First Report of Stem and Leaf Blight Caused by Sclerotinia minor on Geranium carolinianum in North Carolina

The soilborne fungus Sclerotinia minor Jagger is a major pathogen of peanut (Arachis hypogaea L.) in North Carolina and overwinters in soil, on crop debris, or on winter annual weed species (1). Bleached stems and small, black sclerotia are typically seen on peanut plants infected by S. minor. Carolina geranium (Geranium carolinianum L.) is one of several winter annual weed species found during winter fallow in peanut production areas of northeastern North Carolina. During a March 2002 survey of previously harvested peanut fields, plants of Carolina geranium were observed with typical signs and symptoms of infection caused by S. minor. Symptomatic plants with bleached stems and signs of small, black sclerotia were collected in the field and returned to the laboratory. Pathogen isolation and fungal identification were performed from the symptomatic tissues by placing 1- to 2-cm sections of stems on potato dextrose agar after rinsing with tap water and towel drying. Pure cultures of S. minor were obtained and observed to have white, fluffy mycelium and small, black irregular-shaped sclerotia (<2 mm) produced abundantly and scattered over the culture surface. Pathogenicity was tested by inoculating stems of three symptom-free Carolina geranium plants with 2-day-old fungal mycelium from pure isolation. Mycelial agar plugs, 4 mm in diameter, were held in place with self-sticking bandaging gauze. Plants were misted, enclosed in plastic bags, and incubated at ambient temperature (24°C) on the laboratory counter top. Bleached water-soaked lesions developed on the stems, and leaves became chlorotic after 8 days. Following 8 days of incubation, S. minor was reisolated from all inoculated plants. Three noninoculated plants remained healthy over the incubation period. The performance of Koch's postulates confirmed that Carolina geranium is a host of S. minor. To our knowledge, this is the first report of S. minor on G. carolinianum. These results indicate that G. carolinianum is a potential overwintering host for S. minor in peanut fields. Infected weed hosts allow reproduction of the fungus in the winter, potentially resulting in more disease on peanut planted in the spring. Reference: (1) J. E. Hollowell et al. Plant Dis. 87:197, 2003.

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First Report of Sclerotinia minor on Sida spinosa in North Carolina

Plant Disease ◽

10.1094/pd-89-1128a ◽

2005 ◽

Vol 89 (10) ◽

pp. 1128-1128 ◽

Cited By ~ 1

Author(s):

J. E. Hollowell ◽

B. B. Shew

Keyword(s):

North Carolina ◽

Incubation Period ◽

Tap Water ◽

Signs And Symptoms ◽

Fungal Mycelium ◽

Weed Species ◽

Sclerotinia Minor ◽

First Report ◽

Sida Spinosa ◽

Prickly Sida

The soilborne fungus Sclerotinia minor Jagger is a major pathogen of peanut (Arachis hypogaea L.) in North Carolina, Virginia, Oklahoma, and Texas. The pathogen attacks several winter annual weed species (1). Economic crops that are hosts to S. minor are seldom grown in rotation with peanut; therefore, its pathogenicity on weed species is of importance in understanding how inoculum densities are maintained between peanut crops. During September 2004, signs of fluffy, white mycelium, small, black sclerotia, and symptoms of bleached leaves and stems were observed on prickly sida (Sida spinosa L.) in a peanut field in Bertie County, NC. Plants of prickly sida with similar signs and symptoms were observed previously in a Chowan County, NC peanut field. Prickly sida is one of several weed species commonly found in peanut fields and rotational crops in agricultural areas of northeastern North Carolina. Cultivation and herbicides usually keep prickly sida under control in the early part of the growing season, but as the summer progresses into early fall, it can become prevalent, as was true in the two fields reported here. Symptomatic tissues were excised into 1- to 2-cm sections, rinsed in tap water, blotted dry, and placed on potato dextrose agar (PDA). The pure cultures with small, black irregular-shaped sclerotia (<2 mm) scattered abundantly over the culture surface were distinctive of S. minor. Pathogenicity was determined by inoculating stems of two symptom-free prickly sida plants with 2-day-old fungal mycelium. Mycelial agar plugs, 4 mm in diameter, were held in place with self-sticking bandaging gauze. Plants were misted, enclosed in plastic bags, and incubated at ambient temperature (24°C) on the laboratory countertop. Fluffy mycelium developed on the stems in 2 days and water-soaked leaves and bleached lesions formed within 6 days after inoculation. Following the incubation period, S. minor was reisolated from the inoculated plants. Two plants treated similarly with plugs of pure PDA remained healthy over the incubation period. The performance of Koch's postulates confirmed that prickly sida is a host of S. minor. To our knowledge, this report of S. minor on prickly sida is also the first report of a plant in the family Malvaceae as a host of S. minor (2). Reference: (1) J. E. Hollowell et al. Plant Dis. 87:197, 2003. (2) M. S. Melzer et al. Can. J. Plant Pathol. 19:272, 1997.

