Variable adhesion and diurnal population patterns of epiphytic yeasts on creeping bentgrass

2006 ◽  
Vol 52 (5) ◽  
pp. 404-410 ◽  
Author(s):  
Tom W Allen ◽  
Leon L Burpee ◽  
James W Buck
Keyword(s):  
Creeping Bentgrass ◽  
Field Trials ◽  
Agrostis Palustris ◽  
Initial Field ◽  
Vitro Assay ◽  
Yeast Community ◽  
Epiphytic Yeast ◽  
Nonadherent Cells ◽  
Total Yeast

Irrigation and an in vitro agitation assay were used to determine the percentage of the epiphytic yeast community (Cryptococcus, Pseudozyma, Rhodotorula, and Sporobolomyces) adhering to the phylloplane of creeping bentgrass (Agrostis palustris (Huds.) Pers.). Colony-forming units (cfu) of total epiphytic yeast populations (adherent and nonadherent cells) and of adherent populations (cells not removed by agitation) were determined by leaf washing and dilution plating. In an in vitro assay, 40.0% and 57.1% of the yeast adhered to the leaves, whereas, in initial field trials the percentage of adherent yeasts ranged from 40.0% to 71.9% of the total population. Adherent yeast cfu on leaves in the morning were significantly lower on bentgrass (8.0 × 103to 3.1 × 104cfu·cm–2) compared with total yeast cfu (1.4 × 104to 4.7 × 104cfu·cm–2) on the nonirrigated control. No differences in yeast populations were observed between irrigated and nonirrigated plots 2 h after the 0900 treatments. Yeast populations followed a diurnal pattern, with larger cfu recovered from bentgrass leaves in the morning and significantly lower populations recovered in the afternoon. At 1400 the adherent yeast were 83.1%–100% of the total yeast population recovered from the leaves. The relative adhesiveness of the epiphytic yeast community on bentgrass leaves is dynamic with nonadherent cells making up a larger percentage of the population in the mornings than the afternoons.Key words: adherence, Cryptococcus, leaf surface, Rhodotorula, turfgrass.

Effect of foliar disease on the epiphytic yeast communities of creeping bentgrass and tall fescue

2004 ◽  
Vol 50 (10) ◽  
pp. 853-860 ◽  
Author(s):  
Tom W Allen ◽  
Habib A Quayyum ◽  
Leon L Burpee ◽  
James W Buck
Keyword(s):  
Tall Fescue ◽  
Rhodotorula Glutinis ◽  
Creeping Bentgrass ◽  
Cryptococcus Laurentii ◽  
Mechanical Wounding ◽  
Community Size ◽  
Foliar Disease ◽  
Yeast Community ◽  
Epiphytic Yeast ◽  
Total Yeast

The effect of mechanical wounding or foliar diseases caused by Sclerotinia homoeocarpa or Rhizoctonia solani on the epiphytic yeast communities on creeping bentgrass and tall fescue were determined by leaf washing and dilution plating. Total yeast communities on healthy bentgrass and tall fescue leaves ranged from 7.9 × 103 to 1.4 × 105 CFU·cm–2 and from 2.4 × 103 to 1.6 × 104 CFU·cm–2, respectively. Mechanically wounded leaves (1 of 2 trials) and leaves with disease lesions (11 of 12 trials) supported significantly larger communities of phylloplane yeasts. Total yeast communities on S. homoeocarpa infected or R. solani infected bentgrass leaves were 3.6–10.2 times and 6.2–6.4 times larger, respectively, than the communities on healthy leaves. In general, healthy and diseased bentgrass leaves supported larger yeast communities than healthy or diseased tall fescue leaves. We categorized the majority of yeasts as white-pigmented species, including Cryptococcus laurentii, Cryptococcus flavus, Pseudozyma antarctica, Pseudozyma aphidis, and Pseudozyma parantarctica. The percentage of pink yeasts in the total yeast community ranged from 2.6% to 9.9% on healthy leaves and increased to 32.0%–44.7% on S. homoeocarpa infected leaves. Pink-pigmented yeasts included Rhodotorula glutinis, Rhodotorula mucilaginosa, Sakaguchia dacryoidea, and Sporidiobolus pararoseus. Foliar disease significantly affected community size and composition of epiphytic yeasts on bentgrass and tall fescue.Key words: dollar spot, phylloplane, Rhizoctonia blight.

