First Report of Fusarium verticillioides Causing Stalk and Root Rot of Sorghum in Spain

Sweet sorghum (Sorghum bicolor L.) is considered one of the most promising crops for bioethanol production in many countries and is a focus of bioenergy research worldwide. In July 2011, plants of the sweet sorghum cv. Suchro 506 in Oropesa (Toledo, Spain, 40.048577°N, 5.360298°W) (European Datum 1950 UTM zone 30 N) were observed with severe wilting. Upon examination, the lower internodes were found to be straw colored. When the plant was split, the internal pith was reddish, soft, and disintegrating. Small pieces of symptomatic stems and roots were surface disinfected in sodium hypochlorite (0.5% wt/vol) for 2 min and air dried. The sections were then placed on either PDA (potato dextrose agar) medium or Komada agar and incubated for 5 days at 25°C. Isolations from diseased stem and root tissue consistently yielded Fusarium verticillioides (Sacc.) Nirenberg (3). The small, hyaline, mostly single-celled, oval to club-shaped microconidia of F. verticillioides were produced in long catenate chains arising from monophialides. PCR amplification of the ITS1-5.8S-ITS2 was performed using the primers and protocols described elsewhere (4) and the fragments obtained were subsequently sequenced in both directions. Sequences were deposited in the EMBL Sequence Database (Accession Nos. HE652878, HE652879, HE652880, and HE652881). Four of the recovered F. verticilliodes isolates were tested in pathogenicity assays. One-week-old cultures of each isolate were homogenized in 400 ml of sterile water and 200 ml were used to inoculate water-growth-chamber-grown plants in 500-ml pots. Two pots each with three plants of cv. Suchro 506 were inoculated for each isolate. Water with sterile PDA was used as a control. All plants were kept at 20 to 25°C under a photoperiod of 14 h at 12,000 lux. After 21 days, above- and belowground parts were dried for 24 h at 60°C. Total length and dry weight of both sections were obtained. Inoculated plants produced root rot symptoms characteristic of F. verticillioides with dark red discolorations of the cortex of seedling roots (1), whereas the plants watered with water containing only PDA did not produce symptoms. Inoculated plants also had a decrease in dry weight for above- and belowground sections (P = 0.05) compared with the control with 43 and 47% reductions, respectively. The length of aerial parts was approximately 5% less in inoculated plants compared with control plants. F. verticillioides was reisolated from all inoculated plants. Sorghum stalk and root rot caused by F. verticillioides has been reported in different countries including India (2) and the United States (3). To our knowledge, this is the first report of F. verticillioides causing stalk and root rot of sorghum in Spain. An increase of production of this crop is expected to meet targets of the renewable energy share in Spain and any disease compromising yield may be a threat to this endeavour. References: (1) R. A. Frederiksen and G. N. Odvody. Compendium of Sorghum Diseases. The American Phytopathological Society. St. Paul, MN, 2000. (2) N. N. Khune et al. Indian Phytopathol. 37:316, 1984. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

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First Report of Fusarium proliferatum Causing Root Rot on Soybean (Glycine max) in the United States

Plant Disease ◽

10.1094/pdis-04-11-0346 ◽

2011 ◽

Vol 95 (10) ◽

pp. 1316-1316 ◽

Cited By ~ 18

Author(s):

M. M. Díaz Arias ◽

G. P. Munkvold ◽

L. F. Leandro

Keyword(s):

