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 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 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 First Report of Rhizoctonia solani Causing a Disease of Sunflower in India

Plant Disease ◽  
2010 ◽  
Vol 94 (4) ◽  
pp. 488-488 ◽  
Author(s):  
K. Srinivasan ◽  
S. Visalakchi
Keyword(s):  
Rhizoctonia Solani ◽  
Root Rot ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
American Phytopathological Society ◽  
First Report ◽  
Leaf Yellowing ◽  
Crown Tissue ◽  
Symptomatic Tissue ◽  
White Mycelium

During the spring of 2009, symptoms including leaf yellowing and wilting, root rot, and death of plants were noted in sunflower (Helianthus annuus L.) crops in Dharmapuri District, Tamilnadu, India. In some fields, approximately 30% of the plants were affected. The disease began when plants were approximately 10 weeks old and occurred on scattered or adjacent plants. The presence of white mycelium was observed on necrotic crowns. Symptomatic tissue was surface disinfested in 70% alcohol for 30 s and 0.5% sodium hypochlorite for 1 min and plated onto potato dextrose agar (PDA) (1). One isolate (coded SV001) had near right-angle branching with basal constriction and adjacent septa and sclerotia typical of Rhizoctonia spp. (2). Cream-colored colonies produced irregular, light brown sclerotia that were 3.0 to 7.3 mm (average 3.8 mm) in diameter. Hyphae were 6.8 to 7.0 μm (average 6.9 μm) wide and multinucleate (8 to 15 nuclei per cell). On the basis of hyphal anastomosis with several known AG testers, the fungus was characterized as Rhizoctonia solani Kühn AG-IV (3). One culture was deposited at the Madras University Botany Laboratory, Center for Advanced Studies in Botany, University of Madras, Chennai, India. In a pathogenicity test, R. solani SV001 was grown on PDA for 5 days at 24°C in the dark. Five-millimeter-diameter disks were placed at the base of sunflower plants (cv. Mordan). Four sunflower plants in each of three pots were inoculated; noninoculated plants served as controls. Plants were placed in a glasshouse maintained at 25 to 27°C. Inoculated plants developed yellow foliage and crown rot and root rot symptoms after 7 to 12 days and died in 17 to 20 days. No symptoms were observed on noninoculated plants. The pathogen was reisolated from fragments of necrotic crown tissue of inoculated plants. To our knowledge, this is the first report of R. solani AG-IV causing a disease of sunflower plants in India. References: (1). R. C. Fenille et al. Plant Pathol. 54:325, 2005. (2). J. R. Parmeter et al. Phytopathology 59:1270, 1969. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.

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.

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