scholarly journals First Report of Leaf Spot and Blight Caused by Botrytis cinerea on Pygmy Date Palm in Italy

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1398-1398 ◽  
Author(s):  
G. Polizzi ◽  
A. Vitale
Keyword(s):  
Botrytis Cinerea ◽  
Leaf Spot ◽  
Canary Island ◽  
Date Palm ◽  
Southern Italy ◽  
Sterile Water ◽  
Koch’S Postulates ◽  
Date Palms ◽  
First Report ◽  
Koch's Postulates

Pygmy date palm (Phoenix roebelenii O'Brien), native to Laos and southeast Asia, is one of the most commonly cultivated date palms both indoors and out. In early April 2003, a new and widespread leaf disease was detected on 2- to 3-feet high, potted, pygmy date palms growing in open fields or shade-houses in four commercial nurseries of the eastern Sicily Region of southern Italy. Initial symptoms on infected plants were small, chlorotic spots on blades and edges of leaflets. As spots enlarged, yellow or reddish-brown margins and brown or gray, wrinkled, sunken centers developed. Sometimes, spots or lesions coalesced to cause blight of young expanding leaves or death of apical buds. Botrytis cinerea Pers.:Fr was recovered consistently from sections of infected tissues (disinfected for 1 min in 1% NaOCl and rinsed in sterile water) plated on malt extract agar. On potato dextrose agar (PDA), colonies of B. cinerea were first hyaline, then turned white, and later turned dark gray when spores differentiated. Six- to eight-day-old-cultures developed white sclerotia that turned black after three more days. Conidia in 1-month-old-cultures were hyaline or gray, ovoid, and ranged from 5.2 to 8.8 × 8 to 14 μm (average 6.6 × 9.9 μm). Black microsclerotia were round or irregular in shape and ranged from 0.6 to 2.8 × 0.3 to 2.5 mm (average 1.66 × 0.98 mm) (1). Koch's postulates were performed by spraying potted, 9-month-old pygmy date palms (2 feet high) with a spore suspension (1 × 106 CFU per ml from 15-day-old cultures grown on PDA). Six plants were wounded and inoculated, while six plants were inoculated without wounding. An equal number of noninoculated plants sprayed with sterile water served as controls. All plants were maintained in a humid environment at 20°C. Sunken-leaf and rachis lesions were observed on all wounded and most nonwounded plants within 10 to 14 days after inoculation. Symptoms did not develop on the control plants. Koch's postulates were fulfilled by reisolation of the fungus from affected tissues. A field survey revealed the occasional presence of similar leaf spots on canary island date palms (Phoenix canariensis Hort. ex Chabaud), from which B. cinerea was consistently recovered. The unusually cool and humid weather conditions recorded in Sicily during this disease outbreak were very conducive for occurrence of the B. cinerea infections. Although the disease only occasionally caused death of plants, evidence indicated that B. cinerea reduced commercial value of infected pygmy date palms. B. cinerea was previously recorded in northern Italy on canary island date palm (2) and was recently detected in southern Italy on majesty palm (3). To our knowledge, this is the first report of leaf spot and rachis blight caused by B. cinerea on pygmy date palm. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CAB, Kew, Surrey, England, 1971. (2) A. Garibaldi and S. Rapetti. No. 9 Suppl. Flortecnica, 1987. (3) G. Polizzi. Plant Dis. 86:815, 2002.

scholarly journals First Report of Fusarium Wilt of Canary Island Date Palm Caused by Fusarium oxysporum f. sp. canariensis in Louisiana

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1192-1192 ◽  
Author(s):  
R. Singh ◽  
A. Castro ◽  
D. M. Ferrin ◽  
R. S. Harris ◽  
B. Olson
Keyword(s):  
South Carolina ◽  
Fusarium Oxysporum ◽  
New Orleans ◽  
Fusarium Wilt ◽  
Canary Island ◽  
Date Palm ◽  
Distilled Water ◽  
Date Palms ◽  
First Report ◽  
Vascular Discoloration