United States ◽

Root Rot ◽

Morphological Characteristics ◽

Dry Weight ◽

The United States ◽

Growth Stages ◽

Species Identity ◽

First Report ◽

Soybean Roots ◽

Soybean Diseases

Fusarium spp. are widespread soilborne pathogens that cause important soybean diseases such as damping-off, root rot, Fusarium wilt, and sudden death syndrome. At least 12 species of Fusarium, including F. proliferatum, have been associated with soybean roots, but their relative aggressiveness as root rot pathogens is not known and pathogenicity has not been established for all reported species (2). In collaboration with 12 Iowa State University extension specialists, soybean roots were arbitrarily sampled from three fields in each of 98 Iowa counties from 2007 to 2009. Ten plants were collected from each field at V2-V3 and R3-R4 growth stages (2). Typical symptoms of Fusarium root rot (2) were observed. Symptomatic and asymptomatic root pieces were superficially sterilized in 0.5% NaOCl for 2 min, rinsed three times in sterile distilled water, and placed onto a Fusarium selective medium. Fusarium colonies were transferred to carnation leaf agar (CLA) and potato dextrose agar and later identified to species based on cultural and morphological characteristics. Of 1,230 Fusarium isolates identified, 50 were recognized as F. proliferatum based on morphological characteristics (3). F. proliferatum isolates produced abundant, aerial, white mycelium and a violet-to-dark purple pigmentation characteristic of Fusarium section Liseola. On CLA, microconidia were abundant, single celled, oval, and in chains on monophialides and polyphialides (3). Species identity was confirmed for two isolates by sequencing of the elongation factor (EF1-α) gene using the ef1 and ef2 primers (1). Identities of the resulting sequences (~680 bp) were confirmed by BLAST analysis and the FUSARIUM-ID database. Analysis resulted in a 99% match for five accessions of F. proliferatum (e.g., FD01389 and FD01858). To complete Koch's postulates, four F. proliferatum isolates were tested for pathogenicity on soybean in a greenhouse. Soybean seeds of cv. AG2306 were planted in cones (150 ml) in autoclaved soil infested with each isolate; Fusarium inoculum was applied by mixing an infested cornmeal/sand mix with soil prior to planting (4). Noninoculated control plants were grown in autoclaved soil amended with a sterile cornmeal/sand mix. Soil temperature was maintained at 18 ± 1°C by placing cones in water baths. The experiment was a completely randomized design with five replicates (single plant in a cone) per isolate and was repeated three times. Root rot severity (visually scored on a percentage scale), shoot dry weight, and root dry weight were assessed at the V3 soybean growth stage. All F. proliferatum isolates tested were pathogenic. Plants inoculated with these isolates were significantly different from the control plants in root rot severity (P = 0.001) and shoot (P = 0.023) and root (P = 0.013) dry weight. Infected plants showed dark brown lesions in the root system as well as decay of the entire taproot. F. proliferatum was reisolated from symptomatic root tissue of infected plants but not from similar tissues of control plants. To our knowledge, this is the first report of F. proliferatum causing root rot on soybean in the United States. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathologic Society, St. Paul, MN, 1999. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (4) G. P. Munkvold and J. K. O'Mara. Plant Dis. 86:143, 2002.

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First Report of Bacterial Stem and Root Rot of Sweetpotato Caused by a Dickeya sp. (Erwinia chrysanthemi) in China

Plant Disease ◽

10.1094/pdis-06-10-0417 ◽

2010 ◽

Vol 94 (12) ◽

pp. 1503-1503 ◽

Cited By ~ 6

Author(s):

L. F. Huang ◽

B. P. Fang ◽

Z. X. Luo ◽

J. Y. Chen ◽

X. J. Zhang ◽

...

Keyword(s):

