scholarly journals First Report of Basal Stem Rot of Golden Barrel Cactus Caused by Fusarium oxysporum f. sp. opuntiarum in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (1) ◽  
pp. 85-85 ◽  
Author(s):  
G. Polizzi ◽  
A. Vitale
Keyword(s):  
Stem Rot ◽  
Basal Stem Rot ◽  
First Report ◽  
Sterile Needle ◽  
Yellow Orange ◽  
Affected Tissue ◽  
Causal Fungus ◽  
Pathogenicity Tests ◽  
Fusarium Sp ◽  
Barrel Cactus

Golden barrel cactus (Echinocactus grusonii Hildm.) is the most common landscape cactus in southern Italy. During 2000, 2001, and 2002, a basal stem rot of golden barrel cactus was observed in several plastichouses located in eastern Sicily with disease levels of nearly 100% on young plants (up to 15 cm in diameter). On the basal crown area, the plants showed pale brown or yellow-orange, sunken lesions bordered by a reddish orange strip up to 1 mm wide. A water-soaked rot or white mycelium at the soil line was also observed. Thirty pieces (0.5 to 1 cm) from the edge of symptomatic tissues were surface disinfected for 2 min in 0.8% (wt/vol) NaOCl, washed with sterile distilled water (SDW), and placed on potato dextrose agar (PDA). In addition, 20 pieces of affected tissue were ground in 400 μl of SDW (1:3, wt/wt), and the resulting suspensions were streaked by loops on PDA supplemented with 1.1 μl/ml of lactic acid (pH 4.4). A Fusarium sp. was consistently isolated from affected tissue pieces and streaks. Koch's postulates were performed at 25°C by inoculating 24 golden barrel cactus plants in 12-cm-diameter pots (12 plants previously sterile needle wounded) with 10 ml per plant of three suspensions (106 CFU/ml) of three isolates sprayed onto the basal stem. One milliliter per ten g of soil of each suspension was also added in the crown portion of golden barrel cacti. Twelve control cacti (six wounded) were sprayed only with SDW. Further pathogenicity tests were carried out on Thanksgiving cactus (Schlumbergera truncata (Haw.) Moran), devil's tongue barrel cactus (Ferocactus latispinus (Haw.) Britton & Rose), peruvian old man cactus (Espostoa lanata (Kunth) Britton & Rose), and Parodia spp. by inoculating eight plants for each host (four wounded) by placing 9-day-old 6-mm mycelial plugs at the base of the healthy cacti. An equal number of plants (four wounded) was inoculated only with a PDA plug. All cacti were maintained in polyethylene bags (90 to 95% for 72 hr) at 25°C. After 12 to 15 days, all wounded inoculated golden barrel, devil's tongue barrel, and peruvian old man cacti exhibited similar symptoms observed in the plastichouses. Typical symptoms were visible also in nonwounded and inoculated cacti 15 days later. Yellow-orange, tan, sunken, and roughly circular lesions were observed on the wounded and inoculated Thanksgiving and Parodia sp. cacti. Control plants were symptomless. The causal fungus was always reisolated from infected cacti. On the basis of 3-septate macroconidia (27 to 35 μm long × 3 to 4 μm wide [average 31.45 × 3.18 μm]), microconidia aseptate, single or double chlamydospores, and monophialide conidiophores observed on carnation leaf agar, and considering the susceptibility of all other inoculated hosts, the fungus was identified as F. oxysporum Schlechtend. f. sp. opuntiarum (Speg.) (1). To our knowledge, this is the first report of basal stem rot of golden barrel cactus in Italy. Reference: (1) W. Gerlach. Phytopathol. Z. 74, 197, 1972.

