Association of Trechispora alnicola with yellow ring disease of Poa pratensis

Trechispora alnicola (Bourd. & Galz.) Liberia was associated with Poa pratensis L. roots and in the thatch layer of blue-grass sod. These plants had yellowed leaves. On thatch and culture medium, the fungus isolated from diseased plants produced hyaline mycelium typical of T. alnicola, and crystalline material. Conidia produced on thatch or on culture medium germinated by the production of a single germ tube. Basidia from basidiomata produced in nature were arranged in an effused manner; basidiospores were echinulate. This is the first report of T. alnicola associated with a member of the Graminae.

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First Report of Summer Patch of Kentucky Bluegrass Caused by Magnaporthe poae in Colorado

Plant Disease ◽

10.1094/pdis-91-11-1519a ◽

2007 ◽

Vol 91 (11) ◽

pp. 1519-1519 ◽

Cited By ~ 2

Author(s):

C. E. Swift ◽

A. Blessinger ◽

N. Brandt ◽

N. Tisserat

Keyword(s):

Poa Pratensis ◽

Rocky Mountain ◽

Kentucky Bluegrass ◽

The United States ◽

Mountain Region ◽

First Report ◽

Magnaporthe Poae ◽

Rocky Mountain Region ◽

Continental Divide ◽

Species Specific

The ectotrophic, root-infecting fungus Magnaporthe poae is the cause of summer patch of Kentucky bluegrass (Poa pratensis). The disease is widely distributed in the mid-Atlantic Region of the United States and west to central Nebraska and Kansas (2). It also has been found in certain locations of Washington and California (2) but has not been confirmed in the Rocky Mountain Region. In August 2005 and 2006, tan patches and rings of dead turf ranging from 10 to 30 cm in diameter were observed in Kentucky bluegrass swards in Grand Junction and Greeley, CO, respectively. The sites, separated by approximately 360 km, are located west and east of the Continental Divide. A network of ectotrophic hyphae were observed on diseased root segments collected from both sites. A fungus morphologically similar to M. poae (2) was consistently isolated from these segments. DNA was extracted from mycelium of one isolate from each location and amplified by PCR with the M. poae species-specific primers MP1 and MP2 (1). A 453-bp DNA fragment was consistently amplified from DNA of both isolates, diagnostic of M. poae. To our knowledge, this is the first report of summer patch in Colorado and indicates that M. poae may be widely distributed in the central Rocky Mountain Region. References: (1) T. E. Bunting et al. Phytopathology 86:398, 1996. (2) B. B. Clarke and A. B. Gould, eds. Turfgrass Patch Diseases Caused by Ectotrophic Root-Infecting Fungi. The American Phytopathological Society, St. Paul, MN, 1993.

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Occurrence of Powdery Mildew Caused by Blumeria graminis f. sp. poae on Poa pratensis in China

Plant Disease ◽

10.1094/pdis-09-20-2051-pdn ◽

2020 ◽

Author(s):

Mo Zhu ◽

Jie Ji ◽

Wenqi Shi ◽

YongFang Li

Keyword(s):