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First Report of Sclerotium rolfsii on Common Chickweed in North Carolina

Plant Disease ◽

10.1094/pdis.2004.88.4.426b ◽

2004 ◽

Vol 88 (4) ◽

pp. 426-426

Author(s):

J. E. Hollowell ◽

B. B. Shew

Keyword(s):

North Carolina ◽

Tap Water ◽

Sclerotium Rolfsii ◽

Control Treatment ◽

Fungal Mycelium ◽

Weed Species ◽

Stellaria Media ◽

Crop Species ◽

First Report ◽

Pure Cultures

Common chickweed (Stellaria media (L.) Cyrillo) is a common weed species found in agricultural fields of northeastern North Carolina. Symptomatic plants of common chickweed were observed during a March 2001 survey of winter annual weed species in Perquimans County, NC. The plants were growing in a harvested peanut field with a known history of southern stem rot caused by Sclerotium rolfsii Sacc. Water-soaked, bleached stems and chlorotic leaves were collected from plants and brought to the laboratory for isolation. Small portions (1 to 2 cm) of symptomatic stems and entire leaves were rinsed with tap water and placed on potato dextrose agar (PDA). Developing colonies were transferred to obtain pure cultures. The rapidly growing cultures had coarse, white mycelium typical of S. rolfsii and produced abundant, small, round, brown sclerotia approximately 2.0 mm in diameter on the surface of the culture. Clamp connections were observed with microscopic examination of mycelia. Pathogenicity of isolates was tested by placing 4-mm-diameter agar plugs of 2-day-old fungal mycelium on stems of three mature, nonsymptomatic chickweed plants. Agar plugs without fungal mycelium were used for the control treatment. Plugs were held in place with self-sticking bandage gauze. Plants were misted with water, enclosed in plastic bags, and incubated on a laboratory counter top at ambient temperature (24°C). Abundant mycelia developed, and water-soaked lesions and necrotic stems were observed. Noninoculated plants remained healthy and free of signs and symptoms during the incubation period. The fungus was reisolated on PDA, and pure cultures of S. rolfsii were obtained. Koch's postulates confirmed common chickweed was a host of S. rolfsii. To our knowledge, this is the first report of common chickweed as a host of S. rolfsii. Crop species commonly used in peanut rotations (corn, small grains, sorghum, and cotton) do not support populations of S. rolfsii. Many dicotyledonous weed species have been reported as hosts of S. rolfsii, but our observation of active disease on a winter weed species was unexpected. Colonization of winter weed, if prevalent, may enhance survival of S. rolfsii between crops of susceptible hosts such as peanut.

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First Report of Sclerotinia minor on Allium vineale in North Carolina

Plant Disease ◽

10.1094/pd-89-0908c ◽

2005 ◽

Vol 89 (8) ◽

pp. 908-908

Author(s):

J. E. Hollowell ◽

B. B. Shew

Keyword(s):