Canary Island date palm (Phoenix canariensis Hort. Ex Chabaud) is a signature palm planted in New Orleans, LA. Currently, the city has approximately 1,000 mature Canary Island date palms. During the fall of 2009, 153 palms were inspected with 27 palms exhibiting typical symptoms of Fusarium wilt. Symptoms included one-sided death and a reddish brown streak on the rachis of affected fronds and death of the leaflets. Longitudinal sections of affected fronds showed vascular discoloration. Severely infected palms were completely dead. Small pieces of diseased tissue from five palms were surface sterilized with sodium hypochlorite (0.6%) for 2 to 3 min, then rinsed in sterile distilled water, blotted dry, and plated on potato dextrose agar (PDA). Fungal colonies on PDA produced a purple pigment, and both macro- and microconidia that are typical of Fusarium oxysporum were observed under a light microscope. A single-spore culture of isolate PDC-4701 was obtained. DNA from this isolate was extracted with a DNeasy Plant Mini kit (Qiagen Inc., Valencia, CA) and primers ef1 and ef2 were used to amplify and sequence the translation elongation factor 1-α gene (2). NCBI BLAST analysis of the 616-bp sequence resulted in 100% identity with F. oxysporum f. sp. canariensis isolates PLM-385B from Texas and PLM-511A from South Carolina (GenBank Accession Nos. HM 591538 and HM 591537, respectively). Isolate PDC-4701, grown on PDA for 2 weeks, was used to inoculate 10 9-month-old P. canariensis seedlings. An 18-gauge needle was used to inject 15 ml of a 107 conidia/ml suspension into the stem near the soil line. Each seedling was inoculated at two locations and covered with Parafilm at the inoculation sites. Ten control seedlings were injected with sterile distilled water in the same manner. Inoculated and control seedlings were maintained in a greenhouse at 28 ± 2°C. Leaves of all 10 inoculated seedlings started to wilt 3 months after inoculation. Internal vascular discoloration was observed and the pathogen was reisolated from the symptomatic seedlings. No symptoms developed on any of the 10 control seedlings. On the basis of morphology and DNA sequence data, this pathogen is identified as F. oxysporum f. sp. canariensis. Fusarium wilt of Canary Island date palm has been previously reported from California, Florida, Nevada, Texas, and South Carolina (1). To our knowledge, this is the first report of Fusarium wilt of Canary Island date palm caused by F. oxysporum f. sp. canariensis in Louisiana, extending its geographic range. The disease may adversely affect the tradition of planting Canary Island date palms in New Orleans. The sequence of isolate PDC-4701 has been submitted to the NCBI database (GenBank Accession No. JF826442) and a culture specimen has been deposited in the Fusarium Research Center culture collection (Accession No. O-2602) at the Pennsylvania State University, University Park, PA. References: (1) M. L. Elliott et al. Plant Dis. 95:356, 2011. (2) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004.

scholarly journals First Report of Leaf Spot Disease on Walnut Caused by Colletotrichum fioriniae in China

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 289-289 ◽  
Author(s):  
Y. Z. Zhu ◽  
W. J. Liao ◽  
D. X. Zou ◽  
Y. J. Wu ◽  
Y. Zhou
Keyword(s):  
Dna Sequences ◽  
Leaf Spot ◽  
Juglans Regia ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Koch’S Postulates ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Koch's Postulates

In May 2014, a severe leaf spot disease was observed on walnut tree (Juglans regia L.) in Hechi, Guangxi, China. Leaf spots were circular to semicircular in shape, water-soaked, later becoming grayish white in the center with a dark brown margin and bordered by a tan halo. Necrotic lesions were approximately 3 to 4 mm in diameter. Diseased leaves were collected from 10 trees in each of five commercial orchards. The diseased leaves were cut into 5 × 5 mm slices, dipped in 75% ethanol for 30 s, washed three times in sterilized water, sterilized with 0.1% (w/v) HgCl2 for 3 min, and then rinsed five times with sterile distilled water. These slices were placed on potato dextrose agar (PDA), followed by incubating at 28°C for about 3 to 4 days. Fungal isolates were obtained from these diseased tissues, transferred onto PDA plates, and incubated at 28°C. These isolates produced gray aerial mycelium and then became pinkish gray with age. Moreover, the reverse of the colony was pink. The growth rate was 8.21 to 8.41 mm per day (average = 8.29 ± 0.11, n = 3) at 28°C. The colonies produced pale orange conidial masses and were fusiform with acute ends, hyaline, sometimes guttulate, 4.02 to 5.25 × 13.71 to 15.72 μm (average = 4.56 ± 0.31 × 14.87 ± 1.14 μm, n = 25). The morphological characteristics and measurements of this fungal isolate matched the previous descriptions of Colletotrichum fioriniae (Marcelino & Gouli) R.G. Shivas & Y.P. Tan (2). Meanwhile, these characterizations were further confirmed by analysis of the partial sequence of five genes: the internal transcribed spacer (ITS) of the ribosomal DNA, beta-tubulin (β-tub) gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene, chitin synthase 3(CHS-1) gene, and actin (ACT) gene, with universal primers ITS4/ITS5, T1/βt2b, GDF1/GDR1, CHS1-79F/CHS1-354R, and ACT-512F/ACT-783R, respectively (1). BLAST of these DNA sequences using the nucleotide database of GenBank showed a high identify (ITS, 99%; β-tub, 99%; GAPDH, 99%; CHS-1, 99%; and ACT, 100%) with the previously deposited sequences of C. fioriniae (ITS, KF278459.1, NR111747.1; β-tub, AB744079.1, AB690809.1; GAPDH, KF944355.1, KF944354.1; CHS-1, JQ948987.1, JQ949005.1; and ACT, JQ949625.1, JQ949626.1). Koch's postulates were fulfilled by inoculating six healthy 1-year-old walnut trees in July 2014 with maximum and minimum temperatures of 33 and 26°C. The 6-mm mycelial plug, which was cut from the margin of a 5-day-old colony of the fungus on PDA, was placed onto each pin-wounded leaf, ensuring good contact between the mycelium and the wound. Non-colonized PDA plugs were placed onto pin-wounds as negative controls. Following inoculation, both inoculated and control plants were covered with plastic bags. Leaf spots, similar to those on naturally infected plants, were observed on the leaves inoculated with C. fioriniae within 5 days. No symptoms were observed on the negative control leaves. Finally, C. fioriniae was re-isolated from symptomatic leaves; in contrast, no fungus was isolated from the control, which confirmed Koch's postulates. To our knowledge, this is the first report of leaf disease on walnut caused by C. fioriniae. References: (1) L. Cai et al. Fungal Divers. 39:183, 2009. (2) R. G. Shivas and Y. P. Tan. Fungal Divers. 39:111, 2009.

