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 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 Southern Blight Caused by Sclerotium rolfsii on Lily in China

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 109-109 ◽  
Author(s):  
X. M. Yang ◽  
J. H. Wang ◽  
S. P. Qu ◽  
L. H. Wang
Keyword(s):  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
First Report ◽  
Southern Blight ◽  
Inoculation Trial ◽  
Leaf Yellowing ◽  
White Mycelium ◽  
Bulb Rot ◽  
Oriental Lily ◽  
Wheat Kernels

Lily (Lilium spp.) is an economically important cut flower cultivated in China. The soilborne fungus, Sclerotium rolfsii, is a major pathogen on many plants. During July 2005, severe basal stem rot and bulb rot symptoms were observed on an oriental lily cultivar (Sorbonne) in some commercial fields in northern Kunming (China). Disease incidence ranged from 20 to 30% across fields. Leaves of infected plants were chlorotic initially. As the disease progressed, stems and bulbs rotted and plants wilted. In the presence of abundant moisture, a white mycelium occurred on infected tissues. White or light-to-dark brown sclerotia (1 to 3 mm in diameter) developed from mycelium. Fungal isolates from infected bulbs 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 S. rolfsii on the basis of mycelial characteristics and color, size, and distribution of sclerotia. Pathogenicity was tested in the greenhouse on oriental lily cv. Sorbonne grown in pots (1 plant per pot, five replicates). Inoculum that consisted of 1 g per pot of wheat kernels infested with mycelium and sclerotia was placed at the base of each inoculated plant. Five noninoculated plants served as controls. The inoculation trial was repeated once. After inoculation, all plants were covered with a polyethylene bag for 72 h and kept at temperatures ranging between 25 and 27°C. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and then eventually wilted. Control plants remained symptomless. S. rolfsii was reisolated from inoculated plants. To our knowledge, this is the first report of southern blight caused by S. rolfsii on lily in China. Infection of lily bulbs by S. rolfsii may cause losses in production fields in China, and the presence of infected bulbs may also interfere with bulb shipment.

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 Iresine herbstii Caused by Sclerotium rolfsii in Taiwan

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1692-1692
Author(s):  
C. H. Fu ◽  
Y. P. Huang ◽  
F. Y. Lin
Keyword(s):  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Herbaceous Plant ◽  
First Report ◽  
Southern Blight ◽  
Potted Plants ◽  
Agar Plug ◽  
Initial Symptoms ◽  
Pure Cultures ◽  
Causal Fungus

Widely cultivated commercially, Iresine herbstii Hook is a potted herbaceous plant popular for its foliage, which varies from a dark red to brownish maroon. In the summer of 2010, a sudden wilt of I. herbstii plants was observed at a recreational farm in Taipei City in northern Taiwan. The initial symptoms were water-soaked lesions that became soft and then rotted. Necrotic areas on the stems were covered with fans of white mycelium as well as abundant spherical, brown sclerotia. A fungus was isolated from both infected tissue and sclerotia and maintained on potato dextrose agar (PDA) plates incubated at 25°C without light. Colonies were white and cottony, often forming mycelial fans. Pure cultures were prepared by transferring single hyphal tips to PDA. Sclerotia formed after 7 days. Sclerotia were initially white becoming dark brown with age and were 0.8 to 1 mm in diameter at maturity. These are typical features of Sclerotium rolfsii. Koch's postulates were performed by inoculating five healthy, potted I. herbstii plants with 10 fresh sclerotia placed on the soil surface around the base of each plant. In a second test, five healthy potted plants were inoculated with a single 10-mm-diameter mycelial agar plug placed at the stem base of each plant. Five noninoculated plants served as controls. All plants were incubated in a growth chamber at 25 to 35°C. Basal stem rot and wilt developed within 4 days on plants inoculated with sclerotia or mycelial plugs. All plants were dead by 7 days after inoculation whereas the controls remained healthy. The fungus was reisolated from the symptomatic tissue and produced sclerotia and mycelium consistent with S. rolfsii. To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA region of the causal fungus was amplified using the primers ITS4 and ITS5 (3) and sequenced. The resulting sequence of 687 bp was uploaded in NCBI (Accession No. JN543691.1). The sequence was 98% similar to sequences of Athelia rolfsii (anamoprh S. rolfsii). This disease has been observed on many species of plants (1, 2). To our knowledge, this is the first report of I. herbstii caused by S. rolfsii in Taiwan or any other part of the world. References: (1) T. T. Chang. Bull. Taiwan For. Res. Inst. 9:191, 1994. (2) Y. N. Wang et al. J. Exp. For. Nat. Taiwan Univ. 20:45, 2006. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Southern Blight Caused by Sclerotium rolfsii on Laurustinus

