scholarly journals First Report of Phytophthora Blossom Blight of Chrysanthemum Caused by Phytophthora nicotianae

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 923-923 ◽  
Author(s):  
J. M. Mullen ◽  
A. K. Hagan ◽  
D. K. Carey
Keyword(s):  
Chrysanthemum Morifolium ◽  
Selective Medium ◽  
Leaf Blight ◽  
Phytophthora Nicotianae ◽  
Mycelium Growth ◽  
First Report ◽  
Dendranthema Grandiflorum ◽  
Potted Plants ◽  
Plastic Bags ◽  
Growth Room

In October 2000, chrysanthemums (Dendranthema × grandiflorum) cv. Debonair exhibiting blossom blight were submitted to the Plant Diagnostic Lab at Auburn University by a commercial greenhouse where most of the potted plants of this cultivar were symptomatic. At a local retail outlet, approximately 95% of the plants of the same cultivar of chrysanthemum had a similar blossom blight. Blighted petals were examined microscopically, and nonpapillate, internally proliferating sporangia (40 to 45 μm in length), characteristic of some species of Phytophthora, were observed. A species of Phytophthora was isolated repeatedly on PARP selective medium (corn meal agar containing pimaricin, ampicillin, rifamycin, and pentachloronitrobenzene). Isolates recovered were grown on V8 juice agar, under fluorescent lights and in darkness, at room temperature. These isolates were identified as Phytophthora nicotianae (= Phytophthora parasitica), on the basis of morphological and cultural characteristics. Sporangia were papillate (including some with dual apices), noncaducous, 45 to 60 μm in length, and spherical, ovoid, or obpyriform. Mycelium growth occurred at 36°C. Isolates were considered heterothallic because they did not produce oospores when grown on V8 juice agar in the dark for 2 weeks. Sporangia that were nonpapillate and proliferating internally were not observed on any of these isolates. Because we apparently did not isolate the Phytophthora spp. seen microscopically on petals, we cannot comment on its exact identity or significance in causing this disease. We did conduct pathogenicity tests to determine whether isolates of P. nicotianae were capable of causing the observed symptoms. These tests were conducted twice on chrysanthemum cultivars Debonair, Yellow Triumph, Spotlight, Raquel, Jennifer, Grace, and Hot Salsa. In the first test, two plants of each cultivar were sprayed to runoff with a zoospore suspension (105 spores per ml) in sterile, filtered water. Two plants of each cultivar were sprayed with sterile, filtered water as noninoculated controls. Individual plants were placed in loosely closed plastic bags, misted daily, and held at 23 to 24°C with indirect lighting (approximately 12 h per day) for 1 week. In the second test, four plants of each cultivar except Debonair were inoculated as described previously, four plants of each cultivar were left untreated as noninoculated controls, and one Debonair plant was inoculated and one remained noninoculated. Plants were held for 3 days in an environmentally controlled growth room, with 23°C days (11 h)-20°C nights (13 h), under a plastic tent where high levels of humidity were maintained with a humidifier and daily misting. A grow light provided a low level of lighting (4 to 6 μE · m-2 · s-1). All inoculated plants developed severe blossom blight similar to that observed initially. In the first test, symptoms were evident at 2 days. In the growth room, blossom blight first was observed at 24 h postinoculation. In both tests, blossom blight severity increased quickly in the 1 to 2 days after the initial occurrence of symptoms. Only blossoms became diseased; symptoms did not extend to other plant organs. P. nicotianae was reisolated consistently from symptomatic blossoms on selective medium. This is, we believe, the first report of blossom blight on chrysanthemum caused by a species of Phytophthora. Previously, P. nicotianae has been reported to cause leaf blight on artificially inoculated Chrysanthemum × morifolium (Dendranthema × grandiflorum) cultivars Capri and Vermilion in Florida (1) and twig and leaf blight on Chrysanthemum coronarium in India (2). References: (1) C. R. Semer and B. C. Raju. Plant Dis. 69:1005–1006, 1985. (2) N. Sushma and N. D. Sharma. J. Mycol. Plant Pathol. 27:345, 1997.

scholarly journals Shoot Blight of Forsythia × intermedia in Virginia Nurseries Caused by Phytophthora nicotianae