scholarly journals First Report of a Leaf Spot Disease of Tobacco Caused by Pseudomonas cichorii in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Dayu Lan ◽  
Fangling Shu ◽  
Yanhui Lu ◽  
Anfa Shou ◽  
Wei Lin ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Pseudomonas Cichorii ◽  
Koch’S Postulates ◽  
First Report ◽  
Initial Symptoms ◽  
Wide Range ◽  
Koch's Postulates

Tobacco (Nicotiana tabacum L.), one of the chief commercial crops, is wildly cultivated worldwide. In June 2020 and 2021, an unknown bacterial leaf spot on tobacco was found in Hezhou and Hechi City, Guangxi, China. 30% of the tobacco were affected and the rate of diseased leaves reached about 10% in the field under high temperature and rainstorm. The disease mainly damaged the middle and top leaves of tobacco plants at vigorous growing stage. The initial symptoms were water-soaked spots on the frontal half of a leaf, and then expanded into circular to irregular spots with a yellow halo at the edge. The spots mostly appeared dark brown at high air humidity, while yellow brown at low humidity and exhibited a concentric pattern. In severe cases, the lesions coalesced and the whole leaf was densely covered with lesions, resulting in the loss of baking value. A bacterium was consistently isolated from diseased leaf tissues on nutrient agar (NA). Growth on NA was predominantly grayish white circular bacterial colonies with smooth margins, and the bacterium is rod-shaped, gram-negative and fluorescent on King’s B medium. Seven isolates (ND04A-ND04C and ZSXF02-ZSXF05) were selected for molecular identification and pathogenicity tests. Genomic DNA of the bacterium was extracted and the housekeeping gene of cts (encoding citrate synthase) was amplified with the primers cts-Fs/cts-Rs (forward primer cts-Fs: 5’-CCCGTCGAGCTGCCAATWCTGA-3’; reverse primer cts-Rs: 5’-ATCTCGCACGGSGTRTTGAACATC-3’) (Berge et al. 2014; Sarkar et al. 2004). 409-bp cts gene sequences were deposited in the GenBank database for seven isolates (accession no. OK105110-OK105116). Sequence of seven isolates shared 100% identity with several Pseudomonas cichorii strains within the GenBank database (accession no. KY940268 and KY940271), and the phylogenetic tree of cts genes of the seven isolates clustered with the phylogroup 11 of Pseudomonas syringae (accession no. KJ877799 and KJ878111), which was classified as P.cichorii. To satisfy Koch’s postulates, a pathogenicity test was tested by using a needle to dip a suspension of the bacterium (108 CFU/ml) and pricking three holes in the tobacco leaf. The control plants leaves were needled with sterile water. Each tobacco plant was inoculated with three leaves, and the test was repeated three times. All plants were placed in transparent plastic boxes and incubated in a greenhouse at 25 ± 3°C. The water-soaked spots appeared 24h after inoculation and quickly expanded through leaf veins. Three days after inoculation, all the inoculated leaves showed symptoms similar to those observed in the field. Control plants remained healthy. Only P. cichorii was successfully re-isolated from the lesions, confirming Koch’s postulates. Pseudomonas cichorii can infect eggplant, lettuce, tomatoand other crops, and has a wide range of hosts (Timilsina et al. 2017; Ullah et al. 2015). To our knowledge, this is the first report of P. cichorii causing leaf spot on tobacco in China.

scholarly journals First Report of Cylindrocarpon pauciseptatum Associated with Root Rot and Decline of Peach in Southern Italy (Apulia Region)

