scholarly journals First Report of Phytophthora Root Rot Caused by Phytophthora cryptogea on Spinach in California

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 131-131 ◽  
Author(s):  
S. T. Koike ◽  
Frank N. Martin
Keyword(s):  
Root Rot ◽  
Spinacia Oleracea ◽  
Root Zone ◽  
Sequence Data ◽  
Soil Extract ◽  
Phytophthora Root Rot ◽  
Phytophthora Cryptogea ◽  
First Report ◽  
Root Rots ◽  
Zoospore Release

In 2006 and 2007, commercially grown spinach (Spinacia oleracea) in California's coastal Salinas Valley (Monterey County) was affected by an unreported root rot disease. Disease was limited to patches along the edges of fields. Affected plants were stunted with chlorotic older leaves. As disease progressed, most of the older foliage first wilted and then turned tan and dry; youngest leaves remained green but were stunted and leathery in texture. Plants most severely affected died. Symptoms on roots were mostly restricted to the distal portion of the root system, where feeder roots and the main taproot turned black. Isolations from root lesions consistently resulted in the recovery of a Phytophthora sp. The isolates were heterothallic, and on the basis of morphological and cytochrome oxidase 2 gene sequence data (GenBank Accession No. GQ984233), the pathogen was identified as Phytophthora cryptogea. To evaluate pathogenicity, individual inocula of four isolates were prepared by incubating colonized 6-mm-diameter V8 agar plugs in filtered soil extract for 2 days at 20°C to induce sporangia production. These cultures were then chilled at 4°C for 20 min and returned to room temperature for 1 h to induce zoospore release (4). Four-week-old spinach plants (cv. Bolero) were uprooted, soaked in suspensions of 1.0 × 105 zoospores/ml for 10 min, and repotted. After treatment, pots were placed in shallow trays of water for 24 h to saturate the root zone, then were removed from trays and incubated in a greenhouse. After 9 days, inoculated plants showed foliar wilting and chlorosis similar to that observed in the field; after 13 days, roots were examined and found to show the black necrosis as seen in the field. P. cryptogea was isolated from all inoculated plants. Control spinach plants, treated with soil extract only, did not develop disease. This experiment was completed two times and the results were similar. To our knowledge, this is the first report of Phytophthora root rot of spinach caused by P. cryptogea in California. This finding is significant because spinach in California is subject to root rots caused by three other pathogens (Fusarium oxysporum, Pythium spp., and Rhizoctonia solani) (1); symptoms from these root rots are very similar to those caused by P. cryptogea, thereby complicating diagnosis. This pathogen has been documented on spinach in Germany and Sweden (2,3). References: (1) S. T. Koike et al. Vegetable Diseases: A Color Handbook. Manson Publishing LtD. London, 2007. (2) H. Krober and E.-O. Beckmann. Phytopathol. Z. 78:160, 1973. (3) M. Larsson and J. Olofsson. Plant Pathol. 43:251, 1994. (4) S. A. Tjosvold et al. Plant Dis. 93:371, 2009.

scholarly journals First Report of Phytophthora Root Rot of Sugar Beet, Caused by Phytophthora cryptogea, in Greece

Plant Disease ◽  
2000 ◽  
Vol 84 (5) ◽  
pp. 593-593 ◽  
Author(s):  
G. S. Karaoglanidis ◽  
D. A. Karadimos ◽  
K. Klonari
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Soil Extract ◽  
American Phytopathological Society ◽  
Phytophthora Root Rot ◽  
Phytophthora Cryptogea ◽  
First Report ◽  
Solid Media ◽  
Necrotic Spots ◽  
Extract Medium