scholarly journals First Report of Fusarium solani Causing Stunt on Lisianthus

Plant Disease ◽  
2001 ◽  
Vol 85 (4) ◽  
pp. 443-443 ◽  
Author(s):  
S. Wolcan ◽  
G. Lori ◽  
L. Ronco
Keyword(s):  
Methyl Bromide ◽  
Fusarium Solani ◽  
Stem Rot ◽  
Buenos Aires Province ◽  
Eustoma Grandiflorum ◽  
Basal Stem Rot ◽  
First Report ◽  
Flower Production ◽  
Pathogenicity Tests ◽  
The Mean

Fusarium solani Mart. (Sacc.) is the causal agent of stem rot and damping-off of lisianthus (Eustoma grandiflorum (Raf.) Shinn.) (1). Since the end of the 1980s, when this flower crop was introduced in Argentina, it has been affected by a basal stem rot (2). A previously undescribed disease was observed in 100% of the greenhouses in the Buenos Aires Province that grow lisianthus. Symptoms that developed after seedlings were transplanted included stunting, shortened internodes with reduced stem diameter, and small narrow leaves that were a dull green color. Some affected plants turned yellow-brownish and died 2 to 3 months after transplanting. Other plants recovered but produced low quality flowers later than normal. A third group of plants remained stunted (5 to 10 cm high) until the last flower harvest (about 8 to 10 months). F. solani was consistently isolated from basal stems and roots of diseased plants. For pathogenicity tests, inoculum was produced by culturing the fungus for 10 days in petri dishes containing sterile moistened rice. Inoculum was air dried, crushed, and mixed with soil that had been autoclaved at 112°C for 40 min on each of two consecutive days. The propagules in the soil were estimated by soil plate dilutions on the Nash & Snyder-PCNB medium at a ratio of about 104 CFU/g soil. Twenty plants of each cultivar Echo White and Echo Blue, whose roots had been pruned, were planted in both infested and noninfested soil. After about 40 days, stunting was observed in 85% of the inoculated plants, while controls remained asymptomatic. F. solani was reisolated from symptomatic plants, thus fulfilling Koch's postulates. A test also was conducted in a commercial greenhouse that produced lisianthus for several years, in which healthy plants were planted in three plots fumigated with methyl bromide and in three nonfumigated plots. The mean cfu/g soil of F. solani in the methyl-bromide treated plots was 5 × 102 and 1.6 × 104 CFU/g in the nontreated plot. After 120 days, the incidence of stunting in the treated plots was 0.6 and about 88% in the control plots. F. solani was recovered from symptomatic plants. Because disinfestation of soil is generally practiced in flower production, stunted plants are limited and can be confused with root problems. This is the first report of F. solani causing stunt on lisianthus. References: (1) J. J. Taubenhaus and W. N. Ezekiel. Phytopathology 24:19, 1934. (2) S. M. Wolcan and G. A. Lori. Invest. Agr. Prot. Veg. 11:465, 1996.

scholarly journals First Report of Southern Blight of Ruellia brittoniana Caused by Sclerotium rolfsii in Louisiana

Plant Disease ◽  
2004 ◽  
Vol 88 (7) ◽  
pp. 770-770
Author(s):  
G. E. Holcomb
Keyword(s):  
Root Rot ◽  
High Speed ◽  
Sclerotium Rolfsii ◽  
Stem Rot ◽  
Basal Stem Rot ◽  
First Report ◽  
Southern Blight ◽  
Agar Plug ◽  
Leaf Yellowing ◽  
Pathogenicity Tests

