scholarly journals First Report of Phytophthora nicotianae on Limonium in Europe

Plant Disease ◽  
2001 ◽  
Vol 85 (4) ◽  
pp. 445-445
Author(s):  
E. Ilieva ◽  
W. A. Man in 't Veld ◽  
B. F. Wessels-Berk ◽  
R. P. Baayen
Keyword(s):  
The Netherlands ◽  
Mating Type ◽  
Root Rot ◽  
The United States ◽  
Phytophthora Nicotianae ◽  
Isozyme Analysis ◽  
American Phytopathological Society ◽  
Disease Symptoms ◽  
Liquid Cultures ◽  
First Report

Limonium (statice or sea-lavendar, family Plumbaginaceae) is grown in the Netherlands as a perennial (Limonium sinense) or annual (Limonium sinuatum) crop. Plants have tufted leaves and numerous clustered flowers of different colors and are used for flower arrangements. In August 2000, we received diseased plants of L. sinense cv. Diamond and L. sinuatum. Disease symptoms consisted of leaf wilting followed by plant collapse. The base of the leaves showed progressive necrotic areas that later turned dark brown to black. The cortex of the stem and roots was water-soaked and dark brown to black. Longitudinal sections of stems and roots of diseased plants displayed discoloration of tissues. Rotted root tissue was brown with a characteristic black margin. Rotted vascular tissues and other stem parts were also dark brown. Pith parenchyma turned gray-brown and had a firm, wet rot. In plants with advanced disease symptoms, a cavity in the stem parenchyma was observed. Isolations were made from sections of symptomatic leaves, stems and roots of both Limonium species on cherry and water agar (WA), followed by incubation at 20°C. Phytophthora sp. was isolated consistently from the base of leaves, stems, and roots of diseased plants and identification of isolates was based on morphological characteristics and by isozyme analysis (3). Observations of colony morphology and growth at 35°C were made on V8 agar. Mating type was determined in dual cultures with mating type A2 (P. nicotianae, P 1923 [4]) and A1 (P. nicotianae, PD98/8/10402). Sporangial features were observed from liquid cultures of the isolates (autoclaved soil-extract or sterile distilled water). All isolates formed colonies consisting of loose, fluffy aerial mycelia. Sporangia and chlamydospores were present in all fungal isolates and all isolates were able to grow at 35°C. Few sporangia were produced on solid media (WA and V8 juice agar), but were abundant in liquid cultures. Sporangia were borne singly or in simple sympodial sporangiophores (3 to 4 sporangia), and were ovoid/spherical, obturbinate with rounded base and had prominent papillae (some had two papillae). Sporangia measured 40 to 64 × 24 to 56 μm, (average 50.4 × 38.4 μm) and had an average length:breath ratio of 1.3:1. Chlamydospores were terminal and intercalary and measured 18 to 44 μm (average 31.6 μm). Hyphal swellings with hyphal outgrowths were present. Isolates of the fungus were heterothallic and produced oogonia and oospores rapidly and abundantly on V8 agar at 22°C only with the A1 mating type of P. nicotianae. We concluded that all isolates from Limonium had the A2 compatibility type. Antheridia were amphigynous. Oogonia were spherical and ranged from 20 to 30 μm, (average 27.5 μm). Oospores ranged from 18 to 27 μm, (average 23.1 μm). The observed characteristics are similar to those described for P. nicotianae. Isozyme analysis, using the dimeric enzymes malic enzyme (EC 1.1.1.40) and malate dehydrogenase (EC 1.1.1.37), revealed the presence of the Mdhp100 allele and the Mdh-2100 allele. Both alleles are characteristic for P. nicotianae (3). Based on morphological features and isozyme genotyping, isolates of Phytophthora from diseased Limonium plants could be assigned to P. nicotianae van Breda de haan (1). A report from Florida associated Phytophthora sp. with root rot of Limonium plants (2) but did not identify the species. According to the multi-decade records at the Netherlands Plant Protection Service (unpublished data) Phytophthora has never been observed on Limonium before. This is the first report of P. nicotianae associated with root rot and basal rot of Limonium plants in Europe. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (3) W. A. Man in 't Veld et al. Phytopathology 88:922–929, 1998. (4) P. Oudemans and M. D. Coffey. Mycol. Res. 95:1025–1046, 1991.

