First Report of Hypoxylon diatrypeoides Inducing Dieback and Black Trunk Rot on Mesquite (Prosopis laevigata) in Mexico

During 2001, branch dieback, black trunk rot, and resinosis were observed on mesquite in the biosphere reserve of Tehuacan, Mexico (18°15′N, 97°25′W) A light brown growth, which included Nodulosporium-like conidiosphores and hyaline conidia that were green in mass and ellipsoid with one end truncate developed on diseased branches. Below the conidiophores and conidia, glomerate to pulvinate stromata formed with conspicuous, black, perithecial mounds with globose perithecia. Ascospores were dark brown, unicellular, ellipsoid, nonequilateral, with narrowly rounded ends, a straight germ slit with a perispore that was dehiscent in 10% KOH, and a conspicuous coil-like, smooth epispore. Sexual reproduction was induced on sterile toothpicks in potato dextrose agar, malt extract agar, or V8 agar (with 10% calcium chloride). The fungus was identified as Hypoxylon diatrypeoides Rehm (1). Samples of mesquite branches with stromata of H. diatrypeoides were deposited in the J. H. Miller Herbarium of the University of Georgia (GAM16048). During the summer of 2002, three pathogenicity tests were performed under greenhouse conditions using three healthy young mesquite plants (25 cm high) per treatment per test. The treatments were: (i) inoculation of branches by wounding with a colonized toothpick from V8 agar, covered with mycelium and perithecia; (ii) spraying ascospores on branches previously wounded with a sterile toothpick; (iii) spraying ascospores on unwounded plants; (iv) plants wounded with sterile toothpicks; and (v) unwounded and uninoculated plants. Fifteen days after inoculation, branch dieback and black trunk rot symptoms were induced in 100% of mesquite plants inoculated with toothpicks and in 50% of wounded plants inoculated with ascospores. No symptoms were seen in the unwounded plants and control treatments. H. diatrypeoides was reisolated from the symptomatic branches. Previously, the fungus had been reported only from the Southern Hemisphere (Brazil and New Zealand), but to our knowledge, this is the first report from Mexico and the Northern Hemisphere. This is also the first evidence of its role as a plant pathogen. Reference: (1) Y. M. Ju and J. D. Rogers. A revision of the genus Hypoxylon. Mycologia Memoir No 20. The American Phytopathological Society, St. Paul, MN, 1996.

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First Report of Root Rot Caused by Pythium spiculum Affecting Cork Oaks at Doñana Biological Reserve in Spain

Plant Disease ◽

10.1094/pdis-10-12-0952-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 991-991 ◽

Cited By ~ 1

Author(s):

P. De Vita ◽

M. S. Serrano ◽

C. Ramo ◽

C. Aponte ◽

L. V. García ◽

...

Keyword(s):

