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  • 1
    Electronic Resource
    Electronic Resource
    Single-plant chambers to control humidity for pathological studies (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 44 (1995), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The construction of a set of controlled-humidity chambers for single plants is described. Accurate control of relative humidity (r.h.) between 40% and 99% was achieved by mixing dry air with a saturated air stream using solenoid valves controlled by a programmable data logger. At values of r.h. 〉90%, mean values over periods greater than 1 min were constant to within ±0·1% and spot measurements at 3 s intervals were within 0-3% of the mean value. The system responded to a step change of r.h. in about 6-10 min and diurnal changes of r.h. were reproduced, similar to those observed in nature. The stability of control made it possible to differentiate between the requirement of liquid water and very high humidity (98% r.h.) for conidial germination and subsequent infection of groundnut by Phaeoisariopsis personata, the cause of late leaf spot disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1995.tb02710.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Witches' broom disease on cocoa in Rondonia, Brazil: pod infection in relation to pod susceptibility, wetness, inoculum, and phytosanitation (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 36 (1987), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Infection of cocoa pods by Crinipellis perniciosa was examined in the field in relation to pod susceptibility and variations in inoculum and climate over 2 years. The disease was incubated for 13 or 14 weeks in pods inoculated when 2 and 4 weeks old, and for 12 weeks in pods inoculated 6-12 weeks old. Pods were uniformly susceptible to natural infection during the 12 weeks after pollination. Over 75% of rain showers started between 12.00 and 02.00 h, providing sufficient water to rehydrate basidiocarps as well as to wet pods. Pods remained wet after rainfall for decreasing periods when rain occurred after 13.00 h. Incidence of pod disease was shown to be related to the number of wetness periods longer than 4 h, and to the number of open turgid basidiocarps occurring 12 weeks earlier. Wetness periods had a greater influence on disease. Pod infection was modelled by assuming that infection was limited by either wetness periods or turgid basidiocarp numbers; critical numbers of wetness periods when both factors were of equal weight were defined by an exponential equation. The model was used to predict reductions in pod disease associated with different amounts of broom removal in each year.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1987.tb02268.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Respiration rates of apple trees, estimated by CO2-efflux measurements (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Measurements of the efflux of CO2 from 5–6 year old container grown apple trees, in the dark at a range of temperatures (T), indicated that respiration rate (R) can be described by the equation R = SL e kT. The temperature coefficient k, was the same at all times of the year and for all components of the trees, but the values of a varied. At the same temperature respiration rates were low when the trees were dormant, rose rapidly to a peak in spring (before full bloom) and then declined steadily through the season. When respiration was expressed as a flux density, rates for different components of the tree were usually similar. Differences were sometimes statistically significant but no clear pattern emerged. The results obtained are similar to those published for other plants and the equation can be used in the calculation of the carbon balance of apple trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1981.tb01037.x
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  • 4
    Electronic Resource
    Electronic Resource
    Stomatal response to humidity: implications for transpiration (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Transpiration rates from apple leaves are analysed in terms of the ratio of latent heat flux (λE) to leaf net radiation (Q1) and the climatological resistance (ri). Increases in stomatal resistance with increasing leaf to air vapour pressure gradient (D), described by an empirical model, are incorporated in the analysis. This humidity effect causes the proportion of energy dissipated as latent heat to fall as Q1 increases, so that leaf transpiration rates in high energy environments are likely to be similar to those in lower energy environments. Boundary layer resistance (ra) exerts an increasingly important effect on transpiration rates as Q1 increases. At constant Q1 stomatal closure in response to increasing D results in very small changes in leaf temperature (T1) across a wide range of ambient vapour pressure deficits (δe); ra is then the major factor determining T1. The implications of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11580512
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  • 5
    Electronic Resource
    Electronic Resource
    CEREAL DISEASES. THEIR PATHOLOGY AND CONTROL (Book). (1984)
    Oxford, UK : Blackwell Publishing
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11616257
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  • 6
    Electronic Resource
    Electronic Resource
    A model of drop size distribution for a system with evaporation (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 8 (1985), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The size and shape of drops on leaf surfaces strongly affect their persistence. The relationship between volume and exposed surface area of drops on wheat leaves and the log-normal drop size distribution in a wheat canopy after rain are used to derive equations to describe how the total volume and drop number change with evaporation. Firstly, the behaviour of a single drop as it evaporates is considered and then equations describing the change in a population of drops with an initial log-normal distribution are derived. The time taken for all the drops to reach complete dryness is about thirty times that for the same volume of water spread uniformly over the surface with the same potential evaporation rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11604646