scholarly journals First Report of Collar and Root Rot Caused by Phytophthora nicotianae on Daphne odora in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 848-848
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Root Rot ◽  
The United States ◽  
Phytophthora Nicotianae ◽  
Control Treatment ◽  
Peat Moss ◽  
Late Winter ◽  
American Phytopathological Society ◽  
First Report ◽  
Daphne Odora

Daphne odora is becoming popular in gardens because of its variegated foliage and fragrant flowers in late winter and early spring. During October of 2008 in a commercial nursery near Maggiore Lake (Verbano-Cusio-Ossola Province) in northwestern Italy, plants of D. odora showed extensive chlorosis and root rot. Diseased plants eventually wilted and died, dropping leaves in some cases. Most frequently, wilted leaves persisted on stems. At the soil level, dark brown-to-black water-soaked lesions that coalesced often girdled the stem. All of the crown and root system was affected. Disease was widespread and severe with 70% of 2,500 potted plants being affected. A Phytophthora-like organism was isolated consistently on a medium selective for oomycetes (4) after disinfestation of lower stem and root pieces of D. odora for 1 min in a solution containing 1% NaOCl. Tissue fragments of 1 mm2 were excised from the margins of the lesions and plated. The pathogen was identified based on morphological and physiological features as Phytophthora nicotianae (= P. parasitica) (2). Sporangia were produced for identification by growing a pure culture in sterilized soil extract solution at neutral pH (obtained by shaking and then centrifuging 300 g of soil in 1 liter of distilled water). They were spherical to ovoid, papillate, and measured 39.2 to 54.5 × 31.7 to 41.7 μm (average 44.8 × 34.5 μm). Papillae measured 2.4 to 4.9 μm (average 3.7 μm). Chlamydospores were spherical with a diameter ranging from 15.8 to 36.1 μm (average 25.4 μm). The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 804-bp segment showed a 100% homology with the sequence of P. nicotianae EF140988. The nucleotide sequence has been assigned GenBank No. FJ843100. Pathogenicity of two isolates obtained from infected plants was confirmed by inoculating 12-month-old plants of D. odora. Both isolates were grown for 15 days on a mixture of 70:30 wheat/hemp kernels and then 80 g/liter of the inoculum was mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 vol/vol). One plant per 3-liter pot was transplanted into the substrate and constituted the experimental unit. Three replicates were used for each isolate and noninoculated control treatment; the trial was repeated once. All plants were kept in a greenhouse at temperatures from 20 to 25°C. Plants inoculated with isolate no. 1 developed symptoms of chlorosis and root rot within 14 days and then a wilt rapidly followed. Isolate no. 2 was less aggressive causing the same symptoms within 20 days. Control plants remained symptomless. P. nicotianae consistently was reisolated from inoculated plants. Previously, P. nicotianae (= P. parasitica) has been reported in several states of the United States on D. odora (3). To our knowledge, this is the first report of P. nicotianae on D. odora in Italy. The economic importance of the disease is low because of the limited number of farms that grow this crop in Italy, although spread could increase as the popularity of plantings expand. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (3) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) H. Masago et al. Phytopathology, 67:425, 1977.

scholarly journals First Report of Fusarium Wilt of Lettuce Caused by Fusarium oxysporum f. sp. lactucae in Arizona

Plant Disease ◽  
2003 ◽  
Vol 87 (10) ◽  
pp. 1265-1265 ◽  
Author(s):  
M. E. Matheron ◽  
S. T. Koike
Keyword(s):  
Fusarium Oxysporum ◽  
Root Rot ◽  
The United States ◽  
San Joaquin Valley ◽  
Fluorescent Light ◽  
Lettuce Seedling ◽  
Disease Symptoms ◽  
First Report ◽  
Root Rot Disease ◽  
Rot Disease

