scholarly journals First Report of Crown and Root Rot Caused by Phytophthora capsici on Hydroponically Grown Cucumbers in Norway

Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1138-1138 ◽  
Author(s):  
M. L. Herrero ◽  
M. B. Brurberg ◽  
A. Hermansen
Keyword(s):  
Mating Type ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Yield Reduction ◽  
Cox1 Gene ◽  
Pathogenicity Test ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Leaf Stage ◽  
Root And Crown Rot

In December 2004, symptoms of root and crown rot were observed on cucumbers (Cucumis sativus L.) in a greenhouse in Norway. Cucumbers were the only crop of the greenhouse that used rockwool as a growing substrate in a hydroponical system. The first symptoms were detected in propagation material. One week after planting, symptoms of root and crown rot were observed and approximately 10% of the plants died. Later, losses of 50% in some greenhouses were observed. A yield reduction as much as 65% was estimated in the winter period (January and February). The two main cucumber cultivars planted were Armada and Lopez. In February 2005, Phytophthora capsici (Leonian) (1) was isolated on potato dextrose agar from a sample of cv. Lopez. The isolate produced deciduous, papillate sporangia (occasionally with two or three papilla) and pedicels that were sometimes longer than the sporangia. Sequencing of amplicons of the internal transcribed spacer region (ITS) rDNA and of the mitochondrial cytochrome c oxidase subunit 1 (Cox1) gene (2) confirmed the identification. Three isolates collected through 2005 from the same greenhouse were crossed with tester strains of P. cryptogea. Formation of oogonia and amphigynous antheridia was always observed in crosses with mating type A2; thus, all isolates were the A1 mating type. All three isolates grew well at 35°C and did not produce chlamydospores. A pathogenicity test was performed with one isolate of P. capsici. Four plants of cucumber cvs. Indira and Jessica were grown in a growth chamber at 24°C. Plants at the two-leaf stage were drenched with 20 ml of a zoospore suspension of 106 zoospores per ml per plant. After 18 days, all plants of both cultivars developed symptoms of crown rot or wilted and died. P. capsici was reisolated from inoculated plants of both cultivars. The pathogenicity test was repeated in the same way, but in a greenhouse with temperatures that ranged between 18 and 29°C. In addition, four plants of both cultivars at the four-leaf stage were inoculated with a suspension of 105 zoospores per ml. After 1 week, all plants developed crown rot or were irreversibly wilted, independently of the plant age or the zoospore concentration. To our knowledge, this is the first report of P. capsici in Norway. 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. Phytopathology 94:613, 2004.

scholarly journals First Report of Phytophthora capsici on Cucumber and Melon in Southeastern Spain

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 558-558 ◽  
Author(s):  
M. L. Herrero ◽  
R. Blanco ◽  
M. Santos ◽  
J. C. Tello
Keyword(s):  
Mating Type ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Cucumis Sativus L ◽  
Leaf Stage ◽  
Southeastern Spain ◽  
Root And Crown Rot ◽  
Crown And Root Rot ◽  
Cucumis Melo L ◽  
First Time

In autumn 1999, crown and root rot along with wilting of cucumber (Cucumis sativus L.) were observed in greenhouses in southeastern Spain (Granada). Symptoms appeared again during the 2000 to 2001 growing season. In spring 2001, root and crown symptoms were observed also on melon (Cucumis melo L.) in greenhouses in another area of southeastern Spain (Almeria). Isolates from diseased plants from both locations were identified as Phytophthora capsici (Leonian). Isolates produced papillate sporangia of variable shape, some of them with two or three papilla. Sporangia were caducous with pedicels of variable lengths that could be longer than the sporangia. Three isolates were crossed with P. capsici strains of known mating type. All isolates produced amphigynous antheridia and were mating type A1. Isolates grew well at 35°C and did not produce chlamydospores. Pathogenicity was examined for one isolate from cucumber and one from melon. Cucumber and melon plants at the four-leaf stage and pumpkin (Cucurbita maxima × C. moschata) plants at the five-leaf stage were inoculated with a mycelium suspension. Both isolates caused wilting and death of plants on the three host species tested. The pathogen was reisolated from roots and stems of diseased plants. To our knowledge, this is the first time P. capsici has been found on cucumber in Spain. It is also the first time P. capsici has been found on melon in the greenhouses of southeastern Spain, and the first time it has been reported to cause root and crown rot of melon. Previously, P. capsici has been reported to cause disease of field-grown melon (2) and greenhouse-grown pepper (Capsicum annum) (1) in eastern and southeastern Spain, respectively. References: (1) J. C Tello. Comun. INIA 22, 1984. (2) J. J. Tuset Barrachina. An. INIA 7:11, 1977.