Plant Disease ◽  
2005 ◽  
Vol 89 (4) ◽  
pp. 430-430 ◽  
Author(s):  
C. X. Hong ◽  
P. A. Richardson ◽  
P. Kong
Keyword(s):  
Single Strand Conformation Polymorphism ◽  
The United States ◽  
Morphological Characters ◽  
Selective Medium ◽  
Shoot Tips ◽  
Phytophthora Nicotianae ◽  
First Report ◽  
Plastic Bags ◽  
Shoot Blight ◽  
Polymorphism Pattern

A severe blighting of shoots on Forsythia × intermedia cv. Lynwood Gold plants was observed at several commercial nurseries in Virginia from 2001 to 2004. Crop losses ranged from 10 to 35%. Symptoms first occurred at the tips of shoots, including those that were trimmed and not trimmed, and then progressed downward. Diseased shoots wilted quickly and usually turned black, and foliage on these shoots withered and became necrotic. With PARP-V8 selective medium (2), a species of Phytophthora was isolated consistently from symptomatic shoots (including tissues from shoot tips, leaves, and stems) as well as from apparently healthy roots. These isolates produced arachnoid mycelia and numerous noncaducous, papillate sporangia but did not produce sexual structures on isolation plates; these morphological characters are consistent with those of Phytophthora nicotianae. All isolates produced a single-strand conformation polymorphism pattern typical of P. nicotianae (3). To test pathogenicity, 1-year-old, healthy-appearing cv. Lynwood Gold forsythia plants (canopy size = 100 cm × 60 cm) in four 12-liter containers were sheared. Two plants were inoculated by spraying each plant with 200 ml of a zoospore suspension (1.6 × 104 spores per ml, prepared from one isolate), and the other two plants were not treated and served as controls. Plants were covered with plastic bags overnight to encourage infection and then were grown in a field (temperature range = 20 to 33°C). Severe blight developed on trimmed shoots and new shoot tips of inoculated plants within 1 week after inoculation. The same pathogen was isolated from all blighted leaf and stem pieces assayed. Blight symptoms were not observed on control plants during a 1-month observation period. Phytophthora nicotianae has been reported to attack F. viridissima in Italy (1) causing root and collar rot but not shoot blight. To our knowledge, this is the first report of shoot blight on Forsythia spp. caused by P. nicotianae and the first report of P. nicotianae on Forsythia spp. in the United States. References: (1) S. O. Cacciola et al. Plant Dis. 78:525, 1994. (2) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (3) P. Kong et al. Fun. Gen. Biol. 39:238, 2003.

scholarly journals First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (2) ◽  
pp. 287-287
Author(s):  
K. S. Han ◽  
J. H. Park ◽  
S. E. Cho ◽  
H. D. Shin
Keyword(s):  
United States ◽  
Its Region ◽  
Stem Canker ◽  
The United States ◽  
Culture Collection ◽  
Leaf Blight ◽  
First Report ◽  
Cornell University ◽  
Plastic Bags ◽  
Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

scholarly journals First Report of Fusarium Wilt on Eremophila spp. Caused by Fusarium oxysporum in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1509-1509 ◽  
Author(s):  
G. Polizzi ◽  
D. Aiello ◽  
V. Guarnaccia ◽  
A. Vitale ◽  
G. Perrone ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Morphological Characteristics ◽  
Gene Sequences ◽  
Single Spore ◽  
First Report ◽  
Potted Plants ◽  
Plastic Bags ◽  
Gene Coding ◽  
Affected Plant ◽  
Tubulin Protein