A new wilt and root rot disease was observed in 6 and 11 commercial fields of lettuce (Lactuca sativa) in western Arizona during the fall of 2001 and 2002, respectively. Distance between infested sites ranged from approximately 0.5 to 39 km. Five head lettuce cultivars as well as a red leaf lettuce cultivar were affected. Disease symptoms included yellowing and wilting of leaves, as well as stunting and plant death. The cortex of the crown and upper root of infected plants usually was decayed and reddish brown. Disease symptoms first appeared at the time of plant thinning and continued to develop up to plant maturity. Fusarium oxysporum was consistently isolated from symptomatic plant roots. Seeds of cv. Lighthouse were planted in nonsterile vermiculite within 3.0-cm-square × 7.0-cm-deep cells in a transplant tray and thinned to a single plant per cell. When the first true leaves were emerging, 10 individual seedlings were inoculated with a single-spore isolate of F. oxysporum recovered from diseased lettuce root cortex tissue. Inoculum was prepared by growing the fungus on potato dextrose agar in 100-mm-diameter × 15-mm-deep plastic petri dishes at 28°C with a 12-h photoperiod under fluorescent light. Once the fungus completely covered the agar surface, 50 ml of sterile distilled water was added to the dish, and the mycelia and conidia on the surface were scraped off the agar and suspended in the water. This fungal suspension was decanted, and a 2-ml aliquot containing 1.8 × 105 CFU was pipetted into the vermiculite near the stem of each lettuce seedling. Ten plants grown in noninfested vermiculite served as uninoculated controls. After inoculation, plants were maintained in a growth chamber at 28°C with a 12-h photoperiod under fluorescent light for 3 weeks. Symptoms of yellowing, wilt, vascular decay, and often plant death developed during the incubation period on all inoculated plants but not on control plants. Fusarium oxysporum was consistently reisolated from inoculated plants but not from uninoculated plants. The experiment was repeated and yielded the same results. A wilt and root rot disease of lettuce attributed to F. oxysporum f. sp. lactucae was first reported in Japan in 1967 (3) and subsequently in the United States (San Joaquin Valley of California) in 1993 (2), and Italy in 2002 (1). The researchers of the U.S. report did not cite the earlier work from Japan and described the pathogen as F. oxysporum f. sp. lactucum. The Arizona isolate used to demonstrate pathogenicity was of the same vegetative compatibility group as an isolate of the pathogen from lettuce in California reported in 1993. Several companies grow and harvest lettuce in Arizona and California. At the end of production and harvest in the fall, tractors, implements, and harvesting equipment are transported from the San Joaquin Valley in California to western Arizona. The similarity between the isolate of F. oxysporum f. sp. lactucae from western Arizona and the San Joaquin Valley of California suggest a possible introduction of the pathogen into Arizona from California, perhaps on soil adhering to farm equipment. To our knowledge, this is the first report of F. oxysporum f. sp. lactucae infecting lettuce in Arizona. References: (1) A. Garibaldi et al. Plant Dis. 86:1052, 2002. (2) J. C. Hubbard and J. S. Gerik. Plant Dis. 77:750, 1993. (3) T. Matuo and S. Motohashi. Trans. Mycol. Soc. Jpn. 8:13, 1967.

scholarly journals First Report of Phytophthora nicotianae on Skimmia japonica in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (8) ◽  
pp. 905-905
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Root Rot ◽  
Northern Italy ◽  
Ornamental Plant ◽  
Phytophthora Nicotianae ◽  
Plant Production ◽  
Control Treatment ◽  
American Phytopathological Society ◽  
First Report ◽  
Average Temperature ◽  
Lower Stem