Ruellia brittoniana, Mexican petunia, is an herbaceous flowering perennial grown in hardiness zones 8 to 10 in the southern and western United States. Popular dwarf forms with flower colors of white, pink, and blue are used as ground covers and borders. In April of 2003, root and stem rot that caused plant death was observed on cv. Katie (dwarf form, pink flowers) at a wholesale nursery in southern Louisiana. Plants were growing in a vermiculite and sand mix. The grower had purchased the plants from an out-of-state source, and approximately one-half of 1,440 plants were dead or dying. Symptoms included wilt, basal stem rot, and root rot. Peripheral roots were covered with a white mycelial layer that contained white sclerotial initials and small, brown sclerotia. Fungal isolates from infected roots grown on potato dextrose agar (PDA) produced white mycelia and 1- to 2-mm-diameter dark brown sclerotia. Sclerotia were nearly round with smooth surfaces and distributed over the entire colony. Isolates were identified as Sclerotium rolfsii on the basis of mycelial characteristics and color, size, and distribution of sclerotia. Two-month-old seedlings (6 to 10 cm high) of R. brittoniana, from seed of cv. Katie, were used in pathogenicity tests. Inoculum was grown in 10-cm-diameter plastic, culture dishes on PDA medium. Blended inoculum was prepared from a single 1-week-old culture that was composed of mycelia and sclerotia and blended 4 to 6 s at high speed in 100 ml of distilled water. In test one, 5 ml of inoculum was placed at the base of each inoculated plant. In test two, a single 5-mm-diameter agar plug with mycelium plus four sclerotia was placed beside plant stems near soil line. In test three, 5 ml of blended inoculum was dripped on exposed roots after plants were removed from pots. In test four, exposed plant roots were dipped in the blended inoculum. Each test contained 10 inoculated plants, and 10 noninoculated plants served as controls. All plants were placed in a dew chamber maintained at 28°C for 2 days and then returned to a greenhouse to observe development of symptoms and signs of disease. In tests one and two, basal stem rot and wilt developed on inoculated plants after 2 days and after 5 to 8 days all were dead. Inoculated plants from tests three and four were alive 4 months after inoculation, but were showing symptoms including leaf yellowing and drop, moderate to severe root rot, and some plants had begun to show white mycelia and white sclerotial initials on peripheral roots by January 2004. All noninoculated plants remained healthy and S. rolfsii was reisolated from infected plants in each test. To my knowledge, this is the first report of S. rolfsii causing disease on R. brittoniana.

scholarly journals First report of Phytophthora sp. causing a root and basal stem rot of narrowleaf lupin in Australia

2001 ◽  
Vol 50 (6) ◽  
pp. 811-811 ◽  
Author(s):  
A. Nikandrow ◽  
R. L. Gilbert ◽  
D. A. Gunning ◽  
M. A. C. B. Lawler ◽  
K. D. Lindbeck ◽  
...  
Keyword(s):  
Stem Rot ◽  
Basal Stem Rot ◽  
First Report

scholarly journals First Report of Sclerotium rolfsii on Catharanthus roseus

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 200-200
Author(s):  
G. E. Holcomb
Keyword(s):  
Catharanthus Roseus ◽  
Fungal Pathogen ◽  
Baton Rouge ◽  
Sclerotium Rolfsii ◽  
The United States ◽  
Madagascar Periwinkle ◽  
Basal Stem Rot ◽  
First Report ◽  
Pathogenicity Tests ◽  
Stem Necrosis

Wilt, blight, and stem necrosis were observed on Catharanthus roseus (L.) G. Don ‘Mediterranean Deep Rose’ (MDR) plants (Madagascar or rose periwinkle) in August 1999 at Burden Research Plantation in Baton Rouge, LA. MDR was the only prostrate-form cultivar and the only cultivar of 11 that was diseased. Twelve of twenty-four plants of cv. MDR were killed in the trial planting. White mycelia and small (1 mm diameter) light brown sclerotia were present at the base of infected plants. The suspect fungus was isolated consistently on acidified water agar and maintained on acidified potato dextrose agar (APDA). Pathogenicity tests were done by pipetting 1 ml of blended inoculum (contents of one 7-day-old plate culture grown on APDA in 100 ml of deionized water) at the base of nine 15-cm-tall Madagascar periwinkle plants. Inoculated and noninoculated plants were held in a dew chamber for 3 days at 28°C and placed in a greenhouse where temperatures ranged between 25 and 31°C. All inoculated plants showed wilt, blight, and basal stem rot after 3 days and were dead after 10 days. Noninoculated plants remained symptomless. The fungal pathogen was identified as Sclerotium rolfsii Sacc. and was reisolated from inoculated plants. The fungus was previously reported on Lochnera rosea (L.) Rchb. (=C. roseus) from Taiwan (1). This is the first report of the occurrence of S. rolfsii on Madagascar periwinkle in the United States. Reference: (1) K. Goto. Trans. Nat. Hist. Soc. Formosa 23:37, 1933.