Root Rot ◽

Phytophthora Cinnamomi ◽

Quercus Suber ◽

First Report ◽

Root Necrosis ◽

Pathogenicity Tests ◽

Branch Dieback ◽

The University ◽

Virulence Group ◽

Biological Reserve

Cork oaks (Quercus suber L.) are key tree species at Doñana Biological Reserve (DBR), Huelva, Spain. Sampling was conducted on a total of 13 trees exhibiting symptoms of decline (foliar wilting and defoliation, branch dieback, and root necrosis). In 2008. Phytophthora cinnamomi was isolated from feeder roots of one tree and Pythium spiculum from two additional oaks. In 2011, both pathogens were isolated from six oaks, only P. cinnamomi from three oaks, and only Py. spiculum from one oak. This expansion was associated with high winter rainfall levels since 2009 that led to long periods of soil flooding. While P. cinnamomi is well known to cause a root disease on Q. suber (2), P. spiculum is a newly described species isolated from Quercus, Vitis, Prunus, Castanea, and Celtis species, but its pathogenicity was demonstrated only on Q. ilex (syn. Q. rotundifolia) (1). Pathogenicity tests were conducted on 4-year-old Q. suber plants. Inocula consisted of two isolates of Py. spiculum from DBR (DO8 and DO36 from Q. suber). For comparison with these, three isolates previously tested on Q. ilex (1) were included: two isolates of Py. spiculum, PA54 (from Q. suber) and PE156 (from Q. ilex); and one isolate of P. cinnamomi, PE90 (from Q. ilex). All these isolates came from the Andalucía region, stored at the oomycete collection of the University of Córdoba, and showed a 99 to 100% homology with their expected ITS sequences in GenBank (DQ196131 for Py. spiculum and AY943301 for P. cinnamomi). Inoculum was prepared by shaking and mixing propagule-bearing mycelium produced in carrot broth petri dishes (20°C, 4 weeks) in sterile water, to produce a concentration of 3 × 104 oospores × ml−1 (Py. spiculum) or 3 × 104 chlamydospores × ml−1 (P. cinnamomi). One hundred milliliters of inoculum was applied to each root (1). There were 10 inoculated plants per isolate and 10 non-inoculated control plants. All plants were waterlogged 2 days per week to favor root infection and maintained in an acclimatised greenhouse (12–28°C). Three months later, the inoculated plants showed symptoms of root necrosis that resulted in foliar wilting followed occasionally by defoliation. Control plants did not develop foliar symptoms nor root necrosis. Root damage severity assessed on a 0 to 4 scale (3) exhibited significant differences (P < 0.05) in relation to the control plants for all the isolates tested, with isolate PE90 (P. cinnamomi) and isolates PA54, DO8, and DO36 (P. spiculum) all averaging a root necrosis value of 2.5. Isolate PE156 of P. spiculum produced values of root necrosis (1.6 in average) significantly lower (P < 0.05) than the rest. This isolate belongs to the low virulence group of P. spiculum described on Q. ilex (1). The inoculated oomycete was always reisolated from necrotic roots and never from roots of control plants. To the best of our knowledge, this is the first report of P. spiculum as the cause of root rot of Q. suber. References: (1) Romero et al. J. Phytopathol. 155:289, 2007. (2) Sánchez et al. For. Pathol. 32:5, 2002. (3) Sánchez et al. For. Pathol. 35:115, 2005.

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First Report of Diplodia seriata Causing Loquat Fruit Rot in Spain

Plant Disease ◽

10.1094/pdis-08-12-0728-pdn ◽

2013 ◽

Vol 97 (3) ◽

pp. 421-421 ◽

Cited By ~ 5

Author(s):

L. Palou ◽

V. Taberner ◽

C. Montesinos-Herrero

Keyword(s):

