Dendryphion penicillatum and Pleospora papaveracea, Destructive Seedborne Pathogens and Potential Mycoherbicides for Papaver somniferum

Dendryphion penicillatum and Pleospora papaveracea were isolated from blighted Papaver somniferum and Papaver bracteatum plants grown in growth chambers and the field in Beltsville, MD. The etiology of the diseases was determined, and the fungi are being investigated as potential mycoherbicides to control the narcotic opium poppy plant. P. papaveracea is known to be a highly destructive seedborne pathogen of Papaver somniferum, causing seedling blight, leaf blight, crown rot, and capsule rot. Single conidia and ascospores were isolated and cultures established from naturally infested seed and diseased foliage and pods of opium poppy from Iran, Colombia, Venezuela, Sweden, India, and the United States (Maryland and Washington). Mycelia and conidia of P. papaveracea and D. penicillatum produced on necrotic leaf tissues appear morphologically similar, and the fungi were previously considered to be anamorph and teleomorph. However, no anamorph/teleomorph connection could be established, and the fungi appear to be distinct taxa. P. papaveracea produced conidia, mature pseudothecia, and chlamydospores in vitro and on infected stems. D. penicillatum produced conidia, microsclerotia, and macronematous conidiophores. Although both fungi were pathogenic to three poppy cultivars, conidial inoculum from P. papaveracea cultures was more virulent than conidial inoculum from D. penicillatum. Eight-week-old plants became necrotic and died 8 days after inoculation with a conidial suspension of P. papaveracea at 2 × 105 spores per ml. Disease severity was significantly enhanced by inoculum formulations that contained corn oil, by higher conidial inoculum concentrations, and by increased wetness periods. Symptoms on plants inoculated with either pathogen included leaf and stem necrosis, stem girdling, stunting, necrotic leaf spots, and foliar and pod blight. Inoculated seedlings exhibited wire stem, damping-off, and root rot. Conidia, and less frequently pseudothecia, of P. papaveracea and conidia of D. penicillatum were produced abundantly on inoculated, necrotic foliage, pods, and seedlings. Cultures from conidia or ascospores reisolated from these tissues consistently produced fungi whose morphologies were typical of the fungus from which the inoculum was derived.

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Evaluation of Infection Processes and Resulting Disease Caused by Dendryphion penicillatum and Pleospora papaveracea on Papaver somniferum

Phytopathology ◽

10.1094/phyto.2000.90.7.699 ◽

2000 ◽

Vol 90 (7) ◽

pp. 699-709 ◽

Cited By ~ 7

Author(s):

Bryan A. Bailey ◽

Patricia C. Apel-Birkhold ◽

Nichole R. O'Neill ◽

James Plaskowitz ◽

Sharon Alavi ◽

...

Keyword(s):

Corn Oil ◽

Pathogenic Fungi ◽

Infection Process ◽

Opium Poppy ◽

Conidial Suspension ◽

Yield Losses ◽

Poppy Seed ◽

Fungal Treatment ◽

Infection Processes ◽

Stem Lesions

Two pathogenic fungi of opium poppy, Pleospora papaveracea and Dendryphion penicillatum, were isolated from field material in Beltsville, MD. The processes of infection by these two fungi were studied to determine the optimal environmental conditions for infection. Both fungi formed appressoria capable of penetrating directly through the plant epidermal layer. Of the two fungi, P. papaveracea was more aggressive, causing more rapid necrosis. Appressorial formation by P. papaveracea occurred as early as 4 h after application of a conidial suspension to poppy leaves. P. papaveracea formed more appressoria than did D. penicillatum, especially at cool temperatures (7 to 13°C). In greenhouse studies, P. papaveracea caused more damage to opium poppy than did D. penicillatum when applied in 10% unrefined corn oil. In the field, P. papaveracea was more consistent in its effects on opium poppy from a local seed source designated Indian Grocery. P. papaveracea caused higher disease ratings, more stem lesions, and equal or greater yield losses than did D. penicillatum on Indian Grocery. The late-maturing opium poppy variety White Cloud was severely damaged by disease, regardless of formulation or fungal treatment. P. papaveracea was the predominant fungus isolated from poppy seed capsules and the only fungus reisolated from the field the following year. These studies provide a better understanding of the infection process and the differences between these two pathogenic fungi and will be beneficial for the development of the fungi as biological control agents.