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  • 7
    Electronic Resource
    Electronic Resource
    Relationships between temperature and latent periods of rust and leaf-spot diseases of groundnut (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 43 (1994), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effect of temperature on the latent periods of rust, late leaf spot and early leaf spot diseases of groundnut caused by Puccinia arachidis, Phaeoisariopsis personata and Cercospora arachidicola, respectively, was studied. The latent periods (LP) of rust, late leaf spot and early leaf spot ranged from 12–49 days, 13–38 days and 13–39 days, respectively, between 12°C and 33°C An equation relating the rate of pathogen development (1/LP) to temperature was fitted using daily mean temperatures to provide three cardinal temperatures: the minimum (Tmln), optimum (Topl), and maximum (Tmax), Tmln was about 12°C for rust and about 10°C for the two leaf-spot diseases. Topt, for all three diseases was close to 25°C. Tmax was 31°C for early leaf spot, and extrapolated values for late leaf spot and rust were about 35 and 40°C, respectively.For P. personata, a temperature response curve was fitted using data only from controlled environment experiments. This curve was used to simulate latent periods from both mean daily and mean hourly temperatures in the field. There was substantially better agreement between observed and simulated latent period with hourly temperatures, provided the developmental rate of the pathogen was determined at a constant temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1994.tb00561.x
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  • 8
    Electronic Resource
    Electronic Resource
    Requirements of leaf wetness and temperature for infection of groundnut by rust (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 40 (1991), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Experiments are described to quantify the effects of temperature and duration of leaf wetness on infection of groundnut by Puccinia arachidis. After inoculation, a minimum period of leaf wetness, m. was necessary for infection. When leaf wetness duration was greater than m, lesion density increased with increasing wetness duration to an asymptote, Dmax. The principal effects of temperature were on m and Dmax- The value of m decreased linearly from 6 h, as temperature increased from 15 to 25 C and increased slightly at temperatures greater than 25 C Dmax increased with temperature from zero at 8 C to a maximum at 22 C. and decreased to zero again at about 30 C. The experimental results were used to produce a set of curves relating an infection index to leaf wetness duration at different temperatures. The implications for infection of groundnut crops are discussed in relation to the climate at Patancheru in southern India.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1991.tb02396.x
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of leaf wetness duration, relative humidity, light and dark on infection and sporulation by Didymella rabiei on chickpea (1998)
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Plant pathology 47 (1998), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: No infection occurred at less than 95% relative humidity (r.h.) when chickpea plants were dried after inoculation with conidia of Didymella rabiei. Infection was significant when the dry leaves were exposed to 98% r.h. for 48 h. When inoculated plants were subjected to different leaf wetness periods, some infection occurred with 4 h wetness, and disease severity increased with wetness duration according to an exponential asymptote, with a maximum value after about 18 h. Germination of conidia and germ tube penetration increased linearly with increasing wetness periods when recorded 42 h after inoculation. With a 24-h wetness period, germination of conidia was first observed 12 h after inoculation and increased linearly with time up to 52 h (end of the experiment). Dry periods immediately after inoculation, followed by 24-h leaf wetness, reduced disease severity; as the dry period increased the severity decreased. Disease severity increased with increasing periods of darkness after inoculation. The number of pycnidia and the production of conidia on infected leaves increased only slightly with high r.h. (either in the light or in the dark), but large increases occurred over an 8-day period when the leaves were kept wet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3059.1998.0280a.x
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  • 10
    Electronic Resource
    Electronic Resource
    Infection efficiency of Phaeoisariopsis personata and the influence of different wetness patterns on germ-tube growth of the pathogen (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 43 (1994), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Controlled environment studies with Phaeoisariopsis personata, the causal agent of late leaf spot disease of groundnut (Arachis hypogaea), have shown that infection is enhanced if leaves are exposed to alternate wet and dry periods (intermittent wetness) compared with continuous wetness. Detailed investigations to elucidate this phenomenon revealed more germ tubes per conidium and more branching of germ tubes with intermittent wetness than with continuous wetness. With intermittent wetness there was clear evidence of tropic growth of germ tubes and branches towards stomata and subsequent penetration. With continuous wetness, germ tube growth did not appear to be directional and germ tubes commonly passed over the stomatal guard cells, therefore leading to relatively few stomatal penetrations. For both wetness regimes, stomatal penetrations continued to increase with increased leaf wetness for at least 6 days after inoculation and there was a linear relationship between the number of stomatal penetrations and the number of resultant lesions. Infection efficiency was markedly increased when the spore load was reduced to 0.1 conidia per cm2 (about one spore per leaflet).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1994.tb01624.x
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