Plant Disease ◽  
2012 ◽  
Vol 96 (5) ◽  
pp. 764-764 ◽  
Author(s):  
T. Yaseen ◽  
Y. Ahmed ◽  
A. M. D'Onghia ◽  
M. Digiaro
Keyword(s):  
Prunus Persica ◽  
Southern Italy ◽  
Vascular Lesions ◽  
Universal Primers ◽  
Stone Fruits ◽  
Centraalbureau Voor ◽  
Koch’S Postulates ◽  
First Report ◽  
Apulia Region ◽  
Koch's Postulates

During a survey for the sanitary status of stone fruits in southern Italy (Apulia region), symptoms of low vigor, sparse foliage, and chlorosis of leaves, frequently leading to decline or death of the plants, were observed on 3- to 5-year-old peach trees (Prunus persica) cvs. Tardi Belle, Zee Lady, and O'Henry grafted on GF677. Brown-to-black discolorations of the wood were observed in cross-sections of the trunks just below the graft union. Samples were collected from May to June 2010 from two symptomatic orchards in Brindisi and Foggia provinces. Small pieces of brownish, vascular wood and necrotic root tissues were surface disinfested, placed onto potato dextrose agar (PDA), and incubated for 7 days at 25°C in the dark. Single-conidial isolates were subsequently grown on PDA at 25°C for 10 days. Fungal colonies were presumptively identified as members of the genus Cylindrocarpon on the basis of their morphological and conidial characteristics. On PDA, the isolates developed abundant mycelium, which gradually became yellowish or partially brownish. Macroconidia were predominantly three septate, straight and cylindrical with both ends broadly rounded. Chlamydospores and ovoidal microconidia were observed on synthetic nutrient-poor agar (1). Sequence of the ribosomal internal transcribed spacer (ITS) region was obtained using universal primers (ITS6-ITS4) and deposited in GenBank (Accession No. HE577846). This sequence revealed 100% genetic identity with a sequence from Cylindrocarpon pauciseptatum Schroers & Crous (Accession No. EF607090), a recently described species (3). In nature, several species of the genus Cylindrocarpon affect a large number of woody plants, mainly grapevine, olive, and stone fruits, in which they attack the root surface (2). To verify Koch's postulates, the roots of 20 3-month-old peach seedlings (GF305) were dipped for 30 min in a spore suspension of the fungus (1 × 108 conidia ml–1). Seedlings were then transplanted in an artificial soil mix and held under controlled conditions in a greenhouse at 24°C. Typical black-foot symptoms developed on 92% of the inoculated plants within 3 months, whereas the control plants, whose roots had been dipped in distilled water, remained healthy. C. pauciseptatum was reisolated from infected tissues and internal vascular lesions of 45% of the inoculated plants, but none of the plants used as controls, fulfilling Koch's postulates. To our knowledge, this is the first report of this pathogen on peach in the Apulia Region of Italy. Currently, C. pauciseptatum is limited to a few orchards where presumably it was introduced with infected propagating material from extra-regional nurseries. C. pauciseptatum has the potential to negatively affect the stone fruit industry in Italy including reducing nursery production and productivity and vigor of trees in orchards, or even rapid death of young trees. References: (1) W. Gams et al. CBS Course of Mycology. 4th ed. Centraalbureau voor Schimmelcultures, Baarn, the Netherlands, 1998. (2) M. E. S. Hernandez et al. Eur. J. Plant Pathol. 104:347, 1998. (3) H. J. Schroers et al. Mycol. Res. 112:82, 2008.

scholarly journals First report of Stemphylium eturmiunum causing leaf spot and black spot on apple in Zhaotong, Yunnan, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Cong Zhou ◽  
Xin Long Pan ◽  
Bao Hua Kong ◽  
Yueqiu He ◽  
Jun Ma ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Yunnan Province ◽  
Management Practices ◽  
Black Spot ◽  
Parsimony Method ◽  
Koch’S Postulates ◽  
First Report ◽  
The World ◽  
Postharvest Rot ◽  
Koch's Postulates

