scholarly journals Factors Affecting Concentrations of Airborne Conidia of Oidium sp. Among Poinsettias in a Greenhouse

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1089-1095 ◽  
Author(s):  
J. M. Byrne ◽  
M. K. Hausbeck ◽  
B. D. Shaw
Keyword(s):  
Relative Humidity ◽  
Rapid Decrease ◽  
Disease Development ◽  
Factors Affecting ◽  
Influence Of Temperature ◽  
Large Numbers ◽  
Airborne Conidia ◽  
Influence Of Temperature On ◽  
Atmospheric Concentrations

Atmospheric concentrations of Oidium sp. conidia in two research greenhouses containing infected poinsettias were monitored to investigate the role of environment in prompting conidial release and dissemination. Hourly concentrations of conidia of Oidium sp. were estimated using a Burkard volumetric spore sampler. The influence of temperature on disease development was studied by placing healthy poinsettias in each greenhouse for 7-day periods, removing them, and recording the days to the appearance of the first colony. When averaged over 5 December to 1 June, atmospheric conidial concentrations in greenhouse (GH) 2 were greatest during 1000 to 1800 hours with a peak (325 conidia/m3/h) occurring at 1200 hours. In GH 11, peak concentrations occurred at 1300 hours (65 conidia/m3/h) and 1600 hours (75 conidia/m3/h). Large numbers of conidia were sampled (≥100/m3) within 1-h periods, indicating conidial release events (CREs). Fluctuations in relative humidity (RH) (either positive or negative) prompted CREs. In both greenhouses, the highest number of CREs (up to 23) occurred following RH fluctuations of 5 to 15%. Watering resulted in an immediate increase (≤25%) followed by a rapid decrease in RH (≤32%) beginning 1 to 2 h later. In GH 2 and GH 11, 89 and 48%, respectively, of the CREs occurred within 3 h following greenhouse watering. When greenhouse temperatures exceeded 25°C for 21 days in May (GH 2) and 19 days in March (GH 11), atmospheric conidial concentrations were reduced 80 and 75% from the previous months, respectively.

STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. & B.

1956 ◽  
Vol 34 (4) ◽  
pp. 653-673 ◽  
Author(s):  
R. A. Ludwig ◽  
R. V. Clark ◽  
J. B. Julien ◽  
D. B. Robinson
Keyword(s):  
Disease Incidence ◽  
Infested Soil ◽  
Disease Development ◽  
Toxic Activity ◽  
Factors Affecting ◽  
Seedling Disease ◽  
Nutrient Salt ◽  
Helminthosporium Sativum ◽  
Treatment Comparisons

A standard sand – cornmeal – nutrient salt medium, for use in the production of artificial inoculum of Helminthosporium sativum, is described. This inoculum induces uniform plant disease development when thoroughly incorporated with the planting soil. The results presented clearly demonstrate the necessity of using a series of infestation levels in studies of factors affecting disease development in artificially infested soil. It is shown that considerable reliance can be placed on treatment comparisons within an experiment but that comparisons between experiments are much less accurate. The role of a toxin (or toxins) in disease development in barley seedlings has been demonstrated. The toxic activity was found to be distinct from that frequently encountered on addition of organic matter to soil. Results obtained suggest that toxin adsorption by the soil may play an important role in reducing disease incidence and severity.

PHYSIOLOGIC SPECIALIZATION OF OAT STEM RUST IN CANADA

1944 ◽  
Vol 22c (5) ◽  
pp. 201-216 ◽  
Author(s):  
Margaret Newton ◽  
T. Johnson
Keyword(s):  
Stem Rust ◽  
Wide Distribution ◽  
Puccinia Graminis ◽  
Characteristic Type ◽  
Influence Of Temperature ◽  
Physiologic Specialization ◽  
Influence Of Temperature On ◽  
Physiologic Races

An account is given of the results of studies on the physiologic specialization of Puccinia graminis Avenae Erikss. and Henn. in Canada since the inception of the work. Twelve physiologic races were identified from 2586 isolates studied during the period 1921 to 1943. The annual surveys of the prevalence of physiologic races during this period show that each year races 1, 2, and 5 have comprised the bulk of the oat stem rust in all parts of Canada. The predominance of these races has been greatest in the three Prairie Provinces, where barberry is virtually non-existent. In regions where barberry is present, other races of greater range of pathogenicity have been found more frequently than in these three provinces. The occurrence of such races, however, was sporadic until 1943, in which year races 8, 10, and 11 attained a wide distribution, apparently traceable to wind-borne urediospores from the south. There is evidence that the strains of these races present in 1943 remain in the uredial stage for much longer periods than do strains of the same races collected in previous years—a fact that may have favoured their spread in this year.The role of barberry in the origination of generally virulent physiologic races is discussed. The possibility that such races may also originate by mutation is suggested by spontaneous pathogenic changes that occurred, in the greenhouse, in a culture of race 3 that gave rise to several cultures of race 7.The effect of environment on the identification of physiologic races is demonstrated by the seasonal influences on the reaction of the variety Sevnothree to races 1 and 11. On this variety the characteristic type 1 is frequently replaced, in summer, by type x.Experiments on the influence of temperature on the reaction of adult oat plants to stem rust showed that a constant temperature of about 80° F. does not appreciably affect the reaction of White Tartar and Richland, or of other varieties with the same type of resistance, but is capable of breaking down the resistance of certain varieties derived from the crosses Hajira × Joanette, Hajira × Banner, and Victoria × (Hajira × Banner).