Fruit Trees ◽

Culture Collection ◽

Potato Dextrose Agar ◽

Fruit Rot ◽

Eriobotrya Japonica ◽

Its2 Region ◽

Malt Extract ◽

Diplodia Seriata ◽

First Report ◽

Branch Dieback

Spain is the second largest loquat (Eriobotrya japonica Lindl.) producer in the world, with about 40,000 t per year. ‘Algerie’ is the main cultivar planted in Alicante province (SE of Spain; Lat. 38.40° N, Long. 0.08° W), where more than 80% of Spanish commercial loquat plantations are located. In a survey of fruit losses at harvest, irregular brownish superficial dry spots (5 to 15 mm) located mainly near the stem end were observed on fruits from different orchards. After incubation at 20°C for 14 days, the spots on fruit expanded rapidly and turned to dark brown or black, producing black, unilocular, ostiolate, and thick-walled pycnidia. Isolation was performed by disinfecting the surface of symptomatic fruits with alcohol and aseptically cutting pieces of infected peel tissue and plating them in potato dextrose agar (PDA) dishes. The potential causal agent (isolate IVIA GCA-5) was identified in the Spanish Type Culture Collection (CECT, University of Valencia, Valencia, Spain). The fungus grew rapidly on both PDA and malt extract agar (MEA) at 26°C, covering the entire plate surface with dark gray mycelium within 4 days. The plate reverse was dark gray to black. The conidia were brown and aseptate, with the apex broadly rounded and the base rounded or truncate, and 23 × 11 μm (n = 50). The identification of Diplodia seriata De Not. was molecularly confirmed with the amplification with the primers ITS1 and ITS4 and subsequent sequencing of the internal transcribed spacer ITS1-5.8S-ITS2 region of the rDNA extracted from the isolate IVIA GCA-5 (GenBank Accession No. JX987099). Furthermore, the region D1/D2 in the 5′ end of the 28S rDNA gene was amplified with the primers NL1 and NL4 and sequenced (JX997743). A nucleotide BLAST analysis showed in both cases 100% identity with D. seriata [EF127892 (3) and AY928050, respectively]. To fulfill Koch's postulates, 5-mm diameter mycelial plugs from 7-day-old colonies of isolate IVIA GCA-5 grown on PDA at 25°C were aseptically transferred to skin wounds on superficially disinfected ‘Algerie’ loquats (one plug per fruit; n = 9). Wounded but not inoculated fruit were used as controls. The experiment was repeated three times. Inoculated fruit developed lesions of 18 to 100 mm after 7 to 21 days of incubation at 20°C. No lesion was observed on controls. The fungus was consistently reisolated from inoculated fruit. D. seriata is a broadly spread pathogen causing cankers, blight, dieback, and fruit rots in vines and many fruit trees. In Spain, it has been reported to cause fruit rot of olive (1) and branch dieback in olive (2) and grapevine (4). To our knowledge, this is the first report worldwide of D. seriata causing loquat fruit rot. References: (1) J. Moral et al. Plant Dis. 92:311, 2008. (2) J. Moral et al. Phytopathology 100:1340, 2010. (3) A. J. L. Phillips et al. Fungal Divers. 25:141, 2007. (4) J. R. Úrbez-Torres et al. Plant Dis. 90:835, 2006.

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First Report of Occurrence of Eggplant Wilt Caused by Verticillium dahliae in Korea

Plant Disease ◽

10.1094/pdis.2000.84.10.1152a ◽

2000 ◽

Vol 84 (10) ◽

pp. 1152-1152

Author(s):

S. K. Kim ◽

S. S. Hong ◽

K. W. Kim ◽

E. W. Park

Keyword(s):

Verticillium Dahliae ◽

Solanum Melongena ◽

Morphological Characteristics ◽

Wilt Disease ◽

Potato Dextrose Agar ◽

First Report ◽

Vascular Tissues ◽

Fungal Isolates ◽

Pathogenicity Tests ◽

Root Cutting

A wilt disease occurred on greenhouse-grown eggplants (Solanum melongena L.) at Hanam and Yeojoo, Korea, in 1997. Lower leaves on the 2-month-old wilted eggplants exhibited gradual yellowing, interveinal necrosis, and marginal crinkling and dropped prematurely. Vascular tissues of diseased stems were discolored and turned black. Vertical sections of the stems revealed that the pith had been colonized by the fungus. The disease progressed from lower parts of the plants upward. Incidence of diseased eggplants in greenhouses was 5% on 23 May 1997. Although the incidence increased to 10% on 13 June, it remained constant through early July. Fungal isolates from discolored vascular tissues were initially whitish to cream color on potato-dextrose agar, which turned black due to the formation of microsclerotia. The fungus also produced abundant verticillate conidiophores with phialides and conidia. Based on these cultural and morphological characteristics, the fungus was identified as Verticillium dahliae Klebahn. Pathogenicity tests by root cutting, root dipping, or soil drenching resulted in similar symptoms observed in the naturally infected eggplants. Symptoms were first observed on lower leaves of each eggplant 3 weeks after inoculation. Isolation from symptomatic leaves of the inoculated eggplants yielded V. dahliae. This is the first report of occurrence of Verticillium wilt of eggplant in Korea.

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First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy

Plant Disease ◽

10.1094/pdis.2004.88.6.681a ◽

2004 ◽

Vol 88 (6) ◽

pp. 681-681

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Northern Italy ◽

American Phytopathological Society ◽

First Report ◽

Powdery Mildews ◽

The Family ◽

White Mycelium ◽

The University

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.