Powdery Mildew ◽

Germ Tube ◽

Poa Pratensis ◽

Perennial Grass ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

Width Ratio ◽

Leaf Surfaces ◽

Length Width

Poa pratensis, known as bluegrass, is a perennial grass and one of the best varieties with highly valued pasture and turf grass uses. It is widely grown on golf courses and used for lawns in squares and parks (Luo et al. 2020). During April and May 2020, powdery mildew-like signs and symptoms were observed on leaves of P. pratensis in Muye Park, Xinxiang city (35.3°N; 113.9°E), Henan Province, China. White or grayish powdery masses in spots- or coalesced lesions were abundant on the adaxial surfaces of leaves and covered up to 90 % of the leaf area. Some of the mildew-infested leaves appeared chlorotic or began senescence. Mildew-infested leaves were collected to microscopically observe the morphological characteristics of this pathogen. Conidiophores were composed of foot cells, followed by one or two cells, and conidia. The ellipsoid- shaped conidia (n = 50) were 25 - 36 × 10 - 15 μm (length × width), on average 30 × 13 μm, with a length/width ratio of 2.3. Foot-cells (n = 15) were 30 - 44 μm long and 7 - 15 μm wide. On leaf surfaces, germinated conidia produced a short primary germ tube and then a long secondary germ tube that finally differentiated into a hooked appressorium. Chasmothecia were not found. Based on these morphological characteristics, the pathogen was initially identified as B. graminis f. sp. poae, the known forma specialis (f. sp.) of B. graminis on P. pratensis (Braun and Cook 2012; Troch et al. 2014). Mycelia of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method described previously (Zhu et al. 2019). The rDNA internal transcribed spacer (ITS) region was amplified applying primer pairs ITS1/ITS4 (White et al. 1990). The amplicon was cloned and sequenced by Invitrogen (Shanghai, China). The obtained sequence for the pathogen was deposited into GenBank under Accession No. MT892956 and was 100 % identical (549/549 bp) to B. graminis on P. pratensis (AB273530) (Inuma et al. 2007). In addition, the phylogenetic analysis clearly showed that the identified fungus and B. graminis f. sp. poae were clustered in the same branch. To perform pathogenicity analysis, leaf surfaces of eight healthy plants were inoculated by dusting fungal conidia from diseased leaves. Eight non-inoculated plants served as a control. The non-inoculated and inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Twelve to fourteen days after inoculation, B. graminis signs were visible on inoculated leaves, while control plants remained healthy. The pathogenicity assays were repeated twice and showed same results. Therefore, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as B. graminis f. sp. poae. This pathogen has been reported on P. pratensis in Switzerland and Japan (Inuma et al. 2007). This is, to our best knowledge, the first disease note reporting B. graminis on P. pratensis in China. Because the hybridization of B. graminis formae speciales (ff. spp.). allow the pathogens to adapt to new hosts, P. pratensis may serve as a primary inoculum reservoir of B. graminis to threaten other species, including cereal crops (Klingeman et al. 2018; Menardo et al. 2016). In addition, powdery mildew may negatively affect the yield and quality of grasses. Our report expands the knowledge of B. graminis f. sp. poae and provides the fundamental information for future powdery mildew control.

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Effect of Exogenous Siderophores on Iron Uptake Activity of Marine Bacteria under Iron-Limited Conditions

Applied and Environmental Microbiology ◽

10.1128/aem.67.4.1710-1717.2001 ◽

2001 ◽

Vol 67 (4) ◽

pp. 1710-1717 ◽

Cited By ~ 52

Author(s):

Le Luo Guan ◽

Kaneo Kanoh ◽

Kei Kamino

Keyword(s):

Membrane Protein ◽

Outer Membrane ◽

Marine Bacteria ◽

Outer Membrane Protein ◽

Iron Uptake ◽

Culture Medium ◽

Paper Electrophoresis ◽

Marine Sponges ◽

First Report ◽

Uptake Activity

ABSTRACT More than 60% of species examined from a total of 421 strains of heterotrophic marine bacteria which were isolated from marine sponges and seawater were observed to have no detectable siderophore production even when Fe(III) was present in the culture medium at a concentration of 1.0 pM. The growth of one such non-siderophore-producing strain, alpha proteobacterium V0210, was stimulated under iron-limited conditions with the addition of an isolated exogenous siderophore,N,N′-bis (2,3-dihydroxybenzoyl)-O-serylserine from aVibrio sp. Growth was also stimulated by the addition of three exogenous siderophore extracts from siderophore-producing bacteria. Radioisotope studies using 59Fe showed that the iron uptake ability of V0210 increased only with the addition of exogenous siderophores. Biosynthesis of a hydroxamate siderophore by V0210 was shown by paper electrophoresis and chemical assays for the detection of hydroxamates and catechols. An 85-kDa iron-regulated outer membrane protein was induced only under iron-limited conditions in the presence of exogenous siderophores. This is the first report of bacterial iron uptake through an induced siderophore in response to exogenous siderophores. Our results suggest that siderophores are necessary signaling compounds for growth and for iron uptake by some non-siderophore-producing marine bacteria under iron-limited conditions.

