scholarly journals A New Disease of Parthenium hysterophorus Incited by an Undescribed Species of Cryptosporiopsis

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1151-1151
Author(s):  
P. Sreerama Kumar
Keyword(s):  
Fungal Pathogens ◽  
Southwest Monsoon ◽  
Parthenium Hysterophorus ◽  
Commonwealth Mycological Institute ◽  
Invasive Weed ◽  
Leaf Spots ◽  
Brown Leaf ◽  
Detached Leaves ◽  
Intensive Investigation ◽  
Whole Plants

Fungal pathogens of parthenium (Parthenium hysterophorus L.), an invasive weed in India, have been under intensive investigation at our Directorate since 1996 for development of mycoherbicides. During the southwest monsoon month of August 1997, a severe foliar disease of the weed was observed near Hunsur (12° 16′N; 76° 18′E; 779.37 masl) in Mysore district of Karnataka State. The primary symptoms consisted of circular to irregular, light brown leaf spots with a diameter up to 8 mm and surrounded by a diffuse chlorotic margin. Isolations on potato dextrose agar (PDA) yielded a relatively fast-growing (approximately 11.4 mm/day) white fungus. The same fungus was isolated consistently from diseased leaves but not from symptomless leaves collected from the vicinity. The mycelium of the fungus on PDA was immersed, branched, septate, and hyaline to pale brown. Conidia (approximately 10.50 × 2.75 µm) were hyaline, thin-walled, smooth, straight, and ellipsoid with obtuse apex and base abruptly tapered to a distinct truncate scar. Pathogenicity was assessed by inoculating healthy, surface-sterilized, mature detached leaves and whole plants (40-day-old) with spore (1 × 106 conidia/ml) or mycelial (0.2 g/ml) suspensions. For both kinds of inoculation, 10 replicates each for detached leaves and whole plants were maintained with equal number of uninoculated controls. Inoculated leaves and plants were incubated at ambient temperature (28 ± 2°C) and 48 h of continuous leaf wetness. Lesions resembling symptoms that occurred in the field were observed on all detached leaves and whole plants within 3 weeks of inoculation. The same fungus was recovered from the diseased tissues excised from all the inoculated material, satisfying Koch's postulates. All the controls remained symptomless and were negative for the fungus. A virulent isolate of this fungus was referred to CABI Bioscience, UK Centre (Egham) and was identified as Cryptosporiopsis sp. (IMI 378270). Although there are at least 12 described species of Cryptosporiopsis Bub. & Kabát (1), no species has been described on parthenium. This pathogen is being studied for its usefulness as a mycoherbicide for parthenium. Reference: (1) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, Surrey, England.

scholarly journals First Report of a Septoria sp. on Common Ragweed (Ambrosia artemisiifolia) in Europe

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 696-696 ◽  
Author(s):  
Gy. Bohár ◽  
I. Schwarczinger
Keyword(s):  
Ambrosia Artemisiifolia ◽  
Voucher Specimen ◽  
Common Ragweed ◽  
History Museum ◽  
First Report ◽  
Leaf Spots ◽  
Brown Leaf ◽  
Detached Leaves ◽  
Pure Cultures ◽  
Hungarian Natural History Museum

During a survey for potential biocontrol agents of common ragweed (Ambrosia artemisiifolia var. elatior (L.) Descourt) in 1997, plants exhibiting irregular, brown leaf spots were collected repeatedly from six roadside locations in Pest County, Hungary. Many pycnidia developed in the necrotic tissues on detached leaves after 2 days in moist chambers. Pycnidia were globose to slightly flattened, brown, thin walled, 58 to 100 μm in diameter, with a definite ostiole. Conidia were hyaline, filiform with 2 to 3 septa, and 22.0 to 38.0 × 0.7 to 1.3 μm in size. The fungus was isolated on potato dextrose agar and identified as a Septoria sp. To confirm pathogenicity, potted ragweed seedlings were sprayed with a suspension of 5 × 106 conidia per ml from pure cultures of the Septoria sp., placed in a dew chamber for 72 h, and then grown in a greenhouse at 16 to 24°C. After 2 weeks, inoculated plants developed small, brown lesions on leaves and leaf petioles. Three weeks after inoculation, necrotic lesions had enlarged to 1 to 3 mm in diameter with irregular, distinct margins and light brown centers. The lesions on the lower leaves were larger and more numerous than on leaves nearer the tops of the plants. Pycnidia developed on the senescent leaves after 1 month. Infected leaves became completely necrotic and occasionally entire plants died. The pathogen was reisolated from all inoculated plants, thus satisfying Koch's postulates. A voucher specimen was deposited at the Department of Botany of the Hungarian Natural History Museum in Buda-pest (No. BP 92081). Septoria ambrosiae Hemmi et Naito was described on ragweed in Japan (1), but our isolate is morphologically distinct from that species. This is the first report of a Septoria sp. on A. artemisiifolia in Europe. Reference: (1) N. Naito. Mem. Coll. Agric. Kyoto 47:41, 1940.