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First Report of Guignardia psidii, an Ascigerous State of Phyllosticta psidiicola, Causing Fruit Rot on Guava in Venezuela

Plant Disease ◽

10.1094/pd-89-0773c ◽

2005 ◽

Vol 89 (7) ◽

pp. 773-773 ◽

Cited By ~ 1

Author(s):

M. S. González ◽

A. Rondón

Keyword(s):

Psidium Guajava ◽

Potato Dextrose Agar ◽

Fruit Rot ◽

Symptom Development ◽

First Report ◽

Guava Fruit ◽

Pathogenicity Tests ◽

Apical Appendage ◽

Ascigerous State ◽

Gelatinous Envelope

During August 2003, guava fruit (Psidium guajava L.) cv. Red Dominicana from Cojedes state in Venezuela showed circular, purple-to-brown lesions (0.5 to 1.0 cm) that spread over all surfaces and became black and shrunken on severely affected fruit. Symptomatic tissues were plated aseptically on potato dextrose agar (PDA). Colonies that were initially gray and turned black with age were consistently isolated. The fungus was characterized by dense, submerged, brown-to-black mycelium with septate hyphae. Ascocarps were perithecial, abundant, granulose, subglobose to cylindric obpyriform, solitary or aggregated, mostly unilocular with prominent long necks; ascocarp walls were stromatic, composed of several layers of cells, thick walled, and deeply pigmented on the outside. Asci were subclavate to cylindrical, stipitate, 44 to 84 × 7 to 9 μm, and eight-spored; asci walls were thick and bitunicate. Ascospores were unicellular, hyaline, guttulate, fusiform ellipsoid, widest in the mid-region with rounded ends and gelatinous plugs, and 12 to 17 × 4.5 μm. Conidiomata were pycnidial, intermixed among ascocarps, variable in shape, dark brown, solitary or aggregated, ostiolate, and with long necks up to 1 mm. Pycnidial walls were pseudoparenchymatic, multicellular, and composed of many layers of brown compressed cells. Conidiogenous cells were hyaline, subglobose to cylindrical, and smooth, and holoblastic. Conidia were hyaline, unicellular, obovate, 6 to 12 (7.5) × 5 to 8 μm, slightly truncate at the bases, rounded at apices, guttulate, and provided a gelatinous envelope and apical appendage. Appendages were hyaline, tubular, smooth, and 3.0 to 4.5 × 0.5 μm. The fungus is homothallic because single ascospores and single conidia developed ascigerous states. The ascigerous state was identified as Guignardia psidii (1) and the anamorph as Phyllosticta psidiicola (1,2). Pathogenicity tests were conducted on detached fruits inoculated with monosporic cultures. Pathogenesis and symptom development only occurred when a mixture of mycelium, ascospores, and conidia was used as inoculum. The fungus was reisolated from symptomatic fruit tissues. To our knowledge, this is the first report of Guignardia psidii, an ascigerous state of Phyllosticta psidiicola from guava fruits in Venezuela. References: (1) B. A. Ullasa and R. D. Rawal. Curr. Sci. 53:435, 1984. (2) H. A. van der Aa. Page 95 in: No. 5, Stud. Mycol., 1973.

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First Report of Chalara fraxinea on Common Ash in Italy

Plant Disease ◽

10.1094/pdis-94-1-0133a ◽

2010 ◽

Vol 94 (1) ◽

pp. 133-133 ◽

Cited By ~ 20

Author(s):

N. Ogris ◽

T. Hauptman ◽

D. Jurc ◽

V. Floreancig ◽

F. Marsich ◽

...