New York ◽

Root Rot ◽

Type Strain ◽

The United States ◽

Erwinia Chrysanthemi ◽

Dickeya Dadantii ◽

First Report ◽

Guangzhou City ◽

Pcr Products ◽

Production Areas

Since 2006, stem and root rot of sweetpotato has been observed in fields at a number of sweetpotato-production areas in Huidong, Haifeng, Puning, and Zhanjiang counties and Guangzhou City in Guangdong Province of China. Initially, the leaves turn yellow, and a black, water-soaked rot occurs on the bottom of the stems that gradually extends to the top of the stems. Finally, the entire plant collapses and dies. Bacteria were consistently isolated from stems of diseased seedlings by streaking on nutrient agar. Twelve representative isolates were chosen for further characterization. All strains grew at 37°C, were gram negative, facultatively anaerobic, and rod shaped with peritrichous flagella. The strains were negative for oxidase and positive for catalase and tryptophanase (indole production) They fermented glucose, reduced nitrates to nitrites, degraded pectate, produced phosphatase and lecithinase, and utilized citrate, tartrate, malonate, glucose, sucrose, fructose, and maltose, but not trehalose and lactose. These characteristics were similar to those of Erwinia chrysanthemi (Pectobacterium chrysanthemi) (1). PCR was performed on the 16S rDNA gene from isolate H12 (1,503 bp; GenBank Accession No. GU252371) with primers 27f (5′-GAGAGTTTGATCCTGGCTCAG-3′) and reverse primer (5′-GGCTACCTTGTTACGACTTC-3′). Subsequently, PCR products were sequenced. Results of sequence analysis showed the sequence of isolated strain H12 was 99% identical to that of E. chrysanthemi, 99% identical to that of type strain CFBP 1269T of Dickeya dadantii (Accession No. AF520707), and 98% identical to that of type strain CFBP 1200T of D. dianthicola (Accession No. AF520708). Recently, E. chrysanthemi was transferred to Dickeya gen. nov., but it was difficult to identify the species within the genus Dickeya. Seedlings (20 to 30 cm) were planted in 10-cm-diameter plastic pots containing sterilized field soil at room temperature. Four days later, five stem tops of sweetpotato were injected with a bacteria suspension (108 CFU/ml) of approximately 100 μl to fulfill Koch's postulates. Five control plants were inoculated with sterile distilled water. The experiment was conducted three times. All plants were incubated in a chamber at 30°C with high humidity. One to two days after inoculation, symptoms were observed in all inoculated plants and appeared to be identical to those observed in the field. No symptoms were noted on the control plants. The bacterium was reisolated from symptomatic stems of sweetpotato plants. This pathogen was previously reported on sweetpotato in the United States in 1974 (2). To our knowledge, this is the first report of a Dickeya sp. (E. chrysanthemi) causing bacterial stem and root rot of sweetpotato in China. References: (1) D. J. Brenner et al. Page 670 in: Bergey's Manual of Systematic Bacteriology. 2nd ed. Springer, New York, 2005. (2) N. W. Schaad et al. Phytopathology 67:302, 1977.

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First Report of Pythium aphanidermatum Crown and Root Rot of Industrial Hemp in the United States

Plant Disease ◽

10.1094/pdis-09-16-1249-pdn ◽

2017 ◽

Vol 101 (6) ◽

pp. 1038 ◽

Cited By ~ 7

Author(s):

J. Beckerman ◽

H. Nisonson ◽

N. Albright ◽

T. Creswell

Keyword(s):

United States ◽

Root Rot ◽

The United States ◽

Pythium Aphanidermatum ◽

First Report ◽

Crown And Root Rot ◽

Industrial Hemp

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First Report of Subanguina radicicola, the Root-Gall Nematode Infecting Poa annua Putting Greens in Washington State

Plant Disease ◽

10.1094/pdis-91-7-0905c ◽

2007 ◽

Vol 91 (7) ◽

pp. 905-905 ◽

Cited By ~ 2

Author(s):

N. A. Mitkowski

Keyword(s):

United States ◽

New York ◽

The United States ◽

Washington State ◽

Poa Annua ◽

Golf Course ◽

Severe Damage ◽

Surrounding Water ◽

Putting Greens ◽

First Report

In the fall of 2006, a golf course in Snoqualmie, WA renovated five putting greens with commercially produced Poa annua L. sod from British Columbia, Canada. Prior to the renovation, the greens had been planted with Agrostis stolonifera L. cv. Providence, which was removed during the renovation. In February of 2007, chlorotic patches were observed on the newly established P. annua greens. When the roots were examined, extensive galling was observed throughout plant roots. Galls were slender and twisted in appearance and less than one millimeter long. Upon dissection of washed galls, hundreds of eggs were exuded into the surrounding water droplet and both mature male and female nematodes were observed. Further morphometric examination of males, females, and juvenile nematodes demonstrated that they were Subanguina radicicola (Greef 1872) Paramanov 1967 (1). Amplification of nematode 18S, ITS1, and 5.8S regions, using previously published primers (2), resulted in a 100% sequence match with the publicly available sequence for S. radicicola, GenBank Accession No. AF396366. Each P. annua plant had an average of six galls (with a range of 1 to 8), primarily located within the top 2 cm of the soil. All five new P. annua putting greens at the golf course were infested with the nematode. Additionally, P. annua from two A. stolonifera cv. Providence greens that had not been renovated was infected, suggesting that the population occurred onsite and was not imported from the Canadian sod. S. radicicola has been identified as causing severe damage in New Brunswick, Canada on P. annua putting greens and in wild P. annua in the northwestern United States, but to our knowledge, this is the first report of the nematode affecting P. annua on a golf course in the United States. References: (1) E. L. Krall. Wheat and grass nematodes: Anguina, Subanguina, and related genera. Pages 721–760 in: Manual of Agricultural Nematology. Marcel Dekker, New York, 1991. (2) N. A. Mitkowski et al. Plant Dis. 86:840, 2002.