scholarly journals Role of some Factors Affecting Crown Gall Disease Development

2011 ◽  
Vol 39 (1) ◽  
pp. 89-108
Author(s):  
Farouk Barakat ◽  
Maurice Mikhail ◽  
Aly Tawfik ◽  
Rabab Abd-El-Aziz
Keyword(s):  
Crown Gall ◽  
Disease Development ◽  
Factors Affecting ◽  
Crown Gall Disease

COLOUR OF MEAT: II. EFFECT OF DESICCATION ON THE COLOUR OF CURED PORK

1939 ◽  
Vol 17d (2) ◽  
pp. 29-34 ◽  
Author(s):  
C. A. Winkler
Keyword(s):  
Relative Humidity ◽  
Colour Change ◽  
Storage Period ◽  
Moisture Loss ◽  
Influence Of Temperature ◽  
Dry Air ◽  
Intensity Changes ◽  
Influence Of Temperature On

In the absence of air, a linear relation, independent of temperature, was observed between moisture loss and colour change. The change was mainly one of intensity, and was reversible. In air, irrespective of its humidity, changes in both intensity and quality of colour occurred, but no definite relation was found between changes in humidity and colour quality for different samples. In saturated air, intensity changes became complete in the early part of the storage period, but the enhanced changes in air of lower humidity continued to increase. No influence of temperature on the rate of colour change was observed in dry air or in air of 60% relative humidity.

Evaluation of the combined temperature and relative humidity preferences of the Colombian terrestrial salamander Bolitoglossa ramosi (Amphibia: Plethodontidae)

2018 ◽  
Vol 96 (11) ◽  
pp. 1230-1235 ◽  
Author(s):  
C.A. Galindo ◽  
E.X. Cruz ◽  
M.H. Bernal
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Low Temperatures ◽  
Environmental Temperature ◽  
Critical Factors ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Thermal Preferences ◽  
Cutaneous Respiration ◽  
Field Location

Temperature and humidity are critical factors for terrestrial lungless salamanders, as their body temperatures are largely determined by the environmental temperature and require moisture to sustain cutaneous respiration. Herein, we evaluated the preference of Bolitoglossa ramosi Brame and Wake, 1972 between a high temperature and a high relative humidity (RH), the influence of temperature on RH preferences, and the influence of RH on the thermal preferences. This study was performed in a field location in the municipality of Líbano, Tolima, Colombia. There, on different nights, we collected 84 adult B. ramosi and carried out the preference experiments, using aluminum troughs with different thermal and RH gradients. We found that between high temperature and high RH, B. ramosi preferred high RH. However, B. ramosi selected high temperatures when the gradient had a high RH and low temperatures when the gradient had a low RH. These results show that B. ramosi is able to thermoregulate and hydroregulate. Nevertheless, hydroregulation seems to be more important than thermoregulation because B. ramosi always selected the high RH gradients, while their thermal selection relied on the hydric environment.

Thermal luminescence quenching of amine-functionalized silicon quantum dots: a pH and wavelength-dependent study

2015 ◽  
Vol 17 (37) ◽  
pp. 24078-24085 ◽  
Author(s):  
Surajit Chatterjee ◽  
Tushar Kanti Mukherjee
Keyword(s):  
Quantum Dots ◽  
Luminescence Quenching ◽  
Excitation Wavelength ◽  
Silicon Quantum Dots ◽  
Influence Of Temperature ◽  
Amine Functionalized ◽  
Influence Of Temperature On ◽  
Amine Groups

The influence of temperature on the PL properties of silicon quantum dots (Si QDs) as a function of pH and excitation wavelength has been investigated to understand the role of surface amine groups and the bandgap of allylamine-capped Si QDs.

Influence of temperature on sorption of europium onto smectite: The role of organic contaminants

2005 ◽  
Vol 30 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. Bauer ◽  
T. Rabung ◽  
F. Claret ◽  
T. Schäfer ◽  
G. Buckau ◽  
...  
Keyword(s):  
Organic Contaminants ◽  
Influence Of Temperature ◽  
Influence Of Temperature On

scholarly journals Influence of Temperature, Relative Humidity, Ascospore Concentration, and Length of Drying of Colonized Dry Bean Flowers on White Mold Development

Plant Disease ◽  
2006 ◽  
Vol 90 (7) ◽  
pp. 946-950 ◽  
Author(s):  
R. Harikrishnan ◽  
L. E. del Río
Keyword(s):  
Relative Humidity ◽  
Linear Increase ◽  
White Mold ◽  
Post Inoculation ◽  
Disease Development ◽  
Dry Bean ◽  
Influence Of Temperature ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Inoculum Type

Growth chamber studies were conducted using rehydrated dry bean (Phaseolus vulgaris) flowers (RDBF) to assess the influence of temperature (18 and 22°C), relative humidity (RH; 25 and 90%), and ascospore concentrations (102, 103, and 104 ascospores/ml) on white mold incidence in dry bean. Additional studies were carried out to determine the influence of inoculum type (ascospore and mycelium) and to estimate the effect of duration of drying of colonized RDBF on viability of Sclerotinia sclerotiorum and white mold incidence. There was a linear increase in white mold incidence with increase in ascospore concentration but neither temperature nor RH levels significantly affected disease development. In the inoculum type study, both temperature and RH levels significantly affected white mold incidence; however, neither ascospore nor mycelial inocula had a significant effect on white mold incidence. Drying colonized RDBF for up to 96 h did not affect S. sclerotiorum viability; but the amount of white mold incidence depended more on post-inoculation RH and drying duration than on the temperatures tested. Colonized RDBF dried for 96 h took approximately three times longer to achieve 100% white mold incidence compared with colonized RDBF dried for 24 h. These results suggest the potential for greater white mold development with higher ascospore availability and the potential of dry S. sclerotiorum-colonized dry bean flowers as a viable inoculum source.

Sign in / Sign up

Export Citation Format

Share Document