Skimmia japonica, an evergreen flowering shrub, is becoming increasingly popular as a potted ornamental plant in northern Italy and represents 5% of acidophilous plant production; cv. Rubella accounts for 99% of production. During the spring of 2003, in many commercial nurseries located in northwestern Italy, plants of S. japonica cv. Rubella showed extensive chlorosis and root rot, and diseased plants eventually wilted and died without dropping leaves. The disease was widespread and severe, and in some nurseries, 40% of plants were affected. A Phytophthora-like organism was isolated consistently from infected lower stem and root pieces of S. japonica that had been disinfested for 1 min in 1% NaOCl and plated on a medium selective for oomycetes (2). The pathogen was identified based on morphological and physiological features as Phytophthora nicotianae (= P. parasitica [1]). The sporangia produced on V8 medium were ± spherical to obpyriform, obturbinate, papillate, and measured 33 to 94 × 25 to 48 μm (average 56.4 × 36.8 μm). Papillae measured 3.5 to 19 μm (average 7.8 μm). Chlamydospores were spherical with a diameter ranging from 26 to 32 μm (average 29.2 μm). Pathogenicity of four isolates obtained from infected plants was confirmed by inoculating 9-month-old plants of S. japonica cv. Rubella grown in 1-liter pots containing a substrate based on sphagnum peatmoss, pine bark, and clay (70-20-10% vol/vol/vol). Inocula, which consisted of 90-mm-diameter V8 agar disks per pot containing mycelium of each isolate, were introduced and mixed into the substrate in all pots before transplanting. One plant was transplanted into each pot and served as a replicate, and noninoculated plants served as controls. Eight replicates were used for each isolate and the control treatment, and the trial was repeated. All plants were kept outside at temperatures ranging from 16 to 38°C (average temperature 27°C). Inoculated plants developed symptoms of chlorosis, root rot, and wilt within 20 days, while control plants remained symptomless. P. nicotianae consistently was isolated from inoculated plants. Previously, P. nicotianae has been reported on S. japonica in Poland (3). To our knowledge, this is the first report of P. nicotianae on S. japonica in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (2) H. Masago et al. Phytopathology, 67:425, 1977 (3) G. Szkuta and L. B. Orlikowski. Prog. Plant Prot. 42:808, 2002.

scholarly journals First Report of Pythium aphanidermatum Crown and Root Rot of Industrial Hemp in the United States

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 1038 ◽  
Author(s):  
J. Beckerman ◽  
H. Nisonson ◽  
N. Albright ◽  
T. Creswell
Keyword(s):  
United States ◽  
Root Rot ◽  
The United States ◽  
Pythium Aphanidermatum ◽  
First Report ◽  
Crown And Root Rot ◽  
Industrial Hemp

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

Plant Disease ◽  
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.

scholarly journals First Report of Fusarium proliferatum Causing Root Rot on Soybean (Glycine max) in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1316-1316 ◽  
Author(s):  
M. M. Díaz Arias ◽  
G. P. Munkvold ◽  
L. F. Leandro
Keyword(s):  
United States ◽  
Root Rot ◽  
Morphological Characteristics ◽  
Dry Weight ◽  
The United States ◽  
Growth Stages ◽  
Species Identity ◽  
First Report ◽  
Soybean Roots ◽  
Soybean Diseases