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First Report of Grapevine leafroll associated virus-3 in American Vitis spp. Grapevines in Washington State

Plant Disease ◽

10.1094/pd-90-1461a ◽

2006 ◽

Vol 90 (11) ◽

pp. 1461-1461 ◽

Cited By ~ 8

Author(s):

M. J. Soule ◽

K. C. Eastwell ◽

R. A. Naidu

Keyword(s):

New York ◽

Economic Impact ◽

Virus Disease ◽

The United States ◽

Washington State ◽

The State ◽

Enzyme Linked Immunosorbent Assay ◽

Rt Pcr ◽

First Report ◽

Table Grapes

Washington State is the largest producer of juice grapes (Vitis labruscana ‘Concord’ and Vitis labrusca ‘Niagara’) and ranks second in wine grape production in the United States. Grapevine leafroll disease (GLD) is the most wide spread and economically significant virus disease in wine grapes in the state. Previous studies (2) have shown that Grapevine leafroll associated virus-3 (GLRaV-3) is the predominant virus associated with GLD. However, little is known about the incidence and economic impact of GLD on juice and table grapes. Because typical GLD symptoms may not be obvious among these cultivars, the prevalence and economic impact of GLD in Concord and Niagara, the most widely planted cultivars in Washington State, has received little attention from the grape and nursery industries. During the 2005 growing season, 32 samples from three vineyards and one nursery of ‘Concord’ and three samples from one nursery of ‘Niagara’ were collected randomly. Petiole extracts were tested by single-tube reverse transcription-polymerase chain reaction (RT-PCR; 3) with primers LC 1 (5′-CGC TAG GGC TGT GGA AGT ATT-3′) and LC 2 (5′-GTT GTC CCG GGT ACC AGA TAT-3′), specific for the heat shock protein 70 homologue (Hsp70h gene) of GLRaV-3 (GenBank Accession No. AF037268). One ‘Niagara’ nursery sample and eleven ‘Concord’ samples from the three vineyards tested positive for GLRaV-3, producing a single band of the expected size of 546 bp. The ‘Niagara’ and six of the ‘Concord’ RT-PCR products were cloned in pCR2.1 (Invitrogen Corp, Carlsbad, CA) and the sequences (GenBank Accession Nos. DQ780885, DQ780886, DQ780887, DQ780888, DQ780889, DQ780890, and DQ780891) compared with the respective sequence of a New York isolate of GLRaV-3 (GenBank Accession No. AF037268). The analysis revealed that GLRaV-3 isolates from ‘Concord’ and ‘Niagara’ share nucleotide identities of 94 to 98% and amino acid identities and similarities of 97 to 98% with the Hsp70h gene homologue of the New York isolate of GLRaV-3. Additional testing by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using antibodies specific to GLRaV-3 (BIOREBA AG, Reinach, Switzerland) further confirmed these results in the ‘Niagara’ and two of the ‘Concord’ isolates. GLRaV-3 has previously been reported in labrusca cvs. Concord and Niagara in western New York (4) and Canada (1), but to our knowledge, this is the first report of GLRaV-3 in American grapevine species in the Pacific Northwest. Because wine and juice grapes are widely grown in proximity to each other in Washington State and grape mealybug (Pseudococcus maritimus), the putative vector of GLRaV-3, is present in the state vineyards, further studies will focus on the role of American grapevine species in the epidemiology of GLD. References: (1) D. J. MacKenzie et al. Plant Dis. 80:955, 1996. (2) R. R. Martin et al. Plant Dis. 89:763, 2005. (3) A. Rowhani et al. ICGV, Extended Abstracts, 13:148, 2000. (4) W. F. Wilcox et al. Plant Dis. 82:1062, 1998.

