First Report of Cylindrocarpon pauciseptatum Associated with Root Rot and Decline of Peach in Southern Italy (Apulia Region)

During a survey for the sanitary status of stone fruits in southern Italy (Apulia region), symptoms of low vigor, sparse foliage, and chlorosis of leaves, frequently leading to decline or death of the plants, were observed on 3- to 5-year-old peach trees (Prunus persica) cvs. Tardi Belle, Zee Lady, and O'Henry grafted on GF677. Brown-to-black discolorations of the wood were observed in cross-sections of the trunks just below the graft union. Samples were collected from May to June 2010 from two symptomatic orchards in Brindisi and Foggia provinces. Small pieces of brownish, vascular wood and necrotic root tissues were surface disinfested, placed onto potato dextrose agar (PDA), and incubated for 7 days at 25°C in the dark. Single-conidial isolates were subsequently grown on PDA at 25°C for 10 days. Fungal colonies were presumptively identified as members of the genus Cylindrocarpon on the basis of their morphological and conidial characteristics. On PDA, the isolates developed abundant mycelium, which gradually became yellowish or partially brownish. Macroconidia were predominantly three septate, straight and cylindrical with both ends broadly rounded. Chlamydospores and ovoidal microconidia were observed on synthetic nutrient-poor agar (1). Sequence of the ribosomal internal transcribed spacer (ITS) region was obtained using universal primers (ITS6-ITS4) and deposited in GenBank (Accession No. HE577846). This sequence revealed 100% genetic identity with a sequence from Cylindrocarpon pauciseptatum Schroers & Crous (Accession No. EF607090), a recently described species (3). In nature, several species of the genus Cylindrocarpon affect a large number of woody plants, mainly grapevine, olive, and stone fruits, in which they attack the root surface (2). To verify Koch's postulates, the roots of 20 3-month-old peach seedlings (GF305) were dipped for 30 min in a spore suspension of the fungus (1 × 108 conidia ml–1). Seedlings were then transplanted in an artificial soil mix and held under controlled conditions in a greenhouse at 24°C. Typical black-foot symptoms developed on 92% of the inoculated plants within 3 months, whereas the control plants, whose roots had been dipped in distilled water, remained healthy. C. pauciseptatum was reisolated from infected tissues and internal vascular lesions of 45% of the inoculated plants, but none of the plants used as controls, fulfilling Koch's postulates. To our knowledge, this is the first report of this pathogen on peach in the Apulia Region of Italy. Currently, C. pauciseptatum is limited to a few orchards where presumably it was introduced with infected propagating material from extra-regional nurseries. C. pauciseptatum has the potential to negatively affect the stone fruit industry in Italy including reducing nursery production and productivity and vigor of trees in orchards, or even rapid death of young trees. References: (1) W. Gams et al. CBS Course of Mycology. 4th ed. Centraalbureau voor Schimmelcultures, Baarn, the Netherlands, 1998. (2) M. E. S. Hernandez et al. Eur. J. Plant Pathol. 104:347, 1998. (3) H. J. Schroers et al. Mycol. Res. 112:82, 2008.

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First Report of Aspergillus niger Causing Postharvest Fruit Rot of Cherry in the Prefectures of Imathia and Pella, Northern Greece

Plant Disease ◽

10.1094/pdis-07-11-0620 ◽

2012 ◽

Vol 96 (3) ◽

pp. 458-458 ◽

Cited By ~ 1

Author(s):

T. Thomidis ◽

E. Exadaktylou

Keyword(s):