The effects of fungicides on the phylloplane yeast populations of creeping bentgrass

2002 ◽  
Vol 48 (6) ◽  
pp. 522-529 ◽  
Author(s):  
James W Buck ◽  
Leon L Burpee
Keyword(s):  
Biological Control ◽  
Population Size ◽  
Fungicide Resistance ◽  
Creeping Bentgrass ◽  
Potato Dextrose Agar ◽  
Agrostis Palustris ◽  
Biological Control Agents ◽  
Yeast Flora ◽  
Phylloplane Yeasts ◽  
Total Yeast

The effects of fungicides on population size and the development of fungicide resistance in the phylloplane yeast flora of bentgrass was investigated. In the spring of 2001, azoxystrobin, chlorothalonil, flutolanil, and propiconazole were applied separately over a 6-week period to creeping bentgrass (Agrostis palustris Huds.). Total and fungicide-resistant yeast populations were assessed by dilution plating onto either potato dextrose agar or potato dextrose agar amended with the test fungicides. Total yeast populations in the fungicide- treated plots were significantly lower than the check plots on three out of four sample dates. In the fall, azoxystrobin or propiconazole were applied twice to the bentgrass over 3 weeks. Significantly larger total yeast populations were observed compared with resistant or highly resistant populations for each treatment on every sample date. Total yeast populations were significantly higher in the check plots compared with either the propiconazole- or azoxystrobin-treated plots on the first three of five sample dates. A collection of yeasts (N = 114) with no prior exposure to fungicides were more sensitive to chlorothalonil, propiconazole, flutolanil, and iprodione than a second group (N = 115) isolated from fungicide-treated turfgrass. These results suggest that fungicide resistance among phylloplane yeasts is widespread and could be an important factor in the development of biological control agents for turfgrass diseases.Key words: yeast, biological control, fungicide, resistance, phylloplane.

Prevention of fungal diseases in transgenic, bialaphos- and glufosinate-resistant creeping bentgrass (Agrostis palustris)

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Chien-An Liu ◽  
Heng Zhong ◽  
Joseph Vargas ◽  
Donald Penner ◽  
Mariam Sticklen
Keyword(s):  
Antifungal Activity ◽  
Fungal Pathogens ◽  
Creeping Bentgrass ◽  
Inhibitory Effect ◽  
Sclerotinia Homoeocarpa ◽  
Agrostis Palustris ◽  
Symptomatic Infection ◽  
Simultaneous Control ◽  
In Vitro Antifungal Activity

The antifungal activity of the herbicides bialaphos and glufosinate, the active moiety of bialaphos, was assessed. Bialaphos showed a higher level of in vitro antifungal activity againstRhizoctonia solani, Sclerotinia homoeocarpa, andPythium aphanidermatumthan glufosinate. Glufosinate suppressed the mycelial growth ofR. solaniandS. homoeocarpa, but it had no inhibitory effect onP. aphanidermatumup to the highest concentration in our testing regimes. Various concentrations of bialaphos solutions were applied to transgenic, bialaphos- and glufosinate-resistant creeping bentgrass inoculated with fungal pathogens. Bialaphos applications were able to significantly reduce symptomatic infection byR. solaniandS. homoeocarpaon transgenic plants. Bialaphos significantly inhibitedP. aphanidermatum, but not to the same degree thatR. solaniandS. homoeocarpawere inhibited. These results indicate that bialaphos may provide a means for the simultaneous control of weeds and fungal pathogens in turf areas with transgenic, bialaphos-resistant creeping bentgrass.

scholarly journals Potential of Nano-Formulated Zinc Oxide for Control of Citrus Canker on Grapefruit Trees

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2442-2447 ◽  
Author(s):  
J. H. Graham ◽  
E. G. Johnson ◽  
M. E. Myers ◽  
M. Young ◽  
P. Rajasekaran ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Zinc Oxide ◽  
Cuprous Oxide ◽  
Citrus Canker ◽  
Field Trials ◽  
Vitro Assay ◽  
Canker Disease ◽  
Nano Zinc Oxide