A severe rot of sugar beet roots was observed in the Amyndeon area of Greece during summer 1998. Infected plants initially showed a temporary wilt, which became permanent, and finally died. Slightly diseased roots showed necrotic spots toward the base, whereas more heavily diseased roots showed a more extensive wet rot that extended upward. Feeder roots also were infected and reduced in number because of decay. Rotted tissue was brown with a distinguishing black margin. In most of the isolations, carried out on potato dextrose agar (PDA), the pathogen obtained was identified as Phytophthora cryptogea Pethybr. & Lafferty Mycelium consisted of fairly uniform, fine hyphae that showed a slightly floral growth pattern. In autoclaved soil-extract medium, chains or clusters of hyphal swellings (average 12 µm diameter) formed. Sporangia were not produced on solid media but were abundant in soil-extract medium. Sporangia were oval to obpyriform in shape, nonpapillate with rounded bases, and varied in size (39 to 80 × 24 to 40 µm). Oospores were plerotic, thick-walled, and averaged 25 µm in diameter. The isolated pathogen, cultured on PDA, could not grow at all at 36°C. The closely related species P. drechsleri Tucker has been reported to cause similar root rot symptoms on sugar beet (3). However, P. drechsleri grows well at 36°C, while P. cryptogea cannot grow at this temperature; this is the major distinguishing feature that separates the two species (1). To test the pathogenicity of the organism, surface-sterilized sugar beet roots (cv. Rizor) were inoculated with 5-mm-diameter PDA plugs containing actively growing mycelium. Sterile PDA plugs were used to inoculate control sugar beet roots. Inoculated roots were kept at 27°C in the dark for 10 days. Extensive decay of inoculated roots developed, similar to decay observed in the field, whereas control roots showed no decay. P. cryptogea was reisolated from rotted tissues. This pathogen has been recognized previously as a cause of root rot of sugar beet in Japan (1) and Wyoming (2). This is the first report of Phytophthora root rot of sugar beet in Greece. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (2) P. C. Vincelli et. al. Plant Dis. 74:614, 1990. (3) E. D. Whitnew and J. E. Duffus, eds. 1986. Compendium of Beet Diseases and Insects. The American Phytopathological Society, St. Paul, MN.

scholarly journals First Report of Root Rot of Chicory Caused by Phytophthora cryptogea in Chile

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 591-591
Author(s):  
M. Vargas ◽  
C. Loyola ◽  
N. Zapata ◽  
V. Rivera ◽  
G. Secor ◽  
...  
Keyword(s):  
Root Rot ◽  
Sequence Data ◽  
Optimal Growth ◽  
Soil Extract ◽  
Agar Culture ◽  
Phytophthora Root Rot ◽  
First Report ◽  
South Central ◽  
Brown Discoloration ◽  
Single Hypha

Chicory (Cichorium intybus L. var sativum Bisch.), a relatively new high-value crop in Chile, was introduced for commercial production of inulin. Inulins are polysaccharides extracted from chicory tap roots that are used in processed foods because of their beneficial gastrointestinal properties. Approximately 3,000 ha of chicory are grown for local processing in the BioBio Region near Chillan in south central Chile. Recently, a severe rot of 1 to 3% of mature roots in the field and after harvest has been observed in most fields, which caused yield and quality losses. Typical symptoms include a brown discoloration and a soft, watery decay of the root. Tissue pieces from symptomatic roots were placed on water agar and clarified V8 juice agar medium amended with antibiotics (1) for isolation of the causal pathogen. A Phytopthora sp. had been consistently isolated from root lesions, and axenic cultures were obtained using single-hypha transfers. The species was provisionally identified as Phytopthora cryptogea (Pethybridge and Lafferty, 1919) on the basis of morphological and cultural characteristics (1). Mycelia grew between 5 and 30°C with optimal growth at 20 to 25°C and no growth at 35°C. All isolates produced hyphal swellings and nonpapillate, persistent, internally proliferating, and ovoid to obpyriform sporangia with mean dimensions of 45 × 31 μm in sterile soil extract. The isolates were of A1 mating type because they produced oospores only when paired with reference isolates of P. cinnamomi A2 on clarified V8 juice agar amended with thiamine, tryptophan, and β-sitosterol (1) after 20 days at 20°C in the dark. On the basis of morphological and sequence data from cytochrome c oxidase subunit 1 and 2, internal transcribed spacer 2, and β-tubulin (GenBank Accession Nos. JQ037796 to JQ037798, respectively), the pathogen was identified as P. cryptogea. Pathogenicity tests were conducted using three isolates of P. cryptogea by placing a 7-mm-diameter disk from a 1-week-old V8 agar culture on 10 wounded and nonwounded healthy chicory roots (2). Control roots were mock inoculated with agar plugs. The inoculated roots were incubated at 20°C in a moist chamber. Root rot symptoms, identical to those observed both in field and storage, developed after 4 to 6 days only on wounded sites inoculated with the pathogen, and P. cryptogea was reisolated from these inoculated plants. Mock-inoculated roots remained healthy. This experiment was completed twice and similar results were obtained. To our knowledge, this is the first report of Phytophthora root rot of chicory caused by P. cryptogea in Chile. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) M. E. Stanghellini and W. C. Kronland. Plant Dis. 66:262, 1982.