North Carolina ◽

Incubation Period ◽

Tap Water ◽

Early Spring ◽

Fungal Mycelium ◽

Isolation And Identification ◽

Sclerotinia Minor ◽

Fungal Isolation ◽

Pure Cultures ◽

Wild Garlic

Allium vineale L. (wild garlic) is a bulbous perennial that emerges in early spring in many agricultural fields. The soilborne fungus Sclerotinia minor Jagger is a major pathogen found in many peanut (Arachis hypogaea L.) production areas of northeastern North Carolina. During September 2002, symptoms of bleached, water-soaked foliage and wilting were observed on several wild garlic plants growing in a 0.8-ha (2-acre) peanut research plot in Perquimans County, NC. We had previously observed similar symptoms on wild garlic at another location. Two symptomatic wild garlic plants were collected from the field. In the laboratory, symptomatic tissues were excised into 1- to 2-cm sections, rinsed in tap water, towel dried, and placed on potato dextrose agar (PDA) for fungal isolation and identification. Pure cultures with small, black, irregular-shaped sclerotia (<2 mm) scattered abundantly over the culture surface were distinctive of S. minor. Pathogenicity of isolates was tested by inoculating leaf blades near the leaf axils of two symptom-free wild garlic plants (vegetative stage, 4 cm high) with fungal mycelium from 2-day-old cultures. Mycelial agar plugs (4 mm in diameter) were held in place with self-sticking bandaging gauze. Plants were misted, enclosed in plastic bags, and incubated at an ambient temperature (24°C) on the laboratory countertop. Fluffy mycelium developed on leaves within 2 days. Plants wilted and bleached water-soaked lesions formed within 6 days after inoculation. Sclerotia were produced on leaf blades after approximately 14 days. Following the incubation period, S. minor was reisolated from the inoculated plants. Two plants treated similarly with plugs of pure PDA remained healthy over the incubation period. The performance of Koch's postulates confirmed that wild garlic is a host of S. minor. Although few monocots have been reported as hosts of S. minor, the fungus has been reported on two other species of Allium (A. cepa and A. satium), Gladiolus spp., and Cyperus esculentus (1,2). Weed hosts may support populations of S. minor during rotations to nonhosts, serve as reservoirs of inoculum, or act as infection bridges in peanut fields. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. On-line publication. ARS, USDA, 2005. (2) M. S. Melzer et al. Can. J. Plant Pathol. 19:272, 1997.

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Yellow Nutsedge (Cyperus esculentus L.) as a Host of Sclerotinia minor

Plant Disease ◽

10.1094/pdis.2001.85.5.562c ◽

2001 ◽

Vol 85 (5) ◽

pp. 562-562 ◽

Cited By ~ 4

Author(s):

J. E. Hollowell ◽

B. B. Shew

Keyword(s):

Signs And Symptoms ◽

Research Station ◽

Weed Species ◽

Sclerotinia Minor ◽

Yellow Nutsedge ◽

Plastic Bags ◽

Arachis Hypogaea L ◽

Pure Cultures ◽

White Mycelium ◽

Culture Surface

Sclerotinia minor Jagger is a major pathogen of peanut (Arachis hypogaea L.) in North Carolina, Virginia, Oklahoma, and Texas. Economic crops that are hosts to S. minor are seldom grown in rotation with peanut, and the pathogenicity of S. minor to most weed species commonly found in peanut fields is unknown. In September 2000, signs and symptoms of Sclerotinia infection were observed on plants of yellow nutsedge growing in peanut fields in Bertie County, NC. Fluffy white mycelium, water soaked and bleached areas of the leaves were observed on basal portions of plants. Isolations were made from a symptomatic plant growing in a peanut field at the Peanut Belt Research Station at Lewiston-Woodville, NC. Small portions (1 to 2 cm) of symptomatic leaves were placed on potato dextrose agar (PDA) and pure cultures typical of S. minor were obtained. Small black irregular-shaped sclerotia (<2 mm) were produced abundantly and scattered over the culture surface (1). Pathogenicity was tested by placing agar plugs of mycelium of the fungus between the leaf blades of potted mature yellow nutsedge plants. Plants were misted with water, enclosed in plastic bags, and incubated on a lab counter top at ambient temperature (˜24°C). Mycelia developed after 3 to 4 days and chlorotic leaves appeared by day 7. Sclerotia were observed in 11 days on seedheads, which were distal from the site of inoculation. Uninoculated plants did not develop symptoms. The fungus was reisolated on PDA, and typical cultures of S. minor with small sclerotia were obtained. The nutgrass isolate was inoculated onto detached peanut leaves and typical symptoms developed. This is the first report of yellow nutsedge as a host of S. minor. Reference: (1) L. M. Kohn. Mycotaxon 9:365–444, 1979.