Apple is the largest fruit tree crop in the world, and China is the largest apple-producing County in the world. Zhaotong, Yunnan Province is a typical cold and mountainous apple-producing area in China. However, apple production is threatened by diseases during the entire growing season, and among them, apple leaf spot and fruit black spot are severe. In previous reports, the main pathogen causing apple leaf spot and fruit black spot was Alternaria sp. (Lior, et al, 2017), while different pathogens were identified. In the current study, seven red Fuji apple fruit with typical black spot samples were collected randomly in Dongda company orchard, Sujiayuan town, Zhaotong, Yunnan on March 25, 2021. The spots on the surface of these apples appear rounded, the diseased parts turn brown or black in colour and the flesh became soften and rotten. The tissues of fruit epidermis at the edge between diseased and healthy parts were cut, soaked in 75% alcohol for 30 s, washed with sterile water three times, and air-dried. Five pieces of tissue were placed on PDA medium amended with rifampicin (50 mg/ml) and incubated in the dark at 25 ℃ for 3-5 days. After colonies grew, mycelial clumps were picked out from the edges of the colonies, transferred to new PDA plates, and incubated at 25 ℃ for 6 days. The diameter of the colonies reached up to 5.7 cm. A representative isolate was retained for further work and was named P6-3-1. The hyphae were white and dense at an early stage, the culture medium on the underside became yellow and the middle parts of the colonies were darker. With maturity, hyphae were clumped, became red with other colors interspersed, and the medium became dark red. Light brown spores were produced, with more vertical septa and fewer transverse septa. Two to three transverse septa were generally observed with obvious constriction at the transverse septa. Average spore size was 22.83 µm ± 2.04 µm × 14.58 µm ± 1.97 µm. DNA was extracted from mycelium, purified and amplified with two pairs of primers, ITS1/ITS4 (White et al. 1990) and gpdF/gpdR (Marcos P. S. Câmara, et al. 2002). The PCR products were sequenced and deposited in GenBank (accession NO.OK560128 and OK627661 ). The similarity of ITS sequences between the isolate and MH843733 (Stemphylium eturmiunum strain ST14) was 100%, and that of gpd sequences between the isolate and MH843728 (Stemphylium eturmiunum strain ST20) was 100%. The maximum parsimony method of Mega7.0 was used and demonstrated that the studied isolate converged to the same branch as Stemphylium eturmiunum. Koch's postulates was applied to identify the pathogenicity of this isolate. A disc of P6-3-1-culture on PDA (5 mm in diameter) was placed on apple leaves and fruit wounds. Sterile PDA was used as a control. All plants were kept in a growth chamber at 25-30 ℃. Four days after inoculation, the disease spot was observed on the inoculated sites and fruit, and with the extension of incubation time, the diseased spots continue to grow, and the leaf spots were not limited by the veins. The pathogen was re-isolated from the inoculated leaves and fruit, satisfying Koch’s postulates. This pathogen can also cause postharvest rot of sweet cherry (Alice Spadoni, et al, 2020), postharvest rot on tomato (Prencipe Simona, et al, 2021), etc. This is the first report that Stemphylium eturmiunum can cause apple leaf spot and fruit black spot in Yunnan province, China. The apple black spot caused by Stemphylium eturmiunum was accurately identified. By distinguishing between the two similar diseases mentioned above, resistance to the host and management practices can be accrued based on the characteristics of the pathogen, its epidemiological pattern and the choice of an effective chemical fungicide.

scholarly journals Severe Outbreak of Leaf Spot and Blight Caused by Botrytis cinerea on Majesty Palm in Southern Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 815-815
Author(s):  
G. Polizzi
Keyword(s):  
Botrytis Cinerea ◽  
Leaf Spot ◽  
Southern Italy ◽  
Gray Mold ◽  
Limiting Factor ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Leaf Spots ◽  
Important Region ◽  
Leaf Tissues

Sicily is the most important region of Italy for ornamental palm cultivation. Majesty palm (Ravenea rivularis Jum. & H. Perrier) is one of the most stately palms for cultivation in the tropics and subtropics, and has been recently cultivated in containers for indoor and outdoor use in eastern Sicily. R. rivularis, which grows on river banks, is native to Madagascar, and appears to behave as a rheophyte in the seedling stage. This palm is not frost tolerant and will grow in full sun but tends to grow best in partly shaded areas or under greenhouses conditions. Between December and March in 1999, 2000, and 2001, a severe leaf spot and blight was observed on young (6-month- to 3-year-old) plants of majesty palm growing in plastic-covered houses and in open fields in nurseries in Sicily. Affected plants had brown necrotic spots and gray mold on the necrotic leaf tissues. No symptoms were detected in mature (4- to 5-year-old) plants grown in the same nurseries. To isolate the casual agent of the disease, 160 small pieces of tissue cut from leaf spots collected in four nurseries were surface sterilized (20 s in HgCl2 at 1 g/liter), washed with sterile water, and plated on potato dextrose agar (PDA). In addition, conidia and conidiophores were scraped from the leaf surface, suspended in sterile water, and streaked on the agar surface. After 2 days, single hyphal tips were transferred to PDA. Botrytis cinerea Pers.:Fr. was consistently isolated from affected leaf tissues. Colonies of B. cinerea on PDA were at first colorless and became gray to brown with the development of conidia, which ranged from 5.5 to 10 × 7 to 12 μm (average 7.5 × 9). Sclerotia were black, irregular in size and shape, and from 1.4 to 4.5 × 1.5 to 2.7 mm. Inoculating 8-month-old seedlings of R. rivularis tested pathogenicity of six isolates obtained from different nurseries. Wounded (with a needle) and nonwounded leaves of 10 plants (9 wounds per plant) were sprayed with 20 ml of a conidial suspension (105 conidia/ml) of each isolate. An equal number of noninoculated plants were used as controls. All plants where incubated in a greenhouse at ambient temperature (21 ± 2°C) and 72 h of continuous leaf wetness. Five days after inoculation, leaf spots appeared on most of the wounded (approximately 80%) and the nonwounded (about 10%) leaves. No symptoms were observed on control plants. Koch's postulates were satisfied by reisolation of the fungus on PDA. On the basis of 3 years of observations in eastern Sicily, majesty palms were more readily infected by B. cinerea after rainfall, and freezing temperatures injured young plants. Leaf blight caused by B. cinerea was previously reported in Liguria (northern Italy) on Phoenix canariensis (1). The fungus does not appear to be a major disease problem in cultivated ornamental palms other than R. rivularis in Sicily or southern Italy. However, B. cinerea could be a limiting factor in the cultivation of majesty palm in eastern Sicily, and protective fungicides, especially in winter, are necessary for limiting losses. To my knowledge, this is the first report of B. cinerea leaf spot and blight on R. rivularis. Reference: (1) A. Garibaldi et al. Malattie delle piante ornamentali. Calderini Edagricole, Bologna, 2000.