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First Report of Sclerotinia homoeocarpa from the Sedge Trichophorum cespitosum in Eastern Canada, Which Causes Dollar Spot Disease on Lolium perenne and Poa pratensis but not on Agrostis stolonifera

Plant Disease ◽

10.1094/pdis-07-13-0703-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 161-161 ◽

Cited By ~ 1

Author(s):

T. Hsiang ◽

F. Shi ◽

A. Darbyson

Keyword(s):

Lolium Perenne ◽

Poa Pratensis ◽

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Eastern Canada ◽

First Report ◽

Spot Disease ◽

River Region

Sclerotinia homoeocarpa is a fungal pathogen that causes dollar spot disease on more than 40 plant species, mostly in the family Poaceae (1), and is considered the most widespread pathogen of golf course turfgrasses in the St. Lawrence River Region. In June 2011, lesions were observed on tufted bulrush, Trichophorum cespitosum (Poales, Cyperaceae), on the sea shore near Peggys Cove, Nova Scotia, Canada. Single bunches had up to 40% of the leaves affected. The foliar symptoms resembled large hourglass lesions, up to 5 cm long, with a straw colored portion capped at two ends by dark zone lines on surrounding green foliar tissue. Leaf segments were taken, surface sterilized, and placed on potato dextrose agar (PDA). After 3 days of incubation at room temperature, white fluffy mycelia covered the entire petri dish. Brown columnar structures formed in the colony centers after 7 days and cultures became cinnamon colored after 14 days. Dark brown or black substratal stroma were formed on or in the agar, and cultures appeared dark brown from the bottom. DNA was extracted and amplified using primers ITS1 and ITS4 (2), and the amplicon sequenced (GenBank Accession No. KF447776). The sequence showed a top match of 522/524 bp identity with the ITS of an isolate of S. homoeocarpa, with the next 40 top matches also identified as S. homoeocarpa. Two-week-old seedlings of Agrostis stolonifera cv. Penncross, Poa pratensis cv. Touchdown, and Lolium perenne cv. Express were inoculated by placing 5-mm-diameter mycelial plugs from 5-day-old PDA cultures onto the leaves of plants grown in small containers, and incubating under enclosed humid conditions throughout the test. White aerial hyphae on the leaves and straw-colored leaf lesions were observed by 7 days after inoculation on P. pratensis and L. perenne, but no lesions or hyphal growth were observed on A. stolonifera. No signs or symptoms were observed on leaves where sterile agar plugs were used as inoculum. These tests were repeated three times with the same results, and a positive control was included by using an S. homoeocarpa isolate known to be pathogenic to A. stolonifera under the same test conditions. Disease was observed on A. stolonifera with the control isolate. S. homoeocarpa was re-isolated from the lesions on P. pratensis and L. perenne to satisfy Koch's postulates. To the best of our knowledge, this is the first report of S. homoeocarpa on T. cespitosum worldwide, an isolate that was found to cause disease on P. pratensis and L. perenne, but was not pathogenic to A. stolonifera in vitro. The original host was not used in pathogenicity tests because it is considered an endangered species in many locations. References: (1) B. Walsh et al. HortScience 34:13, 1999. (2) T. J. White et al. PCR protocols, a guide to methods and applications 18:315, 1990.

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First Report of Pratylenchus fallax on Turfgrass in Ontario

Plant Disease ◽

10.1094/pdis.1997.81.11.1331a ◽

1997 ◽

Vol 81 (11) ◽

pp. 1331-1331

Author(s):

Q. Yu ◽

J. W. Potter ◽

G. A. Gilby

Keyword(s):