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First Report of Sclerotinia minor Infecting Ipomoea hederacea and I. coccinea in Texas

Plant Disease ◽

10.1094/pdis-92-3-0482c ◽

2008 ◽

Vol 92 (3) ◽

pp. 482-482 ◽

Cited By ~ 3

Author(s):

J. E. Woodward ◽

M. A. Batla ◽

P. A. Dotray ◽

T. A. Wheeler ◽

T. A. Baughman

Keyword(s):

Weed Management ◽

Tap Water ◽

The United States ◽

Plant Diseases ◽

Weed Species ◽

Sclerotinia Minor ◽

Ipomoea Hederacea ◽

First Report ◽

Sclerotinia Blight ◽

Pathogenicity Tests

Sclerotinia blight, caused by the soilborne fungus Sclerotinia minor Jagger, is a major disease of peanut (Arachis hypogaea L.) in parts of west Texas. Previous reports have indicated that annual weed species may serve as collateral hosts for S. minor (2). Several Ipomoea spp. are commonly found in peanut fields throughout the region. In September of 2007, Ipomoea hederacea and I. coccinea plants with bleached, shredded stems, and signs of black sclerotia were collected from a field known to be infested with S. minor. Symptomatic stem sections were rinsed in tap water, surface disinfested in 0.5% sodium hypochlorite for 1 min, air dried, and plated on potato dextrose agar (PDA). Pure cultures of S. minor consisting of white, fluffy mycelia and small (<2 mm), black, irregular sclerotia were consistently recovered. Pathogenicity tests were conducted by wound-inoculating healthy I. hederacea and I. coccinea transplants (n = 3) with agar plugs obtained from the edges of actively growing S. minor cultures. Plants were incubated in a dew chamber at 20°C and 95% relative humidity for 5 days. Plants inoculated with sterile PDA plugs served as controls (n = 3). A similar test was conducted using the susceptible peanut cultivar Flavorunner 458. Characteristic symptoms of Sclerotinia blight (3) were observed on all inoculated weed and peanut plants; whereas, the controls remained healthy. Pathogenicity tests were repeated with similar results. Cultures of S. minor were obtained from all symptomatic tissues, fulfilling Koch's postulates. These results indicate that I. hederacea and I. coccinea are additional hosts of S. minor and that sclerotia produced on infected plants can significantly augment soil inoculum. S. minor has been observed to infect I. batatas seedlings in New Jersey (1); however, this to our knowledge is the first report of S. minor infecting Ipomoea spp. in Texas. Therefore, weed management should inevitability be a part of disease management strategies for the control of Sclerotinia blight in peanut. References: (1) Anonymous. Index of Plant Diseases in the United States. USDA Handb. No. 165, 1960. (2) J. E. Hollowell et al. Plant Dis. 87:197, 2003. (3) D. M. Porter and H. A. Melouk. Sclerotinia blight. Page 34 in: Compendium of Peanut Diseases. 2nd ed. N. Kokalis-Burelle et al., eds. The American Phytopathologicial Society, St. Paul, MN, 1997.

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First Report of Crown and Stem Rot of Orchid (Orchis palustris) Caused by Sclerotinia minor

Plant Disease ◽

10.1094/pd-89-0913c ◽

2005 ◽

Vol 89 (8) ◽

pp. 913-913

Author(s):

C. Eken ◽

S. Ercişli ◽

A. Eşitken ◽

E. Demirci ◽

G. Y. Yuen

Keyword(s):

Potato Dextrose Agar ◽

Stem Rot ◽

Eastern Anatolia ◽

Forage Production ◽

Sclerotinia Minor ◽

Transparent Plastic ◽

First Report ◽

Plastic Bags ◽

White Mycelium ◽

Plant Pathol

Orchis palustris Jacq. is a wild orchid native to wetlands in eastern Anatolia. During June of 2003, near Erzurum, Turkey, a decline of this orchid was observed in several meadows that had been irrigated for forage production. Stems were chlorotic, wilted, and collapsed. There was a soft, watery rot at the crowns and lower stems. White mycelium and black sclerotia formed on necrotic stem and crown tissues. The fungus was isolated from sclerotia on potato dextrose agar (PDA) and identified as Sclerotinia minor Jagger on the basis of small sclerotia (0.5 to 2.5 mm long) scattered throughout the colonies (2). Pathogenicity was confirmed by inoculating stems of 8-week-old plants with mycelial plugs from 5-day-old PDA cultures and enclosing inoculated plants in transparent plastic bags for 3 days. After 2 weeks, symptoms similar to those in the field were observed, and S. minor was reisolated from inoculated plants. Noninoculated control plants remained asymptomatic. The disease was previously observed on O. laxiflora Lam. in Turkey (1), but to our knowledge, this is the first report of S. minor infecting O. palustris References: (1) C. Eken et al. Plant Pathol. 52:802, 2003. (2) L.M. Kohn. Phytopathology 69:881, 1979.