Aspergillus Niger ◽

Fungal Spores ◽

Morphological Characteristics ◽

Fruit Rot ◽

Northern Greece ◽

Centraalbureau Voor ◽

Koch’S Postulates ◽

First Report ◽

Postharvest Rot ◽

Koch's Postulates

In June 2011, symptoms of postharvest rot were observed on approximately 3% of all cherries collected from commercial orchards of cultivars Lapen and Ferrovia in the prefectures of Imathia and Pella (northern Greece). Fruit were harvested in a timely manner to avoid overripeness. No wounds or other predisposing injuries were observed on the infected fruits. Lesions enlarged rapidly and separated easily from healthy tissue when pressure was applied. Infected tissues were pale and water soaked and the associated fungal spores were dark and powdery and easily liberated when mature. The fungus grew rapidly and produced black colonies on acidified potato dextrose agar (2.5 ml of 85% lactic acid per liter of nutrient medium) after 5 days at 24°C. Identification of the pathogen was based on morphological characteristics (1). The conidial head was radiate, vesicles were nearly spherical and covered with metulae and phialides (biseriate). Conidia were globose (3 to 5 μm in diameter) and usually very rough with irregular ridges, bars, and verrucae. Koch's postulates were completed in the laboratory by inoculating mature cherry fruits (cv. Lapen). The fruits were surface sterilized by dipping in 10% chloride bleach solution, allowed to dry in a laminar flow hood, and wounded with a sharp glass rod that was 2 mm in diameter. A 40-μl drop of a suspension containing 20,000 conidia per ml of water was placed on each wound. There were 20 inoculated and 20 control fruits (similarly wounded and inoculated with a 40-μl drop of sterile distilled water) in a randomized design and incubated at 24 to 26°C for 6 days. Koch's postulates were satisfied after reisolating the fungus from inoculated fruit that developed symptoms similar to those observed on fruit collected from orchards. Control fruits did not show any symptom of the disease. To our knowledge, this is the first report of the occurrence of Aspergillus niger as the causal agent of postharvest rots of cherries in Greece. Postharvest fruit rots caused by A. niger have been reported in cherry orchards of other countries around the world (2). Because this disease causes postharvest rots of cherry fruits, measures may need to be implemented to manage the pathogen. References: (1) M. A. Klich. Page 12 in: Identification of Common Aspergillus Species. Centraalbureau Voor Schimmelcultures, Utrecht, the Netherlands, 2002. (2) A. Valiuskaite et al. Phytopathol. Pol. 35:197, 2005.

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First Report of Phomopsis amygdali Causing Fruit Rot on Peaches in Greece

Plant Disease ◽

10.1094/pd-90-1551c ◽

2006 ◽

Vol 90 (12) ◽

pp. 1551-1551 ◽

Cited By ~ 3

Author(s):

T. J. Michailides ◽

T. Thomidis

Keyword(s):

Prunus Persica ◽

Morphological Characteristics ◽

Fruit Rot ◽

Peach Fruit ◽

Koch’S Postulates ◽

Canker Disease ◽

First Report ◽

Immature Fruit ◽

Diseased Fruit ◽

Koch's Postulates

In the summer of 2005, the fungus Phomopsis amygdali (Del.) Tuset & Portilla was frequently isolated from decayed peaches (Prunus persica cv. Andross) grown in the province of Imathia, Greece. Fruit infected by P. amygdali developed gray-to-brown decay lesions with white mycelium forming on the surface of lesions. Identification of the pathogen was based on morphological characteristics. Dark-pigmented pycnidia (flask-shaped, conidia-bearing fruiting bodies) were produced over the surface of potato dextrose agar. The pycnidia exuded conidia in white tendrils 7 days later. Koch's postulates were completed in the laboratory by inoculating mature and immature cv. Andross peach fruits with an isolate of P. amygdali isolated from decayed cv. Andross peaches. Thirty peach fruit were surface sterilized by dipping them into 0.1% chlorine solution and allowing them to dry in a laminar flow hood. The peach fruit were wounded with a 2-mm diameter glass rod and a 40-μl drop of 5 × 105 conidia of P. amygdali per milliliter suspension was applied to the wound. Thirty control fruits were similarly wounded and inoculated with a 40-μl drop of sterile water. All inoculated and noninoculated fruit were incubated at 24 to 26°C for 7 days. Koch's postulates were satisfied when the same fungus was reisolated from 100% of inoculated mature and immature fruit that developed symptoms similar to diseased fruit collected from orchards. Although P. amygdali has been previously reported as a causal agent of canker disease (2) and fruit rots of peaches (1) in other countries, to our knowledge, this is the first report of the occurrence of P. amygdali causing a fruit rot of peaches in Greece. References: (1) Y. Ko and S. Sun. Plant Pathol. Bull. 12:212, 2003. (2) E. I. Zehr, Constriction canker. Page 31 in: Compendium of Stone Fruit Diseases. J. M. Ogawa et al., eds. The American Phytopathological Society, St. Paul, MN, 1995.