Main Type ◽

Poa Pratensis ◽

Secondary Infection ◽

Mature Female ◽

Parasitic Nematodes ◽

Golf Courses ◽

Plant Parasitic Nematodes ◽

First Report ◽

Corn Roots ◽

Significant Damage

During 1995 and 1997 surveys of golf courses throughout southern Ontario for plant parasitic nematodes, one Pratylenchus sp. with a heavily sclerotized cephalic area, lip region with three annules, females with spermatheca full of sperms, and crenate tail was found in 13 of 14 soil samples taken from fairways. Males were also found in the samples. Monoxenic cultures of the nematode were established on excised corn roots, each culture started from a single mature female. In cultures, males were common, averaging about one male per five females. Following a comparative microscope study of about 50 specimens (20 measured), the species was identified as Pratylenchus fallax Seinhorst, 1968. Bluegrass (Poa pratensis L.) was the main type of grass in the fairways surveyed. P. fallax may cause significant damage to turfgrass by directly destroying the roots, and the wounded roots become vulnerable to secondary infection by soilborne pathogens (1). The nematode has been found once in Quebec, Canada, in 1976 (2). This is the first report of Pratylenchus fallax in Ontario. References: (1) S. G. Fushtey and F. D. McElroy. Can. Plant Dis. Surv. 57:54, 1977. (2) P. W. Willis et al. Plant Dis. Rep. 60:207, 1976.

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Germ-tube production by Candida albicans in minimal liquid culture media

Canadian Journal of Microbiology ◽

10.1139/m71-137 ◽

1971 ◽

Vol 17 (7) ◽

pp. 851-856 ◽

Cited By ~ 19

Author(s):

D. N. Mardon ◽

I. S. K. Hurst ◽

E. Balish

Keyword(s):

Candida Albicans ◽

Butyric Acid ◽

Germ Tube ◽

Culture Medium ◽

Culture Media ◽

Tube Formation ◽

Gamma Amino Butyric Acid ◽

Tube Production ◽

Amino Butyric Acid ◽

Germ Tubes

Candida albicans formed germ tubes within 3 h at 37C in a glucose–salts–biotin (GSB) medium containing L-alpha-amino-n-butyric acid as the nitrogen source. Optimal germ-tube production was obtained when the inoculum was grown on Sabouraud dextrose agar. The GSB medium containing L-alpha-amino-n-butyric acid promoted germ-tube formation more effectively than GSB medium plus gamma-amino-butyric acid or Sabouraud dextrose broth.Carbon-14 incorporation studies revealed that during germ-tube formation (0–4 h) the 3 carbon of alpha-amino-n-butyric acid was incorporated intracellularly to a greater extent than the 1 carbon. However, during blastospore formation (5–16 h), this difference was less pronounced.When six other Candida species were grown in GSB plus L-alpha-amino-n-butyric acid medium, few germ tubes were observed with the exception of one Candida stellatoidea strain. However, even this strain of C. stellatoidea produced far fewer germ tubes in this minimal culture medium than any strain of C. albicans tested.

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First Report on Resistance to Pyraclostrobin, Thiophanate-methyl, Fenhexamid and Boscalid in Botrytis cinerea from Eucalyptus Seedlings in Florida Greenhouses

Plant Disease ◽

10.1094/pdis-10-13-1107-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 851-851 ◽

Cited By ~ 6

Author(s):

A. Amiri ◽

A. I. Zuniga ◽

J. Mertely ◽

N. A. Peres

Keyword(s):