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First Report of Plum pox virus (Sharka Disease) in Prunus persica in the United States

Plant Disease ◽

10.1094/pdis.2000.84.2.202b ◽

2000 ◽

Vol 84 (2) ◽

pp. 202-202 ◽

Cited By ~ 65

Author(s):

L. Levy ◽

V. Damsteegt ◽

R. Welliver

Keyword(s):

Prunus Persica ◽

Virus Disease ◽

Sandwich Elisa ◽

Pcr Amplification ◽

The United States ◽

Enzyme Linked Immunosorbent Assay ◽

Plum Pox Virus ◽

Rt Pcr ◽

Peach Fruit ◽

First Report

Plum pox (Sharka) is the most important virus disease of Prunus in Europe and the Mediterranean region and is caused by Plum pox potyvirus (PPV). In September 1999, PPV-like symptoms were observed in peach fruit culls in a packinghouse in Pennsylvania. All symptomatic fruit originated from a single block of peach (P. persica cv. Encore) in Adams County. Trees in the block exhibited ring pattern symptoms on their leaves. A potyvirus was detected in symptomatic fruit using the Poty-Group enzyme-linked immunosorbent assay (ELISA) test from Agdia (Elkhart, IN). Reactions for symptomatic peach fruit and leaves also were positive using triple-antibody sandwich ELISA with the PPV polyclonal antibody from Bioreba (Carrboro, NC) for coating, the Poty-Group monoclonal antibody (MAb; Agdia) as the intermediate antibody, and double-antibody sandwich ELISA with PPV detection kits from Sanofi (Sanofi Diagnostics Pasteur, Marnes-La-Coquette, France) and Agdia and the REAL PPV kit (Durviz, Valencia, Spain) containing universal (5B) and strain typing (4DG5 and AL) PPV MAbs (1). PPV also was identified by immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) amplification and subsequent sequencing of the 220-bp 3′ noncoding region (2) (>99% sequence homology to PPV) and by IC-RT-PCR amplification of a 243-bp product in the coat protein (CP) gene (1). The virus was identified as PPV strain D based on serological typing with strainspecific MAbs and on PCR-restriction fragment length polymorphism of the CP IC-RT-PCR product with Rsa1 and Alu1 (1). This is the first report of PPV in North America. References: (1) T. Candresse et al. Phytopathology 88:198, 1998. (2) L. Levy and A. Hadidi. EPPO Bull. 24:595, 1994.

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First Report of Medical Tree Peony Root Rot Caused by Fusarium solani in Tongling, China

Plant Disease ◽

10.1094/pdis-02-12-0142-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 909-909 ◽

Cited By ~ 10

Author(s):

M. Guo ◽

Y. M. Pan ◽

Z. M. Gao

Keyword(s):

Fusarium Solani ◽

Root Rot ◽

Tap Water ◽

Blood Stasis ◽

The United States ◽

Effective Control ◽

Conidial Suspension ◽

Tree Peony ◽

First Report ◽

Peony Root

Tree peony bark, a main component of Chinese traditional medicine used for alleviating fever and dissipating blood stasis, is mainly produced in Tongling, China. Recently, tree peony cultivation in this area was seriously affected by root rot, with approximately 20 to 30% disease incidence each year. The disease severely affects yield and quality of tree peony bark. During the past 2 years, we collected 56 diseased tree peony plants from Mudan and Fenghuang townships in Tongling. We found reddish brown to dark brown root rot in mature roots, especially on those with injuries. Plant samples collected were disinfected with 2% sodium hypochlorite and isolations were conducted on potato sucrose agar (PSA). Eleven isolates were obtained and all had white fluffy aerial hypha on PSA. Two types of conidia were produced; the larger, reaphook-shaped ones had three to five septa and the smaller, ellipse-shaped ones had one or no septum. The reaphook-shaped conidia were 20.15 to 37.21 × 3.98 to 5.27 μm and the ellipse-shaped conidia were 6.02 to 15.52 × 2.21 to 5.33 μm in size. Chlamydospores were produced, with two to five arranged together. Biological characteristics of the fungi indicated that the optimum temperature for the mycelial growth on PSA was 25 to 30°C and the optimum pH range was 5.5 to 7.0. The above morphological characteristics point the fungal isolates to be Fusarium solani. To confirm pathogenicity, 30 healthy 1-year-old tree peony seedling plants were grown in pots (25 cm in diameter) with sterilized soil and a conidial suspension from one isolate (FH-1, 5 × 105 conidia/ml) was used for soil inoculation. Inoculated seedlings were maintained at 28°C in a greenhouse with a 12-h photoperiod of fluorescent light. Seedlings inoculated with distilled water were used as controls. After 3 weeks, the roots were collected and rinsed with tap water. Dark brown lesions were observed in the inoculated mature roots but not in the control roots. To confirm the identity of the pathogen, F. solani strains were reisolated from the lesions and total genomic DNA was extracted with the cetyltriethylammnonium bromide method from the mycelia of the reisolated strains (1). PCR was performed using the fungal universal primers ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) and ITS5 (5′-GGAAGTAAAAGTCGTAACAAGG-3′) to amplify a DNA fragment of approximately 590 bp. The purified PCR products were sequenced (Invitrogen Co., Shanghai, China) and shared 100% sequence identity with each other. A comparison of the sequence (JQ658429.1) by the Clustal_W program (2) with those uploaded in GenBank confirmed with the fungus F. solani (100% sequence similarity to isolate S-0900 from the Great Plains of the United States; EU029589.1). To our knowledge, this is the first report of F. solani causing medical tree peony root rot in China. The existence of this pathogen in China may need to be considered for developing effective control strategies. References: (1). C. N. Stewart et al. Biotechniques 14:748, 1993. (2). J. D. Thompson et al. Nucleic Acids Res. 22:4673, 1994.