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First Report of Bipolaris peregianensis Causing Leaf Spot of Cynodon dactylon in China

Plant Disease ◽

10.1094/pdis-12-11-1066-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 917-917 ◽

Cited By ~ 2

Author(s):

Z. Y. Wang ◽

S. N. Xie ◽

Y. Wang ◽

H. Y. Wu ◽

M. Zhang

Keyword(s):

Leaf Spot ◽

Cynodon Dactylon ◽

Control Strategies ◽

Tap Water ◽

Morphological Characteristics ◽

Its Region ◽

Basal Cells ◽

First Report ◽

Leaf Spots ◽

Plastic Bags

Cynodon dactylon is widely cultivated as a sod crop in warm climates worldwide. In early September 2009, heavy leaf spot infection was observed on C. dactylon from Zhengzhou, Henan, China. Early symptoms appeared as small, elliptical, pale brown lesions on the leaves. Lesions later expanded to 5 to 10 mm long and 1 to 2 mm wide, becoming brown to dark brown. A fungus was consistently isolated from leaf spots on potato dextrose agar (PDA), but with poor sporulation. Morphological characteristics were observed from single-conidium cultures on tap water agar + wheat straw (TWA+W) after 5 to 7 days. Conidiophores were light to medium brown, cylindrical, solitary or clustered, unbranched, usually with basal cells enlarged, and 94.5 to 147.0 × 4.0 to 9.0 μm. Conidia were fusoid, strongly curved, end cells broadly hemiellipsoidal, brown, 58.5 to 84.5 × 13.5 to 18.5 μm, with 6 to 10 septa. These morphological characteristics are similar to those of Bipolaris peregianensis (2). The identity of our fungus was confirmed to be B. peregianensis by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. JQ316121), which was 99% homologous to those of other B. peregianensis isolates (= Cochliobolus peregianensis; Accession Nos AF071328 and AF158111) (1). Koch's postulates were performed with the leaves of three pots of C. dactylon. Leaves were sprayed with 1 × 105 conidia/ml of B. peregianensis; an equal number of leaves in the pots of the same plant sprayed with sterile distilled water served as the control. All test plants were covered with plastic bags for 24 h to maintain high relative humidity at 23 to 25°C. After 7 days, more than 50% of inoculated leaves showed symptoms identical to those observed in natural condition, whereas controls remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was B. peregianensis. To our knowledge, this is the first report of leaf spots caused by B. peregianensis on C. dactylon in China. The disease cycle and the control strategies in the regions are being further studied. References: (1) M. L. Berbee et al. Mycologia 91:964, 1999. (2) A. Sivanesan. Mycol. Pap. 158:1, 1987.

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First Report on the Occurrence of a New Pathotype, 714, of Plasmopara halstedii (Sunflower Downy Mildew) in Hungary

Plant Disease ◽

10.1094/pdis-02-14-0142-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1580-1580 ◽

Cited By ~ 4

Author(s):

R. Bán ◽

A. Kovács ◽

K. Körösi ◽

M. Perczel ◽

Gy. Turóczi

Keyword(s):