scholarly journals First Report of Fusarium asiaticum Causing Stem Rot of Ligusticum chuanxiong in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Tingting Zhu ◽  
Linxuan Li ◽  
Antonios Petridis ◽  
George Xydis ◽  
Maozhi Ren
Keyword(s):  
Disease Incidence ◽  
Elongation Factor ◽  
Stem Rot ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
First Report ◽  
Ligusticum Chuanxiong ◽  
Fusarium Asiaticum ◽  
Sterile Needle ◽  
Yellow Pigments

Ligusticum chuanxiong (known as Chuanxiong in China) is a traditional edible-medicinal herb, which has been playing important roles in fighting against COVID-19 (Ma et al. 2020). In March 2021, we investigated stem rot of Chuanxiong in six adjacent fields (~100 ha) in Chengdu, Sichuan Province, China. The disease incidence was above 5% in each field. Symptomatic plants showed stem rot, watersoaked lesions, and blackening with white hyphae present on the stems. Twelve symptomatic Chuanxiong plants (2 plants/field) were sampled. Diseased tissues from the margins of necrotic lesions were surface sterilized in 75% ethanol for 45 s, and 2% NaClO for 5 min. Samples were then rinsed three times in sterile distilled water and cultured on potato dextrose agar (PDA) at 25ºC for 72 h. Fourteen fungal cultures were isolated from 18 diseased tissues, of which eight monosporic isolates showed uniform characteristics. The eight fungal isolates showed fluffy white aerial mycelia and produced yellow pigments with age. Mung bean broth was used to induce sporulation. Macroconidia were sickle-shaped, slender, 3- to 5-septate, and averaged 50 to 70 μm in length. Based on morphological features of colonies and conidia, the isolates were tentatively identified as Fusarium spp. (Leslie and Summerell 2006). To identify the species, the partial translation elongation factor 1 alpha (TEF1-α) gene was amplified and sequenced (O’Donnell et al. 1998). TEF1-α sequences of LCSR01, LCSR02 and LCSR05 isolates (GenBank nos. MZ169386, MZ169388 and MZ169387) were 100%, 99.72% and 99.86% identical to that of F. asiaticum strain NRRL 26156, respectively. The phylogenetic tree based on TEF1-α sequences showed these isolates clustered with F. asiaticum using Neighbor-Joining algorithm. Furthermore, these isolates were identified using the specific primer pair Fg16 F/R (Nicholson et al. 1998). The results showed these isolates (GenBank nos. MZ164938, MZ164939 and MZ164940) were 100% identical to F. asiaticum NRRL 26156. Pathogenicity test of the isolate LCSR01 was conducted on Chuanxiong. After wounding Chuanxiong stalks and rhizomes with a sterile needle, the wounds were inoculated with mycelia PDA plugs. A total of 30 Chuanxiong rhizomes and stalks were inoculated with mycelia PDA plugs, and five mock-inoculated Chuanxiong rhizomes and stalks served as controls. After inoculation, the stalks and rhizomes were kept in a moist chamber at 25°C in the dark. At 8 days post inoculation (dpi), all inoculated stalks and rhizomes exhibited water-soaked and blackened lesions. At 10 dpi, the stalks turned soft and decayed, and abundant hyphae grew on the exterior of infected plants, similar to those observed in the field. No disease symptoms were observed on the control plants. The pathogen was re-isolated from the inoculated tissues and the identity was confirmed as described above. Ten fungal cultures were re-isolated from the 10 inoculated tissues, of which nine fungal cultures were F. asiaticum, fulfilling Koch’s postulates. To our knowledge, this is the first report of F. asiaticum causing stem rot of Chuanxiong in China. Chuanxiong has been cultivated in rotation with rice over multiple years. This rotation may have played a role in the increase in inoculum density in soil and stem rot epidemics in Chuanxiong. Diseased Chuanxiong may be contaminated with the mycotoxins produced by F. asciaticum, 3-acetyldeoxynivalenol or nivalenol, which may deleteriously affect human health. Therefore, crop rotations should be considered carefully to reduce disease impacts.