Fusarium spp. are widespread soilborne pathogens that cause important soybean diseases such as damping-off, root rot, Fusarium wilt, and sudden death syndrome. At least 12 species of Fusarium, including F. proliferatum, have been associated with soybean roots, but their relative aggressiveness as root rot pathogens is not known and pathogenicity has not been established for all reported species (2). In collaboration with 12 Iowa State University extension specialists, soybean roots were arbitrarily sampled from three fields in each of 98 Iowa counties from 2007 to 2009. Ten plants were collected from each field at V2-V3 and R3-R4 growth stages (2). Typical symptoms of Fusarium root rot (2) were observed. Symptomatic and asymptomatic root pieces were superficially sterilized in 0.5% NaOCl for 2 min, rinsed three times in sterile distilled water, and placed onto a Fusarium selective medium. Fusarium colonies were transferred to carnation leaf agar (CLA) and potato dextrose agar and later identified to species based on cultural and morphological characteristics. Of 1,230 Fusarium isolates identified, 50 were recognized as F. proliferatum based on morphological characteristics (3). F. proliferatum isolates produced abundant, aerial, white mycelium and a violet-to-dark purple pigmentation characteristic of Fusarium section Liseola. On CLA, microconidia were abundant, single celled, oval, and in chains on monophialides and polyphialides (3). Species identity was confirmed for two isolates by sequencing of the elongation factor (EF1-α) gene using the ef1 and ef2 primers (1). Identities of the resulting sequences (~680 bp) were confirmed by BLAST analysis and the FUSARIUM-ID database. Analysis resulted in a 99% match for five accessions of F. proliferatum (e.g., FD01389 and FD01858). To complete Koch's postulates, four F. proliferatum isolates were tested for pathogenicity on soybean in a greenhouse. Soybean seeds of cv. AG2306 were planted in cones (150 ml) in autoclaved soil infested with each isolate; Fusarium inoculum was applied by mixing an infested cornmeal/sand mix with soil prior to planting (4). Noninoculated control plants were grown in autoclaved soil amended with a sterile cornmeal/sand mix. Soil temperature was maintained at 18 ± 1°C by placing cones in water baths. The experiment was a completely randomized design with five replicates (single plant in a cone) per isolate and was repeated three times. Root rot severity (visually scored on a percentage scale), shoot dry weight, and root dry weight were assessed at the V3 soybean growth stage. All F. proliferatum isolates tested were pathogenic. Plants inoculated with these isolates were significantly different from the control plants in root rot severity (P = 0.001) and shoot (P = 0.023) and root (P = 0.013) dry weight. Infected plants showed dark brown lesions in the root system as well as decay of the entire taproot. F. proliferatum was reisolated from symptomatic root tissue of infected plants but not from similar tissues of control plants. To our knowledge, this is the first report of F. proliferatum causing root rot on soybean in the United States. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathologic Society, St. Paul, MN, 1999. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (4) G. P. Munkvold and J. K. O'Mara. Plant Dis. 86:143, 2002.

scholarly journals First Report of Phoma exigua as a Pathogen of Salal (Gaultheria shallon) in British Columbia, Canada

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 685-685 ◽  
Author(s):  
S. F. Shamoun ◽  
S. Zhao
Keyword(s):  
British Columbia ◽  
The United States ◽  
Gaultheria Shallon ◽  
Centraalbureau Voor ◽  
Potato Dextrose Broth ◽  
Voucher Specimen ◽  
Disease Symptoms ◽  
Phoma Exigua ◽  
First Report ◽  
Plastic Bags