scholarly journals First Report of Pseudomonas syringae pv. coriandricola Causing Bacterial Leaf Spot on Carrot, Parsley, and Parsnip in Serbia

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 416-416 ◽  
Author(s):  
T. Popović ◽  
Ž. Ivanović ◽  
M. Ignjatov ◽  
D. Milošević
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Bacterial Suspension ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Bacterial Leaf Spot ◽  
Koch’S Postulates ◽  
First Report ◽  
Vegetable Farm ◽  
Koch's Postulates

During the spring of 2014, a severe leaf spot disease was observed on carrot (Daucus carota), parsley (Petroselinum crispum), and parsnip (Pastinaca sativa) on a 0.5-ha vegetable farm in Vojvodina Province, Serbia. The disease appeared under wet and cool conditions with 5 to 25% of plants infected for each of the three crops. Symptoms were characterized as brown angular leaf spots, ~2 mm in diameter, often limited by veins. Collected symptomatic leaves were rinsed and dried at room temperature, and leaf sections taken from the margin of necrotic tissue were macerated in sterile phosphate buffer and streaked onto nutrient agar with 5% (w/v) sucrose (NAS). After isolation, whitish, circular, dome-shaped, Levan-positive colonies consistently formed. Five strains from each host (carrot, parsley, and parsnip) were used for further study. Strains were gram-negative, aerobic, and positive for catalase and tobacco hypersensitive reaction but negative for oxidase, rot of potato slices, and arginine dihydrolase. These reactions corresponded to LOPAT group Ia, which includes Pseudomonas syringae pathovars (3). Repetitive extragenic palindromic sequence (Rep)-PCR fingerprint profiles using the REP, ERIC, and BOX primers (4) were identical for all strains. Sequence typing of the housekeeping genes gyrB and rpoD (1) was performed for three representative strains (one from each host). Sequences were deposited in the NCBI GenBank database as accessions KM979434 to KM979436 (strains from carrot, parsnip, and parsley, respectively) for the gyrB gene and KM979437 to KM979439 (strains from parsnip, parsley and carrot, respectively) for the rpoD gene. Sequences were compared with pathotype strain Pseudomonas syringae pv. coriandricola ICMP12471 deposited in the Plant Associated and Environmental Microbes Database ( http://genome.ppws.vt.edu/cgi-bin/MLST/home.pl ). BLAST analysis revealed 100% homology for gyrB and 99% homology for rpoD. Pathogenicity was tested with five representative strains from each host on four-week-old plants of carrot (cv. Nantes), parsley (cv. NS Molski), and parsnip (cv. Dugi beli glatki) using two methods: spraying the bacterial suspension (108 CFU ml−1) on the leaves until runoff (5) and injecting the bacterial suspension into leaves with a hypodermic syringe (2). Four plants were used per strain and method. Sterile distilled water was applied as a negative control treatment for each plant species. All plants were kept in a mist room with 100% humidity for 4 h, then transferred to a greenhouse at 25°C and 80% relative humidity and examined for symptom development over a period of three weeks. For all strains, inoculated leaves first developed water-soaked lesions on the leaves 5 to 7 days after inoculation (DAI); 14 DAI lesions became dark brown, often surrounded by haloes. No symptoms were observed on control plants inoculated with sterile distilled water. For fulfillment of Koch's postulates, re-isolations were done onto NAS. Re-isolated bacteria were obtained from each inoculated host and confirmed to be identical to the original isolates using the LOPAT tests and Rep-PCR fingerprinting profiles. Based on the pathogenicity test accompanied by completion of Koch's postulates, sequence analysis, and bacteriological tests, the strains were identified as P. s. pv. coriandricola. To our knowledge, this is the first report of bacterial leaf spot of carrot, parsley, and parsnip in Serbia. It may present a threat to production due to quality requirements for fresh market. References: (1) P. Ferrente and M. Scortichini. Plant Pathol. 59:954, 2010. (2) M. Gupta et al. Plant Dis. 97:418, 2013. (3) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966. (4) F. J. Louws et al. Appl. Environ. Microb. 60:2286, 1994. (5) X. Xu and S. A. Miller. Plant Dis. 97:988, 2013.