scholarly journals First Report of Collar and Root Rot Caused by Phytophthora nicotianae on Oriental Paperbush (Edgeworthia papyrifera) in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (7) ◽  
pp. 917-917
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Root Rot ◽  
Infected Plant ◽  
Its Region ◽  
Soil Extract ◽  
Phytophthora Nicotianae ◽  
Control Treatment ◽  
Experimental Unit ◽  
Peat Moss ◽  
Late Winter ◽  
First Report

Edgeworthia papyrifera, Oriental paperbush, is a deciduous flowering shrub becoming increasingly popular because of its clove-like perfumed flowers appearing in late winter-early spring. During August of 2009 in a commercial nursery close to Maggiore Lake (Verbano-Cusio-Ossola Province) in northwest Italy, 2-year-old plants of E. papyrifera showed extensive chlorosis and root rot. Twigs 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 formed and coalesced, girdling the stem. All of the crown and root system was affected. Infected plants died within 14 days of the appearance of symptoms. Disease was widespread and severe, affecting 90 of the 100 plants present. After disinfestation for 1 min in a solution containing 1% NaOCl, rotting root and collar pieces of E. papyrifera consistently produced a Phytophthora-like organism when plated on a medium selective for oomycetes (3). The pathogen was identified morphologically as Phytophthora nicotianae (= P. parasitica) (2). On V8 agar, coenocytic hyphae, 4 to 8 μm in diameter, formed fluffy, aerial colonies and spherical, intercalary chlamydospores, 21.0 to 36.5 (average 26.7) μm in diameter. Colonies grew well at 35°C and stopped growing at 40°C. Sporangia were produced by growing a pure hyphal-tip culture in a diluted, sterilized soil-extract. Sporangia were borne singly, laterally attached to the sporangiophore, were noncaducous, spherical to ovoid, papillate, and measured 28.6 to 55.2 × 22.4 to 45.1 (average 42.4 × 34.6) μm, length/breadth ratio (1.1:1)-1.2:1-(1.3:1). Papillae measured 3.1 to 7.6 (average 4.6) μm. The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified with primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 839-bp segment showed 99% homology with the sequence of P. nicotianae (No. AJ854296). The sequence has been assigned the GenBank No. GU353341. Pathogenicity of isolates Edg.1 and Edg.2 obtained, respectively, from the root and collar of an infected plant was confirmed by inoculating 1-year-old plants of E. papyrifera. Both strains were grown for 15 days on a mixture of 70:30 wheat/hemp kernels, and 4 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. Five plants were used for each test strain and noninoculated control treatment; the trial was repeated once. All plants were kept in a greenhouse at 25 to 28°C. Plants inoculated with Edg.1 and Edg.2 developed chlorosis and root rot 18 and 14 days after the inoculation, respectively, and wilt rapidly followed. Control plants remained symptomless. P. nicotianae was consistently reisolated from inoculated plants. To our knowledge, this is the first report of P. nicotianae on E. papyrifera in Italy as well as worldwide. The current economic importance of the disease is minor due to 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 Phtytopathological Society, St Paul, MN, 1996. (3) H. Masago et al. Phytopathology 67:425, 1977.

scholarly journals Soil Salinity Enhances Phytophthora Root Rot of Tomato but Hinders Asexual Reproduction by Phytophthora parasitic