Salal (Gaultheria shallon Pursh.) is an ericaceous, evergreen, and rhizomatous shrub that competes for nutrients and moisture with young conifers in low elevation, coastal British Columbia (BC). A survey was conducted on southern Vancouver Island, BC during the summer of 1999 to find fungal pathogens of salal that might serve as biocontrol organisms (3). Phoma exigua Desmaz. (isolate PFC2705) near Parksville, BC proved to be pathogenic on salal. Identification of PFC2705 at the Centraalbureau voor Schimmelcultures was based on morphology and ITS sequences (GenBank Accession No. AY927784). Pathogenicity was determined with 24 salal seedlings (3-month-old) by inoculating with mycelial suspensions (20% v/v) or conidial suspensions (1 × 106 conidia per ml in 0.5% potato dextrose broth). Inoculated seedlings were placed in plastic bags and incubated in a greenhouse (16 to 23°C with natural light). Plastic bags were removed after 2 days. Initial disease symptoms were observed 2 days after inoculation. Brown, sunken lesions appeared on the surface of young leaves and stems and extended quickly. All seedlings were killed within 14 days. Twelve control plants showed no disease symptoms. With diseased salal leaves incubated at 23°C with 12-h fluorescent light/dark and 100% relative humidity, pycnidia appeared on leaf surfaces within 5 days. Conidia were hyaline, ellipsoid, one-celled, sometimes two- to three-celled, 2.5 to 3.8 × 5 to 12.5 μm, with a rounded base; the colony was gray or dark gray on potato dextrose agar after 5 to 7 days. Reisolation from the inoculated diseased leaves produced a mycelial colony that shared the same growth and morphological characteristics as the initial isolate. Phyllosticta gaultheriae Ellis & Everh., a widely reported foliar pathogen of salal, is distinct morphologically from P. exigua (1). To our knowledge, this is the first report of P. exigua as a pathogen of salal in Canada (2). A voucher specimen has been deposited at the Pacific Forestry Center Herbarium (DAVFP No. 28735). References: (1) J. Bissett and S. J. Darbyshire. No. 275 in: Fungi Canadenses, 1984. (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) S. F. Shamoun et al. Can. J. Plant Pathol. 22:192, 2000.

scholarly journals First Report of Medical Tree Peony Root Rot Caused by Fusarium solani in Tongling, China

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 909-909 ◽  
Author(s):  
M. Guo ◽  
Y. M. Pan ◽  
Z. M. Gao
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Tap Water ◽  
Blood Stasis ◽  
The United States ◽  
Effective Control ◽  
Conidial Suspension ◽  
Tree Peony ◽  
First Report ◽  
Peony Root

Tree peony bark, a main component of Chinese traditional medicine used for alleviating fever and dissipating blood stasis, is mainly produced in Tongling, China. Recently, tree peony cultivation in this area was seriously affected by root rot, with approximately 20 to 30% disease incidence each year. The disease severely affects yield and quality of tree peony bark. During the past 2 years, we collected 56 diseased tree peony plants from Mudan and Fenghuang townships in Tongling. We found reddish brown to dark brown root rot in mature roots, especially on those with injuries. Plant samples collected were disinfected with 2% sodium hypochlorite and isolations were conducted on potato sucrose agar (PSA). Eleven isolates were obtained and all had white fluffy aerial hypha on PSA. Two types of conidia were produced; the larger, reaphook-shaped ones had three to five septa and the smaller, ellipse-shaped ones had one or no septum. The reaphook-shaped conidia were 20.15 to 37.21 × 3.98 to 5.27 μm and the ellipse-shaped conidia were 6.02 to 15.52 × 2.21 to 5.33 μm in size. Chlamydospores were produced, with two to five arranged together. Biological characteristics of the fungi indicated that the optimum temperature for the mycelial growth on PSA was 25 to 30°C and the optimum pH range was 5.5 to 7.0. The above morphological characteristics point the fungal isolates to be Fusarium solani. To confirm pathogenicity, 30 healthy 1-year-old tree peony seedling plants were grown in pots (25 cm in diameter) with sterilized soil and a conidial suspension from one isolate (FH-1, 5 × 105 conidia/ml) was used for soil inoculation. Inoculated seedlings were maintained at 28°C in a greenhouse with a 12-h photoperiod of fluorescent light. Seedlings inoculated with distilled water were used as controls. After 3 weeks, the roots were collected and rinsed with tap water. Dark brown lesions were observed in the inoculated mature roots but not in the control roots. To confirm the identity of the pathogen, F. solani strains were reisolated from the lesions and total genomic DNA was extracted with the cetyltriethylammnonium bromide method from the mycelia of the reisolated strains (1). PCR was performed using the fungal universal primers ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) and ITS5 (5′-GGAAGTAAAAGTCGTAACAAGG-3′) to amplify a DNA fragment of approximately 590 bp. The purified PCR products were sequenced (Invitrogen Co., Shanghai, China) and shared 100% sequence identity with each other. A comparison of the sequence (JQ658429.1) by the Clustal_W program (2) with those uploaded in GenBank confirmed with the fungus F. solani (100% sequence similarity to isolate S-0900 from the Great Plains of the United States; EU029589.1). To our knowledge, this is the first report of F. solani causing medical tree peony root rot in China. The existence of this pathogen in China may need to be considered for developing effective control strategies. References: (1). C. N. Stewart et al. Biotechniques 14:748, 1993. (2). J. D. Thompson et al. Nucleic Acids Res. 22:4673, 1994.