Downy Mildew ◽

Resistance Gene ◽

Disease Incidence ◽

Signs And Symptoms ◽

Weather Conditions ◽

Plasmopara Halstedii ◽

First Report ◽

Severe Stunting ◽

Plastic Bags ◽

Leaf Chlorosis

Downy mildew of sunflower, caused by Plasmopara halstedii (Farlow) Berlese et de Toni, is an economically important disease in Hungary and much of Europe. The known pathotypes (races) of the pathogen influence the resistance genes (Pl genes) incorporated into new sunflower hybrids to manage the disease. There are at least 36 pathotypes of P. halstedii worldwide (3), but the number of races is increasing rapidly. In 2010, race 704 was identified in Hungary for the first time (2). Race 704 has been reported to confer virulence on Pl6, a broad spectrum resistance gene that is widely used in sunflower hybrids. This has coincided with a significant increase in disease severity since 2010 in the country. Our objectives are to continuously monitor this pathogen and identify pathotypes of P. halstedii. Because of the unfavorable weather conditions for downy mildew in 2013, samples were collected at a single site (Kunszentmárton, South Hungary) in the beginning of July from NK Neoma sunflower hybrids. Disease incidence (early and late primary infection) was as high as 40%. Systemically mildewed plants showed severe stunting and leaf chlorosis, signs and symptoms consistent with downy mildew. P. halstedii was identified microscopically. Examination of isolates was carried out using a set of sunflower differential lines based on the internationally standardized method for race identification of P. halstedii (1). Inoculum of the isolates was increased on a susceptible cultivar (cv. Iregi szürke csíkos) and tested by inoculating 3-day-old seedlings of sunflower differential lines. Inoculated seedlings were planted in trays in glasshouse. After 8 to 9 days, seedlings were sprayed with distilled water, covered with black plastic bags, and left overnight to induce sporulation. Disease incidence was determined by examining cotyledons at 9 days after inoculation for sporulation and true leaves on 12 to 13 days after inoculation for secondary symptoms, such as leaf chlorosis and stunting (1). While several differential lines showed no typical susceptible/resistant reactions, i.e., the infection was much lower than 100%, it was concluded that the isolates were mixtures of different P. halstedii pathotypes. To obtain single isolates, we collected zoosporangia from the differential lines in question separately, and then inoculated the seedlings of the same genotype and a uniformly susceptible line. A single isolate caused as high as 100% infection on HA-335, containing resistance gene Pl6. Subsequent evaluation of this isolate with the entire differential set resulted in an aggregate virulence phenotype of 714. As resistance gene Pl6 is incorporated to the majority of sunflower hybrids grown in Hungary, pathotypes virulent on this gene, such as 704 and 714, are likely to spread. This underscores the need to prove the resistance to these races in the newly registered hybrids and for further research to identify P. halstedii pathotypes. It is also important to establish the identity of this new pathotype by already discovered 714 pathotypes in other countries like France and Italy and to discover the real conditions of local evolving of new pathogens. To our knowledge, this is the first report of pathotype 714 of P. halstedii in both Hungary and Central Europe. References: (1) T. J. Gulya et al. Helia 14:11, 1991. (2) K. Rudolf et al. Növényvédelem 47:279, 2011. (3) F. Virányi and O. Spring. Eur. J. Plant Pathol. 129:207, 2011.

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First Report of Rust Caused by Pucciniastrum circaeae on Fuchsia × hybrida in Italy

Plant Disease ◽

10.1094/pdis-11-11-0976-pdn ◽

2012 ◽

Vol 96 (4) ◽

pp. 588-588 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

G. Ortu ◽

M. L. Gullino

Keyword(s):

Phylogenetic Trees ◽

Aqueous Suspension ◽

Morphological Characteristics ◽

Pcr Amplification ◽

Signs And Symptoms ◽

The United States ◽

Pathogenicity Test ◽

First Report ◽

Potted Plants ◽

Plastic Bags

Fuchsia is a genus of flowering plants that is native to South America and New Zealand and belongs to the family Onagraceae. In September 2011, 2-year-old potted plants of Fuchsia × hybrida, cv. Citation, in a garden located near Biella (northern Italy) showed signs and symptoms of a previously unknown disease. Typically, infected plants showed leaf chlorosis followed by the appearance of necrosis on the adaxial leaf surfaces, while the abaxial surfaces showed orange uredinia irregularly distributed. As the disease progressed, infected leaves turned yellow and wilted. Affected plants showed a progressive phylloptosis and also flowering was negatively affected. Urediniospores were globose, yellow to orange, and measured 14.6 to 25.9 (average 19.6) μm. Teliospores were not observed. Morphological characteristics of the fungus corresponded to those of the genus Pucciniastrum. DNA extraction and PCR amplification were carried out with Terra PCR Direct Polymerase Mix (Clontech, Saint Germain-en-Laye, France) and primers ITS1/ITS4 (4). A 700-bp PCR product was sequenced and a BLASTn search (1) confirmed that the sequence corresponded with a 96% identity to Pucciniastrum circaeae. The nucleotide sequence has been assigned the GenBank Accession No. JQ029688. Pathogenicity tests were performed by spraying leaves of healthy 1-year-old potted Fuchsia × hybrida plants with an aqueous suspension of 1 × 103 urediniospores ml–1. The inoculum was obtained from infected leaves. Plants sprayed only with water served as controls. Three plants were used for each treatment. Plants were covered with plastic bags for 4 days after inoculation and maintained outdoors at temperatures ranging between 18 and 25°C. Lesions developed on leaves 20 days after inoculation with the urediniospore suspension, showing the same symptoms as the original plants, whereas control plants remained healthy. The organism that was recovered from the lesions after inoculation was the same as the one obtained from the diseased plants. The pathogenicity test was carried out twice with similar results. The presence of P. fuchsiae, later identified as P. epilobii, was repeatedly reported in the United States (3). P. epilobii and P. circaeae have closely related hosts and morphologically similar urediniospores. These species were reported to form a single group in molecular phylogenetic trees (2). This is, to our knowledge, the first report of P. circaeae on Fuchsia × hybrida in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) Y. M. Liang et al. Mycoscience 47:137, 2006. (3) L. B. Loring and L. F. Roth. Plant Dis. Rep. 48:99, 1964. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