scholarly journals First Report of Root and Basal Stem Rot Caused by Phytophthora nicotianae on Tree Aeonium (Aeonium arboreum) in Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 362-362
Author(s):  
C. Rizza ◽  
R. Faedda ◽  
A. Pane ◽  
S. O. Cacciola
Keyword(s):  
Mating Type ◽  
Phytophthora Nicotianae ◽  
Stem Rot ◽  
Universal Primers ◽  
Infested Soil ◽  
Basal Stem Rot ◽  
First Report ◽  
Reference Isolate ◽  
Morphological Criteria ◽  
Mean Diameter

The genus Aeonium, family Crassulaceae, comprises approximately 35 species that are native to northern Africa and the Canary Islands. Tree aeonium (Aeonium arboreum (L.) Webb & Berthel.) is a bushy, perennial succulent with rosettes of tender, waxy leaves at the apex of few-branched or occasionally single, naked stems. Mature rosettes bear yellowish inflorescences. Aeoniums are cultivated as ornamentals in gardens and containers. During the summer of 2009, in a garden in eastern Sicily (southern Italy), 3-year-old potted plants of tree aeonium showed stunting, shrivelling, and chlorosis of leaves and drop of external leaves associated with root and basal stem rot. Drops of an amber exudate oozed from the basal stem. Tissues of the basal stem were soft, but no external necrosis was visible. A species of Phytophthora was consistently isolated from symptomatic roots and basal stem tissues on a medium selective for Oomycetes (2). Axenic cultures were obtained by single-hypha transfers. The pathogen was identified by morphological criteria as Phytophthora nicotianae B. de Haan; it formed stoloniferous colonies on potato dextrose agar and grew between 8 and 38°C, with the optimum at 30°C. On V8 juice agar it produced spherical, intercalary chlamydospores (mean diameter of 26 μm) and persistent, mono- and bipapillate, spherical to ovoid, ellipsoid, obpyriform sporangia that measured 29 to 56 × 22 to 45 μm with a mean length/breadth ratio of 1.3:1. All isolates were A2 mating type and formed spherical oogonia (mean diameter 28 ± 2 μm) with smooth walls and amphigynous antheridia in dual cultures with a reference isolate of the A1 mating type of P. nicotianae. BLAST analysis of the internal transcribed spacer (ITS) region of rDNA of a representative isolate from aeonium (IMI 398812, GenBank Accession No. HQ433333) amplified by PCR using the ITS6/ITS4 universal primers (1), revealed 99% similarity with the sequences of a reference isolate of P. nicotianae available in GenBank (Accession No. EU331089.1). Pathogenicity of isolate IMI 398812 was demonstrated by transplanting cuttings of A. arboreum into pots filled with a mixture of steam-sterilized sandy loam soil and inoculum (4% vol/vol) produced by growing the isolate for 20 days on wheat kernels. Ten plants were transplanted into 3-liter pots (two plants per pot) while 10 plants, transplanted into pots filled with a mixture of steam-sterilized soil and noninoculated kernels, were used as controls. Plants were kept in a greenhouse at 25 to 28°C and watered daily to field capacity. Thirty to forty days after the transplanting into infested soil, cuttings developed the same symptoms observed on plants with natural infections. Control plants remained symptomless. P. nicotianae was reisolated from symptomatic plants, thereby completing Koch's postulates. To our knowledge, this is the first report of P. nicotianae on an Aeonium species worldwide. The economic relevance of this disease is minor because aeoniums are not cultivated on a large scale. Moreover, the disease may be easily prevented by avoiding excess irrigation water since aeoniums need a well-drained soil or potting mix and do not tolerate soil waterlogging. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) H. Masago et al. Phytopathology 67:425, 1977.