scholarly journals First Report of Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1260-1260 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
D. Minerdi ◽  
M. L. Gullino
Keyword(s):  
Its Region ◽  
The United States ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
Phytophthora Citrophthora ◽  
First Report ◽  
Blastn Analysis ◽  
Root And Crown Rot ◽  
Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

scholarly journals Epipremnum, a new host for Phytophthora capsici

Plant Disease ◽  
2002 ◽  
Vol 86 (9) ◽  
pp. 1050-1050 ◽  
Author(s):  
R. L. Wick ◽  
M. B. Dicklow
Keyword(s):  
Mating Type ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Fluorescent Light ◽  
Pathogenicity Test ◽  
Agar Culture ◽  
New Host ◽  
Solid Media ◽  
Breadth Ratio ◽  
Response To Temperature

From 1999 to 2001, a Massachusetts nursery received a number of shipments of Pothos, Epipremnum aureum (Lindl. & André) Bunting, with significant crown, petiole, and leaf rot. The plants were imported from Costa Rica. Sporangia were observed on diseased tissues, and five presumptive isolates of Phytophthora were recovered from infected petioles and stems for species identification. The five isolates were morphologically indistinguishable from each other. Sporangia were produced in water and on V8 juice agar under fluorescent light at 22°C. Mating type was determined by pairing isolates with A1 and A2 mating types of Phytophthora capsici Leonian. Sporangial measurements were taken from water cultures. Determination of caducity, and measurements of pedicels and oospores were taken from V8 agar cultures. Measurements represent an average of 50 observations a single isolate. In water culture, sporangia were borne in umbellate clusters. Sporangium length/breadth was 48.29 and 22.33 μm respectively; length/breadth ratio 2.16. On solid media, sporangia were upright and caducous. The bases of the sporangia were mostly tapered. Pedicel lengths were 22 to 49 μm (average 35 μm). Oogonia had amphigynous antheridia and developed only in the presence of an opposite mating type, and oospores measured 25.74 μm diameter. All five isolates were the A1 mating type. Chlamydospores were absent in V8 and corn meal agar (CMA) cultures. Metalaxyl sensitivity was determined at 0, 0.1, 0.5, and 5 ppm in CMA with five replications. The isolate was completely sensitive to 5 ppm metalaxyl, but grew as well as the controls at 0.1 ppm metalaxyl. Growth response to temperature was determined on V8 agar at 15, 20, 25, 30, and 35°C in five replications. After 4 days, colony diameters at 20, 25, and 30°C were not significantly different (P = 0.01) and colonies filled the 100-mm petri dishes. At 15 and 35°C, average colony diameter was 65.7 and 71.4 mm, respectively. Based on the above characteristics, the isolates were identified as P. capsici. Koch's postulates were carried out on pepper, Capsicum annuum ‘Italia’, squash, Cucurbita pepo ‘Patty Pan’ seedlings, and rooted cuttings of pothos. Pepper and squash seedlings and rooted pothos were transplanted in 4-in. (10 cm) pots containing a soilless growing medium (Metro Mix 360, W.R. Grace, Columbia, MD). Phytophthora cultures were grown on V8 juice agar for 4 days. An agar culture was added to 200 ml of sterile distilled water and briefly blended. Ten milliliters of the resulting mycelial slurry were pipetted in the soil one cm from the crown on two sides of the plant. Controls received no mycelial slurry. Petiole, leaf, and crown rot of pothos developed within 2 weeks following inoculation. Squash and pepper plants did not become diseased. In a second pathogenicity test, a 1-cm-diameter plug of mycelial growth from a V8 agar culture was placed between the stem and petiole of the lowest leaf of pothos cuttings directly after transplanting. Inoculated plants died within 3 days. The development of umbellate clusters of sporangia, sporangial shape, length/breadth ratio, and lack of pathogenicity to pepper suggest that the P. capsici isolated from pothos belong to the CAPB (tropical) subgroup of Mchau and Coffey (2). References: (1) S. S. A. Al-Hedaithy and P. H. Tsao. Mycologia 71:392, 1979. (2) G. R. Mchau. and M. D. Coffey. Mycol. Res. 99:89, 1995.