Antimicrobial activity of experimental formulations of two structurally different nano-zinc oxide materials, plate-like Zinkicide SG4 and particulate Zinkicide SG6, was evaluated against Xanthomonas citri subsp. citri, the cause of citrus canker. In vitro assay demonstrated Zinkicide SG4 had a twofold lower minimum inhibitory concentration (MIC) against Escherichia coli and X. alfalfae subsp. citrumelonis (62.5 to 250 µg/ml) compared with copper sulfate (250 µg/ml), copper hydroxide (250 to 500 µg/ml), or cuprous oxide/zinc oxide (125 to 250 µg/ml). Zinkicide SG6 had a sevenfold to eightfold lower MIC against Escherichia coli and X. alfalfae subsp. citrumelonis (31 to 250 μg/ml). Leaves of sweet orange (Citrus sinensis) and fruit of ‘Ruby Red’ grapefruit (C. paradisi) were evaluated for citrus canker disease control. A greenhouse assay with foliage demonstrated that spray treatment with Zinkicide reduced citrus canker lesion development after injection-infiltration of X. citri subsp. citri into the leaf intercellular space. In field trials conducted in Southeast Florida in 2014 and 2015, Zinkicide SG4 and SG6 reduction of grapefruit canker incidence exceeded that of cuprous oxide and cuprous oxide/zinc oxide bactericides. Zinkicide formulations were also effective against the fungal diseases, citrus scab (Elsinoe fawcetti) and melanose (Diaporthe citri), on grapefruit. No sign of phytotoxicity to the fruit rind was observed during either season. Antimicrobial activity of Zinkicide for protection of leaves and fruit against X. citri subsp. citri was comparable or exceeded that for commercial copper and zinc oxide formulations which may be attributed to translaminar movement of Zinkicide.

scholarly journals The effect of monocytes in the peripheral blood CFU-C assay system

Blood ◽  
1983 ◽  
Vol 62 (1) ◽  
pp. 112-117 ◽  
Author(s):  
LB To ◽  
DN Haylock ◽  
CA Juttner ◽  
RJ Kimber
Keyword(s):  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Assay System ◽  
Cellular Interaction ◽  
Cellular Interactions ◽  
Peripheral Blood Mononuclear ◽  
Vitro Assay ◽  
Myeloid Progenitor Cells ◽  
Nonadherent Cells

The effect of cellular interactions in the in vitro assay of myeloid progenitor cells in peripheral blood (PB CFU-C) was investigated. Ficoll-Paque-separated peripheral blood mononuclear cells (PB MNC) from 7 healthy subjects were cultured at cell concentrations from 10 to 0.625 X 10(5) MNC/plate in doubling dilutions. The number of colonies per 10(6) lymphocytes plated (corrected colony count, CC) was significantly higher when 2.5 X 10(5) or less PB MNC were cultured than when 5 or 10 X 10(5) cells were cultured. This decrease in CC when large numbers of cells were cultured was not present when the nonadherent cells only were cultured. The inhibition was reproduced when adherent cells were added back to the nonadherent cells. The inhibition appeared to be proportional to the number of monocytes present. A model depicting the role of monocytes in the PB CFU-C assay system is presented. The increased understanding of cellular interaction represents an important step towards the standardization of the PB CFU-C assay.

Timing and Efficacy of Fungicide Applications for Diplodia Ear Rot Management in Corn

2015 ◽  
Vol 16 (3) ◽  
pp. 123-131 ◽  
Author(s):  
Martha P. Romero Luna ◽  
Kiersten A. Wise
Keyword(s):  
Fungal Growth ◽  
The United States ◽  
Field Trials ◽  
Individual Growth ◽  
Growth Stages ◽  
Ear Rot ◽  
Management Options ◽  
Vitro Assay ◽  
Stenocarpella Maydis

Diplodia ear rot, a corn (Zea mays L.) disease caused by the fungus Stenocarpella maydis (Berk.) B. Sutton, has been a persistent ear rot across the United States. Management options are currently limited. Field trials conducted under inoculated and non-inoculated conditions were established at two locations in Indiana from 2011 to 2013 to test the fungicides azoxystrobin plus propiconazole and prothioconazole against Diplodia ear rot. Fungicides were applied at three individual growth stages during each year. Fungicides did not consistently reduce Diplodia ear rot compared to non-fungicide-treated controls in any year. Applications also did not consistently increase yield at any timing under inoculated and non-inoculated plots compared with the non-fungicidetreated control. Fungicides were tested in an in vitro assay to determine the effective fungicide concentration at which 50% of mycelial growth or conidial germination of S. maydis was inhibited (EC50). Propiconazole and prothioconazole EC50 values indicated efficacy in reducing fungal growth under controlled conditions; however, current fungicide application methods and plant barriers to fungicide contact with the pathogen may prevent these products from effectively reducing Diplodia ear rot in a field setting. Accepted for publication 23 August 2015. Published 1 September 2015

scholarly journals Assessment of Azithromycin in Combination with Other Antimalarial Drugs against Plasmodium falciparum In Vitro

2002 ◽  
Vol 46 (8) ◽  
pp. 2518-2524 ◽  
Author(s):  
Colin Ohrt ◽  
George D. Willingmyre ◽  
Patricia Lee ◽  
Charles Knirsch ◽  
Wilbur Milhous
Keyword(s):  
Plasmodium Falciparum ◽  
Single Agent ◽  
In Vitro Study ◽  
Field Trials ◽  
Multidrug Resistant ◽  
Malaria Treatment ◽  
Malaria Prophylaxis ◽  
Initial Field ◽  
Antimalarial Agents