scholarly journals First Report of Lasiodiplodia theobromae as a Foliar Pathogen of Parthenium hysterophorus

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1343-1343 ◽  
Author(s):  
P. Sreerama Kumar ◽  
S. P. Singh
Keyword(s):  
Plant Diseases ◽  
Parthenium Hysterophorus ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Causal Organism ◽  
Lasiodiplodia Theobromae ◽  
Leaf Spots ◽  
Close Proximity ◽  
Karnataka State ◽  
Phytoparasitic Nematodes

Parthenium (Parthenium hysterophorus L.) has been a target of weed researchers in India for more than four decades. The weed is attacked by many pathogens, some of which have been tried as mycoherbicides with mixed results (1). In an effort to identify more pathogens of parthenium, surveys were conducted in different regions. A typical foliar disease was frequently observed in several districts of Karnataka State, especially during the winter months of 1996 to 1998. The primary symptoms were circular to irregular, light brown to gray leaf spots, ranging from 2 to 8 mm in diameter. Careful observation of diseased plants revealed that the development of several lesions in close proximity resulted in a rapid necrosis and withering of the entire leaf. The suspected causal organism, which was a dark, chocolate-brown fungus, grew well on potato-dextrose agar at 25°C and a 12-h photoperiod. It produced slowly maturing conidia (20 to 27 × 12 to 14 μm), which were dark brown, ellipsoid, thick-walled, and single-septate with longitudinal striations. A dense conidial suspension (108 conidia per ml) of the fungus was evenly applied (250 μl per leaf) on detached, surface-sterilized, healthy parthenium leaves (N = 10), and infection was ascertained after 4 days of incubation at 26 ± 2°C in petri dishes lined with moist cotton. When 45-day-old pot-grown parthenium plants (N = 50) were similarly inoculated and maintained above 95% RH for at least 48 h, typical symptoms resembling those of naturally infected plants were visible on 88% of the plants within 3 weeks of incubation at 28 ± 2°C. Whereas the fungus was consistently isolated from diseased leaves of inoculated plants, with 80% frequency of reisolation, uninoculated controls neither displayed symptoms nor yielded the pathogen. The experiment was performed three times with similar results, satisfying Koch's postulates. The identity of one of the virulent isolates, WF(Ph)8 (ex Siddeswaranadurga, Chitradurga district, December 1997), was confirmed as Lasiodiplodia theobromae (Pat.) Griffon. & Maubl. (=Botryodiplodia theobromae Pat.) (IMI 378919a) at CABI Bioscience, UK Centre (Egham). Although it is a ubiquitous tropical and subtropical plant pathogen that occurs between 40°N and 40°S (2), it was not previously recorded as a cause of leaf disease on parthenium. Investigations on the possible use of the pathogen as a mycoherbicide have given encouraging results. References: (1) P. Sreerama Kumar. 1998. Pages 192-210 in: Biological Suppression of Plant Diseases, Phytoparasitic Nematodes and Weeds. S. P. Singh and S. S. Hussaini, eds. Project Directorate of Biological Control, Bangalore, India. (2) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, England.

scholarly journals Characterization of the brown leaf spots pathosystem in Brazilian pecan orchards: pathogen morphology and molecular identification

2021 ◽  
Vol 64 (1) ◽  
pp. 75-86
Author(s):  
Tales Poletto ◽  
Marlove Fátima Brião Muniz ◽  
Vinícius Spolaor Fantinel ◽  
Laís Da Silva Martello ◽  
Lucas Graciolli Savian ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungus ◽  
Large Subunit ◽  
Southern Brazil ◽  
Leaf Spots ◽  
Comprehensive Information ◽  
Brown Leaf ◽  
The World ◽  
Causal Pathogen