scholarly journals First Report of Stem Blight Caused by Calonectria colhounii (Anamorph Cylindrocladium colhounii) on Greenhouse-Grown Blueberries in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1187-1187
Author(s):  
J. J. Sadowsky ◽  
T. D. Miles ◽  
A. M. C. Schilder
Keyword(s):  
United States ◽  
North Carolina ◽  
Root Rot ◽  
The United States ◽  
Vaccinium Corymbosum ◽  
Conidial Suspension ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions ◽  
Β Tubulin

Necrotic stems and leaves were observed on 2- to 4-month-old, rooted microshoot plants (Vaccinium corymbosum L. ‘Liberty’ and ‘Bluecrop’, V. angustifolium Aiton ‘Putte’, and V. corymbosum × V. angustifolium ‘Polaris’) in a Michigan greenhouse in 2008 and 2009. As the disease progressed, leaves fell off and 80 to 100% of the plants died in some cases. Root rot symptoms were also observed. A fungus was isolated from stem lesions. On potato dextrose agar (PDA), cultures first appeared light tan to orange, then rusty brown and zonate with irregular margins. Chains of orange-brown chlamydospores were abundant in the medium. Macroconidiophores were penicillately branched and had a stipe extension of 220 to 275 × 2.5 μm with a narrowly clavate vesicle, 3 to 4 μm wide at the tip. Conidia were hyaline and cylindrical with rounded ends, (1-)3-septate, 48 to 73 × 5 to 7 (average 60 × 5.5) μm and were held together in parallel clusters. Perithecia were globose to subglobose, yellow, 290 to 320 μm high, and 255 to 295 μm in diameter. Ascospores were hyaline, 2- to 3-septate, guttulate, fusoid with rounded ends, slightly curved, and 30 to 88 × 5 to 7.5 (average 57 × 5.3) μm. On the basis of morphology, the fungus was identified as Calonectria colhounii Peerally (anamorph Cylindrocladium colhounii Peerally) (1,2). The internal transcribed spacer region (ITS1 and ITS2) of the ribosomal DNA and the β-tubulin gene were sequenced (GenBank Accession Nos. HQ909028 and JF826867, respectively) and compared with existing sequences using BLASTn. The ITS sequence shared 99% maximum identity with that of Ca. colhounii CBS 293.79 (GQ280565) from Java, Indonesia, and the β-tubulin sequence shared 97% maximum identity with that of Ca. colhounii CBS 114036 (DQ190560) isolated from leaf spots on Rhododendron sp. in North Carolina. The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 129628). To confirm pathogenicity, 5 ml of a conidial suspension (1 × 105/ml) were applied as a foliar spray or soil drench to four healthy ‘Bluecrop’ plants each in 10-cm plastic pots. Two water-sprayed and two water-drenched plants served as controls. Plants were misted intermittently for 2 days after inoculation. After 7 days at 25 ± 3°C, drench-inoculated plants developed necrotic, sporulating stem lesions at the soil line, while spray-inoculated plants showed reddish brown leaf and stem lesions. At 28 days, three drench-inoculated and one spray-inoculated plant had died, while others showed stem necrosis and wilting. No symptoms were observed on control plants. Fungal colonies reisolated from surface-disinfested symptomatic stem, leaf, and root segments appeared identical to the original isolate. Cy. colhounii was reported to cause a leaf spot on blueberry plants in nurseries in China (3), while Ca. crotalariae (Loos) D.K. Bell & Sobers (= Ca. ilicicola Boedijn & Reitsma) causes stem and root rot of blueberries in North Carolina (4). To our knowledge, this is the first report of Ca. colhounii causing a disease of blueberry in Michigan or the United States. Because of its destructive potential, this pathogen may pose a significant threat in blueberry nurseries. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) L. Lombard et al. Stud. Mycol. 66:31, 2010. (3) Y. S. Luan et al. Plant Dis. 90:1553, 2006. (4) R. D. Milholland. Phytopathology 64:831, 1974.

