Rate of Disease Development in Eucalyptus sieberi Growing in Suppressive Soils Inoculated With Phytophthora cinnamomi

1985 ◽  
Vol 33 (2) ◽  
pp. 159 ◽  
Author(s):  
GC Marks ◽  
IW Smith
Keyword(s):  
Post Infection ◽  
Phytophthora Cinnamomi ◽  
Inoculum Density ◽  
Disease Development ◽  
The Core ◽  
Development Rates ◽  
Core Soil ◽  
Compound Interest ◽  
Root Collar

The rate at which root collar infection, caused by Phytophthora cinnamomi Rands, developed in Eucalyptus sieberi L. Johnson was tested by growing 40, 6-month-old seedlings in cores of disease- suppressive (DSS) krasnozem-type soil that had either been treated or not treated with steam. The core soil was inoculated by repotting the seedlings in a jacket of steamed or unsteamed sand or krasnozem that had been mixed with a mycelium-chlamydospore suspension. Disease development was of the compound interest type (sens. Van der Plank) and was slower in unsteamed DSS core soils. Inoculum density (ID) increased more than 10 times at the end of all tests, and the time taken for collar infection to appear was shortened when the inoculum was mixed with unsteamed DSS. The fungus was isolated more frequently from the collar of seedlings growing in steam-treated than in unsteamed DSS. The results showed that the soil used was only mildly disease-suppressive and suggest that post- infection antagonism may be the cause of slower disease development rates in DSS. Introduction

The core soil bacterial genera and enzyme activities in incubated soils from century-old wheat rotations

Geoderma ◽  
2021 ◽  
Vol 404 ◽  
pp. 115275
Author(s):  
Newton Z. Lupwayi ◽  
H. Henry Janzen ◽  
Eric Bremer ◽  
Elwin G. Smith ◽  
Derrick A. Kanashiro ◽  
...  
Keyword(s):  
Enzyme Activities ◽  
The Core ◽  
Soil Bacterial ◽  
Core Soil

Development of Phytophthora cinnamomi Infection in Roots of Eucalypt Species Growing in a Soil That Suppresses Phytophthora Root Disease

1983 ◽  
Vol 31 (3) ◽  
pp. 239 ◽  
Author(s):  
GC Marks ◽  
IW Smith
Keyword(s):  
Inner Core ◽  
Phytophthora Cinnamomi ◽  
Sandy Loam ◽  
Seedling Survival ◽  
Genetic Resistance ◽  
Coarse Sand ◽  
Root Disease ◽  
Phenotypic Resistance ◽  
Eucalypt Species ◽  
Core Soil

When Eucalyptus sieberi was grown in either a steamed or unsteamed krasnozem that suppressed Phytophthora cinnamomi root rot and repotted when either 6 or 12 weeks old in a larger container of inoculated sandy loam, seedling survival was significantly greater in the unsteamed treatments. By varying the treatments in the inner core soil and outer inoculum jacket, substituting a biologically inert coarse sand in place of the krasnozem in the core, and using eucalypt species of varying disease tolerance while maintaining very strict hygiene conditions throughout these experiments, it was possible to either demonstrate or deduce that: (a) the seedlings were killed when infection spread into the major roots, root collar and lower stem; (b) the microflora in the unsteamed krasnozem appeared to slow down the decay process within the root, possibly when the fungus was attempting to establish itself within the root; (c) the phenotypic resistance of a seedling to root disease depended, inter alia, on its genetic resistance and on the microflora in the surrounding soil; (d) once the fungus was established in the suberized tissues the microflora in the external environment had no influence on disease.

scholarly journals Inoculum Density-Disease Development Relationship in Verticillium Wilt of Artichoke Caused by Verticillium dahliae

Plant Disease ◽  
2007 ◽  
Vol 91 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
M. Berbegal ◽  
A. Ortega ◽  
J. García-Jiménez ◽  
J. Armengol
Keyword(s):  
Population Dynamics ◽  
Verticillium Dahliae ◽  
Symptom Severity ◽  
Disease Incidence ◽  
Growing Season ◽  
Inoculum Density ◽  
Disease Development ◽  
Growing Seasons ◽  
Negative Exponential ◽  
The Relationship

The relationship between inoculum density of Verticillium dahliae in soil and disease development was studied in 10 commercial artichoke fields. Inoculum density of V. dahliae varied between 2.2 and 34.2 microsclerotia (ms) g–1 of soil near planting. Artichoke plants were monitored for disease at the beginning and the end of each growing season. There was a significant correlation, which was best described by negative exponential models, between inoculum density and disease incidence, symptom severity, and recovery of the pathogen from the plants. Inoculum densities ranging from 5 to 9 ms g–1 of soil were associated with a mean percentage of infected plants of about 50%. Additionally, three fields were monitored in two consecutive growing seasons to evaluate the population dynamics of V. dahliae microsclerotia in soil and disease development. Numbers of microsclerotia per gram of soil decreased significantly by the end of the first growing season but slightly increased at the end of the second growing season. In these fields, symptom severity was greatest during the second growing season when high percentages of infected plants also were recorded.