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First Report of Volutella Blight on Pachysandra Caused by Volutella pachysandricola in China

Plant Disease ◽

10.1094/pdis-11-11-0997 ◽

2012 ◽

Vol 96 (4) ◽

pp. 584-584

Author(s):

Q. Bai ◽

Y. Xie ◽

R. Dong ◽

J. Gao ◽

Y. Li

Keyword(s):

Morphological Characteristics ◽

Stem Canker ◽

Botanical Garden ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

Conidial Suspension ◽

First Report ◽

Leaf Spots ◽

Plastic Bags

Pachysandra (Pachysandra terminalis, Buxaceae) and Japanese Pachysandra, also called Japanese Spurge, is a woody ornamental groundcover plant distributed mostly in Zhejiang, Guizhou, Henan, Hubei, Sichuan, Shanxi, and Gansu provinces in China. In April 2010, P. terminalis asymptomatic plants were shipped from Beijing Botanical Garden Institute of Botany Chinese Academy of Science to the garden nursery of Jilin Agricultural University (43°48′N, 125°23′E), Jilin Province. In June 2011, Volutella blight (sometimes called leaf blight and stem canker) of P. terminalis was observed on these plants. Infected leaves showed circular or irregular, tan-to-brown spots often with concentric rings and dark margins. The spots eventually grew and coalesced until the entire leaf died. Cankers appeared as greenish brown and water-soaked diseased areas, subsequently turning brown or black, and shriveled and often girdled the stems and stolons. During wet, humid weather in autumn, reddish orange, cushion-like fruiting structures of the fungus appeared on the stem cankers and undersides of leaf spots. Symptoms of the disease were consistent with previous descriptions (2–4). Five isolates were obtained from necrotic tissue of leaf spots and cankers of stems and stolons and cultured on potato dextrose agar. The colony surface was salmon colored and slimy. Conidia were hyaline, one celled, spindle shaped, and 12.57 to 22.23 × 3.33 to 4.15 μm with rounded ends. Morphological characteristics of the fungus were consistent with the description by Dodge (2), and the fungus was identified as Volutella pachysandricola (telemorph Pseudonectria pachysandricola). The internal transcribed spacer (ITS) regions of the nuclear rDNA were amplified using primers ITS4/ITS5 (1). The ITS sequences were 553 bp long and identical among these five isolates (GenBank Accession No. HE612114). They were 100% identical to Pseudonectria pachysandricola voucher KUS-F25663 (Accession No. JN797821) and 99% identical to P. pachysandricola culture-collection DAOM (Accession No. HQ897807). Pathogenicity was confirmed by spraying leaves of clonally propagated cuttings of P. terminalis with a conidial suspension (1 × 106 conidia/ml) of the isolated V. pachysandricola. Control leaves were sprayed with sterile water. Plants were covered with plastic bags and kept in a greenhouse at 20 to 25°C for 72 h. After 5 to 8 days, typical disease symptoms appeared on leaves, while the control plants remained healthy. V. pachysandricola was reisolated from the leaf spots of inoculated plants. Pachysandra leaf blight and stem canker also called Volutella blight, is the most destructive disease of P. terminalis and previously reported in the northern humid areas of the United States (Illinois, Connecticut, Ohio, Indiana, Iowa, Massachusetts, Missouri, Kentucky, and Wisconsin), northern Europe (Britain, Germany, and Poland), and the Czech Republic. To our knowledge, this is the first report of the disease caused by V. pachysandricola in China. The disease may become a more significant problem in P. terminalis cultivation areas if the disease spreads on P. terminalis in nursery beds. References: (1) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (2) B. O. Dodge. Mycologia 36:532, 1944. (3) S. M. Douglas. Online publication. Volutella Blight of Pachysandra. The Connecticut Agricultural Experiment Station, 2008. (4) I. Safrankova. Plant Protect. Sci.43:10, 2007.

