Etiology of Parsley Damping-off and Influence of Temperature on Disease Development

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.

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Influence of Temperature on Phymatotrichum Sclerotial Formation and Disease Development

Phytopathology ◽

10.1094/phyto-61-728 ◽

1971 ◽

Vol 61 (6) ◽

pp. 728 ◽

Cited By ~ 7

Author(s):

Stuart D. Lyda

Keyword(s):

Disease Development ◽

Influence Of Temperature ◽

Sclerotial Formation ◽

Influence Of Temperature On

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The effect of temperature on high-resolution TEM image contrast

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139573 ◽

1995 ◽

Vol 53 ◽

pp. 640-641

Author(s):

T. Geipel ◽

W. Mader ◽

P. Pirouz

Keyword(s):

Form Factor ◽

Inelastic Scattering ◽

Accurate Method ◽

Waller Factor ◽

Effect Of Temperature ◽

Specimen Thickness ◽

Influence Of Temperature ◽

Debye Waller Factor ◽

Influence Of Temperature On ◽

Atomic Form Factor

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

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