Eremophila spp. (Myoporaceae family), endemic to Australia, are evergreen shrubs or small trees occurring in arid, semi-arid, tropical, or temperate regions. In Europe, Eremophila spp. are grown for their horticultural appeal. During 2009 and 2010, extensive wilting was observed on 2-month to 1-year-old potted plants of Eremophila laanii F. Muell., E. glabra subsp. carnosa Chinnock, and E. maculata (Ker Gawl.) F. Muell. grown in a commercial nursery near Catania (southern Italy). Internally, symptomatic plants had conspicuous vascular discoloration from the crown to the canopy. Diseased crown and stem tissues were surface disinfested for 30 s in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate, and incubated at 25°C. A Fusarium sp. was consistently isolated from affected plant tissues. Colonies with purple mycelia and violet reverse colors developed after 9 days. On carnation leaf agar, single-spore isolates produced microconidia on short monophialides, macroconidia that were three to five septate with a pedicellate base, and solitary and double-celled or aggregated chlamydospores. A PCR assay was conducted on two representative isolates (ITEM 12591 and ITEM 12592) by analyzing sequences of the partial CaM gene (coding calmodulin protein) and benA (coding beta-tubulin protein) using the primers as reported by O'Donnell et al. (1). Calmodulin sequences of ITEM 12951 and ITEM 12952 isolates (GenBank Nos. FR671157 and FR671158) exhibited 99.8 and 99.5% identity with Fusarium oxysporum strain ITEM 2367 (GenBank No. AJ560774), respectively, and had 99.5% homology between them. BenA gene sequences of ITEM 12951 (GenBank No. FR671426) exhibited an identity of 100% to F. oxysporum f. sp. vasinfectum strain CC-612-3 (GenBank No. AY714092.1), and benA gene sequences of ITEM 12952 (GenBank No. FR671427) exhibited an identity of 100% to F. oxysporum f. sp. vasinfectum strain LA 140 (GenBank No. FJ466740.1), whereas the homology between the two strains is 99.5%. Morphological characteristics, as well as CaM and benA sequences, identified the isolates as F. oxysporum Schlechtend:Fr. Pathogenicity tests were performed by placing 1-cm2 plugs of PDA from 9-day-old mycelial cultures near the crown on potted, healthy, 3-month-old cuttings of E. laanii, E. glabra subsp. carnosa, and E. maculata. Twenty plants for each species were inoculated with each isolate. The same number of plants served as noninoculated controls. All plants were enclosed for 4 days in plastic bags and placed in a growth chamber at 24 ± 1°C. Plants were then moved to a greenhouse where temperatures ranged from 23 to 27°C. Symptoms identical to those observed in the nursery developed 20 days after inoculation with both strains. Crown and stem discoloration was detected in all inoculated plants after 45 days. Wilting was detected on 15% of plants. Control plants remained symptomless. F. oxysporum was consistently reisolated from symptomatic tissues and identified as previously above. To our knowledge, this is the first report of F. oxysporum causing disease of Eremophila spp. worldwide. Reference: (1) K. O'Donnell et al. Mycoscience 41:61, 2000.

scholarly journals First Report of Leaf Blight in Chinese Hickory (Carya cathayensis) Caused by Alternaria petroselini in China

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1253-1253 ◽  
Author(s):  
Y. H. Liu ◽  
C. Q. Zhang ◽  
B. C. Xu
Keyword(s):  
Management Practices ◽  
Morphological Characteristics ◽  
Morphological Characterization ◽  
Leaf Blight ◽  
Internal Transcribed Spacers ◽  
Infected Leaf ◽  
First Report ◽  
Plastic Bags ◽  
Initial Symptoms ◽  
Carya Cathayensis

Chinese hickory (Carya cathayensis) is one of the important economic forest crops in Zhejiang and Anhui Provinces, China. In 2012, nearly 40% of hickory orchards and 6.8% of hickory trees were affected by leaf blight in Zhejiang. Initial symptoms consisted of small, brown, water-soaked lesions, which subsequently enlarged and developed a black sporulating necrotic center surrounded by a chlorotic halo. Infected leaf samples collected from 25 different orchards in Lin'an and 13 different orchards in Chun'an were surface sterilized with 1.5% sodium hypochlorite for 1.5 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on PDA and V8 agar for morphological characterization (1,3). On both agar media, colonies were dark olive brown with smooth margins and concentric rings of sporulation. Conidia were solitary, darkly pigmented, predominantly ovoid-subsphaeroid, and 23 to 52 × 13 to 23 μm with up to six or seven transepta and one to three longisepta. The ribosomal internal transcribed spacers ITS1 and ITS2 of 10 isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of A. petroselini (GenBank Accession Nos. AY154685.1 and EU807868.1). To confirm pathogenicity, 10 uninfected leaves from each of 10 C. cathayensis trees were sprayed either with a conidia suspension (105 conidia per ml) or with distilled water only to serve as an un-inoculated control. Leaves were subsequently wrapped in plastic bags to retain moisture, and incubated for 48 h. After 1 week, 8 of 10 isolates caused lesions identical to those initially described whereas no symptoms developed on water inoculated leaves. Cultures reisolated from lesions and cultured on PDA exhibited morphological characteristics identical to A. petroselini (1,2,3), confirming Koch's postulates. To our knowledge, this is the first report of leaf blight in C. cathayensis, and this identification would allow producers to identify for appropriate management practices. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, UK, 2008. (2) B. M. Pryor et al. Mycologia 94:49, 2002. (3) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007.