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 310-310
Author(s):  
G. Polizzi ◽  
A. Vitale ◽  
G. Parlavecchio
Keyword(s):  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
First Report ◽  
Southern Blight ◽  
Soil Line ◽  
Sterile Needle ◽  
Pathogenicity Tests ◽  
On Line ◽  
Polyethylene Bags

Laurustinus (Viburnum tinus L.), native to the Mediterranean Region, is an evergreen shrub commonly used as a specimen shrub or small tree or used in border plantings. During August 2003, a blight occurred on 2-year-old-plants of laurustinus growing in pots in a nursery in eastern Sicily (Italy). Disease incidence ranged from 2 to 5% across the field. Symptoms included 3 to 4 cm long lesions and the development of white mycelial strands and brown, 1.0 to 1.8 mm, nearly spherical sclerotia on the crown of plants at the soil line that are typical of Sclerotium rolfsii Sacc. The foliage of infected plants wilted, followed by a sudden collapse of the plant. The fungus was consistently isolated on acidified potato dextrose agar (PDA) (pH 4.5) by plating symptomatic tissues that were surface disinfested (1.2% NaOCl) for 1 min. and rinsed in sterile water. Pathogenicity tests were performed by sprinkling 50 sclerotia, obtained from infected oat kernels (2), on the soil surface around the collar of each of 10 healthy, potted 1-year-old plants of laurustinus. Five of the plants were previously wounded on the crown 1.5 cm above or below the soil line with a sterile needle. Five noninoculated plants served as controls. All plants were maintained at 25 ± 2°C and enclosed for 72 hr in polyethylene bags (90 to 95% relative humidity). Blight symptoms similar to those seen in nursery were observed on inoculated plants 20 to 25 days after inoculation, while no symptoms developed on control plants. Koch's postulates were fulfilled by reisolation of the fungus on acidified PDA from all infected laurustinus plants. S. rolfsii was previously recorded on Prague viburnum (Viburnum × pragense L.) as the causal agent of southern blight (1). To our knowledge, this is the first report of southern blight caused by S. rolfsii on laurustinus. References: (1) A. Hagan. Southern blight on flowers, shrubs, and trees. On-line publication ANR-1157. Alabama A & M, and Auburn University ( www.aces.edu/dept/extcomm/publications/html ). (2) R. Rodriguez-Kabana et al. Plant Dis. Rep. 59:5, 1975.

scholarly journals First Report of Southern Blight of Mexican Petunia (Ruellia brittoniana) Caused by Sclerotium rolfsii in Taiwan

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1822-1822
Author(s):  
C. H. Fu ◽  
Y. P. Huang ◽  
F. Y. Lin
Keyword(s):  
Sclerotium Rolfsii ◽  
Stem Rot ◽  
Pathogenicity Test ◽  
Academic Press ◽  
First Report ◽  
Southern Blight ◽  
Inoculation Techniques ◽  
Pure Cultures ◽  
Causal Fungus ◽  
Garden Plant

Mexican petunia (Ruellia brittoniana) is an herbaceous flowering perennial with strikingly colored flowers, widely cultivated commercially as a potted plant and a popular garden plant. In July of 2010, root and stem rot that caused death was observed on Mexican petunia at the flower nursery of the Council of Agriculture & Chiayi County in Taiwan. Plants had rotted and girdled stem bases. Necrotic areas were covered with fans of white mycelium as well as abundant spherical sclerotia. A fungus was isolated from infected tissue and sclerotia, and maintained on potato dextrose agar (PDA) plates incubated at 25°C without light. Colonies were white, cottony, often forming fans; pure cultures were prepared by transferring hyphal tips to PDA. Sclerotia formed after 10 days, initially white becoming dark brown with age, and 0.5 to 0.6 mm in diameter. To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA region of the causal fungus was amplified using the primers ITS4 and ITS5 (2) and sequenced. The resulting sequence of 687 bp was uploaded in NCBI. The sequence was 98% similar to sequences of Athelia rolfsii (Sclerotium rolfsii) in NCBI (Accession No. JN543691.1). Koch's postulates were performed using two inoculation techniques. The soil near the base of healthy Mexican petunia plants (four plants per pot) were exposed to recently matured sclerotia (10 sclerotia per plant) developed from pure fungal cultures or 10-mm-diameter agar plugs of mycelium (one plug per plant). Noninoculated plants, in a separate pot, were used as a control. All plants were incubated in a growth chamber at 28 to 33°C. Disease symptoms occurred on all inoculated plants by 5 to 7 days and included yellowing of leaves, basal stem rot, and wilt. Ten days after inoculation, inoculated plants were dead whereas control plants remained healthy. The pathogenicity test was repeated twice with similar results and S. rolfsii was reisolated from infected plants in each test. The pathogen has been reported to cause substantial loss of Mexican petunia in Louisiana (1). The disease is becoming more common in Taiwan and could cause losses in Mexican petunia production. To our knowledge, this is the first report of disease on Mexican petunia caused by S. rolfsii in Taiwan. References: (1) G. E. Holcomb. Plant Dis. 88:770, 2004. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, 1990.

