Survival of Sclerotia of Rhizoctonia solani AG3PT and Effect of Soil-Borne Inoculum Density on Disease Development on Potato

2012 ◽  
Vol 161 (3) ◽  
pp. 180-189 ◽  
Author(s):  
Faye Ritchie ◽  
Ruairidh Bain ◽  
Mark Mcquilken
Keyword(s):  
Rhizoctonia Solani ◽  
Inoculum Density ◽  
Disease Development

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

Effect of inoculum density and quantitative PCR-based detection of Rhizoctonia solani AG-2-1 and Fusarium avenaceum on canola

2014 ◽  
Vol 59 ◽  
pp. 71-77 ◽  
Author(s):  
Qixing Zhou ◽  
Yongyan Chen ◽  
Yalong Yang ◽  
Hafiz U. Ahmed ◽  
Sheau-Fang Hwang ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Quantitative Pcr ◽  
Inoculum Density ◽  
Fusarium Avenaceum

Relationship of Rhizoctonia solani inoculum density to incidence of hypocotyl rot and damping-off in dry beans

1989 ◽  
Vol 35 (12) ◽  
pp. 1132-1140 ◽  
Author(s):  
A. J. L. Phillips
Keyword(s):  
Phaseolus Vulgaris ◽  
Linear Regression ◽  
Rhizoctonia Solani ◽  
Disease Incidence ◽  
Inoculum Density ◽  
Damping Off ◽  
Dry Beans ◽  
Site Model ◽  
Relationship Of

The effect of inoculum density on preemergence disease incidence was described by linear regression. Variations in virulence among 10 isolates formed a continuum. The effect of inoculum density on hypocotyl disease incidence was described by a limiting site model and variations in virulence among the isolates also formed a continuum. The ability of an isolate to cause preemergence disease was not necessarily related to its ability to cause hypocotyl disease. Both saprophytic colonization and preemergence infection arose from propagules in the spermosphere, while depending on the isolate, infection of hypocotyls was from propagules in either the rhizosphere or the rhizoplane. The observed number of hypocotyl lesions was greater than that estimated from the percentage of plants infected. This effect was more pronounced when seeds were sown at 4 than at 1 cm depth.Key words: beans, epidemiology, Phaseolus vulgaris, Rhizoctonia solani.

scholarly journals Cutinase and Other Lipolytic Esterases Protect Bean Leaves from Infection by Rhizoctonia solani

1998 ◽  
Vol 11 (6) ◽  
pp. 514-522 ◽  
Author(s):  
Diana M. Parker ◽  
Wolfram Köller
Keyword(s):  
Rhizoctonia Solani ◽  
Esterase Activity ◽  
Venturia Inaequalis ◽  
Protective Mechanism ◽  
Disease Development ◽  
Mechanical Wounding ◽  
Small Areas ◽  
Pathogenesis Related ◽  
Web Blight ◽  
Bean Leaves

The results describe a novel activity of fungal cutinase, the protection of bean leaves from disease. Development of web blight symptoms on bean leaves infected with Rhizoctonia solani (AG-1) was prevented in the presence of cutinase purified from Venturia inaequalis. Instead of disease, small areas of tissue necrosis became visible, and the tissue in which the pathogen was restricted displayed strong autofluorescence beneath the inoculation sites. Mechanical wounding of the leaf surface had no effect on disease development and the permeability of the cuticle was not increased by cutinase action, indicating that surface wounding was not the cause for this novel activity of cutinase. A comparative study involving cutinase and other serine hydrolases revealed that the disease prevention resided in the lipolytic esterase activity rather than the cutinase activity. The pattern of expression of four pathogenesis-related (PR) protein genes provided no evidence for the modulation of known resistance responses of bean leaves in response to cutinase action. The protective mechanism of the esterase activity remains unknown.

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 Effect of Air and Growing Medium Temperatures on Rhizoctonia Foot Rot of Epipremnum aureum

1990 ◽  
Vol 8 (3) ◽  
pp. 139-141
Author(s):  
A.R. Chase ◽  
R.T. Poole
Keyword(s):  
Rhizoctonia Solani ◽  
Fungal Pathogen ◽  
Disease Development ◽  
Foot Rot ◽  
Growth Reduction ◽  
Growing Medium ◽  
Epipremnum Aureum ◽  
Significant Disease ◽  
Continuous Temperature

Abstract Air and growing medium temperatures affected severity of foot rot of Epipremnum aureum (pothos) caused by Rhizoctonia solani AG4. Maximum daily temperatures of 30°C (86°F) for either air or soil resulted in optimal disease development. Maximum daily temperatures of 35°C (95°F) decreased disease development significantly due to fungal pathogen growth reduction. A continuous temperature of 30°C (86°F) was also too high for significant disease development.

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.

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