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First Report of Soybean Neocosmospora Stem Rot Caused by Neocosmospora vasinfecta var. vasinfecta in China

Plant Disease ◽

10.1094/pdis-04-11-0287 ◽

2011 ◽

Vol 95 (8) ◽

pp. 1031-1031

Author(s):

Y. Gai ◽

R. Pan ◽

D. Xu ◽

C. Ji ◽

M. Deng ◽

...

Keyword(s):

Soil Surface ◽

Its Region ◽

The United States ◽

Crown Rot ◽

Stem Rot ◽

Universal Primers ◽

Conidial Suspension ◽

Fruiting Bodies ◽

Gentle Pressure ◽

Stem Lesions

During October 2009, the occurrence of a disease on soybean (Glycine max) was observed in several fields in Boluo County and Zengcheng City, Guangdong Province. Top leaves of infected plants initially turned yellow and plants eventually were defoliated, while stems and roots became black and rotted. The stem lesions sometimes extended 10 to 15 cm upward from the soil surface. Orange-to-brown spherical fruiting bodies, which were very similar with those of the soybean red crown rot pathogen, scattered or congregated on the stem lesions. Plants with symptoms were sampled from fields. Fruiting bodies were excised from diseased tissues. Microscopic examination revealed that they were perithecia, globose to pyriform, ostiolate with a short neck, and measured 160 to 298 × 151 to 235 μm. Under gentle pressure, asci and ascospores were exuded from these perithecia. Asci were eight spored, narrowly cylindrical to clavate, thin walled, with a short stalk, and measured 58 to 124 μm long and 8 to 15 μm in diameter. Ascospores were uniseriately arranged, globose to ellipsoid, thick walled, one celled, hyaline to pale, and measured 14 to 17 × 8 to 12 μm. Isolation was made from stem tissues at the edge of disease lesions on potato dextrose agar (PDA) amended with streptomycin sulfate and incubated at 25°C. Mycelia were white and floccose. Conidia were cylindrical to oblong-ellipsoidal, hyaline, one celled, and measured 6 to 22 × 2 to 5 μm, aggregating in a slimy mass on the apex of the conidiogenous cell. Abundant orange-to-brown spherical perithecia were produced on the colony. Ascospores had walls with a rugose ornamentation that could be clearly seen under a scanning electron microscope. The fungus was identified as Neocosmospora vasinfecta var. vasinfecta (anamorph Acremonium sp.) (1). The internal transcribed spacer (ITS) region of rDNA of two isolates were amplified with universal primers ITS1/ITS4 and sequenced (GenBank Accession No. JF705861 and JF705862), and comparisons with GenBank accessions showed 99% similarity with N. vasinfecta strain Pec070 (Accession No. FJ940902) and strain NRRL22497 (Accession No. AY381142). Pathogenicity tests were conducted. Five, 3-week-old seedlings of soybean cv. Huaxia No. 3 planted in plastic pots (20 cm in diameter) were wounded with a needle at the base of the stem below the soil line and near the root system, and then inoculated by drenching the soil with a conidial suspension (105 per ml). Control plants were inoculated with sterile water. There were six replicates for each treatment. The treated plants were incubated at 25 ± 2°C in a greenhouse. All inoculated plants exhibited symptoms of leaf yellowing and black rot of stems and roots 3 weeks after inoculation. N. vasinfecta var. vasinfecta was reisolated from the diseased plants. All control plants remained healthy. To our knowledge, this is the first observation of Neocosmospora stem rot of soybean in China. The pathogen could pose a threat to soybean, which is a major crop in China. This disease has been previously reported in the United States though the anamorph of the pathogen has either not been identified or has been identified as a Cylindrocarpon sp. (2,4). This fungus is also associated with human infections (3). References: (1) P. F. Cannon and D. L. Hawksworth. Trans. Br. Mycol. Soc. 82:673, 1984. (2) F. A. Gray et al. Plant Dis. 64:321, 1980. (3) P. Manikandan et al. Med. Mycol. 46:279, 2008. (4) D. V. Phillips. Phytopathology 62:612, 1972.

