Relative humidity and wind velocity associated with diurnal rhythmicity of aerial dispersal ofPuccinia arachidis urediniospores

Relatieve luchtvochtigheid en windsnelheid en het dagelijks ritme in de verspreiding van urediniosporen van Puccinia arachidis

  • S. Savary
Article

Abstract

Four groundnut plots were inoculated withPuccinia arachidis during the growing season 1984 in Adiopodoumé (Ivory Coast). Rust intensity assessments and spore trappings were performed during the development of the resulting epidemics. Spore density in the air at canopy height ranged from 0 to 800 spores m−3. A significant linear regression was found of the logit of the relative air spore content on the logit of rust intensity expressed as the number of lesions m−2 of field. During the first sporulation wave following inoculation, the spore density in the air and the spore content of the pustules were determined at regular intervals. These data were related to weather parameters measured simultaneously. The spore content of the air ranged from 0 to 20 spores m−3. A pronounced daily rhythmicity was found in the spore density of the air, related to a daily rhythm in the depletion and repletion of uredinia. The major explanatory variable was relative humidity, a secondary was wind velocity. The hypothesis is made that this periodicity affects the whole range of variation of aerial spore densities measured at different rust intensities.

Samenvatting

Vier veldjes met aardnoten in Adiopodoumé (Ivoorkust) werden in het groeiseizoen kunstmatig besmet metPuccinia arachidis. Gedurende het verloop van de daaropvolgende epidemie werd de mate van aantasting door roest bepaald en werden de gevangen sporen geteld. De sporendichtheid op gewashoogte varieerde van 0–800 sporen m−3. Een significante lineaire regressie tussen de sporendichtheid en de roest-aantasting (uitgedrukt in het aantal lesies m−2) kon worden vastgesteld na logit transformaties van de relatieve aantallen. Gedurende de eerste sporulatiegolf na de inoculatie werden de sporedichtheid in de lucht en de hoeveelheid sporen in de sporenhoopjes periodiek bepaald. De hoeveelheid sporen in de lucht varieerde van 0 tot 20 sporen m−3. Er werd een duidelijke dagelijkse ritmiek van de sporendichtheid in de lucht gevonden. Deze hield verband met het dagelijks ritme in het verlies en de aanwas van sporen in de sporenhoopjes. De belangrijkste verklarende factor was de relatieve luchtvochtigheid, gevolgd door de windsnelheid. Er wordt verondersteld dat de gevonden periodiciteit geldt voor de gehele variatiebreedte aan sporendichtheid, bepaald bij verschillende niveaus van roestaantasting.

Additional keywords

epidemiology groundnut rust weather 

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Copyright information

© Koninklijke Nederlandse Planteziektenkundige Vereniging 1986

Authors and Affiliations

  • S. Savary
    • 1
  1. 1.Laboratoire de Phytopathologie, ORSTOMInstitut Français de Recherche Scientifique pour le Développement en Coopération, Centre d'AdiopodouméAbidjanIvory Coast

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