scholarly journals First Report of Root and Basal Stem Rot Caused by Phytophthora cryptogea and P. inundata on Dwarf Banana in Italy

Plant Disease ◽  
2018 ◽  
Vol 102 (3) ◽  
pp. 684 ◽  
Author(s):  
A. Pane ◽  
R. Faedda ◽  
G. Granata ◽  
I. Puglisi ◽  
F. Aloi ◽  
...  
Keyword(s):  
Stem Rot ◽  
Basal Stem Rot ◽  
Phytophthora Cryptogea ◽  
First Report

scholarly journals First Report of Black Rot Caused by Phomopsis cucurbitae on Cantaloupe (Cucumis melo) in the Piedmont Region of Northern Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1317-1317
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
Cucumis Melo ◽  
Morphological Characteristics ◽  
Its Region ◽  
Northern Italy ◽  
Pathogenicity Test ◽  
First Report ◽  
Sterile Needle ◽  
Pathogenicity Tests ◽  
Cucumis Melo L ◽  
Piedmont Region

Cucumis melo L., belonging to the Cucurbitaceae family, is cultivated on more than 23,000 ha in Italy. Cantaloupe (C. melo L. var. cantalupensis Naudin) is the most popular variety. In summer 2010, a previously unknown rot was observed on fruits produced in Italy and marketed in the Piedmont Region of northern Italy. Early symptoms on fruit consisted of irregular, brown, soft, sunken lesions up to 10 cm in diameter. No surface mold was visible and pycnidia were not present. Internally, the decay is adjacent to the sunken area of the fruit's surface and is soft, water soaked, spongy, with a nearly circular margin, and easily separated from healthy tissues. Fragments (approximately 3 mm3) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at 24 ± 1°C, (16 h of light and 8 h of darkness). Fungal colonies initially appeared coarse, at first whitish then buff brown, and produced dark pycnidia 0.5 mm in diameter, which exuded numerous conidia belonging to two types. Type A conidia were hyaline, unicellular, ellipsoidal to fusiform, sometimes slightly constricted in the middle, and measured 5.6 to 10.3 × 1.7 to 2.6 (average 8.0 × 2.1) μm. Type B conidia were hyaline, long, slender, curved, and measured 17.1 to 26.6 × 0.7 to 1.4 (average 22.0 × 1.0) μm. Sclerotia were not produced. The morphological characteristics of the fungus corresponded to those of the genus Phomopsis (1). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis of the 543-bp segment showed a 99% similarity with the sequence of a Phomopsis sp. (GenBank Accession No. HM999947). The nucleotide sequence has been assigned the GenBank Accession No. JN032733. Both Phomopsis cucurbitae and P. sclerotioides are pathogenic to Cucurbitaceae, however P. cucurbitae is identifiable by the production of B conidia and the absence of sclerotia. Therefore, P. cucurbitae has been considered the causal agent of the disease. Pathogenicity tests were performed by inoculating three wounded cantaloupe fruits after surface disinfesting in 1% sodium hypochlorite. Six wounds per fruit, 1 cm deep, were made with a sterile needle. Mycelial disks (10 mm in diameter), obtained from PDA cultures of one strain, were placed on each wound. Three control fruits were inoculated with PDA. Fruits were incubated at 16 ± 1°C in the dark. The first symptoms developed 4 days after the artificial inoculation. Two days later, the rot developed at all inoculation points and the pathogen was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice with similar results. P. cucurbitae has been reported on melon in many countries (2,3). To our knowledge, this is the first report of the disease in Italy. Currently, the relevance of the disease in the country is not yet well known. However, attention must be paid considering that the pathogen can be transmitted through seeds. References: (1) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (2) L. Beraha and M. J. O'Brien. Phytopathol. Z. 94:199, 1979. (3) E. Punithalingam and P. Holliday. Phomopsis cucurbitae. IMI Descriptions of Fungi and Bacteria. 47, Sheet 469, 1975.