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First Report of Septoria apocyni Causing Spot Blight on the Species of Apocynum venetum and Poacynum pictum in China

Plant Disease ◽

10.1094/pdis-02-14-0133-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1429-1429 ◽

Cited By ~ 1

Author(s):

P. Gao ◽

T. Y. Duan ◽

Z. B. Nan ◽

P. J. O'Connor

Keyword(s):

Tap Water ◽

Disease Incidence ◽

Relevant Literature ◽

Fungal Mycelium ◽

Infected Leaf ◽

Colorless Needle ◽

Literature Report ◽

First Report ◽

Apocynum Venetum ◽

Mycelial Suspension

The species of Apocynum venetum and Poacynum pictum grow widely from the middle to northwestern regions of China. During the summers of 2011 to 2013, a spot blight was found in wild and cultivated both species in Altay Prefecture of the Xinjiang Uygur Autonomous Region, China. The spot blight caused leaf yellowing and leaf drop, and serious damage to plant phloem. Lesions were circular to irregular, and the diameter of lesions on A. venetum and P. pictum was 1.84 to 6.84 × 1.23 to 4.24 mm and 2.05 to 7.09 × 1.46 to 5.65 mm, respectively. Pycnidia were 70 to 115 × 52 to 120 μm, scattered, spherical, buried, and had a brown hard shell with a prominent ostiole. Conidia were colorless, needle-shaped, or linear. The conidia base was obtuse, containing 3 to 5 indistinct septa, 46.3 to 110.3 × 2 to 2.5 μm. Fungal cultures were obtained by cutting 1-cm-long infected leaf pieces from the margins of the lesions following routine surface sterilizing procedures. The sections were placed on potato dextrose agar (PDA) in petri dishes and incubated at 23°C for 4 weeks (4). Hyphae had septa, the aerial and base mycelium was white and rufous, and the back of the colony was sunken and cracked after 2 weeks, but no spore was observed. To verify the identity, total DNA was extracted directly from fungal mycelium with a UNIQ-10 fungal genomic DNA extraction kit (Sangon Biotech, Shanghai, China) and PCR amplification performed with primers ITS1/ITS4 (3). A 512-bp PCR product was sequenced and contrasted with GenBank sequences using BLAST, which revealed 99% identity with Septoria sp. (GenBank Accession No. KC134322.1). To confirm pathogenicity, A. venetum and P. pictum were planted in pots and grown in a greenhouse. After 6 weeks of growth, plants were inoculated by spraying a mycelial suspension onto the foliage while control plants received a similar application of sterilized distilled water. Five pots (3 plants per pot) were used for each treatment. The pots were then placed on plates filled with tap water and covered with Plexiglas hoods in the greenhouse at 20 to 25°C. Lesions began to appear 6 to 7 days after inoculation with the mycelial suspension, whereas control plants remained healthy. The average disease incidence was 19.3%. The symptoms and morphology were similar to Septoria apocyni in Teterevnikova (2). It was determined that spot blight of A. venetum and P. pictum was caused by S. apocyni based on morphological comparison. There is one relevant literature report of spot blight on A. venetum and P. pictum in China, but without any details of the pathogenicity or morphology of the pathogen (1). We believe that this is the first report of S. apocyni occurring on the species of A. venetum and P. pictum in China. References: (1) W. Sun et al. Special Economic Animal and Plant 8:23, 2005. (2) D. N. Teterevnikova. Page 79 in: Septoria sp. Fungus of USSR. Armenian Academy of Sciences Publishing, Armenia, USSR, 1987. (3) G. J. M. Verkley et al. Mycologia 96:558, 2004. (4) W. Zhang et al. Plant Dis. 96:1374, 2012.

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