scholarly journals Pre- and Post-Infection Activity of Pyraclostrobin for Control of Anthracnose Fruit Rot of Strawberry Caused by Colletotrichum acutatum

Plant Disease ◽  
2006 ◽  
Vol 90 (7) ◽  
pp. 862-868 ◽  
Author(s):  
William W. Turechek ◽  
Natália A. Peres ◽  
Nicole A. Werner
Keyword(s):  
New York ◽  
Post Infection ◽  
Field Studies ◽  
Fruit Rot ◽  
Colletotrichum Acutatum ◽  
Disease Development ◽  
Infection Period ◽  
Significant Control ◽  
Infection Treatment ◽  
Control Equivalent

The effect of pre- and post-infection-period applications of pyraclostrobin (Cabrio EG) on the development of anthracnose fruit rot was characterized in a controlled-climate study and validated in field studies in New York and Florida. Plants of the day-neutral cv. Tristar were inoculated with C. acutatum and placed into mist chambers at 14, 22, or 30°C. The plants were removed from the chambers after 3, 6, 12, or 24 h of misting and placed on greenhouse benches to allow disease development. The fungicide pyraclostrobin was applied to the berries at a concentration equivalent to 168 g a.i./ha at 3, 8, 24, and 48 h prior to inoculation and exposure to their wetting period, or 3, 8, 24, and 48 h following inoculation and exposure to their wetting period. All pyraclostrobin treatments suppressed disease compared with the corresponding untreated control treatments. The highest incidence of disease occurred on plants exposed to the longest wetness durations (12 and 24 h) or highest temperature treatments (22 and 30°C). Post-infection applications of pyraclostrobin provided significant control when applications were made within 3 and often up to 8 h after wetting, but generally were less effective than protective sprays. We further tested the ability of pyraclostrobin to control anthracnose when applied as a protectant or as an after-infection application in inoculated field plots exposed to a short (8 h) or long (24 h) wetting period in Florida and in New York. In three of the four experimental plots, disease control equivalent to or better than the protective spray was achieved when pyraclostrobin was applied up to 24 h after infection for long and short wetting periods. In the remaining plot, conditions for disease development were exceptionally favorable. The protective treatment provided approximately 75% control, whereas the best post-infection treatment provided only 50% control. Our study indicates that for short wetting events, such as those associated with seasonal thunderstorms, growers can wait until after such an infection event before applying pyraclos-trobin and achieve control equivalent to a protective application.

Regeneration of Vegetation in the Brisbane Ranges After Fire and Infestation by Phytophthora cinnamomi

1985 ◽  
Vol 33 (1) ◽  
pp. 15 ◽  
Author(s):  
P Dawson ◽  
G Weste ◽  
D Ashton
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Phytophthora Cinnamomi ◽  
Basal Area ◽  
First Record ◽  
Inoculum Density ◽  
Crown Cover ◽  
Bush Fire ◽  
Crown Density ◽  
Sclerophyll Forest

The distribution, population density and regeneration of some prominent spp. of understorey and overstorey (dominant Eucalyptus spp.) were monitored over a period of 20 yr in seasonally well drained dry sclerophyll forest. Changes varied with susceptibility to the pathogen and to fire. Changes in spp. composition and crown density of the overstorey were attributed to fire. Population density, basal area and crown cover of the Eucalyptus spp. which were associated with the pathogen, also declined in 1962-82. Both distribution and population density of Xanthorrhoea australis and Isopogon ceratophyllus declined markedly following the spread of infestation, whereas those of Hakea sericea and Lepidosperma semiteres increased. Regeneration of X. australis but not of I. Ceratophyllus was observed in certain areas of the infested plots 12-20 years after infection. This is the first record of such regeneration. It is postulated that a bush fire in 1967 both stimulated X. australis seed production and reduced further an already declining pathogen inoculum density.

scholarly journals Quantitative Modeling of the Effects of Temperature and Inoculum Density of Fusarium oxysporum f. sp. ciceris Races 0 and 5 on Development of Fusarium Wilt in Chickpea Cultivars

2007 ◽  
Vol 97 (5) ◽  
pp. 564-573 ◽  
Author(s):  
Juan A. Navas-Cortés ◽  
Blanca B. Landa ◽  
Miguel A. Méndez-Rodríguez ◽  
Rafael M. Jiménez-Díaz
Keyword(s):  
Soil Temperature ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Beta Function ◽  
Geographical Area ◽  
Intrinsic Rate ◽  
Inoculum Density ◽  
Weibull Function ◽  
Disease Development ◽  
Response Variables