scholarly journals First Report of Phytophthora nicotianae and P. citricola Associated with English Walnut Decline in Europe

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 315-315 ◽  
Author(s):  
A. Belisario ◽  
M. Maccaroni ◽  
A. M. Vettraino ◽  
A. Vannini
Keyword(s):  
Lateral Roots ◽  
Juglans Regia ◽  
The United States ◽  
Phytophthora Nicotianae ◽  
Malt Extract ◽  
Veneto Region ◽  
Internal Transcribed Spacer Region ◽  
Campania Region ◽  
First Report ◽  
English Walnut

English (Persian) walnut (Juglans regia), among the most widely cultivated species of Juglans worldwide, is cultivated primarily for fruit production but also for timber. In the last 10 years, walnut decline causing leaf yellowing, sparse foliage, overall decline, and plant death has increased in Italian commercial orchards. In Italy, Phytophthora cactorum, P. cambivora, P. cinnamomi, and P. cryptogea are associated with this disease (1,4). Over the last 5 years, P. cinnamomi was the most widely isolated and destructive species (1). Recently, a different species of Phytophthora was isolated from diseased roots and soil from around lateral roots of 10 declining trees in two orchards in the Veneto Region of northern Italy. Another species of Phytophthora was isolated consistently from rotted roots of declining walnut trees in two orchards in the Campania Region of southern Italy. Phytophthora spp. were isolated directly from plant material or Rhododendron spp. leaf baiting on soil samples with PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, 20 g of agar in 1,000 ml of H2O). Two species of Phytophthora were identified based on morphological and cultural characteristics (2). The species from trees in the Veneto Region was identified as P. nicotianae. All isolates produced papillate, spherical to obturbinate, occasionally caducous sporangia with short pedicels, terminal and intercalary chlamydospores, and were mating type A2. The species isolated from trees in the Campania Region was identified as P.citricola. Isolates were homothallic, produced semipapillate, persistent, obclavate to obpyriform sporangia, occasionally with two apices, and antheridia paragynous. Identifications were confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of rDNA with those obtained from previously identified species of Phytophthora. Pathogenicity of two isolates each of P. citricola and P. nicotianae was tested on 2-year-old potted walnut seedlings. Inocula were prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and incubated for 4 weeks at 20°C in the dark. Infested seeds were added to potting soil at a rate of 3% (wt/vol). One day later, pots were flooded for 48 h to promote sporulation. Ten noninoculated seedlings were used as the control. Symptoms were assessed 2 months after inoculation. Seedlings inoculated with P. nicotianae developed necrosis of feeder and lateral roots, but only limited infection of taproots. Seedlings inoculated with P. citricola developed necroses at the insertion points of lateral roots. All four isolates produced visible damage to lateral roots on inoculated plants. P. nicotianae and P. citricola were reisolated from respectively infected roots. Results from these inoculations confirmed P. nicotianae and P. citricola as root pathogens of English walnut. Both species were associated with walnut decline as reported in the United States (3). To our knowledge, this is the first report of P. nicotianae and P. citricola on J. regia in Europe. References: (1) A. Belisario et al. Petria 11:149. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) M. E. Matheron and S. M. Mircetich. Phytopathology 75:977, 1985. (4) A. M. Vettraino et al. Plant Dis. 86:328, 2002.

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