Botrytis Cinerea ◽

Germ Tube ◽

Crop Protection ◽

Malt Extract ◽

Thiophanate Methyl ◽

First Report ◽

Research Triangle ◽

Extract Agar ◽

Bayer Cropscience ◽

Syngenta Crop Protection

Botryotinia fuckeliana de Bary (anamorph Botrytis cinerea Pers.) is an ubiquitous plant pathogen causing gray mold disease on more than 200 crops grown in the field or in greenhouses. Eucalyptus seedlings originating from three different greenhouses showing stem lesions were submitted to the Gulf Coast Research and Education Center Disease Clinic in June 2012. Ten single spore isolates of B. cinerea were obtained and tested for sensitivity using spore germination and germ tube elongation assays described previously (4). Fungicides tested were pyraclostrobin at 100 μg/ml (Cabrio, BASF, Research Triangle Park, NC), thiophanate-methyl at 100 μg/ml (Topsin-M, UPI, King of Prussia, PA), fenhexamid at 1 and 50 μg/ml (Elevate, Arysta Life Sciences, Cary, NC), fludioxonil at 0.1 and 10 μg/ml (Medallion, Syngenta Crop Protection, Research Triangle Park, NC), and iprodione at 5 and 50 μg/ml (Rovral, Bayer CropScience, Greensboro, NC) on 1% malt extract agar (MEA, 10 g malt extract and 15 g agar), and to cyprodinil at 1 and 25 μg/ml (Vanguard, Syngenta Crop Protection) on 0.5% sucrose agar (4). Sensitivity to the succinate dehydrogenase inhibitors (SDHIs) boscalid at 5 μg/ml (Endura, BASF), penthiopyrad at 1 and 3 μg/ml (Fontelis, DuPont Crop Protection, Willington, DE), and fluopyram at 3 μg/ml (Luna Privilege, Bayer CropScience) was evaluated on yeast bacto acetate agar (YBA) (3). The discriminatory dose for boscalid was adapted from (2) whereas those used for penthiopyrad and fluopyram were developed in this study. Isolates were grown on malt yeast extract agar for 7 to 10 days and spore suspensions were prepared in sterile distilled water and diluted to 106 conidia/ml. Respective media in 9-cm petri dishes were seeded with 7-μl droplets from each isolate allowing testing for all isolates on one plate. Two plates were used for each fungicide and sensitivity tests were repeated twice. Germination and germ tube growth were assessed microscopically after 16 to 24 h incubation at 22°C. The frequency of isolates resistant to two, three, and four fungicides was 90, 60, and 10%, respectively. Nine isolates (90%) were resistant to thiophanate-methyl and pyraclostrobin, simultaneously, whereas six (60%) and two isolates (20%) were resistant to boscalid and fenhexamid, respectively. All boscalid-resistant isolates were also resistant to pyraclostrobin and thiophanate-methyl, but one fenhexamid-resistant isolate was sensitive to the other three fungicides. Eight isolates that germinated at 5 μg/ml iprodione but not at 50 μg/ml were considered sensitive. All isolates were sensitive to the SDHIs penthiopyrad and fluopyram as well as to cyprodinil and fludioxonil. To our knowledge, this is the first report of resistance to pyraclostrobin, thiophanate-methyl, fenhexamid, and boscalid in B. cinerea from eucalyptus seedlings in Florida. The absence of resistance to fludioxonil and iprodione is likely because these fungicides are not registered in nurseries as well as fluopyram and penthiopyrad which were developed only recently. Management practices should be developed to limit the selection and spread of additional resistant populations in eucalyptus nurseries as has occurred in Florida strawberries where multi-fungicide resistance is widespread (1). References: (1) A. Amiri et al. Plant Dis. 97:393, 2013. (2) M. Leroch et al. Appl. Environ. Microbiol. 79:159, 2013. (3) G. Stammler and J. Speakman. J. Phytopathol. 154:508, 2006. (4) R. W. S. Weber and M. Hahn. J. Plant Dis. Prot. 118:17, 2011.

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First Report of Leaf blight of Poa pratensis Caused by Peyronellaea glomerata in China

Plant Disease ◽

10.1094/pdis-08-15-0954-pdn ◽

2016 ◽

Vol 100 (4) ◽

pp. 862 ◽

Cited By ~ 2

Author(s):

C.-D. Yang ◽

Y.-L. Yao ◽

Z.-F. Zhang ◽

L. Xue

Keyword(s):

Poa Pratensis ◽

Leaf Blight ◽

First Report

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First Report of Powdery Mildew Caused by Erysiphe heraclei on Chervil in California

Plant Disease ◽

10.1094/pdis.2004.88.10.1163a ◽

2004 ◽

Vol 88 (10) ◽

pp. 1163-1163

Author(s):

S. T. Koike ◽

G. S. Saenz

Keyword(s):