scholarly journals Insensitivity to Metalaxyl Among Isolates of Phytophthora capsici Causing Root and Crown Rot of Pepper in Southern Italy

Plant Disease ◽  
1998 ◽  
Vol 82 (11) ◽  
pp. 1283-1283 ◽  
Author(s):  
A. M. Pennisi ◽  
G. E. Agosteo ◽  
S. O. Cacciola ◽  
A. Pane ◽  
R. Faedda
Keyword(s):  
Mating Type ◽  
Southern Italy ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Metalaxyl Resistance ◽  
Local Selection ◽  
Capsicum Spp ◽  
Root And Crown Rot ◽  
Single Hypha

Pepper (Capsicum annuum L.) has become an economically important crop in the coastal provinces of Catanzaro and Vibo Valentia, in Calabria (southern Italy). An old local selection Riggitano, very susceptible to root and crown rot caused by Phytophthora capsici Leonian, is the prevalent cultivar in this area. Although repeated applications of metalaxyl are used as a soil drench, severe outbreaks occur each year on greenhouse crops. To examine metalaxyl resistance in P. capsici, 60 single-hypha isolates of P. capsici were tested in vitro for their level of sensitivity to metalaxyl. The isolates were collected from 1992 to 1997, during epidemic outbreaks of root and crown rot, from two commercial greenhouse pepper crops, near Vibo Valentia and Lametia Terme (Catanzaro). Fungicide sensitivity was determined by plating mycelial plugs onto potato dextrose agar (PDA) amended with metalaxyl. The fungicide was added to PDA after autoclaving, at final concentrations of 0.1, 1, 5, 10, 50, 100, and 200 μg/ml a.i. The percentage of inhibition of radial growth on metalaxyl-amended medium compared with the growth on unamended medium was determined after 6 days of incubation in the dark at 25°C. Three replicate petri dishes were used per treatment and each test was performed twice. The isolates were paired in culture on V8 agar with isolates of P. capsici of known mating type and all proved to be A2 mating type. Significant variation was observed among the isolates tested in responce to metalaxyl. The ED50 values for in vitro inhibition of mycelial growth by metalaxyl ranged from 1 to 11 μg/ml, whereas an ED 50 value of 0.1 μg/ml had been reported for a wild-type isolate of P. capsici obtained from pepper in northern Italy (3). The variation observed among the isolates from Calabria appeared unrelated to both the geographical origin and the year of isolation. The isolates from Calabria were inhibited by between 1 and 12% at 0.1 μg/ml and by between 7 and 27% at 1 μg/ml, proving to be less sensitive to metalaxyl than isolates from Capsicum spp. originating from Central America, tested by other authors (1). According to the criterion used in a recent screening for sensitivity to metalaxyl (2), 19% of the isolates from Calabria should be considered sensitive, as they were inhibited by more than 60% at 5 μg/ml, while all the others were intermediate, as they were inhibited less than 60% at 5 μg/ml but more than 60% at 100 μg/ml. On the basis of this preliminary screening, we report the presence of insensitivity to metalaxyl in field isolates of P. capsici in southern Italy. Although no isolate tested appeared highly resistant to metalaxyl, the presence of a high proportion of isolates with an intermediate level of resistance should be a reason for the growers to use metalaxyl more cautiously to control root and collar rot. References: (1) M. D. Coffey and L. A. Bower. Phytopathology 74:502, 1984. (2) G. Parra and J. Ristaino. Plant Dis. 82:711, 1998. (3) M. L. Romano and A. Garibaldi. La difesa delle piante 3:153, 1984.