scholarly journals First Report of Brown Leaf Spot of Rice (Oryza sativa L.) Caused by Bipolaris sorokiniana in Pakistan

Plant Disease ◽  
2021 ◽  
Author(s):  
Hafiz Muhammad Usman Aslam ◽  
Nasir Ahmad Khan ◽  
Syed Ismat Hussain ◽  
Yasir Ali ◽  
Muhammad Raheel ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Bipolaris Sorokiniana ◽  
Infected Leaf ◽  
Potato Dextrose Agar Medium ◽  
Koch’S Postulates ◽  
First Report ◽  
Brown Leaf Spot ◽  
Brown Leaf ◽  
Koch's Postulates

Brown leaf spot of rice is one of the major seed-borne diseases and can diminish grain production up to 52% (Barnwal et al. 2013). In 2018, infected leaf samples showing the typical symptoms of brown spots were collected from the vicinity of the University of Agriculture, Faisalabad (31°26'10.3"N 73°03'35.1"E). The symptoms were brown-dark spots, with gray-light gray or brown centers surrounded by dark margins and with chlorotic halos and of oval or cylindrical shapes (5 to 9 mm in diameter). Disease incidence averaged 61% across the seven fields observed. Leaves were collected from the seven infected fields and symptomatic leaf tissues of 5 mm2 were excised from representative necrotic spots in each. These tissues were surface disinfected with 70% ethanol, rinsed with sterile distilled water (SDW), dried by blotting on paper, and placed on potato dextrose agar medium. For pathogen growth, the plates were placed at 25oC (±2oC) with a 12-hour photoperiod for 5 days. Five samples from each of the infected fields were taken for pathogen isolation and among them ten isolates were sub-cultured and purified by using the single spore method. The resulting fungal colonies were fluffy and ranged in color from grayish black/black to light brown. Fifteen conidia were measured that are olivaceous-brown to dark brown in color, elliptical to oblong with narrow (tapered) ends, with 3-10 septa and 35.6-65.4 µm in length x 13.1-25.7 µm in width. Conidiophores were yellowish-brown, geniculate, and solitary (Pratt 2003). For molecular studies, rDNA of the internal transcribed spacer (ITS) region, translation elongation factor (tef), RNA polymerase II second largest subunit (rpb2) and glyceraldehyde-3-phosphate dehydrogenase (gpd) gene were amplified by using the primers ITS1F/ITS4R (White et al. 1990), EF1-983F/EF1-2218R (Rehner and Buckley 2005), 5F2/7CR (O’Donnell et al. 2007), and GPD1/GPD2 (Berbee et al. 1999) respectively. The sequence of all the amplified gene regions of one SUL-1 isolate was deposited into GenBank with accession numbers MN314844 (ITS), MN326866 (tef), MN990457 (rpb2) and MN990456 (gpd). BLASTn queries of the obtained sequences (ITS, tef, rpb2 and gpd) showed 99-100% homology with the corresponding nucleotide sequences of B. sorokiniana (GenBank accession nos. GU480767, MF490855, LT715652 and MK558818 respectively). To fulfill the Koch’s postulates, twenty rice plants (cv. Basmati-385) were sprayed at 2 to 3 leaf stages by using the two representative isolates with a spore suspension of 105 spores/ml. SDW was sprayed on ten control plants. The plants were covered with polyethylene bags to keep the moisture contents and incubated at 25oC (±2oC) for 7 days. After a week, same symptoms as those described above were observed. In the repeated experiment, B. sorokiniana was re-isolated from the infected rice leaves and confirmed morphologically; fulfill the Koch’s postulates. With grave worry, the other species of the genus Bipolaris (B. oryzae, and B. victoriae) have also been found to the cause brown leaf spot of rice (Motlagh and Kaviani 2008). To our knowledge, this is the first report of Bipolaris sorokiniana causing brown leaf spot of rice in Pakistan. Because rice is highly consumable grain in Pakistan, so the rapid spread of this disease in the rice farming areas is of a serious concern.

scholarly journals Mycovellosiella robbsii sp. nov. causing leaf-spot on Mimosa caesalpiniaefolia