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First Report of Aspergillus niger Causing Root Rot of Peanut in China

Plant Disease ◽

10.1094/pdis-05-14-0530-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 284-284 ◽

Cited By ~ 3

Author(s):

M. L. Xu ◽

J. G. Yang ◽

J. X. Wu ◽

Y. C. Chi ◽

L. H. Xie

Keyword(s):

Aspergillus Niger ◽

Root Rot ◽

Genomic Dna ◽

Dense Layer ◽

Causal Organism ◽

Centraalbureau Voor ◽

Koch’S Postulates ◽

First Report ◽

Initial Symptoms ◽

Koch's Postulates

Peanut (Arachis hypogaea) is one of the most important oil crops and food legumes worldwide. China sows approximately 3.5 million hectares each year and produces 40% of the world's peanuts. Fungal diseases are among the main biotic stresses affecting peanut production. Root rot is a serious disease caused by several fungi. Pythium spp., Fusarium spp., and Rhizopus spp. are some of the root rot fungi that have been reported in China. In 2012 and 2013, root rot symptoms were observed in several fields in Laixi District, Qingdao City, Shandong Province, China. The first symptoms appeared in July. Initial symptoms of the disease were brown spots on the stem base and root. Affected plants were stunted, with leaf chlorosis, reduced growth, or sudden wilting. As disease progressed, the infected tissues showed brown discoloration and rot, and abundant dark brown and black powdery spores were visible on the surfaces of affected parts. Eventually, affected plants collapsed and died. To isolate the causal organism, roots and stems were cut into sections, which were surface-disinfected with 70% ethanol solution (v/v) for 20 s, soaked in 0.1% mercuric chloride solution for 50 s, rinsed with sterilized water three times, dried, placed on Czapek's Dox agar supplemented with chloramphenicol (100 μg/ml), and incubated at 28°C for 7 days. Fungal colonies were white initially and then covered with a dense layer of dark brown or black conidial heads. The conidial head was radiate; vesicles were nearly spherical and covered with irregular metulae and phialides. Conidia were globose or subglobose (3.0 to 5.5 μm in diameter), dark brown to black, with rough cell walls. Total genomic DNA was extracted from mycelia using the EasyPure Genomic DNA Kit (TransGEN, Beijing, China). The rDNA-ITS region was amplified using PCR with the universal fungal primers ITS1 and ITS4 (2). The purified products were separately sequenced in both directions using the same primer pair. The sequences (GenBank Accession No. KJ848716) obtained were 99% similar to the ITS sequence of isolates of Aspergillus niger. This, together with the morphological characters (1) described above, suggested that the microorganism we had isolated was A. niger. Koch's postulates were completed in the laboratory by inoculating peanut. Thirty Huayu20 peanut seeds were placed in a 500-ml sterile pot with 300 g of autoclaved soil. Twenty days after seedling emergence, 15 peanut plants were wounded with a needle and inoculated with 5 ml of conidia suspension (106 ml−1). The same number of peanuts were similarly wounded and inoculated with 5 ml of sterile distilled water to serve as controls in the same pot. All peanuts were kept in a randomized complete block design at 30°C under a 12-h photoperiod. After 7 days, disease symptoms similar to those observed in the field appeared in all inoculated but not in non-inoculated peanuts. The tests were repeated three times in the greenhouse. Koch's postulates were satisfied after re-isolating the A. niger from inoculated peanuts using the method described above. To our knowledge, this is the first report of A. niger causing root rot in peanut in China. References: (1) M. A. Klich. Page 12 in: Identification of Common Aspergillus Species. Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands, 2002. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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First Report of Leaf Spot and Blight Caused by Botrytis cinerea on Pygmy Date Palm in Italy