Keyword(s):

Morphological Characteristics ◽

Aluminum Foil ◽

Malt Extract ◽

First Report ◽

Chalara Fraxinea ◽

Ash Trees ◽

Mycelial Plug ◽

Northeastern Italy ◽

Xylem Discoloration ◽

Branch Dieback

In many European countries, the anamorphic Chalara fraxinea Kowalski (teleomorph Hymenoscyphus albidus [Roberge ex Desm.] Phillips; 1–3) is responsible for a severe and rapidly spreading dieback of common ash (Fraxinus excelsior L.) since it was first reported in Poland. Recently, this disease was added to the EPPO Alert List and the NAPPO Phytosanitary Alert System. Symptomatic trees were observed in a 1.8-ha ash-maple forest in northeastern Italy (Fusine, UD; 46°30′N, 13°37′E; 782 m above sea level) along the Italo-Slovenian border in July 2009. Symptoms were found on approximately 10% of mature common ash and 70% of seedlings. Main symptoms were shoot, twig, and branch dieback, wilting, and bark cankers (1). Fungal fruiting bodies were not found on or near the canker surface. Furthermore, longitudinal and radial sections through the cankers revealed gray-to-brown xylem discoloration. One symptomatic 3-year-old plant was randomly selected and from the necrotic margin of one canker previously surface-sterilized with 3% sodium hypochlorite and rinsed, four 2-mm-wide chips were placed on malt extract agar (MEA) and incubated at 21 ± 1°C in the dark. Among a variety of microorganisms, after 19 days, slow-growing colonies (mean radius of 12 mm) appeared that were effuse, cottony, and often fulvous brown but sometimes dull white with occasional gray-to-dark gray patches. The purified isolate was then transferred to the same medium at 4 ± 1°C in the dark, and after 11 days, hyaline-to-dark gray phialides were observed producing numerous conidia in slimy droplets and sometimes in chains. Phialophores measured 8.6 to 21.0 (15.1) μm long (n = 20), 4.2 to 13.4 (8.8) × 3.6 to 5.5 (4.7) μm at the base, and 5.2 to 8.7 (6.5) × 2.5 to 3.1 (2.8) μm at the collarette; conidia measured 2.8 to 4.2 (3.4) × 1.9 to 2.5 (2.2) μm (n = 40); and first formed conidia measured 5.5 to 6.5 (5.9) × 1.8 to 2.5 (2.1) μm (n = 20). These morphological characteristics matched Kowalski's (1) description of C. fraxinea. In August of 2009, the fungal isolate was used to test pathogenicity with current year shoots of 25 6-year-old (150 to 210 cm high) asymptomatic common ash trees under quarantine conditions (Slovenian Forestry Institute's experimental plots). For every plant, the bark of the main shoot (10 to 13 mm in diameter) was wounded with a 6-mm-diameter cork borer. Twenty saplings were inoculated with one 6-mm-diameter mycelial plug obtained from the margin of a 26-day-old culture (MEA), while five saplings were inoculated with sterile MEA plugs. All wounds were sealed with Parafilm and aluminum foil. After 28 days, all plants inoculated with the C. fraxinea showed bark lesions (2 to 39 mm long, mean 7 mm) and wood discoloration (6 to 85 mm long, mean 22 mm) from which the pathogen was reisolated. These symptoms were absent from controls and the pathogen was never reisolated. To our knowledge, this is the first report of C. fraxinea in Italy. Investigations on its presence in all Fraxinus species naturally growing in the investigated area and in the nearest regions are in progress. The obtained isolate is preserved in both Padova and Ljubljana herbaria as CFIT01. References: (1) T. Kowalski. For. Pathol. 36:264, 2006. (2) T. Kowalski and O. Holdenrieder. For. Pathol. 39:1, 2009. (3) T. Kowalski and O. Holdenrieder. For. Pathol. 39:304, 2009.

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Verticillium—Induced Scorch and Chlorosis in Ash

Journal of Environmental Horticulture ◽

10.24266/0738-2898-12.3.124 ◽

1994 ◽

Vol 12 (3) ◽

pp. 124-130 ◽

Cited By ~ 2

Author(s):

G. L. Worf ◽

R. N. Spear ◽

M. F. Heimann

Keyword(s):

Distribution Patterns ◽

Potato Dextrose Agar ◽

Green Ash ◽

Upper Midwest ◽

Branch Dieback ◽

And Control ◽

Intensive Sampling ◽

Landscape Trees ◽

Light Green ◽

Symptom Recurrence

Abstract Verticillium dahliae appears to be the causal agent of a common disorder of white and green ash that has increasingly affected nursery and landscape trees in the Upper Midwest. Affected trees are without wilting or vascular discoloration typical of Verticillium symptoms on other woody hosts, although upper branch and unilateral distribution patterns remain common and important clues. Symptoms include considerable light green to chlorotic foliage followed by irregular leaf scorch, defoliation and branch dieback. The fungus was best isolated from leaf petioles on potato dextrose agar containing 100 ppm iprodione + 200 ppm chloramphenicol. Repeated and intensive sampling was often necessary to detect the fungus. Symptom recurrence in following years was common but erratic and unpredictable. A discussion of environmental influences and control possibilities is included.