Races 0 (Foc-0) and 5 (Foc-5) of Fusarium oxysporum f. sp. ciceris differ in virulence and induce yellowing or wilting syndrome, respectively, in chickpea. We modeled the combined effects of soil temperature and inoculum density of Foc-0 and Foc-5 on disease developed in chickpea cvs. P-2245 and PV-61 differing in susceptibility to those races, using quantitative nonlinear models. Disease development over time in the temperature range of 10 to 30°C and inoculum densities between 6 and 8,000 chlamydospores g−1 of soil was described by the Weibull function. Four response variables (the reciprocal incubation period, the final disease intensity, the standardized area under the disease progress curve, and the intrinsic rate of disease development) characterized the disease development. Response surface models that expressed the combined effect of inoculum density and temperature were developed by substituting the intrinsic rate of disease development in the Weibull or exponential functions with a beta function describing the relationship of response variables to temperature. The models estimated 22 to 26°C as the most favorable soil temperature for infection of cvs. P-2245 and PV-61 by Foc-5, and 24 to 28°C for infection of cv. P-2245 by Foc-0. At 10°C, no disease developed except in cv. P-2245 inoculated with Foc-5. At optimum soil temperature, maximum disease intensity developed with Foc-5 and Foc-0 at 6 and 50 chlamydospores g−1 of soil respectively, in cv. P-2245, and with Foc-5 at 1,000 chlamydospores g−1 of soil in cv. PV-61. The models were used to construct risk threshold charts that can be used to estimate the potential risk of Fusarium wilt epidemics in a geographical area based on soil temperature, the race and inoculum density in soil, and the level of susceptibility of the chickpea cultivar.

scholarly journals The Core Mouse Response to Infection by Neospora Caninum Defined by Gene Set Enrichment Analyses

2012 ◽  
Vol 6 ◽  
pp. BBI.S9954 ◽  
Author(s):  
John Ellis ◽  
Stephen Goodswen ◽  
Paul J Kennedy ◽  
Stephen Bush
Keyword(s):  
Microarray Data ◽  
Post Infection ◽  
Transcription Initiation ◽  
Neospora Caninum ◽  
Protein Kinase Activity ◽  
Gene Set Enrichment ◽  
Gene Set ◽  
The Core ◽  
Time Post Infection ◽  
Mouse Response

In this study, the BALB/c and Qs mouse responses to infection by the parasite Neospora caninum were investigated in order to identify host response mechanisms. Investigation was done using gene set (enrichment) analyses of microarray data. GSEA, MANOVA, Romer, subGSE and SAM-GS were used to study the contrasts Neospora strain type, Mouse type (BALB/c and Qs) and time post infection (6 hours post infection and 10 days post infection). The analyses show that the major signal in the core mouse response to infection is from time post infection and can be defined by gene ontology terms Protein Kinase Activity, Cell Proliferation and Transcription Initiation. Several terms linked to signaling, morphogenesis, response and fat metabolism were also identified. At 10 days post infection, genes associated with fatty acid metabolism were identified as up regulated in expression. The value of gene set (enrichment) analyses in the analysis of microarray data is discussed.

scholarly journals Assessing the Role of Temperature, Inoculum Density, and Wounding on Disease Progression of the Fungal Pathogen Ceratocystis fimbriata Causing Black Rot in Sweetpotato

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 930-937 ◽  
Author(s):  
M. Stahr ◽  
L. M. Quesada-Ocampo
Keyword(s):  
Disease Management ◽  
Disease Incidence ◽  
Management Strategies ◽  
The United States ◽  
Storage Conditions ◽  
Inoculum Density ◽  
Separate Experiment ◽  
Black Rot ◽  
Disease Development ◽  
Ceratocystis Fimbriata

In 2014, Ceratocystis fimbriata, causal agent of black rot in sweetpotato, reemerged and inflicted large financial losses on growers in the United States. Black rot continues to damage sweetpotatoes and has become a priority to the industry since then. In contrast, little is known about the biology of C. fimbriata and the epidemiology of sweetpotato black rot. In this study, effects of environmental factors such as inoculum density, RH, and temperature on sweetpotato black rot were determined. Cured sweetpotatoes were wounded with a toothpick to simulate puncture wounds, inoculated with different spore suspensions (inoculum density) (104, 105, or 106 spores/ml), and incubated under different RH (85.53, 94.09, or 97.01%) and temperature (13, 18, 23, 29, or 35°C) for 21 days. In a separate experiment, five root wounding types (cuts, punctures, abrasions, end breaks, and macerating bruises) were compared. All wounded roots were subsequently soaked in a 103 spores/ml suspension and incubated at 100% RH and 23°C for 21 days. This study found 29 and 23°C to be the optimal temperature for black rot disease development and sporulation, respectively. No pathogen growth was observed at 13 and 35°C. Increased inoculum density significantly (P < 0.0001) increased disease incidence, but increasing RH had an effect only on sporulation area. All wound types resulted in increased disease incidence and sporulation as early as 7 days postinoculation. Our results highlight the importance of characterizing factors that affect disease development for achieving successful disease management strategies. Findings from this study will be used to improve disease management for sweetpotato black rot by suggesting tighter regulation of curing and storage conditions and better postharvest handling of sweetpotato roots to avoid unnecessary wounding.

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