Plant Disease ◽

10.1094/pdis.2003.87.11.1398b ◽

2003 ◽

Vol 87 (11) ◽

pp. 1398-1398 ◽

Cited By ~ 1

Author(s):

G. Polizzi ◽

A. Vitale

Keyword(s):

Botrytis Cinerea ◽

Leaf Spot ◽

Canary Island ◽

Date Palm ◽

Southern Italy ◽

Sterile Water ◽

Koch’S Postulates ◽

Date Palms ◽

First Report ◽

Koch's Postulates

Pygmy date palm (Phoenix roebelenii O'Brien), native to Laos and southeast Asia, is one of the most commonly cultivated date palms both indoors and out. In early April 2003, a new and widespread leaf disease was detected on 2- to 3-feet high, potted, pygmy date palms growing in open fields or shade-houses in four commercial nurseries of the eastern Sicily Region of southern Italy. Initial symptoms on infected plants were small, chlorotic spots on blades and edges of leaflets. As spots enlarged, yellow or reddish-brown margins and brown or gray, wrinkled, sunken centers developed. Sometimes, spots or lesions coalesced to cause blight of young expanding leaves or death of apical buds. Botrytis cinerea Pers.:Fr was recovered consistently from sections of infected tissues (disinfected for 1 min in 1% NaOCl and rinsed in sterile water) plated on malt extract agar. On potato dextrose agar (PDA), colonies of B. cinerea were first hyaline, then turned white, and later turned dark gray when spores differentiated. Six- to eight-day-old-cultures developed white sclerotia that turned black after three more days. Conidia in 1-month-old-cultures were hyaline or gray, ovoid, and ranged from 5.2 to 8.8 × 8 to 14 μm (average 6.6 × 9.9 μm). Black microsclerotia were round or irregular in shape and ranged from 0.6 to 2.8 × 0.3 to 2.5 mm (average 1.66 × 0.98 mm) (1). Koch's postulates were performed by spraying potted, 9-month-old pygmy date palms (2 feet high) with a spore suspension (1 × 106 CFU per ml from 15-day-old cultures grown on PDA). Six plants were wounded and inoculated, while six plants were inoculated without wounding. An equal number of noninoculated plants sprayed with sterile water served as controls. All plants were maintained in a humid environment at 20°C. Sunken-leaf and rachis lesions were observed on all wounded and most nonwounded plants within 10 to 14 days after inoculation. Symptoms did not develop on the control plants. Koch's postulates were fulfilled by reisolation of the fungus from affected tissues. A field survey revealed the occasional presence of similar leaf spots on canary island date palms (Phoenix canariensis Hort. ex Chabaud), from which B. cinerea was consistently recovered. The unusually cool and humid weather conditions recorded in Sicily during this disease outbreak were very conducive for occurrence of the B. cinerea infections. Although the disease only occasionally caused death of plants, evidence indicated that B. cinerea reduced commercial value of infected pygmy date palms. B. cinerea was previously recorded in northern Italy on canary island date palm (2) and was recently detected in southern Italy on majesty palm (3). To our knowledge, this is the first report of leaf spot and rachis blight caused by B. cinerea on pygmy date palm. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CAB, Kew, Surrey, England, 1971. (2) A. Garibaldi and S. Rapetti. No. 9 Suppl. Flortecnica, 1987. (3) G. Polizzi. Plant Dis. 86:815, 2002.