Powdery Mildew ◽

Host Range ◽

Germ Tube ◽

Apium Graveolens ◽

Petroselinum Crispum ◽

First Report ◽

Tube Forming ◽

Disease Impact ◽

Symptoms And Signs ◽

Culinary Herb

Chervil (Anthriscus cerefolium) is a culinary herb in the Apiaceae family that is grown commercially in California. In 2003 and 2004, shade house plantings of chervil in central coastal California exhibited symptoms and signs of a powdery mildew disease. White, epiphytic mycelia and conidia were present on petioles and leaves. Severely affected leaflets became slightly twisted and bent. Mycelium was amphigenous and effused or in patches. Hyphae measured 5.0 to 7.5 μm in diameter and had lobed appressoria. Conidiophores were straight and had cylindric foot cells measuring 25.0 to 37.5 × 7.5 to 10.0 μm, followed by a longer cell and one to two shorter cells. Conidia formed singly, were cylindric, and measured (37.5-) 40.0 to 50.0 (-52.5) × 15.0 to 17.5 μm. Conidia lacked fibrosin bodies and germinated at the ends with either a very short or a long germ tube forming a lobed appressorium (Polygoni type). No cleistothecia were observed. On the basis of these characteristics, the fungus was identified as Erysiphe heraclei (1). To confirm pathogenicity, severely colonized chervil leaves from a commercial nursery were gently pressed onto leaves of potted chervil plants. Plants were then maintained in a greenhouse (22 to 24°C). After 10 to 12 days, signs of powdery mildew developed on the foliage of inoculated plants, and the pathogen morphology matched that of the originally observed pathogen. Noninoculated control plants did not develop powdery mildew. To investigate the host range of this chervil isolate, parsley (Petroselinum crispum) and celery (Apium graveolens) plants were inoculated in the same way as described. However, after more than 3 weeks, no powdery mildew developed on these two Apiaceae plants. Control chervil plants again developed the disease. To our knowledge, this is the first report of powdery mildew of chervil caused by E. heraclei in California. Disease impact was severe, and in some cases, chervil crops were not harvested. The inability of the chervil isolate to infect two other Apiaceae plants that are listed as hosts of E. heraclei indicates that this pathogen may consist of strains having different host ranges. Reference: (1) U. Braun. Nova Hedwigia 89:1, 1987.

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STUDIES ON THE CHITAN (CHITIN: POLY-N-ACETYLGLUCOSAMINE) FIBERS OF THE DIATOM THALASSIOSIRA FLUVIATILIS HUSTEDT: I PRODUCTION AND ISOLATION OF CHITAN FIBERS

Canadian Journal of Botany ◽

10.1139/b65-079 ◽

1965 ◽

Vol 43 (6) ◽

pp. 707-713 ◽

Cited By ~ 91

Author(s):

J. McLachlan ◽

A. G. McInnes ◽

Michael Falk

Keyword(s):

Crystalline State ◽

Culture Medium ◽

Cellular Material ◽

Subsequent Paper ◽

Electron Microscopic ◽

First Report

Growth of the planktonic, euryhaline diatom (Bacillariophyceae) Thalassiosira fluviatilis, both in nature and in culture, is accompanied by the production of a large amount of extracellular "mucilage". This mucilagenous condition is due to the formation of long, narrow fibers, composed of a number of microfibrils, which originate from the marginal and central pores in the silica valves. These fibers, previously referred to as mucilage or slime threads, were found upon hydrolysis to be composed entirely of glucosamine residues. Evidence will be presented in a subsequent paper (20) to show that these fibers consist entirely of pure, crystalline poly-N-acetyl-D-glucosamine linked by β-(1→4) bonds. This polymer has been given the systematic name chitan to distinguish it from chitin as isolated from other sources. This is the first report of the occurrence of this glycan in diatoms, and in a pure crystalline state in nature. The chitan was localized in the extracellular fibers, and was not found as part of the protoplasmic constituents. Approximately 18% of the nitrogen added to the culture medium was incorporated into the chitan fibers, which, in turn, comprised 31–38% of the cellular material (including the silica) of this diatom. Methods of production and isolation of the fibers are described, together with a discussion of the nature of the fibers as derived from light and electron microscopic observations. The presence of chitin in other algae also is discussed.

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