Due to the increase in pecan nuts demand, plantation areas are expanding around the world and more frequent epidemics caused by fungal pathogens may occur in orchards and nurseries. Ragnhildiana diffusa is a pathogenic fungus reported to cause brown leaf spots on pecans in numerous countries. The scarcity of comprehensive information in symptoms on the host and morphology of the fungus lead this disease to be initially incorrectly identified in Brazil. In this study, we employed different approaches to characterize the pathogen morphology and pathogenicity and to molecularly identify the organism causing brown leaf spots in southern Brazil. A phylogenetic analysis based on the internal transcribed spacer (ITS) and the large subunit (LSU) gene sequences confirmed R. diffusa as the causal pathogen of the disease. Inoculation tests on healthy leaflets confirmed pathogenicity isolates, although some variation in their virulence was observed. Variation in the morphology of the asexual stage was observed among and within isolates. This study brought unprecedented morphological, genetic and pathogenic information that aids elucidating the disease. The accurate and prompt identification of the disease may assist in controlling further spread of the pathogen into orchards and nurseries still free of the disease in South America.

scholarly journals Antimicrobial activity of the water-soluble ash extract from the invasive weed Parthenium hysterophorus L.

2020 ◽  
Vol 4 (02) ◽  
pp. 1-6
Author(s):  
Sunil Kumar Joshi ◽  
Deepak Kumar Semwal ◽  
Ankit Kumar ◽  
Ashutosh Chauhan
Keyword(s):  
Antimicrobial Activity ◽  
Fungal Pathogens ◽  
Bacterial Species ◽  
Water Soluble ◽  
Parthenium Hysterophorus ◽  
Diffusion Method ◽  
Invasive Weed ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Medicinal Properties

Parthenium hysterophorus L., also known as congress grass or carrot grass, is a widely distributed invasive weed which is a big challenge for sustainable agriculture. For the past several years, a number of attempts have been made to evaluate its medicinal properties. The present study aimed to evaluate the antimicrobial activity of the water-soluble ash extract of P. hysterophorus against different bacterial and fungal pathogens. The disc diffusion method was used to measure zone of inhibition (ZOI) whereas broth microdilution method was used to evaluate minimum inhibitory concentration (MIC) of the extract. The extract was found most effective against Staphylococcus aureus with a ZOI value of 33.5 mm at 33 mg/mL concentration when compared with ofloxacin (ZOI = 39.5 mm at 5 μg/disc). The extract was also found active against Salmonella enterica, Staphylococcus epidermidis and Escherichia coli with ZOI values of 25.5, 32.5 and 25.5 mm, respectively. The present study revealed that the ash extract of P. hysterophorus has potential to inhibit various bacterial species. However, the tested fungal pathogens like Candida albicans were found unaffected after treating with the ash extract.

scholarly journals Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans

BioControl ◽  
2021 ◽  
Author(s):  
Mudassir Iqbal ◽  
Maha Jamshaid ◽  
Muhammad Awais Zahid ◽  
Erik Andreasson ◽  
Ramesh R. Vetukuri ◽  
...  
Keyword(s):  
Root Rot ◽  
Fungal Pathogens ◽  
Aureobasidium Pullulans ◽  
Grey Mould ◽  
Lesion Size ◽  
Plant Diseases ◽  
Crown Rot ◽  
Whole Plants

AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.

Cercostigmina protearum var. protearum. [Descriptions of Fungi and Bacteria].

1999 ◽  
Author(s):  
P. M. Kirk
Keyword(s):  
South Africa ◽  
Geographical Distribution ◽  
Leaf Spots ◽  
Brown Leaf

Abstract A description is provided for Cercostigmina protearum var. protearum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Causing round or sometimes irregular, pale brown or greyish-brown leaf spots 5-17 mm diameter. HOSTS: Leucospermum conocarpum, Protea. TRANSMISSION: By air-borne conidia. GEOGRAPHICAL DISTRIBUTION: AFRICA: South Africa.