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First Report of Nigrospora sphaerica Causing Leaf Spots on Chinese Wisteria: A New Host of the Pathogen

Plant Disease ◽

10.1094/pdis-10-10-0770 ◽

2011 ◽

Vol 95 (2) ◽

pp. 219-219 ◽

Cited By ~ 3

Author(s):

S. Soylu ◽

S. Dervis ◽

E. M. Soylu

Keyword(s):

Dead Leaf ◽

Conidial Suspension ◽

New Host ◽

First Report ◽

Leaf Spots ◽

Leaf Tissues ◽

Wisteria Sinensis ◽

Polyethylene Bags ◽

Environment Chamber ◽

Leaf Pathogen

Chinese wisteria, Wisteria sinensis (Sims) DC., is a woody, twining vine and is commonly cultivated as an ornamental for its foliage and striking, drooping racemes of white, pink, or lavender sweet pea-like flower. Distinct leaf spots were observed in several gardens, retail nurseries, and parks located in Hatay Province since May 2009. The primary infection zones are frequently observed on the leaf margins and apices, brown, up to 2 mm in diameter, and often surrounded by a yellow zone. Foliar symptoms are characterized by grayish, round, semicircular or irregular-shaped, numerous spots (up to 9 mm in diameter) with dark brown borders and the appearance of black, granular structure within the dead leaf tissues. A fungus was consistently isolated from symptomatic tissues on potato dextrose agar (PDA). Fungal colonies were initially white, becoming light to dark gray with the onset of sporulation with black, spherical to subspherical single-celled conidia (15 to 18 × 12 to 15 μm), which were borne on a hyaline vesicle at the tip of the conidiophore. These characteristics agree with published descriptions of Nigrospora sphaerica (Sacc.) E.W. Mason 1927 (1,3). To fulfill Koch's postulates, a conidial suspension (106 conidia per ml) collected from PDA cultures was used to spray inoculate leaves of potted 3-year-old Chinese wisteria plants. Inoculated plants were kept for 48 h in polyethylene bags and maintained in a controlled environment chamber at 20°C with a 12-h photoperiod. The bags were removed after 3 days. In addition, five 3-year-old plants were sprayed with sterile water to serve as controls. After 14 to 20 days, inoculated leaves showed infection symptoms similar to those observed on naturally infected leaves with N. sphaerica. The pathogen was reisolated from the margins of necrotic tissues, but not from the controls. Although N. sphaerica is frequently encountered as a secondary invader or as a saprophyte on many plant species, this fungal agent is also known as a leaf pathogen on several hosts worldwide (2,4). To our knowledge, this is the first report of N. sphaerica as a leaf pathogen of Chinese wisteria in Turkey or worldwide. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory. Online publication. ARS, USDA. Retrieved 28 October from http://nt.ars-grin.gov/fungaldatabases/ , 2010. (3) P. M. Kirk. IMI Descr. Fungi Bact. 106:1056, 1991. (4) E. R. Wright et al. Plant Dis. 92:171, 2008.

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First U.S. Report of Pseudocercospora paederiae Leaf Spot on the Invasive Exotic Paederia foetida

Plant Disease ◽

10.1094/pdis.2001.85.2.232b ◽

2001 ◽

Vol 85 (2) ◽

pp. 232-232 ◽

Cited By ~ 2

Author(s):

S. E. Walker ◽

N. E. El-Gholl ◽

P. D. Pratt ◽

T. S. Schubert

Keyword(s):