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First Report of Typhula Blight on Agrostis stolonifera and Poa annua in Italy

Plant Disease ◽

10.1094/pdis.2003.87.7.875c ◽

2003 ◽

Vol 87 (7) ◽

pp. 875-875 ◽

Cited By ~ 1

Author(s):

P. Titone ◽

M. Mocioni ◽

A. Garibaldi ◽

M. L. Gullino

Keyword(s):

Agrostis Stolonifera ◽

Northern Italy ◽

Potato Dextrose Agar ◽

Poa Annua ◽

Golf Course ◽

Pathogenicity Test ◽

Potato Dextrose Broth ◽

First Report ◽

Pathogenicity Tests ◽

Typhula Incarnata

During January 2002, Agrostis stolonifera and Poa annua turfgrasses on a golf course in Avigliana (northern Italy) exhibited 10- to 45-cm-diameter circular patches when the snow melted from the greens, tees, and fairways. Many patches coalesced to form large areas of strawcolored blighted turfgrass. At the patch margin, infected plants were covered with white-to-gray mycelium. Plants within patches were matted and appeared slimy with mycelium and sclerotia that were light pink, irregularly shaped, and less than 5 mm in diameter. Isolation from infected leaves on potato dextrose agar, supplemented with 100 mg/l of streptomycin sulfate, consistently yielded a fungus with mycelial, sclerotia, and cultural characteristics of Typhula incarnata (1). Pathogenicity tests were performed by spraying a suspension of mycelium and sclerotia, prepared by chopping mycelium and sclerotia produced in potato dextrose broth, onto 8-week-old A. stolonifera plants grown in plastic trays (45 × 30 cm). Trays were maintained at 0°C for 8 weeks in the dark. Blight symptoms developed on inoculated plants after 6 weeks. Non-inoculated plants remained healthy. The pathogen was reisolated from inoculated plants, and the pathogenicity test was repeated once. Typhula blight incited by T. incarnata was reported in Scandinavian countries and in several European countries including Holland, Germany, Austria, and Switzerland (1). To our knowledge, this is the first report of Typhula blight on turfgrass in Italy. Reference: (1) J. D. Smith et al. 1989. Fungal Diseases of Amenity Turf Grasses. E & FN Spong Ltd, London.

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First Report of Leaf Spot Caused by Alternaria alternata on Kiwifruit in Italy

Plant Disease ◽

10.1094/pdis.1999.83.5.487d ◽

1999 ◽

Vol 83 (5) ◽

pp. 487-487 ◽

Cited By ~ 3

Author(s):

L. Corazza ◽

L. Luongo ◽

M. Parisi

Keyword(s):

New Zealand ◽

Alternaria Alternata ◽

Leaf Spot ◽

Southern Italy ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

First Report ◽

Leaf Spots ◽

Detached Leaves ◽

Pathogenicity Tests

A leaf spot of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferg.) leaves was recently observed on plants of the cultivar Hayward in an orchard near Salerno, in southern Italy. The affected plants showed early severe defoliation. The fungus isolated from the infected leaves was identified as Alternaria alternata (Fr.:Fr.) Keissl., based on conidial morphological characteristics. Pathogenicity tests were made by inoculating detached leaves of male pollinator cultivar Tomuri and the female cultivars Hayward and Bruno with a 7-mm disk taken from actively growing cultures of the fungus on potato dextrose agar (PDA). After 14 days, necrotic leaf spots developed and A. alternata was consistently isolated from the inoculated leaves. A. alternata has been observed as a pathogen on leaves and fruits in New Zealand. In the Mediterranean, it has been reported in Israel (2) and in the island of Crete (1). This is the first report of Alternaria leaf spot on kiwifruit in Italy. References: (1) V. A. Bourbos and M. T. Skoudridakis. Petria 7:111, 1997. (2) A. Sive and D. Resnizky. Alon Hanotea 41:409, 1987.