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

Plant Disease ◽  
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.

scholarly journals First Report of Target Spot of Broadleaf Tobacco Caused by Rhizoctonia solani (AG-3) in Connecticut

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1378-1378 ◽  
Author(s):  
J. A. LaMondia ◽  
C. R. Vossbrinck
Keyword(s):  
Rhizoctonia Solani ◽  
Sequence Data ◽  
Its Region ◽  
Anastomosis Group ◽  
Growth Chamber ◽  
First Report ◽  
Potted Plants ◽  
Plastic Bags ◽  
Target Spot ◽  
Half Strength

In June 2011, 15 transplant beds of broadleaf cigar wrapper tobacco (Nicotiana tabacum L., cv. C9) plants in Hartford County, Connecticut, were observed with almost every plant diseased. Leaf lesion symptoms ranged from small (2 to 3 mm) water-soaked spots to larger (2 to 3 cm) lesions. Disease was subsequently observed, also at nearly 100% incidence in a 10-hectare field on that farm and at additional broadleaf tobacco farms from two other towns in Hartford County and one town in Tolland County. Lesions exhibited a pattern of concentric rings, necrotic centers and tears in the centers, and margins that often resulted in a shot-hole appearance. Some lesions had chlorotic halos. Rhizoctonia solani Kuhn (Thanatephorus cucumeris A. B. Frank) was isolated from the margins of lesions that had been surface sterilized in 0.5% NaOCl for 30 s and then rinsed in sterile distilled water and placed on the surface of half-strength potato dextrose agar (PDA). Multiple isolations were made and the pathogen was identified on the basis of mycelial characteristics including multinucleate cells, septate hyphae wider than 7 μm, and hyphal branches occurring at approximately right angles, constricted at the base (4). Eight-week-old potted tobacco plants were each inoculated by spraying with a mycelial suspension (1 × 105 CFU) of an isolate of R. solani recovered from tobacco onto leaves, or with water alone (five plants each). The plants were placed in plastic bags in a 24°C growth chamber and misted. After 2 days, the bags were removed and the potted plants placed in trays filled to a depth of 1 cm with water in the growth chamber. After 8 days, the pathogen was reisolated from all inoculated plants exhibiting water-soaked spots as disease symptoms. Leaves inoculated with water or half-strength PDA plugs alone were asymptomatic. DNA was liberated from hyphae of the R. solani isolate by bead beating in STE buffer using 0.15 mm zirconium beads. Two microliters of the eluate was used to amplify the ITS region. Amplified DNA was purified in a Qiagen QIAquick PCR purification kit and submitted to the Yale science hill genomic facility for standard Sanger dideoxy sequencing. The sequence was exactly the same as an isolate from Massachusetts that we sequenced in 2010 (GenBank Accession No. HQ241274). The ITS sequence confirmed our identification of this new isolate as R. solani anastomosis group (AG) 3. This disease has been previously reported on tobacco from South America, South Africa, and the southern United States (1), Canada (3), and Massachusetts (2). Conditions were very conducive for disease because 2011 was a very wet year in Connecticut. To our knowledge, this is the first report of this disease in broadleaf cigar wrapper tobacco in Connecticut. The sequence data suggested that it may have been introduced to Connecticut from Massachusetts. We have found the target spot pathogen distributed across the tobacco producing area of Connecticut. This constitutes a serious threat as there are no systemic fungicides currently registered for control of this disease in broadleaf tobacco. References: (1) J. S. Johnk et al. Phytopathology 83:854, 1993. (2) J. A. LaMondia and C. R. Vossbrinck, Plant Dis. 95:496, 2010. (3) R. D. Reeleder et al., Plant Dis., 80:712. (4) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St. Paul, MN, 1991.

scholarly journals First Report of Bacterial Bark Canker of Walnut Caused by Brenneria nigrifluens in Hungary