South Carolina ◽

The United States ◽

Western Hemisphere ◽

Conidial Suspension ◽

Native Plant ◽

Natural Areas ◽

Central Florida ◽

Leaf Spots ◽

Wide Range ◽

Paederia Foetida

Paederia foetida L., commonly referred to as skunk vine, is a native of eastern and southern Asia and was introduced into the United States prior to 1897. By 1916 it was already a troublesome weed in central Florida. It is a fast growing perennial twining vine (up to 7 m) with a woody rootstock adapted to a wide range of light, soil, water, and salt conditions (4). Naturalized in Florida, Georgia, Hawaii, Louisiana, North Carolina, South Carolina, and Texas, it occurs most often in disturbed areas. In Florida, where it is listed by the Florida Department of Agriculture and Consumer Services as a noxious weed, it invades various native plant communities including sandhills, flood plains, and upland mixed forests, where it creates dense canopies leading to injury or death of native vegetation and structural alteration of the native plant community (2,4). Current work underway to find biological control agents for invasive weeds led to the discovery in central Florida of a skunk vine plant with irregular to angular, sunken leaf spots ranging in color from shiny black to dark brown, some with tan centers and dark brown borders. Leaf spots had coalesced in some areas, blighting portions of leaves. Pseudocercospora paederiae (Sawada ex) Goh & Hsieh (1,3) was recovered from these leaf spots. Fruiting was amphigenous (chiefly epiphyllous) with globular or subglobular stromata, formed singly or coalesced, 37.2 μm wide (range = 19.9 to 62.3 μm). Conidia were hyaline to faintly olivaceous, with up to 6 septa, straight to mildly curved, measuring 49.6 μm (range = 18.8 to 72.3 μm) × 4 μm (range = 3 to 5 μm). To confirm Koch's postulates, a healthy, vigorous P. foetida plant in a 12 liter pot was spray-inoculated with 47 ml of a conidial suspension (13,000/ml) of P. paederiae. The plant was covered with a clear plastic bag to create a moist atmosphere and kept at room temperature (25°C) for 3 days after which it was uncovered and moved into a greenhouse. The greenhouse temperature fluctuated between 15°C (nighttime) and 29°C (daytime). Symptoms started appearing after 2 weeks, becoming more prominent by the third and fourth week. The inoculated plant showed irregular to angular dark brown to black leaf spots with dark brown borders. Necrosis along veins was observed and severely infected leaves abscised. The fungus was consistently recovered from inoculated symptomatic leaf tissue. Continued incubation of the plant under greenhouse and outdoor raised bench conditions eventually resulted in the secondary infection and leaf spotting of new foliage. P. paederiae was recovered from these secondary lesions. P. paederiae has been previously reported from Taiwan, China, and Japan. This represents the first report of the pathogen in the Western Hemisphere. Pathogenicity tests suggest possible application as a mycoherbicide. References: (1) C. Chupp. 1953. A Monograph of the Fungus Genus Cercospora. Cornell University Press. Ithaca, New York. (2) G. Gann and D. Gordon. Natural Areas J. 18:169, 1998. (3) W. H. Hsieh and T. K. Goh. 1990. Cercospora and Similar Fungi from Taiwan. Maw Chang Book, Taiwan, Republic of China. (4) K. A. Langeland and K. C. Burks, eds. 1998. Identification & Biology of Non-Native Plants in Florida's Natural Areas. University of Florida Press, Gainesville, FL.

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First Report of a Root and Crown Rot Disease of Myrtle in California Caused by Cylindrocladium pauciramosum

Plant Disease ◽

10.1094/pdis.2001.85.4.448c ◽

2001 ◽

Vol 85 (4) ◽

pp. 448-448 ◽

Cited By ~ 3

Author(s):

S. T. Koike ◽

P. W. Crous

Keyword(s):

Species Complex ◽

The United States ◽

Crown Rot ◽

Conidial Suspension ◽

First Report ◽

Potted Plants ◽

Crown Tissue ◽

Root And Crown Rot ◽

Plant Pathol ◽

Rot Disease

Myrtle (Myrtus communis) is a woody, evergreen plant used in California as a landscape shrub or potted plant. In 2000, a new root and crown disease was found in commercial nursery myrtle being grown as potted plants. Roots were necrotic and crown tissue was brown. Affected plants became gray-green in color, withered, and died. A Cylindrocladium sp. was consistently isolated from roots, crowns, and lower stems of symptomatic plants. Isolates were characterized by having penicillate conidiophores terminating in obpyriform to broadly ellipsoidal vesicles. Conidia were hyaline, 1-septate, straight with rounded ends, (50-) 53 to 56 (-58) × (3.5-) 4 to 6 μm, placing it in the Cylindrocladium candelabrum Viégas species complex. Single-conidial isolates (STE-U 4012 to 4018) produced perithecia with viable progeny of Calonectria pauciramosa C.L. Schoch & Crous when mated on carnation leaf agar with tester strains of Cylindrocladium pauciramosum C.L. Schoch & Crous (2). Matings with tester strains of all other species in this complex proved unsuccessful. Only one mating type of C. pauciramosum has thus far been found in the United States. Pathogenicity of representative isolates was confirmed by applying 5 ml of a conidial suspension (1.0 × 106 conidia/ml) to the crowns of potted, 5-month-old, rooted mytle cuttings that were subsequently maintained in a greenhouse (23 to 25°C). After 4 weeks, plant crowns and roots developed symptoms similar to those observed in the nursery, and plants later wilted and died. C. pauciramosum was re-isolated from all plants. Control plants, which were treated with water, did not develop any symptoms. The tests were repeated and the results were similar. This is the first report of C. pauciramosum as a pathogen of myrtle in California. The disease has been reported on myrtle in Europe (1). References: (1) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (2) C. L. Schoch et al. Mycologia 91:286, 1999.