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First Report of Pathogenicity of Fusarium sporotrichioides and Fusarium acuminatum on Sunflowers in the United States

Plant Health Progress ◽

10.1094/php-2010-0915-02-br ◽

2010 ◽

Vol 11 (1) ◽

pp. 42 ◽

Cited By ~ 4

Author(s):

F. Mathew ◽

B. Kirkeide ◽

T. Gulya ◽

S. Markell

Keyword(s):

United States ◽

Helianthus Annuus ◽

The United States ◽

Fusarium Sporotrichioides ◽

Charcoal Rot ◽

Koch’S Postulates ◽

First Report ◽

Fusarium Acuminatum ◽

Helianthus Annuus L ◽

Koch's Postulates

Widespread infection of charcoal rot was observed in a commercial sunflower field in Minnesota in September 2009. Based on morphology, isolates were identified as F. sporotrichioides and F. acuminatum. Koch's postulates demonstrated pathogencity of both species. To our knowledge, this is the first report of F. sporotrichoides and F. acuminatum causing disease on Helianthus annuus L. in the United States. Accepted for publication 23 August 2010. Published 15 September 2010.

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First Report of Stemphylium botryosum Causing Leaf Blight of Kiwi in the Province Imathia, Northern Greece

Plant Disease ◽

10.1094/pdis-92-4-0650b ◽

2008 ◽

Vol 92 (4) ◽

pp. 650-650 ◽

Cited By ~ 1

Author(s):

T. Thomidis ◽

T. J. Michailides

Keyword(s):

Apical Cell ◽

Morphological Characteristics ◽

Leaf Blight ◽

Width Ratio ◽

Northern Greece ◽

Cell Width ◽

Koch’S Postulates ◽

First Report ◽

Stemphylium Botryosum ◽

Koch's Postulates

In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000

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First Report of Brown Rot Caused by Monilinia fructicola Affecting Peach Orchards in Slovenia

Plant Disease ◽

10.1094/pdis-94-9-1166a ◽

2010 ◽

Vol 94 (9) ◽

pp. 1166-1166 ◽

Cited By ~ 15

Author(s):

A. Munda ◽

M. Viršček Marn

Keyword(s):

Prunus Persica ◽

Brown Rot ◽

Fruit Rot ◽

Morphological Identification ◽

Monilinia Fructicola ◽

Conidial Suspension ◽

Stone Fruits ◽

The European Union ◽

First Report ◽

Representative Isolate

Monilinia fructicola, the causal agent of brown rot, is a destructive fungal pathogen that affects mainly stone fruits (Prunoideae). It causes fruit rot, blossom wilt, twig blight, and canker formation and is common in North and South America, Australia, and New Zealand. M. fructicola is listed as a quarantine pathogen in the European Union and was absent from this region until 2001 when it was detected in France. In August 2009, mature peaches (Prunus persica cv. Royal Glory) with brown rot were found in a 5-year-old orchard in Goriška, western Slovenia. Symptoms included fruit lesions and mummified fruits. Lesions were brown, round, rapidly extending, and covered with abundant gray-to-buff conidial tufts. The pathogen was isolated in pure culture and identified based on morphological and molecular characters. Colonies on potato dextrose agar (PDA) incubated at 25°C in darkness had an average daily growth rate of 7.7 mm. They were initially colorless and later they were light gray with black stromatal plates and dense, hazel sporogenous mycelium. Colony margins were even. Sporulation was abundant and usually developed in distinct concentric zones. Limoniform conidia, produced in branched chains, measured 10.1 to 17.7 μm (mean = 12.1 μm) × 6.2 to 8.6 μm (mean = 7.3 μm) on PDA. Germinating conidia produced single germ tubes whose mean length ranged from 251 to 415 μm. Microconidia were abundant, globose, and 3 μm in diameter. Morphological characters resembled those described for M. fructicola (1). Morphological identification was confirmed by amplifying genomic DNA of isolates with M. fructicola species-specific primers (2–4). Sequence of the internal transcribed spacer (ITS) region (spanning ITS1 and ITS 2 plus 5.8 rDNA) of a representative isolate was generated using primers ITS1 and ITS4 and deposited in GenBank (Accession No. GU967379). BLAST analysis of the 516-bp PCR product revealed 100% identity with several sequences deposited for M. fructicola in NCBI GenBank. Pathogenicity was tested by inoculating five mature surface-sterilized peaches with 10 μl of a conidial suspension (104 conidia ml–1) obtained from one representative isolate. Sterile distilled water was used as a control. Peaches were wounded prior to inoculation. After 5 days of incubation at room temperature and 100% relative humidity, typical brown rot symptoms developed around the inoculation point, while controls showed no symptoms. M. fructicola was reisolated from lesion margins. Peach and nectarine orchards in a 5-km radius from the outbreak site were surveyed in September 2009 and M. fructicola was confirmed on mummified fruits from seven orchards. The pathogen was not detected in orchards from other regions of the country, where only the two endemic species M. laxa and M. fructigena were present. To our knowledge, this is the first report of M. fructicola associated with brown rot of stone fruits in Slovenia. References: (1) L. R. Batra. Page 106 in: World Species of Monilinia (Fungi): Their Ecology, Biosystematics and Control. J. Cramer, Berlin, 1991. (2) M.-J. Côté et al. Plant Dis. 88:1219, 2004. (3) K. J. D. Hughes et al. EPPO Bull. 30:507, 2000. (4) R. Ioos and P. Frey. Eur. J. Plant Pathol. 106:373, 2000.