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 988-988 ◽  
Author(s):  
A. Végh ◽  
A. Tóth ◽  
Á. Zámbó ◽  
G. Borsos ◽  
L. Palkovics
Keyword(s):  
16S Rdna ◽  
Juglans Regia ◽  
Negative Control ◽  
Bacterial Suspension ◽  
Lake Balaton ◽  
Biochemical Tests ◽  
First Report ◽  
Potted Plants ◽  
Sequence Identity ◽  
Plastic Bags

During August 2012, vertical oozing cankers were sporadically observed on trunks and branches of walnut trees (Juglans regia) in the city of Zánka, near Lake Balaton and other parts of Hungary including Budapest, Győr, and Tatabánya cities. Cankers were observed on trunks and branches where brownish-black exudates staining the bark appeared mainly in the summer. Isolations were performed primarily from exudates but also from infected tissues using King's medium B (KB) (3) and EMB medium (2). Colonies similar in appearance to Brenneria nigrifluens (syn.: Erwinia nigrifluens) (1,5) were isolated. The bacterium, first reported in California, was also recorded in Iran, Spain, France, and several Italian locations, on walnut trees. The bacterial strain was gram negative and did not induce a hypersensitive response on tobacco (Nicotiana tabacum L. ‘White Burley’) leaves. The bacterium grew at 26°C. Colonies on KB were white and non-fluorescent, but on EMB medium were a typical dark purple with metallic green sheen. The results of substrate utilization profiling using the API 20E kit (Biomérieux, Marcy l'Etoile, France) showed that the bacterium belonged to the Enterobacteriaceae. The strain was positive for citrate utilization, H2S, and acetoin production and urease, glucose, inositol, saccharose, and arabinose reactions. Pathogenicity was tested by injecting five young healthy walnut branches on two separate 2-year-old grafted potted plants with a bacterial suspension containing 107 CFU/ml. Negative controls were walnut branches injected with sterile distilled water. Branches were enclosed in plastic bags and incubated in a greenhouse under 80% shade at 26°C day and 17°C night temperatures. Three months after inoculation, necrotic lesions were observed in the inner bark and dark lines were observed in internal wood, but no external cankers were observed on inoculated branches. The negative control appeared normal. B. nigrifluens was re-isolated from lesions on inoculated branches and identified as described above; thus, Koch's postulates were fulfilled. For molecular identification of the pathogen, 16S rDNA amplification was performed using genomic DNA from strain Bn-WalnutZa-Hun1 with a universal bacterial primer set (63f and 1389r) (4). The PCR products were cloned into a pGEM T-Easy vector (Promega, Madison, WI) and transformed into Escherichia coli DH5α cells. A recombinant plasmid (2A2.5) was sequenced using M13 forward and reverse primers. The sequence was deposited in NCBI GenBank (Accession No. HF936707) and showed 99% sequence identity with a number of B. nigrifluens strains, including type strains Z96095.1, AJ233415.1, JX484740.1, JX484739.1, JX484738.1, and FJ611884.1. On the basis of the symptoms, colony morphology, biochemical tests, and 16S rDNA sequence identity, the pathogen was identified as Brenneria nigrifluens. To our knowledge, this is the first report of a natural outbreak of bacterial bark canker on walnut in Hungary and the presence of the pathogen may seriously influence in local orchards and garden production in the future. References: (1) L. Hauben et al. Appl Microbiol 21:384, 1998. (2) J. E. Holt-Harris and O. Teague. J. Infect. Dis. 18:596, 1916. (3) E. O. King et al. J. Lab. Clin. Med. 44:301, 1954. (4) A. M. Osborn et al. Environ. Microbiol. 2:39, 2000. (5) E. E. Wilson et al. Phytopathology 47:669, 1957.

scholarly journals First Report of Leaf Blight and Root and Foot Rot of a Strelitzia Caused by Phytophthora nicotianae in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 134-134 ◽  
Author(s):  
L. Luongo ◽  
M. Galli ◽  
L. Riccioni ◽  
A. Belisario
Keyword(s):  
Leaf Blight ◽  
Phytophthora Nicotianae ◽  
Flowering Plant ◽  
Foot Rot ◽  
In Planta ◽  
Phytophthora Blight ◽  
Tissue Samples ◽  
First Report ◽  
Leaf Spots