ABSTRACT Initial field malaria prophylaxis trials with azithromycin revealed insufficient efficacy against falciparum malaria to develop azithromycin as a single agent. The objective of this in vitro study was to determine the best drug combination(s) to evaluate for future malaria treatment and prophylaxis field trials. In vitro, azithromycin was tested in combination with chloroquine against 10 representative Plasmodium falciparum isolates. Azithromycin was also assessed in combination with eight additional antimalarial agents against two or three multidrug-resistant P. falciparum isolates. Parasite susceptibility testing was carried out with a modification of the semiautomated microdilution technique. The incubation period was extended from the usual 48 h to 68 h. Fifty percent inhibitory concentrations (IC50s) were calculated for each drug alone and for drugs in fixed combinations of their respective IC50s (1:1, 3:1, 1:3, 4:1, 1:4, and 5:1). These data were used to calculate fractional inhibitory concentrations and isobolograms. Chloroquine-azithromycin studies revealed a range of activity from additive to synergistic interactions for the eight chloroquine-resistant isolates tested, while an additive response was seen for the two chloroquine-sensitive isolates. Quinine, tafenoquine, and primaquine were additive to synergistic with azithromycin, while dihydroartemisinin was additive with a trend toward antagonism. The remaining interactions appeared to be additive. These results suggest that a chloroquine-azithromycin combination should be evaluated for malaria prophylaxis and that a quinine-azithromycin combination should be evaluated for malaria treatment in areas of drug resistance.

scholarly journals The effect of monocytes in the peripheral blood CFU-C assay system

Blood ◽  
1983 ◽  
Vol 62 (1) ◽  
pp. 112-117 ◽  
Author(s):  
LB To ◽  
DN Haylock ◽  
CA Juttner ◽  
RJ Kimber
Keyword(s):  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Assay System ◽  
Cellular Interaction ◽  
Cellular Interactions ◽  
Peripheral Blood Mononuclear ◽  
Vitro Assay ◽  
Myeloid Progenitor Cells ◽  
Nonadherent Cells

Abstract The effect of cellular interactions in the in vitro assay of myeloid progenitor cells in peripheral blood (PB CFU-C) was investigated. Ficoll-Paque-separated peripheral blood mononuclear cells (PB MNC) from 7 healthy subjects were cultured at cell concentrations from 10 to 0.625 X 10(5) MNC/plate in doubling dilutions. The number of colonies per 10(6) lymphocytes plated (corrected colony count, CC) was significantly higher when 2.5 X 10(5) or less PB MNC were cultured than when 5 or 10 X 10(5) cells were cultured. This decrease in CC when large numbers of cells were cultured was not present when the nonadherent cells only were cultured. The inhibition was reproduced when adherent cells were added back to the nonadherent cells. The inhibition appeared to be proportional to the number of monocytes present. A model depicting the role of monocytes in the PB CFU-C assay system is presented. The increased understanding of cellular interaction represents an important step towards the standardization of the PB CFU-C assay.

Use of TEM in Plant Disease Diagnosis: A Xylem-Limited Bacterium Associated with Diseased ‘Toronto’ Creeping Bentgrass

1981 ◽  
Vol 39 ◽  
pp. 414-415
Author(s):  
Karen K. Baker ◽  
David L. Roberts
Keyword(s):  
Osmium Tetroxide ◽  
Plant Disease ◽  
Leaf Tissue ◽  
Infectious Agent ◽  
Creeping Bentgrass ◽  
Disease Diagnosis ◽  
Unknown Etiology ◽  
Agrostis Palustris ◽  
Putting Greens ◽  
Plant Disease Diagnosis

Plant disease diagnosis is most often accomplished by examination of symptoms and observation or isolation of causal organisms. Occasionally, diseases of unknown etiology occur and are difficult or impossible to accurately diagnose by the usual means. In 1980, such a disease was observed on Agrostis palustris Huds. c.v. Toronto (creeping bentgrass) putting greens at the Butler National Golf Course in Oak Brook, IL.The wilting symptoms of the disease and the irregular nature of its spread through affected areas suggested that an infectious agent was involved. However, normal isolation procedures did not yield any organism known to infect turf grass. TEM was employed in order to aid in the possible diagnosis of the disease.Crown, root and leaf tissue of both infected and symptomless plants were fixed in cold 5% glutaraldehyde in 0.1 M phosphate buffer, post-fixed in buffered 1% osmium tetroxide, dehydrated in ethanol and embedded in a 1:1 mixture of Spurrs and epon-araldite epoxy resins.

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