1991 ◽  
Vol 116 (3) ◽  
pp. 471-477 ◽  
Author(s):  
T.J. Swiecki ◽  
J.D. MacDonald
Keyword(s):  
Lycopersicon Esculentum ◽  
Asexual Reproduction ◽  
Root Rot ◽  
Crown Rot ◽  
Saline Soils ◽  
Phytophthora Root Rot ◽  
Tomato Plants ◽  
Zoospore Release ◽  
Root Necrosis ◽  
Root And Crown Rot

Exposure of tomato plants (Lycopersicon esculentum Mill.) to salinity stress either before or after inoculation with Phytophthora parasitica increased root and crown rot severity relative to nonstressed controls. The synergy between salinity and P. parasitic was most pronounced on young (prebloom) plants and least pronounced on older (postbloom) plants. Salt stressed, inoculated plants had significantly reduced top weight, significantly more root necrosis, greater incidence of crown necrosis, and significantly greater mortality. Increased disease severity occurred even though experiments showed salinity reduced zoospore release arid motility of P. parasitic, suggesting that even low inoculum levels can result in severe root rot on young tomato plants in saline soils.

scholarly journals First Report of Phytophthora cactorum and P. citrophthora Causing Root Rot of Ribes lobbii in Oregon

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 157-157 ◽  
Author(s):  
J. E. Weiland
Keyword(s):  
Root Rot ◽  
Sequence Data ◽  
Sequence Similarity ◽  
Negative Control ◽  
Broad Host Range ◽  
Initial Symptom ◽  
Its Sequence ◽  
First Report ◽  
Its Sequence Analysis ◽  
Negative Controls

Ribes lobbii (Gray) is a native, deciduous shrub from British Columbia, California, Oregon, and Washington that is grown for its pendulous red and white flowers, bristly fruit, and attractive, aromatic foliage. It is uncommon in nature and has only recently begun being propagated for sale in ornamental and native nurseries. In April 2013, 2-year-old containerized plants (15/50 plants) were found with severe wilt and chlorosis symptoms at a nursery production facility in western Oregon. Most fine roots were completely rotted and larger roots exhibited numerous black lesions. By the end of August, 50% of the plants were affected and most died within a few weeks of initial symptom development. At least three initially asymptomatic plants developed symptoms after being sold and planted. Isolation was attempted from 10 plants by plating pieces of necrotic root tissue (3 mm2) that had been surface disinfested for 1 min in 10% bleach and 1 min in 70% ethanol onto PARP medium (2). Eight Phytophthora isolates were recovered and identified as P. cactorum (seven isolates, GenBank Accession No. KM085441) and P. citrophthora (one isolate, KM085442) on the basis of morphology and 99 to 100% internal transcribed spacer (ITS) sequence similarity to published sequence data (1). One isolate of each species was used to prepare vermiculite inoculum (3) and subsequently to infest potting media (Sunshine Professional Growing Mix) at 100 propagules per gram. Due to the scarcity of R. lobbii in nature and the nursery trade, only a limited number of plants were available for pathogenicity tests. Three 1-year-old rooted cuttings of R. lobbii (~15 to 30 cm tall) were transplanted into individual 10-cm2 pots containing 175 g of the respective infested media for each pathogen. Three plants transplanted into individual pots of noninfested media served as negative controls. Plants were then watered to pot capacity and incubated in a greenhouse at 28/24°C day/night. The entire experiment was repeated 2 weeks later. Within 1 week after inoculation, all inoculated plants in both trials wilted and died, regardless of the Phytophthora species used; negative control plants remained healthy. Each pathogen (with identity confirmed by ITS sequence analysis) was re-isolated from the roots and stem of each respective inoculated plant, but was not isolated from negative controls, thus fulfilling Koch's postulates. Therefore, to my knowledge, this is the first report of P. cactorum and P. citrophthora as root rot pathogens of R. lobbii. The use of infected, but asymptomatic native plants in habitat restoration efforts will likely compromise success and there is considerable risk to nearby plant species given the broad host range of both pathogens. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) M. E. Kannwischer and D. J. Mitchell. Phytopathology 68:1760, 1978. (3) J. E. Weiland et al. Plant Dis. 97:744, 2013.