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First Report of Root Rot Caused by Binucleate Rhizoctonia Anastomosis Group F on Musa spp.

Plant Disease ◽

10.1094/pdis-08-10-0602 ◽

2011 ◽

Vol 95 (4) ◽

pp. 490-490

Author(s):

J. Yin ◽

D. Koné ◽

M. Rodriguez-Carres ◽

M. A. Cubeta ◽

L. L. Burpee ◽

...

Keyword(s):

Root Rot ◽

Lateral Roots ◽

Anastomosis Group ◽

Molecular Characteristics ◽

First Report ◽

Binucleate Rhizoctonia ◽

Musa Spp ◽

University Of Georgia ◽

Its Regions ◽

The University

A research program was initiated at the University of Georgia in 2003 to identify banana cultivars suitable for production in the coastal and southern areas of the state. During a root disease survey conducted in October 2007 on bananas (Musa spp.) grown at the University of Georgia Bamboo Farm and Coastal Gardens in Savannah, GA, root lesions and root rot were observed on banana cvs. Gold Finger, Kandarian, and Manzano. Root lesions were dark brown to black and irregular in shape, with partial or entire roots affected. Lateral roots and outer layers of cord roots (roots arising from interior layers of the corm) of infected plants were blackened and rotted. Diseased root samples were collected from three plants of each cultivar, surface sterilized with 0.6% sodium hypochlorite, and placed on tannic acid benomyl agar (TABA). Pure cultures of the fungus consistently associated with diseased tissue were obtained by subculturing hyphal tips on TABA. Mycelia of the fungus on potato dextrose agar (PDA) were light to deep brown and the hyphae tended to branch at right angles. A septum was present in each hyphal branch near the point of origin and a slight constriction at the branch was observed. The hyphae of two isolates were stained with 0.6% phenosafranin and 3% KOH and binucleate hyphal cells were observed. On the basis of these morphological features, the isolates appeared to be binucleate Rhizoctonia anamorphs (teleomorph Ceratobasidium Rogers). For molecular identification, the internal transcribed spacer (ITS) regions and the 5.8S gene from rDNA of the isolates were cloned and sequenced (GenBank Accession No. HQ168370). The ITS regions (775 bp) were 100% identical between the two isolates and 99% identical to Ceratobasidium sp. AG-F strain SIR-1 isolated from sweet potato in Japan (GenBank Accession No. AF354085). The anastomosis group of the isolates was confirmed by pairing with strain SIR-1 on PDA. On the basis of morphological and molecular characteristics and the anastomosis assay, the two isolates were identified as a Ceratobasidium sp. AG-F (1–3). Pathogenicity assays were conducted by inoculating banana plants (cv. Golden pillow, synonym = Manzano) grown in pots under greenhouse conditions (25 to 27°C). Twenty wheat seeds infested with each isolate were placed uniformly around each plant at a depth of 10 cm in the soil. The plants were incubated in the greenhouse and the roots were examined 2 months after inoculation. Brown-to-black lesions and root rot, identical to symptoms associated with field banana roots, were observed on all inoculated plants but not on the noninoculated control plants. The fungus was reisolated from affected root samples and the identity was confirmed by morphological and molecular characteristics and the anastomosis assay. To our knowledge, this is the first report of banana root rot caused by binucleate Rhizoctonia anastomosis group F. With the increased interest in producing bananas for food and ornamental purposes, the occurrence of Ceratobasidium root rot on bananas needs to be considered when designing disease management programs and searching for suitable cultivars for banana production. References: (1) L. L. Burpee et al. Mycologia 70:1281, 1978. (2) D. González et al. Mycologia 93:1138, 2001. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN. 1991.

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