scholarly journals First Report of Phytophthora capsici Causing Wilting and Root and Crown Rot on Capsicum annuum (Bell Pepper) in Ecuador

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 2032-2032 ◽  
Author(s):  
Jefferson Bertin Vélez-Olmedo ◽  
Luis Saltos ◽  
Liliana Corozo ◽  
Bianca Samay Bonfim ◽  
Sergio Vélez-Zambrano ◽  
...  
Keyword(s):  
Capsicum Annuum ◽  
Phytophthora Capsici ◽  
Bell Pepper ◽  
Crown Rot ◽  
First Report ◽  
Root And Crown Rot

scholarly journals First Report of Neopestalotiopsis mesopotamica causing root and crown rot on strawberry in Ecuador

Plant Disease ◽  
2021 ◽  
Author(s):  
Joussy Hidrobo ◽  
Dario Ramirez-Villacis ◽  
Noelia Barriga-Medina ◽  
Karen Herrera ◽  
Antonio Leon-Reyes
Keyword(s):  
Disease Diagnosis ◽  
Crown Rot ◽  
Fruit Rot ◽  
Production Cycle ◽  
Diseased Plant ◽  
Pathogenicity Test ◽  
First Report ◽  
Consensus Sequences ◽  
Root And Crown Rot ◽  
Β Tubulin

In Ecuador, strawberry production is located in the Andean region with an area of 1000 ha. Albion is the most popular cultivar due to its conical fruit shape, fruit size, bright red color, and sweetness. Since June 2014, farmers reported a reduction in the production cycle from 24 months to 6-8 months and a decreased yield of around 50% due to an unknown soil pathogen. Plant symptoms presented a reddish discoloration on new leaves, coming through the leaf apex to the petiole until turning wholly brown in old leaves leading to plant death. Additionaly, a brown-reddish spot inside the strawberry crown and root rot were reported (Fig. S1). In 2020, in Ecuador's most extensive production area, called Yaruqui (Pichincha province), 25 diseased plants were collected for pathogen isolation. The pathogen was isolated on water agar medium from the crowns internal tissue using 0.5 cm diseased plant fragments, previously disinfected with 2% sodium hypochlorite, and rinsed with sterile water. After two days, single hyphal tip was reisolated on potato dextro agar (PDA). A total of 18 pure isolates were grown at 25°C for 12 days, then 3-7 days of blacklight treatment was applied to induce sporulation. All the isolates presented a cottony beige mycelium with undulate edges. The conidia were ellipsoidal (range between 20.73 to 29 µm in length and 6.2 to 8.77 µm in width; n=60), multiseptated (4 segments) showing hyaline apical (3.8 to 5 µm) and basal (4.87 to 8 µm) cells, and three brown median cells, the second and third were darker than the fourth one, with one basal and 2 to 4 apical appendages (26.09 to 38.7 µm; Fig. S1). According to colony and conidia morphology, the isolates were identified as Neopestalotiopsis sp. (Dung et al. 2016; Essa et al. 2018; Maharachchikumbura et al. 2011). Five isolates were select randomly for DNA extraction and sequencing of the internal transcribed spacer (ITS) region (ITS4/ITS5), β-tubulin (Bt2b/ T1), and translation elongation factor 1-alpha (TEF-1a) region (EF1-728/ EF1-986) (Maharachchikumbura et al. 2014). DNA sequences obtained from each marker were identical for all isolates. Consensus sequences and alignment were built using ClustalX in MEGA X (Kumar et al. 2018). The consensus sequences were deposited in GenBank with the following accession numbers: ITS, MZ047602; β-tubulin, MZ054301; and TEF-1a, MZ054302. A multilocus Bayesian inference phylogenetic tree was constructed using the concatenated sequences in the Beast software (version 1.8.4)(Drummond et al. 2012; Maharachchikumbura et al. 2014). The isolate in our study clustered with isolates of Neopestalotiopsis mesopotamica with a posterior probability of 1, confirming its identity (Fig. S2). For Koch's postulates, healthy plants were grown in sterile soil for four months. Conidia of the pathogen were suspended in potato dextro broth (PDB) (1 x 104 conidia/ml), and it was sprayed on 15 healthy plants that previously had their crowns wounded with a sterile needle (0.6 cm deep) at the four cardinal points. The control treatment (15 plants) was wounded and sprayed with PDB alone. The plants were maintained at 25°C and more than 85% relative humidity (Sigillo et al. 2020). Twelve days after inoculation, plants showed reddish discoloration on new leaves, and old leaves presented low-level wilt, rusty color, and necrotic petioles. Forty-one days later, 75% of the treated plants had severe wilt or were dead, showing root and crown rot. Control plants presented no symptoms of the disease. Reisolation of the pathogen from the disease crown tissues was done on water agar and PDA as previously described. The isolates presented the exact morphology of pure cultures obtained from field diseased strawberry crowns. The pathogenicity test was performed twice. To our knowledge, this is the first report of Neopestalotiopsis mesopotamica being the causal agent of root and crown rot on strawberries in Ecuador. N. iranensis and N. mesopotamica have been reported as causal agents of strawberries fruit rot and leaf lesions in Iran (Ayoubi and Soleimani, 2016), and N. clavispora was reported to be causing root and crown rot on strawberry plants in Argentina (Obregon et al. 2018). Disease diagnosis contributes to providing strategies against this new disease. Further investigations are needed to find biological/chemical techniques or cultivar resistance to control this pathogen in strawberries in Ecuador.