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First report of Pestalotiopsis diospyri causing canker on persimmon trees

Revista Brasileira de Fruticultura ◽

10.1590/s0100-29452011005000103 ◽

2011 ◽

Vol 33 (3) ◽

pp. 1019-1022 ◽

Cited By ~ 2

Author(s):

Giselda Alves ◽

Francineia Silva Verbiski ◽

Themis J. Michaelides ◽

Louise Larissa May-de Mio

Keyword(s):

Diospyros Kaki ◽

Southern Brazil ◽

Severe Damage ◽

Santa Catarina ◽

Koch’S Postulates ◽

Canker Disease ◽

First Report ◽

Koch's Postulates

During 2006 to 2009 season symptoms of a canker disease were observed on twigs and branches of young and mature persimmon trees (Diospyros kaki L.) cv. Fuyu in the States of Santa Catarina and Paraná in the Southern Brazil. The cankers result in severe damage and reduced production. Isolations from the margins of these cankers revealed a genus of Pestalotiopsis. Koch's postulates were confirmed using two isolates of the pathogen which was identified as Pestalotiopsis diospyri.

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Red Crown Rot of Hop in Oregon Caused by Phomopsis tuberivora

Plant Health Progress ◽

10.1094/php-2013-0624-01-br ◽

2013 ◽

Vol 14 (1) ◽

pp. 52

Author(s):

David H. Gent ◽

George Mueller-Warrant ◽

Joanna L. Woods ◽

Melodie L. Putnam ◽

Megan C. Twomey

Keyword(s):

Crown Rot ◽

Management Implications ◽

Koch’S Postulates ◽

First Report ◽

Red Crown Rot ◽

Weak Growth ◽

Koch's Postulates

During July 2007, symptoms including weak growth and death of plants of cultivar Fuggle were reported by a hop grower in Marion Co., OR. Phomopsis tuberivora H.T. Güssow & W.R. Foster 1932 was consistently recovered from affected plants. Koch's postulates were fulfilled with three isolates of the fungus, establishing the pathogen and the disease red crown rot as the cause of the damage. This is the first report of red crown rot on hop in Oregon, which may have important management implications for affected hop yards and farms. Accepted for publication 19 March 2013. Published 24 June 2013.

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First Report of Phytophthora ramorum Infecting Grand fir in California

Plant Health Progress ◽

10.1094/php-2011-0401-01-br ◽

2011 ◽

Vol 12 (1) ◽

pp. 37

Author(s):

Kathleen L. Riley ◽

Gary A. Chastagner ◽

Cheryl Blomquist

Keyword(s):

Phytophthora Ramorum ◽

Christmas Tree ◽

Native Range ◽

Tree Plantation ◽

Koch’S Postulates ◽

First Report ◽

Stem Lesions ◽

Koch's Postulates

Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum in both tests. This work provides the completion of Koch's postulates to establish grand fir as a host of P. ramorum. The potential for grand fir to be infected within its native range is unknown. Accepted for publication 1 February 2011. Published 1 April 2011.

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