2002 ◽  
Vol 27 (6) ◽  
pp. 605-608
Author(s):  
ROBERT W. BARRETO ◽  
FILLIPE S. MARINI
Keyword(s):  
New Species ◽  
Leaf Spot ◽  
Fungal Disease ◽  
Koch’S Postulates ◽  
First Report ◽  
Leaf Spots ◽  
Multiple Uses ◽  
Koch's Postulates ◽  
Distinct Taxon ◽  
Mycelial Suspension

This is a description of the new species Mycovellosiella robsii, a cercosporoidal hyphomycete, associated with leaf spots on Mimosa caesalpiniaefolia, an important hedge plant with multiple uses in Brazil. The new species was compared to other cercosporoid species associated with plants of the genus Mimosa and other species of the genus Mycovellosiella described on legumes, and is recognized as a distinct taxon. Koch's postulates were carried out and the disease was reproduced by inoculating healthy plants with mycelial suspension or disk, confirming the pathogenicity. This is the first report of a fungal disease on this host.

scholarly journals First Report of Leaf Spot Caused by Didymella americana on Cassia nomame in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Weiming Sun ◽  
Lina Feng ◽  
Xiaolei Wen ◽  
Bojia Han ◽  
Danrun Xing ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Rrna Gene ◽  
Pathogenicity Test ◽  
Koch’S Postulates ◽  
First Report ◽  
Initial Symptoms ◽  
Koch's Postulates

Cassia nomame (Sieb.) Kitagawa is an annual plant in the Leguminousae family. The aerial parts of C. nomame have been used as tonic and diuretic in Korea and Japan (Syed et al. 2019). A leaf spot was observed on the leaves of a 1-year-old C. nomame landrace in Changli County (39.42°N, 119.10°E), Qinhuangdao City, Hebei Province during August to October in 2018. In many fields (n≥3), the disease incidence over 80% in the middle and late stage of plant growth. Symptoms on leaves in one field began with many small, dark necrotic spot lesions. Later, the lesions spread to round-to-oval, slightly sunken in the center, and large necrotic patches with indefinite margins. Finally, lesions coalesced and resulted in defoliation. Lesions were occasionally observed on the pods. Symptoms on the pods were initially small, dark spots and then expanded to large necrotic patches with irregular edges. Symptomatic tissues (n=32) from pods and leaves were cut into 3 to 8 mm2 squares, surface disinfested with 75% ethanol for 10 s, rinsed with sterile distilled water, then placed on potato dextrose agar (PDA) at 28℃. After 3 days, ten isolates with consistent characteristics were obtained with a frequency 52.6%. The isolates on PDA were round, initially pale and had little aerial mycelium, gradually turned olive green and had dense wool-like dense aerial mycelia after 3 days. Conidia were hyaline, smooth, solitary, and elliptical. The conidia measured 5.4 to 8.2 μm × 2.5 to 3.8 μm (n=50), and has two oil bodies positioning at opposite poles. Pigmented chlamydospores were spherical or nearly pear-shaped, and solitary. Black fructifications (pycnidia) were produced profusely on PDA after subculture for 3 days. All the isolates were similar to Didymella sp. in morphology (Aveskamp et al. 2009). Choice three isolates YSGUO8 YSGGUO8-a and YSGGUO8-b to be further characterized by sequencing of the internal transcribed spacer (ITS), actin gene, and 28S large subunit of the nuclear rRNA gene (LSU) (Zhang et al. 2017). The sequences of three strains (MK836417 MZ484072 and MZ484073 for ITS, MK837604 MZ593675 and MZ593676 for actin, MK843781 MZ836208 and MZ836207 for LSU, respectively) showed 99% to 100% similarity with Didymella americana K-004 (KY070279 for ITS,KY070285 for LSU), Phoma americana CBS 256.65 (FJ426973 for ITS, FJ426871 for actin, MH870196 for LSU) and P. americana CBS 185.85 (FJ426972 for ITS, FJ426870 for actin, GU237990 for LSU) in GenBank. The fungi were identified as D. americana (formerly P. americana or Peyronellaea americana) on the basis of morphological characteristics and sequence analysis. A pathogenicity test was conducted with three times on 1-year-old C. nomame strain at the 4 to 6 compound leaf stage. Conidia were obtained from 7-day-old PDA cultures grown at 28℃ with a 12-h photoperiod. Koch’s postulates were fulfilled by spray inoculating ten healthy young plants with 106 conidia per milliliter of D. americana strain YSGUO8, and sterile water as the control. After inoculation, the plants were managed at 28℃, 60% relative humidity and a 12-h photoperiod. After 5 to 8 days, the inoculated leaves developed small and dark spots lesions similar to those observed on the leaves with initial symptoms in the field. The control leaves remained symptomless. The same fungi were re-isolated from infected leaves by morphology observation and sequence analysis, confirming Koch's postulates. D. americana has caused leaves spot on Table Beet in New York (Vaghefi et al. 2016). To our knowledge, this is the first report of D. americana causing leaf spot of C. nomame in China.

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