Mechanisms of pathogenesis in Sclerotium bataticola on sunflowers. 1. Production and translocation of a necrosis-inducing toxin

1969 ◽  
Vol 47 (7) ◽  
pp. 1147-1151 ◽  
Author(s):  
Yu-Ho Chan ◽  
W. E. Sackston
Keyword(s):  
Activated Carbon ◽  
Root System ◽  
Vascular System ◽  
Early Symptom ◽  
Vascular Tissues ◽  
Detached Leaves ◽  
Necrotic Spots ◽  
Whole Plants ◽  
Necrotic Spotting

Necrotic spotting of leaves is an early symptom of attack by Sclerotium bataticola on sunflowers. Spots appear after invasion of vascular tissues by the pathogen, which does not spread appreciably from the point of inoculation.Inoculation of one stem of plants split apically to give twin stems on one root system resulted in necrotic spotting of leaves first on the inoculated, and later on the uninoculated stem. Introducing cell-free filtrates of cultures of S. bataticola into sunflower plants or detached leaves resulted in production of the same type of necrotic spots. Introduction of eosin dye, which is translocated in the vascular system, into whole plants and detached leaves produced patterns of coloration similar to the patterns of necrotic spotting. The necrosis may be attributed to a translocatable toxin produced by the fungus.It is indicated that the toxin is neither an enzyme nor a protein. It has not been eluted after adsorption by activated carbon.

scholarly journals First Report of Stigmina palmivora Causing Leaf Spots on Phoenix roebelenii in Brazil

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 849-849 ◽  
Author(s):  
A. Colmán ◽  
R. A. da Silva ◽  
R. Alves ◽  
M. Silva ◽  
R. W. Barreto
Keyword(s):  
Pure Culture ◽  
Leaf Surface ◽  
The United States ◽  
Culture Collection ◽  
Commonwealth Mycological Institute ◽  
First Report ◽  
Leaf Spots ◽  
Nucleotide Homology ◽  
Query Coverage ◽  
Representative Samples

Phoenix roebelenii (Arecaceae), known as dwarf date (tamareira-anã in Brazil), is a palm native to Southeast Asia and widely cultivated worldwide because of its ornamental value and ease of adaptation to a broad range of climates and soil types (4). In June 2012, some individuals were observed in a private garden in the municipality of Viçosa (state of Minas Gerais, Brazil) bearing numerous necrotic lesions on its leaves. Representative samples were taken, dried in a plant press, and brought to the laboratory for examination. A fungus was regularly associated with the leaf spots. Fungal structures were mounted in lactophenol and slides were examined under a microscope (Olympus BX 51). Spores were taken from sporulating colonies with a sterile fine needle and plated on PDA for isolation. A pure culture was deposited in the culture collection of the Universidade Federal de Viçosa (accession COAD1338). A dried herbarium sample was deposited in the local herbarium (VIC39741). The fungus had the following morphology: conidiophores grouped on sporodochia, cylindrical, 12 to 29 × 5 to 6 μm, dark brown; conidiogenous cells, terminal, proliferating percurrently (annellidic), 8 to 20 × 5 to 6 μm, pale to dark brown; conidia obclavate to subcylindrical, straight, 58 to 147 × 5 to 6 μm, 6 to 16 septate, hila thickened and darkened with a thin-walled projecting papilla, dark brown, and verrucose. The morphology of the Brazilian collections agrees well with the description of Stigmina palmivora (2), a species known to cause leaf spots on P. roebelenii in the United States (Florida) and Japan (3). Pathogenicity was demonstrated through inoculation of leaves of healthy plants by placing 6 mm diameter cuture disks of COAD1338 on the leaf surface followed by incubation in a moist chamber for 48 h and then transferred to a greenhouse bench at 21 ± 3°C. Typical leaf spots were observed 15 days after inoculation. DNA was extracted from the isolate growing in pure culture and ITS and LSU sequences were generated and deposited in GenBank under the accession numbers KF656785 and KF656786, respectively. These were compared by BLASTn with other entries in GenBank, and the closest match for each region were Mycosphaerella colombiensis strain X215 and M. irregulariamosa strain CPC 1362 (EU514231, GU2114441) with 93% of nucleotide homology (over 100% query coverage) for ITS and 98% of nucleotide homology (over 100% query coverage) for LSU. There are no sequences for S. palmivora deposited in public databases for comparison, but for Stigmina platani, the type species in this genus, 86% and 96% nucleotide homology for ITS and LSU with S. palmivora were found. The genus Stigmina is regarded as being polyphyletic (1) and this is probably reflected by these low homology levels found in the BLASTn search. To our knowledge, this is the first report of Stigmina palmivora in Brazil. References: (1) P. W. Crous et al. Stud. Mycol. 75:37, 2012. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, UK, 1971. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 2013. (4) H. Lorenzi et al. Palmeira no Brasil: Exóticas e Nativas, 2nd ed. Editora Plantarum, Nova Odessa, Brazil, 2005.

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