolated from balloon flower on leaves of healthy potted P. grandiflorum plants (4-month-old). Five fragments were placed on each plant. Plants inoculated with PDA alone served as controls. Ten plants per treatment were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a greenhouse at temperatures between 18 and 23°C. The first foliar lesions developed on leaves 3 days after inoculation, and after 5 days, 80% of the leaves were severely infected. As the infection progressed after the inoculation, the stems also became infected. Control plants remained healthy. B. cinerea was consistently reisolated from leaf and stem lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on P. grandiflorum in Italy, as well as in Europe. Blight on balloon flower attributed to Botrytis spp. was previously reported in the United States (3). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, England, 1971. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

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First Report of Fusarium Root Rot of Stored Carrot Caused by Fusarium avenaceum in Serbia

Plant Disease ◽

10.1094/pdis-07-14-0724-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 286-286

Author(s):

I. Stanković ◽

K. Milojević ◽

A. Vučurović ◽

D. Nikolić ◽

B. Krstić ◽

...

Keyword(s):

Root Rot ◽

Apical Cell ◽

Morphological Characteristics ◽

Fusarium Avenaceum ◽

Control Treatment ◽

Fluorescent Light ◽

Fungal Mycelium ◽

Vegetable Crops ◽

Orange Pigment ◽

First Report

Carrot (Daucus carota L. subsp. sativus (Hoffm.) Thell., Apiaceae), a widely consumed antioxidant-rich plant, is among the major vegetable crops grown in Serbia, with average annual production of 65,400 tons on approximately 7,000 ha (4). In May 2013, a severe root rot was observed on approximately 20% of cold-stored carrot roots originating from Gospođinci, South Bačka District, Serbia. Symptoms included dry rot of the collar and crown as well as large, brown to dark brown, circular, sunken lesions on the stored roots. Frequently, abundant whitish mycelium was observed covering the surface of the colonized roots. To determine the causal agent, small pieces of infected tissue were surface-disinfested with 2% NaOCl without rinsing, air-dried, and placed on potato dextrose agar. Five single-spore isolates obtained from collar and crown tissue sections, as well as nine isolates from root sections, all formed abundant, cottony white to pale salmon fungal colonies with reddish orange pigment on the reverse surface of the agar medium when grown at 25°C under 12 h of fluorescent light per day. All recovered isolates formed numerous, three- to six-septate, hyaline, needle-like, straight to slightly curved, fusoid macroconidia (30 to 80 × 4 to 5.5 μm, average 58.3 × 4.9 μm, n = 100 spores) each with a tapering apical cell. Microconidia of all isolates were generally scarce, two- to four-septate, spindle-shaped, and 15 to 35 × 3 to 5 μm (average 21.3 × 4.2 μm). Chlamydospores were not observed. Based on these morphological characteristics, the pathogen was identified as Fusarium avenaceum (Fries) Saccardo (1). The pathogenicity on carrot was tested for isolate 19-14 by inoculating each of five carrot roots surface-disinfected with 2% NaOCl, by placing a mycelial plug into the surface of a wound created with a cork borer. Carrot roots inoculated with sterilized PDA plugs served as a negative control treatment. After 5 days of incubating the roots at 25°C, root rot symptoms identical to those observed on the source carrot plants developed on all inoculated roots, and the pathogen was re-isolated from each of these roots using the same procedure descibed above. There were no symptoms on the control roots. Morphological species identification was confirmed by sequencing the translation elongation factor (EF-1α) gene (2). Total DNA was extracted directly from fungal mycelium of isolate 19-14 with a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany), and PCR amplification was performed with primer pair EF-1/EF-2 (2). Sequence analysis of the EF-1α gene revealed 100% nucleotide identity of isolate 19-14 (GenBank Accession No. KM102536) with the EF-1α sequences of two F. avenaceum isolates from Canada (KC999504 from rye and JX397864 from Triticum durum). To our knowledge, this is the first report of F. avenaceum causing collar, crown, and root rots of stored carrot in Serbia. Since F. avenaceum can produce several mycotoxins, including moniliformin, acuminatopyrone, and chrysogine (3), the presence of this pathogen on stored carrots could represent a significant constraint for carrot production in Serbia, for both direct yield losses and potential mycotoxin contamination. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual, Blackwell Publishing, London, UK, 2006. (2) K. O'Donnell et al. Proc. Natl. Acad. Sci. U.S.A. 95:2044, 1998. (3) J. L. Sorenson. J. Agric. Food Chem. 57:1632, 2009. (4) Statistical Office, Republic of Serbia. Retrieved from http://webrzs.stat.gov.rs in May 2014.

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First Report of Fusarium Wilt in Blueberry (Vaccinium corymbosum) Caused by Fusarium oxysporum in China

Plant Disease ◽

10.1094/pdis-02-14-0167-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1158-1158 ◽

Cited By ~ 1

Author(s):

Y. H. Liu ◽

T. Lin ◽

C. S. Ye ◽

C. Q. Zhang

Keyword(s):

Fusarium Oxysporum ◽

Infected Plant ◽

Morphological Characteristics ◽

Vaccinium Corymbosum ◽

Morphological Characterization ◽

Internal Transcribed Spacers ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report

Blueberry (Vaccinium corymbosum) production is developing quickly in China with about 20,000 ha presently cultivated. In 2010 in Lin'an, Zhejiang Province, plants developed an apparently new disease of blueberry (cv. Duke) with symptoms consisting of wilting of foliage, stunting of plants, and reduced fruit yields. Internal vascular and cortical tissues of plant crowns showed a brown to orange discoloration. Approximately 3% of the plants in the commercial plantings were affected and eventually died after 50 to 60 days. Infected plant samples (stems and roots) collected from different fields were surface sterilized with 1.5% sodium hypochlorite for 2 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on acidified PDA (APDA) for morphological characterization (1,2). Colonies were light with purple mycelia, and beige or orange reverse colony colors developed after 7 days incubation at 25°C. Colonies producing abundant microconidia and macroconidia. Microconidia were hyaline and oval-ellipsoid to cylindrical (3.9 to 9.6 × 1.1 to 3.4 μm). Macroconidia were 3 to 5 septate and fusoid-subulate with a pedicellate base (28.6 to 37.5 × 3.3 to 4.2 μm). Morphology and development of macroconidia and microconida were consistent with a description of Fusarium oxysporum Schltdl (1,2). The ribosomal internal transcribed spacers ITS1 and ITS2 of eight isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of F. oxysporum. To confirm pathogenicity, 20 blueberry plants (cv. Duke) were inoculated by dipping the roots into a conidial suspension (107 conidia per ml) for 30 min. The inoculated plants were transplanted into pots containing sterilized peat and maintained at 25°C and 100% relative humidity in a growth chamber with a daily 12-h photoperiod of fluorescent light. The pathogenicity test was conducted twice. Within 40 days, all inoculated plants developed wilt symptoms similar to that observed in the field. No symptoms were observed on plants dipped into distilled water. The fungus was successfully re-isolated from crowns and roots cultured on APDA, exhibiting morphological characteristics identical to F. oxysporum (1,2), confirming Koch's postulates. To our knowledge, this is the first report of blueberry wilt caused by Fusarium. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, Wallingford, UK, 2008. (2) W. C. Snyder and H. N. Hansen. Am. J. Bot. 27:64, 1940.

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