Bird of paradise, also known as crane flower (Strelitzia reginae Aiton), is a monocotyledonous flowering plant indigenous to South Africa. It is commonly grown and commercialized as an ornamental plant and it is appreciated for its beautiful flowers. In October of 2008, dark leaf spots and leaf blight associated with a severe root and foot rot were observed on several plants of S. reginae grown in a private garden located in Fiumicino, Italy. Small fragments of tissues (approximately 3 mm) collected from the base of leaves and roots and the margins of brown lesions, previously surface disinfected with 0.5% NaOCl, were plated onto potato dextrose agar (PDA) and incubated at 22°C in the dark. White, web-like, slow-growing colonies with coenocytic mycelium and hyphal swellings consistently developed from all plated tissue samples. Sporangia were ovoid or ellipsoid with prominent papillae (including some bipapillate) and frequently caducous with a short stalk. The dimensions of sporangia were 27 to 64 × 23 to 45 μm (average 43 × 35 μm). Chlamydospores were terminal or intercalary and approximately 30 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, isolates were identified as Phytophthora nicotianae (Breda de Haan). The identity was confirmed by internal transcribed spacer (ITS) sequence comparison in NCBI database with 99% identity with sequences available in GenBank (e.g., EU331089) and with cytochrome c oxidase subunit I (Cox I) with 99% identity with AY564196 by Kroon et al. (2). The sequences of one isolate, AB177, were deposited in GenBank (Accession Nos. FN430681 and FN552051 for ITS and Cox I, respectively). Pathogenicity tests were conducted in the greenhouse on leaves of a 1-year-old potted S. reginae plant by placing 5-mm-diameter mycelial plugs, cut from the margins of 10-day-old actively growing cultures, with mycelium in contact with plant tissues gently wounded with a needle. Controls were treated as described above, except that PDA sterile plugs were used. Plants were misted with water and placed in sealed plastic bags for 48 h. After 10 days, artificially wounded strelitzia leaves showed lesions (approximately 1 cm long). Controls remained symptomless. All inoculated leaves showed the same leaf symptoms as observed on naturally diseased plants. The pathogen was consistently reisolated from lesions. P. nicotianae has been reported as the causal agent of leaf blight and stem, collar, and root rot on several plants (1). It has been reported as an agent of Phytophthora blight on strelitzia in Japan (3). To our knowledge, this is the first report of P. nicotianae on strelitzia in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) L. P. N. M. Kroon et al. Fungal Genet. Biol. 41:766, 2004. (3) S. Uematsu et al. Ann. Phytopathol. Soc. Jpn. 60:746, 1994.

scholarly journals First Report of Phytophthora tentaculata Causing Root and Stem Rot of Oregano in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 843-843 ◽  
Author(s):  
P. Martini ◽  
A. Pane ◽  
F. Raudino ◽  
A. Chimento ◽  
S. Scibetta ◽  
...  
Keyword(s):  
Dna Amplification ◽  
Its Region ◽  
Selective Medium ◽  
Stem Rot ◽  
Universal Primers ◽  
Basal Stem Rot ◽  
First Report ◽  
Soilborne Disease ◽  
Potted Plants ◽  
Morphological Criteria