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First Report of Aecidium magnatum Anamorph of Uromyces acuminatus Causing Rust on Viburnum sargentii in Korea

Plant Disease ◽

10.1094/pdis-02-13-0150-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1251-1251

Author(s):

Y. H. Yun ◽

S. Y. Son ◽

S. H. Kim

Keyword(s):

New York ◽

Sequence Similarity ◽

The United States ◽

28S Rdna ◽

Morphological Data ◽

Morphological Properties ◽

Morphological Description ◽

Mountainous Area ◽

First Report ◽

Dna Database

Viburnum sargentii Koehne belongs to the family Caprifoliaceae. It is a deciduous shrub that grows in wet mountainous area in Korea, Japan, and China. On July 2011, rust symptoms were observed on V. sargentii Koehne in Balwang mountain, Gangwon Province, Korea, at an altitude of 1,450 meters. The specimen was coded as DUCC506 and used to study in detail. Rust symptoms were present on leaves, floral axes, and petioles. The infected lesions slightly swelled and leaflets and leaves were distorted. These caused sharp bends in the petioles and wart-like galls on twigs. Defoliation and deflowering could result when infection was severe. The first symptom was small and pale yellow spots on the upper surfaces of the leaves. As the spots increased in size, they turned brown and tanned. Bright orange or yellow powdery masses of spores were produced in tiny cup-like structures that appeared on the undersurfaces of leaves and the surface of floral axes and petioles. Aecia were gregarious, cupulate, yellowish, and erumpent with a peridium having a lacerate, somewhat recurved margin. Peridial cells were hyaline to whitish, rhomboidal, 18 to 25 (avg. 21.5) × 15 to 20 (avg. 18) μm, smooth to finely verrucose, and not observed in aecial stage on floral axes and petioles. Aeciospores were globose to ellipsoid, 14 to 16 (avg. 15.4) × 15 to 16.5 (avg. 16) μm, hyaline to yellowish, with many verrucose surface and hyaline walls. These morphological properties correspond to the aecial stage of Uromyces acuminatus (1,4). From extracted genomic DNA, the D1 and D2 region of 28S ribosomal DNA was amplified with LROR (5′- ACCCGCTGAACTTAAGC-3′) and LR4 (5′-ACCAGAGTTTCCTCTGG- 3′) primer set. The 28S rDNA sequence of DUCC506 was deposited in GenBank DNA database under accession number KC570451. A nucleotide sequence similarity search through BLAST in the GenBank database revealed that the DUCC506's 28S rDNA shared 98% (607/622) similarity with that of U. acuminatus LD1005 (GU058004). Aecidium magnatum Arthur is the anamorph of U. acuminatus (2). Aecial and telial hosts of U. acuminatus belong to several families of Angiosperms and Spartina spp., respectively. No telial host was found near the infected aecial host V. sargentii. These morphological and molecular results support the morphological data to identify DUCC506 specimen is A. magnatum. To our knowledge, this is the first report of rust caused by A. magnatum on V. sargentii in Korea or elsewhere in the world. Rust caused by A. viburni was reported on V. sargentii in Korea without any morphological description (3). Peoples in Asia are interested in this host plant as it is used for ornamental and medicinal purpose. Therefore, our report would be useful information for the management of V. sargentii. References: (1) G. B. Cummins. The Rust Fungi of Cereals, Grasses and Bamboos. Springer-Verlag, New York, 1971. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. Page 1009. American Phytopathological Society Press, St. Paul, MN, 1989. (3) C. J. Kim. Kor. J. Micorbiol. 1:51, 1963. (4) H. Y. Yun et al. Plant Dis. 94:279, 2010.