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Severe Outbreak of Leaf Spot and Blight Caused by Botrytis cinerea on Majesty Palm in Southern Italy

Plant Disease ◽

10.1094/pdis.2002.86.7.815b ◽

2002 ◽

Vol 86 (7) ◽

pp. 815-815

Author(s):

G. Polizzi

Keyword(s):

Botrytis Cinerea ◽

Leaf Spot ◽

Southern Italy ◽

Gray Mold ◽

Limiting Factor ◽

Conidial Suspension ◽

Sterile Water ◽

Leaf Spots ◽

Important Region ◽

Leaf Tissues

Sicily is the most important region of Italy for ornamental palm cultivation. Majesty palm (Ravenea rivularis Jum. & H. Perrier) is one of the most stately palms for cultivation in the tropics and subtropics, and has been recently cultivated in containers for indoor and outdoor use in eastern Sicily. R. rivularis, which grows on river banks, is native to Madagascar, and appears to behave as a rheophyte in the seedling stage. This palm is not frost tolerant and will grow in full sun but tends to grow best in partly shaded areas or under greenhouses conditions. Between December and March in 1999, 2000, and 2001, a severe leaf spot and blight was observed on young (6-month- to 3-year-old) plants of majesty palm growing in plastic-covered houses and in open fields in nurseries in Sicily. Affected plants had brown necrotic spots and gray mold on the necrotic leaf tissues. No symptoms were detected in mature (4- to 5-year-old) plants grown in the same nurseries. To isolate the casual agent of the disease, 160 small pieces of tissue cut from leaf spots collected in four nurseries were surface sterilized (20 s in HgCl2 at 1 g/liter), washed with sterile water, and plated on potato dextrose agar (PDA). In addition, conidia and conidiophores were scraped from the leaf surface, suspended in sterile water, and streaked on the agar surface. After 2 days, single hyphal tips were transferred to PDA. Botrytis cinerea Pers.:Fr. was consistently isolated from affected leaf tissues. Colonies of B. cinerea on PDA were at first colorless and became gray to brown with the development of conidia, which ranged from 5.5 to 10 × 7 to 12 μm (average 7.5 × 9). Sclerotia were black, irregular in size and shape, and from 1.4 to 4.5 × 1.5 to 2.7 mm. Inoculating 8-month-old seedlings of R. rivularis tested pathogenicity of six isolates obtained from different nurseries. Wounded (with a needle) and nonwounded leaves of 10 plants (9 wounds per plant) were sprayed with 20 ml of a conidial suspension (105 conidia/ml) of each isolate. An equal number of noninoculated plants were used as controls. All plants where incubated in a greenhouse at ambient temperature (21 ± 2°C) and 72 h of continuous leaf wetness. Five days after inoculation, leaf spots appeared on most of the wounded (approximately 80%) and the nonwounded (about 10%) leaves. No symptoms were observed on control plants. Koch's postulates were satisfied by reisolation of the fungus on PDA. On the basis of 3 years of observations in eastern Sicily, majesty palms were more readily infected by B. cinerea after rainfall, and freezing temperatures injured young plants. Leaf blight caused by B. cinerea was previously reported in Liguria (northern Italy) on Phoenix canariensis (1). The fungus does not appear to be a major disease problem in cultivated ornamental palms other than R. rivularis in Sicily or southern Italy. However, B. cinerea could be a limiting factor in the cultivation of majesty palm in eastern Sicily, and protective fungicides, especially in winter, are necessary for limiting losses. To my knowledge, this is the first report of B. cinerea leaf spot and blight on R. rivularis. Reference: (1) A. Garibaldi et al. Malattie delle piante ornamentali. Calderini Edagricole, Bologna, 2000.