scholarly journals First Report of a Ceratobasidium sp. Causing Root Rot on Canola in Washington State

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 591-591 ◽  
Author(s):  
K. L. Schroeder ◽  
T. C. Paulitz
Keyword(s):  
Plant Height ◽  
Root Rot ◽  
Root Zone ◽  
Dry Weight ◽  
Washington State ◽  
Infested Soil ◽  
Damping Off ◽  
Root Tips ◽  
Hordeum Vulgare L ◽  
First Report

Rhizoctonia root rot occurs commonly on canola (Brassica napus L.) in Washington State. Recently, isolates of an additional pathogen were found to be involved in this disease complex. Isolates of an AG-I-like Ceratobasidium sp. were collected from roots and root zone soil in central Washington near Ritzville. Identity of selected isolates was verified by sequencing the internal transcribed spacer (ITS) region of the rDNA (GenBank Accession Nos. JQ247570, JQ247571, and JQ247572), with a 90 to 93% identity to AG-I. All isolates also amplified with AG-I-like specific primers (1). Six isolates were included in pathogenicity assays conducted in the greenhouse. There were five replicates of three plants for each treatment and the experiment was conducted twice. Pasteurized soil was infested with ground oat inoculum (1%) and placed into containers (3.8 × 21 cm). Infested soils were seeded with canola, chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.), pea (Pisum sativum L.), barley (Hordeum vulgare L.), or wheat (Triticum aestivum L.). After 3 weeks of incubation at 15°C, the plants were destructively harvested. The emergence of canola was consistently reduced in soil infested with a Ceratobasidium sp., with reductions of 0 to 23% (average 11%). There was no postemergence damping-off, a symptom commonly associated with AG-2-1 (2). Plant height and top dry weights were significantly reduced for canola seeded into infested soil. Heights of plants growing in infested soil was reduced by 25 to 53% (average 42%) and top dry weight was reduced by 37 to 81% (average 61%) compared with the noninfested control. The legume hosts tested in this study were also affected by this Ceratobasidium sp., but to a lesser extent. Compared with the noninfested controls, there was evidence of preemergence damping-off in chickpea (0 to 27%, average 13%) and pea plants were consistently stunted (5 to 23%, average 12%). Chickpea and pea plants grown in infested soil also had reduced top dry weights of 9 to 28% (average 17%) and 13 to 35% (average 21%), respectively. The roots of all infected hosts had a characteristic brown discoloration with tapered, rotted root tips (spear tips). There was no reduction in emergence or plant height of wheat and barley; there was inconsistent reduction in dry weight of these plants. To our knowledge, this is the first report of a Ceratobasidium sp. causing disease on canola in Washington State. References: (1) P. A. Okubara et al. Phytopathology 98:837, 2008. (2) T. C. Paulitz et al. Plant Dis. 90:829, 2006.

scholarly journals Ecology and control of grapevine root diseases in New Zealand a review

2015 ◽  
Vol 68 ◽  
pp. 396-404
Author(s):  
D.C. Mundy
Keyword(s):  
New Zealand ◽  
Root Rot ◽  
Economic Loss ◽  
Foot Rot ◽  
Phytophthora Root Rot ◽  
Root Rots ◽  
Root Diseases ◽  
Armillaria Root Rot ◽  
Verticillium Dahlia ◽  
Black Foot

Grapevine root diseases can result in economic loss during vineyard establishment Symptoms may not be noticed in vineyards until vines die The death of young vines as a result of root rots can be a point of contention between the grower and the nursery supplying the plants In New Zealand root diseases include black foot rot (caused by Cylindrocarpon spp) verticillium wilt (caused by Verticillium dahlia) phytophthora root rot (caused by various Phytophthora spp) and armillaria root rot (caused in New Zealand by Armillaria novaezelandiae and A limonea) Of these diseases black foot rot is the most commonly observed in the field in New Zealand and has received the most study This review provides information on symptoms causal organisms disease cycles and where available control of grapevine root rots under New Zealand conditions

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