scholarly journals First Report of Root and Crown Rot of Sage Caused by Phytophthora cryptogea in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (10) ◽  
pp. 1176-1176 ◽  
Author(s):  
S. O. Cacciola ◽  
A. Pane ◽  
F. Raudino ◽  
S. Davino
Keyword(s):  
Mating Type ◽  
Sandy Loam ◽  
Ornamental Plants ◽  
Electrophoretic Pattern ◽  
Crown Rot ◽  
Infested Soil ◽  
Mycelium Growth ◽  
First Report ◽  
Electrophoretic Patterns ◽  
Root And Crown Rot

Sages are cultivated as aromatic and ornamental plants in Italy and represent the common name of certain species of Salvia and Phlomis (family Lamiaceae). In Sicily (southern Italy) during the summer of 2001, ≈40% of 1,400 2-year-old landscape plants of S. leucantha Cav. (Mexican bush sage or velvet sage) showed symptoms of stunting, chlorosis, and gradual dieback or sudden wilt, which are associated with root and crown rot. Plants were supplied by a commercial nursery, transplanted from pots in the spring, and irrigated using a trickle system. Phytophthora was isolated consistently from roots and basal stems of symptomatic plants on a BNPRAH medium (2). The species was identified as P. cryptogea Pethybr. & Laff., primarily on the basis of morphological and cultural characteristics. Five representative single-hypha isolates were characterized. On potato dextrose agar, they formed colonies with a slight petaloid pattern. Cardinal temperatures for mycelium growth were 2°C, minimum; 25°C, optimum; and 30 to 35°C, maximum. Hyphal swellings were abundant in aqueous culture. Sporangia were obpyriform, persistent, nonpapillate, and proliferous (2). All isolates were the A1 mating type and formed oogonia, amphigynous antheridia, and oospores in dual cultures with reference isolates of the A2 mating type of P. cryptogea and P. drechsleri. Identification was confirmed by electrophoresis of mycelium proteins on a polyacrylamide slab gel (1). Electrophoretic patterns of total soluble proteins from the sage isolates were identical or very similar to those from 10 reference isolates of P. cryptogea from various hosts, including isolate IMI 180615 (ex-type isolate). Conversely, the electrophoretic pattern of the isolates of P. cryptogea from sage was clearly distinct from those from reference isolates of other species included in Waterhouse's taxonomic group VI. Esterase (EC 3.1.1.2.) zymograms of the sage isolates corresponded to those of isolates of P. cryptogea included in electrophoretic group 2 (1). The pathogenicity of a representative isolate of P. cryptogea from sage was tested in the greenhouse using 4-month-old plants of Mexican bush sage. Inoculum was produced on a mixture of vermiculite and autoclaved oat seeds (4) and mixed with steam-sterilized sandy loam soil at a concentration of 4% (vol/vol). Plants were transplanted in pots (12 cm diameter) filled with infested soil; control plants were grown in pots containing noninfested soil. After transplanting, all pots were placed in shallow trays filled with water for 24 h to saturate the soil. All plants grown in infested soil showed extensive root necrosis and dieback ≈30 days after transplanting, and P. cryptogea was reisolated from roots of symptomatic plants. Control plants did not develop symptoms. Root and crown rot of sage caused by P. cryptogea has been reported previously in California (3). To our knowledge, this is the first report of P. cryptogea on sage in Italy. Root rot caused by P. cryptogea may be a potential problem for commercial cultivation of sage as no serious disease of this plant has been reported in Italy so far. References: (1) S. O. Cacciola et al. EPPO Bull. 20:47, 1990. (2) D. C Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul MN. 1996. (3) S. T. Koike et al. Plant Dis. 81:959, 1997. (4) E. Sánchez-Hernández et al. Plant Dis. 85:411, 2001.