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First Report of Daylily Leaf Streak Caused by Kabatiella microsticta in China

Plant Disease ◽

10.1094/pdis-04-12-0381-pdn ◽

2012 ◽

Vol 96 (10) ◽

pp. 1579-1579 ◽

Cited By ~ 1

Author(s):

Q. R. Bai ◽

S. Han ◽

Y. Y. Xie ◽

R. Dong ◽

J. Gao ◽

...

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Control Treatment ◽

Conidial Suspension ◽

First Report ◽

Perennial Plant ◽

Leaf Spots ◽

Plastic Bags ◽

Hemerocallis Citrina

Daylily (Hemerocallis spp.) is an herbaceous, perennial plant, cultivated for its flowers. Daylily is sold in Asian markets as fresh or dried flowers (the flowers of some species, e.g., Hemerocallis citrina, are edible) or as the corm, which is used for medicinal purposes. In June 2011, daylily leaf streak was found in a nursery of Jilin Agricultural University, Jilin Province, China. Symptoms included water-soaked, irregular spots along the leaf midvein that turned orange to reddish brown and eventually enlarged to coalesce into extensive, necrotic streaks along the length of the leaf, as previously reported (2). Heavily infected leaves often withered and died. Four isolates were recovered from necrotic tissue of leaf spots and cultured on potato dextrose agar (PDA) at 25°C. All colonies were initially cream to peach colored and appeared slimy. With the maturation of the culture, the colonies became dark brown to black with sparse aerial hyphae. Blastic conidia formed simultaneously on intercalary or terminal, undifferentiated conidiogenous cells, and were scattered in dense sections on culture surface. When the conidia dropped from conidiogenous cell, an indistinct scar or a denticle remained. Conidia were hyaline, one-celled, smooth, ellipsoidal, and variable in size (2.73 to 6.01 × 8.45 to 19.36 μm), and all morphological characteristics were consistent with Kabatiella microsticta Bubak (syn. Aureobasidium microstictum; 2,4). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (1). ITS (534 bp) was identical among all four isolates (GenBank Accession No. HE798117) and 100% identical to that of K. microsticta CBS 114.64 (FJ150873). Pathogenicity was confirmed by spraying 20 seedlings of daylily, propagated in tissue-culture medium, with a conidial suspension (106 conidia/ml) of each isolate. A second set of 20 seedlings was sprayed with the same volume of sterile water as the noninoculated control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 5 days, the foliar symptoms described earlier for the field plants appeared on the leaves, whereas the control plants remained healthy. K. microsticta was reisolated from the leaf spots of all 20 inoculated plants. Leaf streak is the most destructive disease of daylily, and was previously reported in Japan and the United States (Illinois, Kentucky, Mississippi, Louisiana, Pennsylvania, Maryland, Virginia, Florida, North Carolina, and Georgia) (3). To our knowledge, this is the first report of the disease caused by K. microsticta in China. References: (1) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (2) E. J. Hermanides-Nijhof. Stud. Mycol. 15:153, 1977. (3) R. M. Leahy et al. Plant Pathology Circular No. 376, 1996. (4) P. Zalar et al. Stud. Mycol. 61:21, 2008.

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(281) Effects of Colchicine and Oryzalin on Callus and Adventitious Shoot Formation of Euphorbia pulcherrima `Winter Rose'™

HortScience ◽

10.21273/hortsci.40.4.1051a ◽

2005 ◽

Vol 40 (4) ◽

pp. 1051A-1051

Author(s):

Kimberly A. Pickens ◽

(Max) Zong-Ming Cheng ◽

Stephen A. Kania

Keyword(s):