scholarly journals First Report of Basal Stem Rot of Apple Cactus (Cereus peruvianus monstruosus) Caused by Fusarium oxysporum in Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 877-877
Author(s):  
A. Garibaldi ◽  
P. Pensa ◽  
D. Bertetti ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
The United States ◽  
Stem Rot ◽  
Fluorescent Light ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
Basal Stem Rot ◽  
First Report

During the summer of 2010, 20% of 7,000 4-month-old plants of apple cactus (Cereus peruvianus monstruosus) showed symptoms of a basal stem rot in a commercial nursery located in Liguria (northern Italy). Affected plants showed yellow orange-to-pale brown color from the crown level to the stem apex and a water-soaked rot was observed on the stem starting from the base. Brown discoloration was observed in the vascular system. Eventually stems bent, plants collapsed and died, and affected tissues dried out. A Fusarium sp. was consistently and readily isolated from symptomatic tissue on Komada selective medium. Isolates were purified and subcultured on potato dextrose agar (PDA). Single-spore cultures on PDA, Spezieller Nährstoffarmer agar (SNA) (3), and carnation leaf-piece agar (CLA) (2) were incubated at 26 ± 1°C (12-h fluorescent light, 12-h dark). On PDA, cultures produced a thick growth of white-to-pink mycelium and pale pink pigments in the agar. On SNA, cultures produced short monophialides with unicellular, ovoid-elliptical microconidia measuring 4.3 to 8.2 × 2.3 to 3.8 (average 6.0 × 2.8) μm. Chlamydospores were abundant, single or paired, terminal and intercalary, rough walled, and 6 to 8 μm in diameter. On CLA, cultures produced orange sporodochia with macroconidia that were 3 to 4 septate, nearly straight with a foot-shaped basal cell and a short apical cell, and measured 31.1 to 51.5 × 4.4 to 3.5 (average 43.2 × 3.8) μm. Such characteristics are typical of Fusarium oxysporum (3). Amplification of the ITS (internal transcribed spacer) of the rDNA using primers ITS1/ITS4 (4) yielded a 498-bp band. Sequencing and BLASTn analysis of this band showed an E-value of 0.0 with F. oxysporum. The nucleotide sequence has been assigned GenBank Accession No. JF422071. To confirm pathogenicity, five 6-month-old healthy plants of C. peruvianus monstruosus were inoculated by dipping roots in a conidial suspension (2.4 × 106 CFU/ml) of F. oxysporum isolated from affected plants. Inoculum was obtained from pure cultures of three single-spore isolates grown for 10 days on casein hydrolysate liquid medium. Roots were not wounded before the inoculation. Plants were transplanted into pots filled with steam-sterilized substrate (sphagnum peat/perlite/pine bark/clay 50:20:20:10). Five noninoculated plants served as a control. Plants were placed in a climatic chamber at 25 ± 1°C (12-h fluorescent light, 12 h-dark). Basal stem rot and vascular discoloration in the crown and stem developed within 30 days on each inoculated plant. Noninoculated plants remained healthy. F. oxysporum was consistently isolated from symptomatic plants. The pathogenicity test was conducted twice. F. oxysporum has been reported on Cereus spp. in the United States (1). To our knowledge, this is the first report of F. oxysporum on C. peruvianus monstruosus in Italy as well as in Europe. Currently, this disease is present in a few nurseries in Liguria. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (2) N. L. Fisher et al. Phytopathology 72:151, 1982. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

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

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

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

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