scholarly journals First Report of Rhizoctonia solani AG 4 on Lamb's Lettuce in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (8) ◽  
pp. 1109-1109 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Morphological Characteristics ◽  
Northern Italy ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
First Report ◽  
Pathogenicity Tests ◽  
Hyphal Diameter ◽  
Wheat Kernels ◽  
Extensive Necrosis

Lamb's lettuce or corn salad (Valerianella olitoria) is increasingly grown in Italy and used primarily in the preparation of mixed processed salad. In the fall of 2005, plants of lamb's lettuce, cv Trophy, exhibiting a basal rot were observed in some commercial greenhouses near Bergamo in northern Italy. The crown of diseased plants showed extensive necrosis, progressing to the basal leaves, with plants eventually dying. The first symptoms, consisting of water-soaked zonate lesions on basal leaves, were observed on 30-day-old plants during the month of October when temperatures ranged between 15 and 22°C. Disease was uniformly distributed in the greenhouses, progressed rapidly in circles, and 50% of the plants were affected. Diseased tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with 100 μg/liter of streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani was consistently and readily isolated and maintained in pure culture after single-hyphal tipping (3). The five isolates of R. solani, obtained from affected plants successfully anastomosed with tester isolate AG 4, no. RT 31, received from R. Nicoletti of the Istituto Sperimentale per il Tabacco, Scafati, Italy (2). The hyphal diameter at the point of anastomosis was reduced, and cell death of adjacent cells occurred (1). Pairings were also made with AG 1, 2, 3, 5, 7, and 11 with no anastomoses observed between the five isolates and testers. For pathogenicity tests, the inoculum of R. solani (no. Rh. Vale 1) was grown on autoclaved wheat kernels at 25°C for 10 days. Plants of cv. Trophy were grown in 10-liter containers (20 × 50 cm, 15 plants per container) on a steam disinfested substrate (equal volume of peat and sand). Inoculations were made on 20-day-old plants by placing 2 g of infected wheat kernels at each corner of the container with 3 cm as the distance to the nearest plant. Plants inoculated with clean wheat kernels served as controls. Three replicates (containers) were used. Plants were maintained at 25°C in a growth chamber programmed for 12 h of irradiation at a relative humidity of 80%. The first symptoms, consisting of water-soaked lesions on the basal leaves, developed 5 days after inoculation with crown rot and plant kill in 2 weeks. Control plants remained healthy. R. solani was consistently reisolated from infected plants. The pathogenicity test was carried out twice with similar results. This is, to our knowledge, the first report of R. solani on lamb's lettuce in Italy as well as worldwide. The isolates were deposited at the AGROINNOVA fungal collection. The disease continues to spread in other greenhouses in northern Italy. References: (1) D. Carling. Rhizoctonia Species: Pages 37–47 in: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. B. Sneh et al., eds. Kluwer Academic Publishers, the Netherlands, 1996. (2) J. Parmeter et al. Phytopathology, 59:1270, 1969. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1996.