Oregano (Origanum vulgare L.; Lamiaceae) is cultivated for culinary and medicinal purposes and as an ornamental. In October of 2007, 1- to 2-year-old potted plants of oregano showed symptoms of decline associated with root and basal stem rot in a nursery in Liguria (northern Italy) that produces 1 million to 1.5 million potted aromatic plants per year. Aboveground symptoms included leaf russeting and chlorosis, wilt, defoliation and dieback of twigs, browning of the basal stem, and subsequent collapse of the entire plant. Approximately 80% of the plants died within 30 days after the appearance of the first symptoms on the canopy. Approximately 20% of a stock of 30,000 oregano plants was affected. Stocks of other aromatic species, such as mint, lavender, rosemary, and sage, appeared healthy. A Phytophthora species was consistently isolated from symptomatic stems and roots of oregano plants on BNPRAH selective medium (2). Ten pure cultures were obtained by single-hypha transfers, and the species was identified as Phytophthora tentaculata Kröber & Marwitz by morphological criteria and sequencing of the internal transcribed spacer (ITS) region of rDNA using the ITS 4 and ITS 6 universal primers for DNA amplification. Isolates from oregano formed stoloniferous colonies with arachnoid mycelium on potato dextrose agar and had a growth rate of 2 to 3 mm per day at 24°C with optimum, minimum, and maximum temperatures of 24, 8, and 34°C, respectively. Sporangia formed in soil extract solution and were papillate and spherical or ovoid to obpyriform with a length/breadth ratio of 1.3:1. Few sporangia were caducous and all had a short pedicel (<5 μm). Hyphal swellings and chlamydospores were produced in sterile distilled water and corn meal agar, respectively. All isolates were homothallic and produced globose terminal oogonia (mean diameter of 34 μm) with one or occasionally two paragynous, monoclinous, or diclinous antheridia. Amphigynous antheridia were also observed. The sequence of the ITS region of the rDNA (GenBank No. FJ872545) of an isolate from oregano (IMI 395782) showed 99% similarity with sequences of two reference isolates of P. tentaculata (Accession Nos. AF266775 and AY881001). To test for pathogenicity, the exposed root crowns of 10 6-month-old potted plants of oregano were drench inoculated with 10 ml of a suspension of 2 × 104 zoospores/ml of isolate IMI 395782. Sterile water was pipetted onto the roots of 10 control plants. All plants were maintained in 100% humidity at 22 to 24°C in a greenhouse under natural light and watered once a week. Within 3 weeks after inoculation, all inoculated plants developed symptoms identical to those observed in the nursery and died within 30 to 40 days after the appearance of the first symptoms. Control plants remained healthy. P. tentaculata was reisolated solely from symptomatic plants. P. tentaculata has been reported previously on several herbaceous ornamental plants (1,3). However, to our knowledge, this is the first report of this species on O. vulgare. Root and basal stem rot caused by P. tentaculata is the most serious soilborne disease of oregano reported in Italy so far. References: (1) G. Cristinzio et al. Inf. Fitopatol. 2:28, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) H. Kröber and R. Marwitz. Z. Pflanzenkr. Pflanzenschutz 100:250, 1993.

scholarly journals First Report of Botrytis Blight Caused by Botrytis cinerea on Sweet Basil in Hungary

Plant Disease ◽  
2007 ◽  
Vol 91 (8) ◽  
pp. 1052-1052
Author(s):  
G. Nagy
Keyword(s):  
Botrytis Cinerea ◽  
Northern Region ◽  
Conidial Suspension ◽  
Large Area ◽  
Field Surveys ◽  
First Report ◽  
Sweet Basil ◽  
Potted Plants ◽  
Plastic Bags ◽  
Disease Occurrence

In Hungary, sweet basil (Ocimum basilicum L.) is an important medicinal and aromatic plant cultivated over a large area. During field surveys conducted in August and September of 2001 and 2002, significant blossom and leaf blight were observed in plant stands located near Budapest and in the northern region of Hungary at Herencsény. Incidence of disease occurrence ranged between 49 and 92%. Abundant grayish-brown mold consisting of mycelia and conidiophores was observed on necrotic flowers and upper leaves. The fungus was identified as Botrytis cinerea Pers.:Fr.. Conidia were one-celled, ovoid to elliptical, and measured 11.2 × 7.4 μm (7.5 to 15.0 × 5.0 to 10.0 μm). The fungus was isolated on Leonian malt media. In culture, small and large irregular sclerotia, as well as conidiophores, were produced abundantly. Size of large sclerotia ranged between 45 and 95 mm. Sclerotia were produced only in culture. Pathogenicity of two isolates originating from Herencsény was confirmed by spraying eight sweet basil potted plants with a conidial suspension (6.3 × 105 conidia/ml) made from a pure culture. Two noninoculated plants served as controls. Half of the plants were wounded with needles to make incisions on the leaves and flower axes prior to the inoculation, while the remaining plants were directly sprayed. After inoculation, plants were kept in plastic bags in a greenhouse to maintain 90 to 100% relative humidity at 15 to 40°C. After 5 days, water-soaked chlorotic lesions appeared on the wounded leaves of the inoculated plants. After day 12, brown necrosis developed on the flowers of all inoculated plants. Flower axes often broke. Sporulation of the fungus was abundant. Wounding contributed to earlier appearance of the symptoms and more intensive disease development. To our knowledge, this is the first report of botrytis blight on sweet basil in Hungary. In Europe, the disease has been observed in Italy (1) and Greece (2). References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) C. D. Holevas et al. Benaki Phytopathol. Inst. Kiphissia, Athens 19:1, 2000.

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