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First Report of Stem Blight Caused by Calonectria colhounii (Anamorph Cylindrocladium colhounii) on Greenhouse-Grown Blueberries in the United States

Plant Disease ◽

10.1094/pdis-02-11-0117 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1187-1187

Author(s):

J. J. Sadowsky ◽

T. D. Miles ◽

A. M. C. Schilder

Keyword(s):

United States ◽

North Carolina ◽

Root Rot ◽

The United States ◽

Vaccinium Corymbosum ◽

Conidial Suspension ◽

Centraalbureau Voor ◽

First Report ◽

Stem Lesions ◽

Β Tubulin

Necrotic stems and leaves were observed on 2- to 4-month-old, rooted microshoot plants (Vaccinium corymbosum L. ‘Liberty’ and ‘Bluecrop’, V. angustifolium Aiton ‘Putte’, and V. corymbosum × V. angustifolium ‘Polaris’) in a Michigan greenhouse in 2008 and 2009. As the disease progressed, leaves fell off and 80 to 100% of the plants died in some cases. Root rot symptoms were also observed. A fungus was isolated from stem lesions. On potato dextrose agar (PDA), cultures first appeared light tan to orange, then rusty brown and zonate with irregular margins. Chains of orange-brown chlamydospores were abundant in the medium. Macroconidiophores were penicillately branched and had a stipe extension of 220 to 275 × 2.5 μm with a narrowly clavate vesicle, 3 to 4 μm wide at the tip. Conidia were hyaline and cylindrical with rounded ends, (1-)3-septate, 48 to 73 × 5 to 7 (average 60 × 5.5) μm and were held together in parallel clusters. Perithecia were globose to subglobose, yellow, 290 to 320 μm high, and 255 to 295 μm in diameter. Ascospores were hyaline, 2- to 3-septate, guttulate, fusoid with rounded ends, slightly curved, and 30 to 88 × 5 to 7.5 (average 57 × 5.3) μm. On the basis of morphology, the fungus was identified as Calonectria colhounii Peerally (anamorph Cylindrocladium colhounii Peerally) (1,2). The internal transcribed spacer region (ITS1 and ITS2) of the ribosomal DNA and the β-tubulin gene were sequenced (GenBank Accession Nos. HQ909028 and JF826867, respectively) and compared with existing sequences using BLASTn. The ITS sequence shared 99% maximum identity with that of Ca. colhounii CBS 293.79 (GQ280565) from Java, Indonesia, and the β-tubulin sequence shared 97% maximum identity with that of Ca. colhounii CBS 114036 (DQ190560) isolated from leaf spots on Rhododendron sp. in North Carolina. The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 129628). To confirm pathogenicity, 5 ml of a conidial suspension (1 × 105/ml) were applied as a foliar spray or soil drench to four healthy ‘Bluecrop’ plants each in 10-cm plastic pots. Two water-sprayed and two water-drenched plants served as controls. Plants were misted intermittently for 2 days after inoculation. After 7 days at 25 ± 3°C, drench-inoculated plants developed necrotic, sporulating stem lesions at the soil line, while spray-inoculated plants showed reddish brown leaf and stem lesions. At 28 days, three drench-inoculated and one spray-inoculated plant had died, while others showed stem necrosis and wilting. No symptoms were observed on control plants. Fungal colonies reisolated from surface-disinfested symptomatic stem, leaf, and root segments appeared identical to the original isolate. Cy. colhounii was reported to cause a leaf spot on blueberry plants in nurseries in China (3), while Ca. crotalariae (Loos) D.K. Bell & Sobers (= Ca. ilicicola Boedijn & Reitsma) causes stem and root rot of blueberries in North Carolina (4). To our knowledge, this is the first report of Ca. colhounii causing a disease of blueberry in Michigan or the United States. Because of its destructive potential, this pathogen may pose a significant threat in blueberry nurseries. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) L. Lombard et al. Stud. Mycol. 66:31, 2010. (3) Y. S. Luan et al. Plant Dis. 90:1553, 2006. (4) R. D. Milholland. Phytopathology 64:831, 1974.

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