scholarly journals First Report of Neopestalotiopsis clavispora Causing Root and Crown Rot on Strawberry in Italy

Plant Disease ◽  
2019 ◽  
Vol 103 (11) ◽  
pp. 2959-2959 ◽  
Author(s):  
G. Gilardi ◽  
F. Bergeretti ◽  
M. L. Gullino ◽  
A. Garibaldi
Keyword(s):  
Crown Rot ◽  
First Report ◽  
Root And Crown Rot

scholarly journals First Report of Phomopsis citri Associated with Dieback of Citrus lemon in India

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1281-1281 ◽  
Author(s):  
S. Mahadevakumar ◽  
Vandana Yadav ◽  
G. S. Tejaswini ◽  
S. N. Sandeep ◽  
G. R. Janardhana
Keyword(s):  
Fungal Pathogen ◽  
The United States ◽  
Apical Region ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
Productivity Level ◽  
First Report ◽  
Dieback Disease

Lemon (Citrus lemon (L.) Burm. f.) is an important fruit crop cultivated worldwide, and is grown practically in every state in India (3). During a survey conducted in 2013, a few small trees in a lemon orchard near Mysore city (Karnataka) (12°19.629′ N, 76°31.892′ E) were found affected by dieback disease. Approximately 10 to 20% of trees were affected as young shoots and branches showed progressive death from the apical region downward. Different samples were collected and diagnosed via morphological methods. The fungus was consistently isolated from the infected branches when they were surface sanitized with 1.5% NaOCl and plated on potato dextrose agar (PDA). Plates were incubated at 26 ± 2°C for 7 days at 12/12 h alternating light and dark period. Fungal colonies were whitish with pale brown stripes having an uneven margin and pycnidia were fully embedded in the culture plate. No sexual state was observed. Pycnidia were globose, dark, 158 to 320 μm in diameter, and scattered throughout the mycelial growth. Both alpha and beta conidia were present within pycnidia. Alpha conidia were single celled (5.3 to 8.7 × 2.28 to 3.96 μm) (n = 50), bigittulate, hyaline, with one end blunt and other truncated. Beta conidia (24.8 to 29.49 × 0.9 to 1.4 μm) (n = 50) were single celled, filiform, with one end rounded and the other acute and curved. Based on the morphological and cultural features, the fungal pathogen was identified as Phomopsis citri H.S. Fawc. Pathogenicity test was conducted on nine healthy 2-year-old lemon plants via foliar application of a conidial suspension (3 × 106); plants were covered with polythene bags for 6 days and maintained in the greenhouse. Sterile distilled water inoculated plants (in triplicate) served as controls and were symptomless. Development of dieback symptoms was observed after 25 days post inoculation and the fungal pathogen was re-isolated from the inoculated lemon trees. The internal transcribed spacer region (ITS) of the isolated fungal genomic DNA was amplified using universal-primer pair ITS1/ITS4 and sequenced to confirm the species-level diagnosis (4). The sequence data of the 558-bp amplicon was deposited in GenBank (Accession No. KJ477016.1) and nBLAST search showed 99% homology with Diaporthe citri (teleomorph) strain 199.39 (KC343051.1). P. citri is known for its association with melanose disease of citrus in India, the United States, and abroad. P. citri also causes stem end rot of citrus, which leads to yield loss and reduction in fruit quality (1,2). Dieback disease is of serious concern for lemon growers as it affects the overall productivity level of the tree. To the best of our knowledge, this is the first report of P. citri causing dieback of lemon in India. References: (1) I. H. Fischer et al. Sci. Agric. (Piracicaba). 66:210, 2009. (2) S. N. Mondal et al. Plant Dis. 91:387, 2007. (3) S. P. Raychaudhuri. Proc. Int. Soc. Citriculture 1:461, 1981. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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