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 Southern Blight Caused by Sclerotium rolfsii on St.-John's-Wort

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 696-696 ◽  
Author(s):  
A. P. Keinath ◽  
J. W. Rushing ◽  
R. J. Dufault
Keyword(s):  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
The United States ◽  
Pathogenicity Test ◽  
First Report ◽  
Southern Blight ◽  
St John’S Wort ◽  
St John's Wort ◽  
Pathogenicity Tests ◽  
Hypericum Perforatum L

Interest in commercial production of common St.-John's-wort (Hypericum perforatum L.), an herb that is dried, processed, and used as an anti-depressant medication, is increasing. In August 1998, St.-John's-wort growing in the field at Charleston, SC, showed blight symptoms. Leaves on prostrate branches turned reddish-yellow, then brown, and then abscised. As the disease progressed, branches and approximately 10% of the plants were killed. Coarse, white mycelia were present on the bases of dead branches. Segments cut from symptomatic branches were disinfested in 0.5% sodium hypochlorite and placed on potato dextrose agar (PDA) at 25°C. Sclerotium rolfsii Sacc. was isolated from one of 12 branches with discolored leaves and six of six dead branches. For pathogenicity tests, sclerotia were harvested from 6-week-old cultures on PDA. Ten-week-old St.-John's-wort plants, growing in potting mix in 10-cm pots, were inoculated by placing four sclerotia on the soil surface 1 to 1.5 cm from the main stem of each plant. Plants were grown in a greenhouse at 90% relative humidity and 25 to 35°C. Single blighted branches were observed on three plants 12 days after inoculation and all plants were blighted 28 days after inoculation. S. rolfsii was recovered from 10 and 9 of 10 plants inoculated with isolates of S. rolfsii from St.-John's-wort and tomato, respectively. All 10 noninoculated plants remained symptomless. The pathogenicity test was repeated and the results were similar. This is the first report of S. rolfsii causing Southern blight on St.-John's-wort in the United States.

scholarly journals First Report of Southern blight Incited by Sclerotium rolfsii on Dichondra repens in Italy

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 203-203 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
The United States ◽  
First Report ◽  
Southern Blight ◽  
Inoculation Trial ◽  
Leaf Yellowing ◽  
White Mycelium ◽  
Wheat Kernels ◽  
Reddish Brown Color

Kidney weed (Dichondra repens) is increasingly used for low maintenance turf in Italy, particularly for gardens and parks in areas characterized by mild climate. During September 2003, on the D. repens turf of a private garden located near Imperia (northern Italy), yellow, circular areas as much as 60 cm in diameter appeared with the grass becoming chlorotic and thin. A ring of the patch at its periphery exhibited a reddish brown color and eventually died. An area of green grass remained in the center of the patch. Rings of dead grass enlarged rapidly during hot, humid weather. In the presence of abundant moisture, a white mycelium occurred on the dying grass at the periphery of the ring. White or light-to-dark brown sclerotia (1 to 3 mm in diameter) developed from mycelium on the dead grass. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with 100 mg/l of streptomycin sulphate. Sclerotium rolfsii was consistently isolated from infected plants. Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating healthy D. repens turf (1 m2 plots and three replicates). Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface. Noninoculated plots served as controls. The inoculation trial was repeated once. Turf was covered with a plastic film for 7 days, kept at temperatures ranging between 22 and 25°C, and watered as needed. Inoculated plants developed symptoms of leaf yellowing within 11 days, soon followed by the appearance of white mycelium and sclerotia, and then eventually wilted. Control plants remained symptomless. Sclerotium rolfsii was re-isolated from inoculated plants. To our knowledge, this is the first report of S. rolfsii on D. repens in Italy. This disease has been reported on kidney weed in several countries such as the United States (3), Brazil (1), and India (2). References: (1) M. Menezes and J. A. A. Lima. Fitossanidade 1:18, 1974. (2) K. Ranganathan and N. Shanmugam. Indian Phytopathol, 27:113, 1974. (3) J. D. Smith et al. Fungal Diseases of Amenity Turf Grasses. E & F.N. Spon, London, 1989.

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
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