Chromosome Doubling ◽

Adventitious Shoots ◽

Adventitious Shoot ◽

Shoot Formation ◽

The United States ◽

Euphorbia Pulcherrima ◽

Adventitious Shoot Formation ◽

Leaf Tissues ◽

Stems And Leaves

Poinsettia, Euphorbia pulcherrima, is an important holiday symbol and is the number one flowering potted plant in the United States. The technique of chromosome doubling has been utilized to increase size of flowers, stems, and leaves of many species, and has been used in poinsettia breeding to obtain new cultivars. Application of colchicine or oryzalin to in vitro tissues may be used to enlarge the inflorescences and brackets and reduce the height of `Winter Rose'™ poinsettias, reduce the likelihood of chimeric tetraploids, and provide a rapid means for producing many tetraploid plants. The purpose of this research was to evaluate the effect of colchicine and oryzalin on callus and adventitious shoot formation of `Winter Rose'™ poinsettia with in vitro grown leaf tissues and its potential for tetraploid induction. In vitro grown leaf midvein sections were placed on various media supplemented with either colchicine or oryzalin at various concentrations for 1–4 days. Colchicine was least damaging to leaf tissues at concentrations of 0.25 or 250.4 μm. A large amount of callus, as well as adventitious shoots, were produced. Regenerated shoots were found to be diploid, determined by flow cytometry. On media with oryzalin (28.9–144 μm), leaf tissues produced callus, but not adventitious shoots. Calluses produced on oryzalin-containing media were tested using the flow cytometer and were found to be diploid.

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First Report of Leaf Spot on Japanese Plum Caused by an Alternaria sp. in Korea

Plant Disease ◽

10.1094/pd-89-0343a ◽

2005 ◽

Vol 89 (3) ◽

pp. 343-343 ◽

Cited By ~ 3

Author(s):

Youngjun Kim ◽

Hyang Burm Lee ◽

Seung Hun Yu

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Conidial Suspension ◽

First Report ◽

Japanese Plum ◽

Leaf Spots ◽

Causal Fungus ◽

Pathogenicity Tests ◽

Alternaria Sp

Japanese plum (Prunus salicina Lindley) is a deciduous tree in the family Rosaceae. In Korea, this plant is widely distributed in orchards as an important stone fruit as well as in gardens as an ornamental tree because of their abundant white blossoms. Every September to November since 2001, leaf spots were observed on Japanese plum in a garden in Cheongyang, Chungnam District, Korea. Early symptoms consisted of small, brown spots that were 2 to 5 mm in diameter. Later, the leaf lesions became circular or irregular, dark brown, expanded to 15 mm in diameter, and resulted in discoloration with necrosis on twisted leaves that was followed by defoliation. In November, older lesions sometimes appeared blackish brown as sporulation occurred on the lesions. The causal fungus was isolated from diseased leaves and cultured on potato dextrose agar. A culture has been placed in the CABI Herbarium (IMI Accession No. 387139). Conidial dimension averaged 34 × 12 μm. On the basis of morphological characteristics of conidia and conidiophores, the causal fungus was identified as a small-spored species of Alternaria as described by E. G. Simmons (1). Pathogenicity tests were conducted by inoculating slightly wounded and nonwounded leaves with a conidial suspension adjusted to 1 × 106 conidia/ml. Four leaves per each experiment were either wounded or not and inoculated with a spore suspension. The eight leaves were placed in a moist chamber at 25°C. After 6 to 10 days, small brown spots appeared on 87% of the wounded and nonwounded leaves. Control leaves sprayed with distilled water did not develop any symptoms. The causal fungus was consistently reisolated from the leaf spots. Results from pathogenicity tests were similar in a repeated test. It is possible that small-spored Alternaria spp. isolates are host specific (2). Eight Alternaria spp., including A. alternata, A. tenuis, A. tenuissima, and A. citri, have been found to cause black spot on fifteen Prunus spp. in China, Japan, Hong Kong, Libya, Mexico, Australia, and the United States (2). Further studies on the host-specific toxin production, geographical distribution, and host ranges for the species of Alternaria isolated from Japanese plum are in progress. To our knowledge, this is the first report of leaf spot on Japanese plum (P. salicina) caused by a small-spored Alternaria sp. in Korea. References: (1) E. G. Simmons. Mycotaxon 55:79, 1995. (2) K. Inoue and H. Nasu. J. Gen. Plant Pathol. 66:18, 2002.

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