Plant Disease (2005) 89, 1060-1066

J.M. Byrne, M.K. Hausbeck and L.E. Sconyers (2005)
Influence of environment on atmospheric concentrations of Peronospora antirrhini sporangia in field-grown snapdragon
Plant Disease 89 (10), 1060-1066
Abstract: Hourly concentrations of airborne sporangia of Peronospora antirrhini at a commercial snapdragon farm were investigated over three growing seasons to determine the influence of the environment on their occurrence and concentration. Hourly concentrations of sporangia of P. antirrhini were estimated using a Burkard volumetric spore sampler. Atmospheric sporangial concentrations followed a diurnal pattern and were greatest during 0500 to 1200 h. Minimum daily temperatures <10.0ºC appeared to have a moderate limiting effect on atmospheric sporangial concentrations, whereas temperatures <6.0ºC had more severe limiting effects. Maximum daily temperatures >30.0ºC limited concentrations of atmospheric sporangia. Long dew periods (>6 h) were associated with relatively large sporangia releases. On 69 days (1999 to 2001), the total number of sporangia trapped was >100/m³/day, and the average length of leaf wetness duration prior to these releases was 11 h. Consecutive days with short leaf wetness periods were associated with low atmospheric sporangial concentrations. Significant positive correlations (P = 0.0502 and P = 0.0174) were found between total rainfall and total spore count for both research plots in 2000. Information gained from this study will contribute to the development of a disease management program that utilizes environmental cues to prompt fungicide applications, thus increasing the efficiency of fungicide programs and delaying the development of pathogen resistance.
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Database assignments for author(s): Mary K. Hausbeck

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Peronospora antirrhini	Antirrhinum (crop)